Patent Grant
11884949
The present disclosure provides methods for the production of diverse benzylisoquinoline alkaloids (BIAs) in engineered host cells. The present disclosure further provides compositions of diverse alkaloids produced in engineered host cells. Additionally, the present disclosure provides methods for the production of a thebaine synthase in engineered host cells. In particular cases, the disclosure provides methods for producing diverse alkaloid products through the conversion of a promorphinan alkaloid into a morphinan alkaloid in an engineered host cell. In further particular cases, the present disclosure provides methods for producing diverse alkaloid products through the conversion of salutaridinol-7-O-acetate to thebaine.
An aspect of the invention provides an engineered non-plant cell having increased tyrosine hydroxylase activity relative to a non-engineered cell. Another aspect of the invention provides an engineered non-plant cell having increased tyrosine hydroxylase activity relative to a cell that expresses wild-type TyrH. An additional aspect of the invention provides an engineered non-plant cell having increased tyrosine hydroxylase activity relative to a cell that expresses wild-type TyrH without mutations that increase tyrosine hydroxylase activity as provided herein. In particular, the engineered non-plant cell has at least one modification selected from a group consisting of: a substrate inhibition alleviating mutation; a product inhibition alleviating mutation; and a cofactor recovery promoting mechanism.
An aspect of the invention provides an engineered plant cell having increased tyrosine hydroxylase activity relative to a non-engineered cell. Another aspect of the invention provides an engineered plant cell having increased tyrosine hydroxylase (TyrH) activity relative to a cell that expresses wild-type TyrH. An additional aspect of the invention provides an engineered plant cell having increased tyrosine hydroxylase activity relative to a cell that expresses wild-type TyrH without mutations that increase tyrosine hydroxylase activity as provided herein. In particular, the engineered plant cell has at least one modification selected from a group consisting of: a substrate inhibition alleviating mutation; a product inhibition alleviating mutation; and a cofactor recovery promoting mechanism.
In some embodiments, the disclosure provides methods for increasing production of diverse alkaloid products through the epimerization of a (S)-1-benzylisoquinoline alkaloid to a (R)-1-benyzlisoquinoline alkaloid via engineered epimerases in an engineered host cell. In further embodiments, the present disclosure provides methods for increasing production of diverse alkaloid products through the epimerization of (S)-reticuline to (R)-reticuline via an engineered epimerase comprising two separate enzymes encoding an oxidase and a reductase compared to the production of diverse alkaloid products through the epimerization of (S)-reticuline to (R)-reticuline via a wild-type epimerase.
While engineered split epimerases may be composed of a separate oxidase enzyme and reductase enzyme that originate from a parent or wild-type epimerase, engineered epimerases may also comprise a separate oxidase enzyme and reductase enzyme that originate from separate parent or wild-type epimerases. Examples of parent epimerases having an oxidase and reductase component comprise amino acid sequences selected from the group consisting of: SEQ ID NOs: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, and 16, as listed in Table 1.
In some embodiments, the disclosure provides methods for increasing production of diverse alkaloid products through the conversion of a promorphinan alkaloid to a morphinan alkaloid via thebaine synthases in an engineered host cell. In further embodiments, the present disclosure provides methods for increasing production of diverse alkaloid products through the conversion of salutaridinol-7-O-acetate to thebaine via a thebaine synthase. Examples of parent thebaine synthases comprise amino acid sequences selected from the group consisting of: SEQ ID NOs: 30, 31, 32, 33, 34, 35, 36, and 37 as listed in Table 2.
In some embodiments, the disclosure provides methods for increasing production of diverse alkaloid products through the conversion of a promorphinan alkaloid to a morphinan alkaloid via engineered thebaine synthases in an engineered host cell. In further embodiments, the present disclosure provides methods for increasing production of diverse alkaloid products through the conversion of salutaridinol-7-O-acetate to thebaine via an engineered thebaine synthase.
In some embodiments, the engineered thebaine synthase is a fusion enzyme. In further embodiments, the thebaine synthase is fused to an acetyl transferase enzyme. In further embodiments, the thebaine synthase is encoded within an acetyl transferase enzyme. In other embodiments, the thebaine synthase is fused to a reductase enzyme.
In some examples, an engineered non-plant cell comprises a plurality of coding sequences each encoding an enzyme that is selected from the group of enzymes listed in Table 3. In some examples, the heterologous coding sequences may be operably connected. Heterologous coding sequences that are operably connected may be within the same pathway of producing a particular benzylisoquinoline alkaloid product via a thebaine synthase activity or an engineered thebaine synthase activity.
In some embodiments this disclosure provides a method of converting a tetracyclic promorphinan precursor to a thebaine, comprising contacting the tetracyclic promorphinan precursor with at least one enzyme, wherein contacting the tetracyclic promorphinan precursor with the at least one enzyme converts the tetracyclic promorphinan precursor to a thebaine. In some cases, the at least one enzyme is produced by culturing an engineered non-plant cell having a coding sequence for encoding the at least one enzyme. In some cases, the method further comprises adding a tetracyclic promorphinan precursor to the cell culture. In some cases, the method further comprises recovering the thebaine, or a derivative thereof, from the cell culture. In some cases, the at least one enzyme comprises a thebaine synthase. In some cases, the thebaine synthase comprises an amino acid sequence selected from the group consisting of: SEQ ID NOs: 30, 31, 32, 33, 34, 35, 36, and 37. In some cases, the thebaine synthase enzyme is a Bet v 1 fold protein.
All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference.
The novel features of the invention are set forth with particularity in the appended claims. A better understanding of the features and advantages of the invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings of which:
The present disclosure provides methods for the production of diverse benzylisoquinoline alkaloids (BIAS) in engineered host cells. The present disclosure further provides compositions of diverse alkaloids produced in engineered host cells. Additionally, the present disclosure provides methods for the production of a thebaine synthase in engineered host cells. Additionally, the present disclosure provides methods for the production of an engineered thebaine synthase in engineered host cells. In particular cases, the disclosure provides methods for producing promorphinan, morphinan, nal-opioid and nor-opioid alkaloid products through the increased conversion of a promorphinan alkaloid to a morphinan alkaloid in an engineered host cell. In further particular cases, the disclosure provides methods for producing morphinan, nal-opioid and nor-opioid alkaloid products through the increased conversion of a promorphinan alkaloid to a morphinan alkaloid in an engineered host cell. In further particular cases, the present disclosure provides methods for producing diverse alkaloid products through the increased conversion of a promorphinan alkaloid to a morphinan alkaloid.
Benzylisoquinoline Alkaloids (BIAs) of Interest
Host cells which produce BIAs of interest are provided. In some examples, engineered strains of host cells such as the engineered strains of embodiments discussed herein may provide a platform for producing benzylisoquinoline alkaloids of interest and modifications thereof across several structural classes including, but not limited to, precursor BIAs, benzylisoquinolines, promorphinans, morphinans, nal-opioids, nor-opioids, and others. Each of these classes may include biosynthetic precursors, intermediates, and metabolites thereof, of any convenient member of an engineered host cell biosynthetic pathway that may lead to a member of the class. Non-limiting examples of compounds are given below for each of these structural classes. In some cases, the structure of a given example may or may not be characterized itself as a benzylisoquinoline alkaloid. In some cases, the present chemical entities may include all possible isomers, including single enantiomers, racemic mixtures, optically pure forms, mixtures of diastereomers, and intermediate mixtures.
BIA precursors may include, but are not limited to, norcoclaurine (NC) and norlaudanosoline (NL), as well as NC and NL precursors, such as tyrosine, tyramine, 4-hydroxyphenylacetaldehyde (4-HPA), 4-hydroxyphenylpyruvic acid (4-HPPA), L-3,4-dihydroxyphenylalanine (L-DOPA), 3,4-dihydroxyphenylacetaldehyde (3,4-DHPA), and dopamine. In some embodiments, the one or more BIA precursors are 3,4-dihydroxyphenylacetaldehyde (3,4-DHPA) and dopamine. In certain instances, the one or more BIA precursors are 4-hydroxyphenylacetaldehyde (4-HPA) and dopamine. In particular, NL and NC may be synthesized, respectively, from precursor molecules via a Pictet-Spengler condensation reaction, where the reaction may occur spontaneously or may by catalyzed by any convenient enzymes.
Benzylisoquinolines may include, but are not limited to, norcoclaurine, norlaudanosoline, coclaurine, 3′-hydroxycoclaurine, 4′-O-methylnorlaudanosoline, 4′-O-methyl-laudanosoline, N-methylnorcoclaurine, laudanosoline, N-methylcoclaurine, 3′-hydroxy-N-methylcoclaurine, reticuline, norreticuline, papaverine, laudanine, laudanosine, tetrahydropapaverine, 1,2-dihydropapaverine, and orientaline.
Promorphinans may include, but are not limited to, salutaridine, salutaridinol, and salutaridinol-7-O-acetate.
Morphinans may include, but are not limited to, thebaine, codeinone, codeine, morphine, morphinone, oripavine, neopinone, neopine, neomorphine, hydrocodone, dihydrocodeine, 14-hydroxycodeinone, oxycodone, 14-hydroxycodeine, morphinone, hydromorphone, dihydromorphine, dihydroetorphine, ethylmorphine, etorphine, metopon, buprenorphine, pholcodine, heterocodeine, and oxymorphone. In particular, thebaine may be synthesized from salutaridinol-7-O-acetate, where the reaction may occur spontaneously or may be catalyzed by any convenient enzymes.
Nal-opioids may include, but are not limited to, naltrexone, naloxone, nalmefene, nalorphine, nalorphine, nalodeine, naldemedine, naloxegol, 6β-naltrexol, naltrindole, methylnaltrexone, methylsamidorphan, alvimopan, axelopran, bevenpran, dinicotinate, levallorphan, samidorphan, buprenorphine, dezocine, eptazocine, butorphanol, levorphanol, nalbuphine, pentazocine, phenazocine, norbinaltorphimine, and diprenorphine.
Nor-opioids may include, but are not limited to, norcodeine, noroxycodone, northebaine, norhydrocodone, nordihydro-codeine, nor-14-hydroxy-codeine, norcodeinone, nor-14-hydroxy-codeinone, normorphine, noroxymorphone, nororipavine, norhydro-morphone, nordihydro-morphine, nor-14-hydroxy-morphine, normorphinone, and nor-14-hydroxy-morphinone.
In certain embodiments, the engineered strains of the invention may provide a platform for producing compounds related to tetrahydrobiopterin synthesis including, but not limited to, dihydroneopterin triphosphate, 6-pyruvoyl tetrahydropterin, 5,6,7,8-tetrahydrobiopterin, 7,8-dihydrobiopterin, tetrahydrobiopterin 4a-carbinolamine, quinonoid dihydrobiopterin, and biopterin.
Host Cells
Any convenient cells may be utilized in the subject host cells and methods. In some cases, the host cells are non-plant cells. In some instances, the host cells may be characterized as microbial cells. In certain cases, the host cells are insect cells, mammalian cells, bacterial cells, or yeast cells. Any convenient type of host cell may be utilized in producing the subject BIA-producing cells, see, e.g., US2008/0176754, and US2014/0273109 the disclosures of which are incorporated by reference in their entirety. Host cells of interest include, but are not limited to, bacterial cells, which may be either Gram positive bacterial cells or Gram negative bacterial cells, insect cells such as Drosophila melanogaster S2 and Spodoptera frugiperda Sf9 cells, and yeast cells such as Saccharomyces cerevisiae, Schizosaccharomyces pombe, and Pichia pastoris cells. Non-limiting examples of bacterial cells include Bacillus subtilis, Escherichia coli, Streptomyces, Anabaena, Arthrobacter, Acetobacter, Acetobacterium, Bacillus, Bifidobacterium, Brachybacterium, Brevibacterium, Carnobacterium, Clostridium, Corynebacterium, Enterobacter, Escherichia, Gluconacetobacter, Gluconobacter, Hafnia, Halomonas, Klebsiella, Kocuria, Lactobacillus, Leucononstoc, Macrococcus, Methylomonas, Methylobacter, Methylocella, Methylococcus, Microbacterium, Micrococcus, Microcystis, Moorella, Oenococcus, Pediococcus, Prochlorococcus, Propionibacterium, Proteus, Pseudoalteromonas, Pseudomonas, Psychrobacter, Rhodobacter, Rhodococcus, Rhodopseudomonas, Serratia, Staphylococcus, Streptococcus, Streptomyces, Synechococcus, Synechocystis, Tetragenococcus, Weissella, Zymomonas, and Salmonella typhimuium cells. In some examples, the host cells are yeast cells or E. coli cells. In some cases, the host cells are yeast cells or E. coli cells. In some cases, the host cell is a yeast cell. In some instances, the host cell is from a strain of yeast engineered to produce a BIA of interest, such as a morphinan alkaloid. In some instances, the host cell is from a strain of yeast engineered to produce an enzyme of interest. In some instances, the host cell is from a strain of yeast engineered to produce a thebaine synthase.
The thebaine synthase may be able to more efficiently convert a salutaridinol-7-O-acetate to a thebaine relative to a spontaneous reaction. In some instances, the host cell is from a strain of yeast engineered to produce an engineered thebaine synthase. In some embodiments, an engineered thebaine synthase may be an engineered fusion enzyme. Additionally, the engineered thebaine synthase may be able to more efficiently convert a salutaridinol-7-O-acetate to a thebaine relative to a thebaine synthase. In some embodiments, the thebaine synthase may be a wild-type thebaine synthase. In some embodiments, a thebaine synthase may be substantially similar to a wild-type thebaine synthase. In some cases, a thebaine synthase that is substantially similar to a wild-type thebaine synthase may have an amino acid sequence that is at least 75% or more, 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more similar to an amino acid sequence of a wild-type thebaine synthase. The engineered thebaine synthase may be engineered as a fusion enzyme to another enzyme to more efficiently convert a salutaridinol-7-O-acetate to a thebaine relative to the thebaine synthase.
Any of the host cells described in US2008/0176754 and US2014/0273109 by Smolke et al. may be adapted for use in the subject cells and methods. In certain embodiments, the yeast cells may be of the species Saccharomyces cerevisiae (S. cerevisiae). In certain embodiments, the yeast cells may be of the species Schizosaccharomyces pombe. In certain embodiments, the yeast cells may be of the species Pichia pastoris. Yeast is of interest as a host cell because cytochrome P450 proteins are able to fold properly into the endoplasmic reticulum membrane so that their activity is maintained. In examples, cytochrome P450 proteins are involved in some biosynthetic pathways of interest. In additional examples, cytochrome P450 proteins are involved in the production of BIAs of interest. In further examples, cytochrome P450 proteins are involved in the production of an enzyme of interest.
Yeast strains of interest that find use in the invention include, but are not limited to, CEN.PK (Genotype: MATa/α ura3-52/ura3-52 trpl-289/trpl-289 leu2-3_112/1eu2-3_112 his3 Δ1/his3 Δ1 MAL2-8C/MAL2-8C SUC2/SUC2), S288C, W303, D273-10B, X2180, A364A, Σ1278B, AB972, SK1, and FL100. In certain cases, the yeast strain is any of S288C (MATα; SUC2 mal mel gal2 CUP1 flo1 flo8-1 hap1), BY4741 (MATα; his3Δ1; leu2Δ0; met15Δ0; ura3Δ0), BY4742 (MATα; his3Δ1; leu2Δ0; lys2Δ0; ura3A0), BY4743 (MATα/MATα; his3Δ1/his3Δ1; leu2Δ0/leu2Δ0; met15Δ0/MET15; LYS2/lys2Δ0; ura3Δ0/ura3A0), and WAT11 or W(R), derivatives of the W303-B strain (MATα; ade2-1; his3-11, -15; leu2-3, -112; ura3-1; canR; cyr+) which express the Arabidopsis thaliana NADPH-P450 reductase ATR1 and the yeast NADPH-P450 reductase CPR1, respectively. In another embodiment, the yeast cell is W303alpha (MATα; his3-11,15 trpl-1 leu2-3 ura3-1 ade2-1). The identity and genotype of additional yeast strains of interest may be found at EUROSCARF (web.uni-frankfurt.de/fb15/mikro/euroscarf/col_index.html).
In some instances the host cell is a fungal cell. In certain embodiments, the fungal cells may be of the Aspergillus species and strains include Aspergillus Niger (ATCC 1015, ATCC 9029, CBS 513.88), Aspergillus oryzae (ATCC 56747, RIB40), Aspergillus terreus (NIH 2624, ATCC 20542) and Aspergillus nidulans (FGSC A4).
In certain embodiments, heterologous coding sequences may be codon optimized for expression in Aspergillus sp. and expressed from an appropriate promoter. In certain embodiments, the promoter may be selected from phosphoglycerate kinase promoter (PGK), MbfA promoter, cytochromes oxidase subunit promoter (CoxA), SrpB promoter, TvdA promoter, malate dehydrogenase promoter (MdhA), beta-mannosidase promoter (ManB). In certain embodiments, a terminator may be selected from glucoamylase terminator (GlaA) or TrpC terminator. In certain embodiments, the expression cassette consisting of a promoter, heterologous coding sequence, and terminator may be expressed from a plasmid or integrated into the genome of the host. In certain embodiments, selection of cells maintaining the plasmid or integration cassette may be performed with antibiotic selection such as hygromycin or nitrogen source utilization, such as using acetamide as a sole nitrogen source. In certain embodiments, DNA constructs may be introduced into the host cells using established transformation methods such as protoplast transformation, lithium acetate, or electroporation. In certain embodiments, cells may be cultured in liquid ME or solid MEA (3% malt extract, 0.5% peptone, and ±1.5% agar) or in Vogel's minimal medium with or without selection.
In some instances the host cell is a bacterial cell. The bacterial cell may be selected from any bacterial genus. Examples of genuses from which the bacterial cell may come include Anabaena, Arthrobacter, Acetobacter, Acetobacterium, Bacillus, Bifidobacterium, Brachybacterium, Brevibacterium, Carnobacterium, Clostridium, Corynebacterium, Enterobacter, Escherichia, Gluconacetobacter, Gluconobacter, Hafnia, Halomonas, Klebsiella, Kocuria, Lactobacillus, Leucononstoc, Macrococcus, Methylomonas, Methylobacter, Methylocella, Methylococcus, Microbacterium, Micrococcus, Microcystis, Moorella, Oenococcus, Pediococcus, Prochlorococcus, Propionibacterium, Proteus, Pseudoalteromonas, Pseudomonas, Psychrobacter, Rhodobacter, Rhodococcus, Rhodopseudomonas, Serratia, Staphylococcus, Streptococcus, Streptomyces, Synechococcus, Synechocystis, Tetragenococcus, Weissella, and Zymomonas. Examples of bacterial species which may be used with the methods of this disclosure include Arthrobacter nicotianae, Acetobacter aceti, Arthrobacter arilaitensis, Bacillus cereus, Bacillus coagulans, Bacillus licheniformis, Bacillus pumilus, Bacillus sphaericus, Bacillus stearothermophilus, Bacillus subtilis, Bifidobacterium adolescentis, Brachybacterium tyrofermentans, Brevibacterium linens, Carnobacterium divergens, Corynebacterium flavescens, Enterococcus faecium, Gluconacetobacter europaeus, Gluconacetobacter johannae, Gluconobacter oxydans, Hafnia alvei, Halomonas elongata, Kocuria rhizophila, Lactobacillus acidifarinae, Lactobacillus jensenii, Lactococcus lactis, Lactobacillus yamanashiensis, Leuconostoc citreum, Macrococcus caseolyticus, Microbacterium foliorum, Micrococcus lylae, Oenococcus oeni, Pediococcus acidilactici, Propionibacterium acidipropionici, Proteus vulgaris, Pseudomonas fluorescens, Psychrobacter celer, Staphylococcus condiments, Streptococcus thermophilus, Streptomyces griseus, Tetragenococcus halophilus, Weissella cibaria, Weissella koreensis, Zymomonas mobilis, Corynebacterium glutamicum, Bifidobacterium bifidum/breve/longum, Streptomyces lividans, Streptomyces coelicolor, Lactobacillus plantarum, Lactobacillus sakei, Lactobacillus casei, Pseudoalteromonas citrea, Pseudomonas putida, Clostridium ljungdahliilaceticum/acetobutylicum/beijerinckii/butyricum, and Moorella themocellum/thermoacetica.
In certain embodiments, the bacterial cells may be of a strain of Escherichia coli. In certain embodiments, the strain of E. coli may be selected from BL21 DH5a, XL1-Blue, HB101, BL21, and K12. In certain embodiments, heterologous coding sequences may be codon optimized for expression in E. coli and expressed from an appropriate promoter. In certain embodiments, the promoter may be selected from T7 promoter, tac promoter, trc promoter, tetracycline-inducible promoter (tet), lac operon promoter (lac), lacO1 promoter. In certain embodiments, the expression cassette consisting of a promoter, heterologous coding sequence, and terminator may be expressed from a plasmid or integrated into the genome. In certain embodiments, the plasmid is selected from pUC19 or pBAD. In certain embodiments, selection of cells maintaining the plasmid or integration cassette may be performed with antibiotic selection such as kanamycin, chloramphenicol, streptomycin, spectinomycin, gentamycin, erythromycin or ampicillin. In certain embodiments, DNA constructs may be introduced into the host cells using established transformation methods such as conjugation, heat shock chemical transformation, or electroporation. In certain embodiments, cells may be cultured in liquid Luria-Bertani (LB) media at about 37° C. with or without antibiotics.
In certain embodiments, the bacterial cells may be a strain of Bacillus subtilis. In certain embodiments, the strain of B. subtilis may be selected from 1779, GP25, RO-NN-1, 168, BSn5, BEST195, 1A382, and 62178. In certain embodiments, heterologous coding sequences may be codon optimized for expression in Bacillus sp. and expressed from an appropriate promoter. In certain embodiments, the promoter may be selected from grac promoter, p43 promoter, or trnQ promoter. In certain embodiments, the expression cassette consisting of the promoter, heterologous coding sequence, and terminator may be expressed from a plasmid or integrated into the genome. In certain embodiments, the plasmid is selected from pHP13, pE194, pC194, pHT01, or pHT43. In certain embodiments, integrating vectors such as pDG364 or pDG1730 may be used to integrate the expression cassette into the genome. In certain embodiments, selection of cells maintaining the plasmid or integration cassette may be performed with antibiotic selection such as erythromycin, kanamycin, tetracycline, and spectinomycin. In certain embodiments, DNA constructs may be introduced into the host cells using established transformation methods such as natural competence, heat shock, or chemical transformation. In certain embodiments, cells may be cultured in liquid Luria-Bertani (LB) media at 37° C. or M9 medium plus glucose and tryptophan.
Genetic Modifications to Host Cells
The host cells may be engineered to include one or more modifications (such as two or more, three or more, four or more, five or more, or even more modifications) that provide for the production of BIAs of interest. Additionally or alternatively, the host cells may be engineered to include one or more modifications (such as two or more, three or more, four or more, five or more, or even more modifications) that provide for the production of enzymes of interest. In some cases, a modification is a genetic modification, such as a mutation, addition, or deletion of a gene or fragment thereof, or transcription regulation of a gene or fragment thereof. As used herein, the term “mutation” refers to a deletion, insertion, or substitution of an amino acid(s) residue or nucleotide(s) residue relative to a reference sequence or motif. The mutation may be incorporated as a directed mutation to the native gene at the original locus. In some cases, the mutation may be incorporated as an additional copy of the gene introduced as a genetic integration at a separate locus, or as an additional copy on an episomal vector such as a 2μ or centromeric plasmid. In certain instances, the substrate inhibited copy of the enzyme is under the native cell transcriptional regulation. In some instances, the substrate inhibited copy of the enzyme is introduced with engineered constitutive or dynamic regulation of protein expression by placing it under the control of a synthetic promoter. In some examples, the object of one or more modifications may be a native gene. In some examples, the object of one or more modifications may be a non-native gene. In some examples, a non-native gene may be inserted into a host cell. In further examples, a non-native gene may be altered by one or more modifications prior to being inserted into a host cell.
An engineered host cell may overproduce one or more BIAs of interest. By overproduce is meant that the cell has an improved or increased production of a BIA molecule of interest relative to a control cell (e.g., an unmodified cell). By improved or increased production is meant both the production of some amount of the BIA of interest where the control has no BIA of interest production, as well as an increase of about 10% or more, such as about 20% or more, about 30% or more, about 40% or more, about 50% or more, about 60% or more, about 80% or more, about 100% or more, such as 2-fold or more, such as 5-fold or more, including 10-fold or more in situations where the control has some BIA of interest production.
An engineered host cell may overproduce one or more (S)-1-benzylisoquinoline alkaloids. In some cases, the engineered host cell may produce some amount of the (S)-1-benzylisoquinoline alkaloid of interest where the control has no (S)-1-benzylisoquinoline alkaloid production, as well as an increase of about 10% or more, such as about 20% or more, about 30% or more, about 40% or more, about 50% or more, about 60% or more, about 80% or more, about 100% or more, such as 2-fold or more, such as 5-fold or more, including 10-fold or more in situations where the control has some (S)-1-benzylisoquinoline alkaloid of interest production.
An engineered host cell may further overproduce one or more (R)-1-benzylisoquinoline alkaloids. In some cases, the engineered host cell may produce some amount of the (R)-1-benzylisoquinoline alkaloid of interest where the control has no (R)-1-benzylisoquinoline alkaloid production, as well as an increase of about 10% or more, such as about 20% or more, about 30% or more, about 40% or more, about 50% or more, about 60% or more, about 80% or more, about 100% or more, such as 2-fold or more, such as 5-fold or more, including 10-fold or more in situations where the control has some (R)-1-benzylisoquinoline alkaloid of interest production.
An engineered host cell may further overproduce one or more morphinan alkaloids. In some cases, the engineered host cell may produce some amount of the morphinan alkaloid of interest where the control has no morphinan alkaloid production, as well as an increase of about 10% or more, such as about 20% or more, about 30% or more, about 40% or more, about 50% or more, about 60% or more, about 80% or more, about 100% or more, such as 2-fold or more, such as 5-fold or more, including 10-fold or more in situations where the control has some morphinan alkaloid of interest production. An engineered host cell may further overproduce one or more of promorphinan, nor-opioid, or nal-opioid alkaloids.
In some cases, the engineered host cell is capable of producing an increased amount of (R)-reticuline relative to a control host cell that lacks the one or more modifications (e.g., as described herein). In some cases, the engineered host cell having an engineered split epimerase is capable of producing an increased amount of (R)-reticuline relative to a host cell having a fused epimerase. In some cases, the engineered host cell having modifications to an oxidase portion of an engineered epimerase is capable of producing an increased amount of (R)-reticuline relative to a control host cell that lacks the one or more modifications to the oxidase portion of the engineered epimerase. In certain instances, the increased amount of (R)-reticuline is about 10% or more relative to the control host cell, such as about 20% or more, about 30% or more, about 40% or more, about 50% or more, about 60% or more, about 80% or more, about 100% or more, about 2-fold or more, about 5-fold or more, or even about 10-fold or more relative to the control host cell. In some cases, (R)-reticuline is the product of an epimerization reaction within an engineered host cell. In some cases, (R)-reticuline is the product of an epimerization reaction catalyzed by at least one engineered epimerase within an engineered host cell. In these cases, (5)-reticuline may be the substrate of the epimerization reaction.
In some cases, the engineered host cell is capable of producing an increased amount of thebaine relative to a control host cell that lacks the one or more modifications (e.g., as described herein). In some cases, the engineered host cell having a thebaine synthase is capable of producing an increased amount of thebaine relative to a host cell that lacks a thebaine synthase. In some cases, the engineered host cell having an engineered thebaine synthease is capable of producing an increased amount of thebaine relative to a host cell having a non-engineered thebaine synthase (e.g., as described herein). In certain instances, the increased amount of thebaine is about 10% or more relative to the control host cell, such as about 20% or more, about 30% or more, about 40% or more, about 50% or more, about 60% or more, about 80% or more, about 100% or more, about 2-fold or more, about 5-fold or more, or even about 10-fold or more relative to the control host cell. In some cases, thebaine is the product of a thebaine synthase reaction within an engineered host cell. In some cases, thebaine is the product of a thebaine synthase reaction catalyzed by at least one engineered thebaine synthase within an engineered host cell. In these cases, salutaridinol-7-O-acetate may be the substrate of the thebaine synthase reaction.
Additionally, an engineered host cell may overproduce one or more enzymes of interest. By overproduce is meant that the cell has an improved or increased production of an enzyme of interest relative to a control cell (e.g., an unmodified cell). By improved or increased production is meant both the production of some amount of the enzyme of interest where the control has no production, as well as an increase of about 10% or more, such as about 20% or more, about 30% or more, about 40% or more, about 50% or more, about 60% or more, about 80% or more, about 100% or more, such as 2-fold or more, such as 5-fold or more, including 10-fold or more in situations where the control has some enzyme of interest production.
An engineered host cell may overproduce one or more DRS-DRR enzymes. In some cases, the engineered host cell may produce some amount of the DRS-DRR enzyme where the control has no DRS-DRR enzyme production, as well as an increase of about 10% or more, such as about 20% or more, about 30% or more, about 40% or more, about 50% or more, about 60% or more, about 80% or more, about 100% or more, such as 2-fold or more, such as 5-fold or more, including 10-fold or more in situations where the control has some DRS-DRR enzyme production.
An engineered host cell may overproduce one or more engineered DRS-DRR enzymes. In some cases, the engineered host cell may produce some amount of the engineered DRS-DRR epimerase where the control has no DRS-DRR enzyme production, or where the control has a same level of production of wild-type epimerases in comparison to the engineered host cell, as well as an increase of about 10% or more, such as about 20% or more, about 30% or more, about 40% or more, about 50% or more, about 60% or more, about 80% or more, about 100% or more, such as 2-fold or more, such as 5-fold or more, including 10-fold or more in situations where the control has some DRS-DRR enzyme production. In some cases, an engineered DRS-DRR epimerase may be an engineered split epimerase. In some cases, an engineered DRS-DRR epimerase may be an engineered fused epimerase.
An engineered host cell may further overproduce one or more enzymes that are derived from the DRS-DRR enzyme. In some cases, the engineered host cell may produce some amount of the enzymes that are derived from the DRS-DRR enzyme, where the control has no production of enzymes that are derived from the DRS-DRR enzyme, as well as an increase of about 10% or more, such as about 20% or more, about 30% or more, about 40% or more, about 50% or more, about 60% or more, about 80% or more, about 100% or more, such as 2-fold or more, such as 5-fold or more, including 10-fold or more in situations where the control has some production of enzymes that are derived from the DRS-DRR enzyme.
An engineered host cell may overproduce one or more thebaine synthase enzymes. In some cases, the engineered host cell may produce some amount of the thebaine synthase enzyme where the control has no thebaine synthase enzyme production, as well as an increase of about 10% or more, such as about 20% or more, about 30% or more, about 40% or more, about 50% or more, about 60% or more, about 80% or more, about 100% or more, such as 2-fold or more, such as 5-fold or more, including 10-fold or more in situations where the control has some thebaine synthase enzyme production.
An engineered host cell may overproduce one or more engineered thebaine synthase enzymes. In some cases, the engineered host cell may produce some amount of the engineered thebaine synthase where the control has no thebaine synthase enzyme production, or where the control has a same level of production of wild-type thebaine synthase in comparison to the engineered host cell, as well as an increase of about 10% or more, such as about 20% or more, about 30% or more, about 40% or more, about 50% or more, about 60% or more, about 80% or more, about 100% or more, such as 2-fold or more, such as 5-fold or more, including 10-fold or more in situations where the control has some thebaine synthase enzyme production. In some cases, an engineered thebaine synthase may be an engineered fusion enzyme.
An engineered host cell may further overproduce one or more enzymes that are derived from the thebaine synthase enzyme. In some cases, the engineered host cell may produce some amount of the enzymes that are derived from the thebaine synthase enzyme, where the control has no production of enzymes that are derived from the thebaine synthase enzyme, as well as an increase of about 10% or more, such as about 20% or more, about 30% or more, about 40% or more, about 50% or more, about 60% or more, about 80% or more, about 100% or more, such as 2-fold or more, such as 5-fold or more, including 10-fold or more in situations where the control has some production of enzymes that are derived from the thebaine synthase enzyme.
In some cases, the one or more (such as two or more, three or more, or four or more) modifications may be selected from: a substrate inhibition alleviating mutation in a biosynthetic enzyme gene; a product inhibition alleviating mutation in a biosynthetic enzyme gene; a cofactor recovery promoting mechanism; a feedback inhibition alleviating mutation in a biosynthetic enzyme gene; a transcriptional modulation modification of a biosynthetic enzyme gene; an inactivating mutation in an enzyme gene; an epimerization modification; and a heterologous coding sequence that encodes an enzyme. A cell that includes one or more modifications may be referred to as an engineered cell.
In some cases, the one or more (such as two or more, three or more, or four or more) modifications may be selected from: a localization mutation; a cytochrome P450 reductase interaction mutation; an accessibility mutation; an activity enhancing mutation; an engineered fused thebaine synthase modification, and an engineered split epimerase modification. A cell that includes one or more modifications may be referred to as an engineered cell.
Substrate Inhibition Alleviating Mutations
In some instances, the engineered host cells are cells that include one or more substrate inhibition alleviating mutations (such as two or more, three or more, four or more, five or more, or even more) in one or more biosynthetic enzyme genes of the cell. In some examples, the one or more biosynthetic enzyme genes are native to the cell (e.g., is present in an unmodified cell). In some examples, the one or more biosynthetic enzyme genes are non-native to the cell. As used herein, the term “substrate inhibition alleviating mutation” refers to a mutation that alleviates a substrate inhibition control mechanism of the cell.
A mutation that alleviates substrate inhibition reduces the inhibition of a regulated enzyme in the cell of interest relative to a control cell and provides for an increased level of the regulated compound or a downstream biosynthetic product thereof. In some cases, by alleviating inhibition of the regulated enzyme is meant that the IC50 of inhibition is increased by 2-fold or more, such as by 3-fold or more, 5-fold or more, 10-fold or more, 30-fold or more, 100-fold or more, 300-fold or more, 1000-fold or more, or even more. By increased level is meant a level that is 110% or more of that of the regulated compound in a control cell or a downstream product thereof, such as 120% or more, 130% or more, 140% or more, 150% or more, 160% or more, 170% or more, 180% or more, 190% or more, or 200% or more, such as at least 3-fold or more, at least 5-fold or more, at least 10-fold or more or even more of the regulated compound in the engineered host cell or a downstream product thereof.
A variety of substrate inhibition control mechanisms and biosynthetic enzymes in the engineered host cell that are directed to regulation of levels of BIAs of interest, or precursors thereof, may be targeted for substrate inhibition alleviation. The engineered host cell may include one or more substrate inhibition alleviating mutations in one or more biosynthetic enzyme genes. The one or more mutations may be located in any convenient biosynthetic enzyme genes where the biosynthetic enzyme is subject to regulatory control. In some embodiments, the one or more biosynthetic enzyme genes encode one or more tyrosine hydroxylase enzymes. In certain instances, the one or more substrate inhibition alleviating mutations are present in a biosynthetic enzyme gene that is TyrH. In some embodiments, the engineered host cell may include one or more substrate inhibition alleviating mutations in one or more biosynthetic enzyme genes such as one of those genes described in Table 3.
In certain embodiments, the one or more substrate inhibition alleviating mutations are present in the TyrH gene. The TyrH gene encodes tyrosine hydroxylase, which is an enzyme that converts tyrosine to L-DOPA. However, TyrH is inhibited by its substrate, tyrosine. Mammalian tyrosine hydroxylase activity, such as that seen in humans or rats, can be improved through mutations to the TyrH gene that relieve substrate inhibition. In particular, substrate inhibition from tyrosine can be relieved by a point mutation W166Y in the TyrH gene. The point mutation W166Y in the TyrH gene may also improve the binding of the cosubstrate of tyrosine hydroxylase, BILI, to catalyze the reaction of tyrosine to L-DOPA. The mutants of TyrH, when expressed in yeast strains to produce BIAs from sugar (such as those described in U.S. Provisional Patent Application Ser. No. 61/899,496) can significantly improve the production of BIAs.
Any convenient numbers and types of mutations may be utilized to alleviate a substrate inhibition control mechanism. In certain embodiments, the engineered host cells of the present invention may include 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, 11 or more, 12 or more, 13 or more, 14 or more, or even or more substrate inhibition alleviating mutations, such as 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15 substrate inhibition alleviating mutations in one or more biosynthetic enzyme genes within the engineered host cell.
Cofactor Recovery Promoting Mechanisms
In some instances, the engineered host cells are cells that include one or more cofactor recovery promoting mechanisms (such as two or more, three or more, four or more, five or more, or even more) in one or more biosynthetic enzyme genes of the cell. In some examples, the one or more biosynthetic enzyme genes are native to the cell (e.g., is present in an unmodified cell). In some examples, the one or more biosynthetic enzyme genes are non-native to the cell. As used herein, the term “cofactor recovery promoting mechanism” refers to a mechanism that promotes a cofactor recovery control mechanism of the cell.
A variety of cofactor recovery control mechanisms and biosynthetic enzymes in the engineered host cell that are directed to regulation of levels of BIAs of interest, or precursors thereof, may be targeted for cofactor recovery promotion. The engineered host cell may include one or more cofactor recovery promoting mechanism in one or more biosynthetic enzyme genes. In examples, the engineered host cell may include a heterologous coding sequence that encodes dihydrofolate reductase (DHFR). When DHFR is expressed, it may convert 7,8-dihydrobiopterin (BH2) to the tetrahydrobiopterin (BH4), thereby recovering BH4 as a TyrH cosubstrate. In some examples, the engineered host cell may include one or more cofactor recovery promoting mechanisms in one or more biosynthetic enzyme genes such as one of those genes described in Table 2.
Any convenient numbers and types of mechanisms may be utilized to promote a cofactor recovery control mechanism. In certain embodiments, the engineered host cells of the present invention may include 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, 11 or more, 12 or more, 13 or more, 14 or more, or even 15 or more cofactor recovery promoting mechanisms such as 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15 cofactor recovery promoting mechanisms in one or more biosynthetic enzyme genes within the engineered host cell.
Product Inhibition Alleviating Mutations
In some instances, the engineered host cells are cells that include one or more product inhibition alleviating mutations (such as two or more, three or more, four or more, five or more, or even more) in one or more biosynthetic enzyme genes of the cell. In some examples, the one or more biosynthetic enzyme genes are native to the cell (e.g., is present in an unmodified cell). In some examples, the one or more biosynthetic enzyme genes are non-native to the cell. As used herein, the term “product inhibition alleviating mutation” refers to a mutation that alleviates a short term and/or long term product inhibition control mechanism of an engineered host cell. Short term product inhibition is a control mechanism of the cell in which there is competitive binding at a cosubstrate binding site. Long term product inhibition is a control mechanism of the cell in which there is irreversible binding of a compound away from a desired pathway.
A mutation that alleviates product inhibition reduces the inhibition of a regulated enzyme in the cell of interest relative to a control cell and provides for an increased level of the regulated compound or a downstream biosynthetic product thereof. In some cases, by alleviating inhibition of the regulated enzyme is meant that the IC50 of inhibition is increased by 2-fold or more, such as by 3-fold or more, 5-fold or more, 10-fold or more, 30-fold or more, 100-fold or more, 300-fold or more, 1000-fold or more, or even more. By increased level is meant a level that is 110% or more of that of the regulated compound in a control cell or a downstream product thereof, such as 120% or more, 130% or more, 140% or more, 150% or more, 160% or more, 170% or more, 180% or more, 190% or more, or 200% or more, such as at least 3-fold or more, at least 5-fold or more, at least 10-fold or more or even more of the regulated compound in the engineered host cell or a downstream product thereof.
A variety of product inhibition control mechanisms and biosynthetic enzymes in the engineered host cell that are directed to regulation of levels of BIAs of interest may be targeted for product inhibition alleviation. The engineered host cell may include one or more product inhibition alleviating mutations in one or more biosynthetic enzyme genes. The mutation may be located in any convenient biosynthetic enzyme genes where the biosynthetic enzyme is subject to regulatory control. In some embodiments, the one or more biosynthetic enzyme genes encode one or more tyrosine hydroxylase enzymes. In certain instances, the one or more product inhibition alleviating mutations are present in a biosynthetic enzyme gene that is TyrH. In some embodiments, the engineered host cell includes one or more product inhibition alleviating mutations in one or more biosynthetic enzyme genes such as one of those genes described in Table 3.
In certain embodiments, the one or more product inhibition alleviating mutations are present in the TyrH gene. The TyrH gene encodes tyrosine hydroxylase, which is an enzyme that converts tyrosine to L-DOPA. TyrH requires tetrahydrobiopterin (BH4) as a cosubstrate to catalyze the hydroxylation reaction. Some microbial strains, such as Saccharomyces cerevisiae, do not naturally produce BH4, but can be engineered to produce this substrate through a four-enzyme synthesis and recycling pathway, as illustrated in
TyrH is inhibited by its product L-DOPA, as well as other catecholamines, particularly dopamine. Mammalian tyrosine hydroxylase activity, such as from humans or rats, can be improved through mutations that relieve product inhibition. For example, short term product inhibition, such as competitive binding at the cosubstrate binding site, can be relieved by a point mutation W166Y on the TyrH gene. In particular, the point mutation W166Y on the TyrH gene may improve binding of the cosubstrate. Additionally, short term product inhibition to relieve competitive binding at the cosubstrate binding site may be improved by a point mutation S40D on the TyrH gene. Short term product inhibition may also be improved by the joint mutations of R37E, R38E on the TyrH gene. In particular, R37E, R38E mutations may together specifically improve tyrosine hydroxylase activity in the presence of dopamine.
Additionally, long term product inhibition may be relieved by point mutations on the TyrH gene. Long term product inhibition relief may include the irreversible binding of catecholamine to iron in the active site such that there is less catecholamine present to act as a product inhibitor of tyrosine hydroxylase activity. Long term product inhibition can be relieved by the mutations E332D and Y371F, respectively, in the TyrH gene.
Combinations of the mutations can be made (such as two or three or more mutations at once) to relieve multiple types of substrate and product inhibition to further improve the activity of TyrH. The mutants of TyrH, when expressed in yeast strains to produce BIAs from sugar (such as those described in U.S. Provisional Patent Application Ser. No. 61/899,496) can significantly improve the production of BIAs.
Any convenient numbers and types of mutations may be utilized to alleviate a product inhibition control mechanism. In certain embodiments, the engineered host cells of the present invention may include 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, 11 or more, 12 or more, 13 or more, 14 or more, or even 15 or more product inhibition alleviating mutations, such as 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15 product inhibition alleviating mutations in one or more biosynthetic enzyme genes within the engineered host cell.
Feedback Inhibition Alleviating Mutations
In some instances, the engineered host cells are cells that include one or more feedback inhibition alleviating mutations (such as two or more, three or more, four or more, five or more, or even more) in one or more biosynthetic enzyme genes of the cell. In some cases, the one or more biosynthetic enzyme genes are native to the cell (e.g., is present in an unmodified cell). Additionally or alternatively, in some examples the one or more biosynthetic enzyme genes are non-native to the cell. As used herein, the term “feedback inhibition alleviating mutation” refers to a mutation that alleviates a feedback inhibition control mechanism of an engineered host cell. Feedback inhibition is a control mechanism of the cell in which an enzyme in the synthetic pathway of a regulated compound is inhibited when that compound has accumulated to a certain level, thereby balancing the amount of the compound in the cell. A mutation that alleviates feedback inhibition reduces the inhibition of a regulated enzyme in the engineered host cell relative to a control cell. In this way, engineered host cell provides for an increased level of the regulated compound or a downstream biosynthetic product thereof. In some cases, by alleviating inhibition of the regulated enzyme is meant that the IC 50 of inhibition is increased by 2-fold or more, such as by 3-fold or more, 5-fold or more, 10-fold or more, 30-fold or more, 100-fold or more, 300-fold or more, 1000-fold or more, or even more. By increased level is meant a level that is 110% or more of that of the regulated compound in a control cell or a downstream product thereof, such as 120% or more, 130% or more, 140% or more, 150% or more, 160% or more, 170% or more, 180% or more, 190% or more, or 200% or more, such as at least 3-fold or more, at least 5-fold or more, at least 10-fold or more or even more of the regulated compound in the host cell or a downstream product thereof.
A variety of feedback inhibition control mechanisms and biosynthetic enzymes that are directed to regulation of levels of BIAs of interest may be targeted for alleviation in the host cell. The host cell may include one or more feedback inhibition alleviating mutations in one or more biosynthetic enzyme genes native to the cell. The one or more mutations may be located in any convenient biosynthetic enzyme genes where the biosynthetic enzyme is subject to regulatory control. In some embodiments, the one or more biosynthetic enzyme genes may encode one or more enzymes selected from a 3-deoxy-d-arabinose-heptulosonate-7-phosphate (DAHP) synthase and a chorismate mutase. In some embodiments, the one or more biosynthetic enzyme genes encode a 3-deoxy-d-arabinose-heptulosonate-7-phosphate (DAHP) synthase. In some instances, the one or more biosynthetic enzyme genes may encode a chorismate mutase. In certain instances, the one or more feedback inhibition alleviating mutations may be present in a biosynthetic enzyme gene selected from ARO4 and ARO7. In certain instances, the one or more feedback inhibition alleviating mutations may be present in a biosynthetic enzyme gene that is ARO4. In certain instances, the one or more feedback inhibition alleviating mutations are present in a biosynthetic enzyme gene that is ARO7. In some embodiments, the engineered host cell may include one or more feedback inhibition alleviating mutations in one or more biosynthetic enzyme genes such as one of those genes described in Table 3.
Any convenient numbers and types of mutations may be utilized to alleviate a feedback inhibition control mechanism. As used herein, the term “mutation” refers to a deletion, insertion, or substitution of an amino acid(s) residue or nucleotide(s) residue relative to a reference sequence or motif. The mutation may be incorporated as a directed mutation to the native gene at the original locus. In some cases, the mutation may be incorporated as an additional copy of the gene introduced as a genetic integration at a separate locus, or as an additional copy on an episomal vector such as a 2μ or centromeric plasmid. In certain instances, the feedback inhibited copy of the enzyme is under the native cell transcriptional regulation. In some instances, the feedback inhibited copy of the enzyme is introduced with engineered constitutive or dynamic regulation of protein expression by placing it under the control of a synthetic promoter.
In certain embodiments, the one or more feedback inhibition alleviating mutations may be present in the ARO4 gene. ARO4 mutations of interest may include, but are not limited to, substitution of the lysine residue at position 229 with a leucine, a substitution of the glutamine residue at position 166 with a lysine residue, or a mutation as described by Hartmann M, et al. ((2003) Proc Natl Acad Sci USA 100(3):862-867) or Fukuda et al. ((1992) J Ferment Bioeng 74(2):117-119). In some instances, mutations for conferring feedback inhibition may be selected from a mutagenized library of enzyme mutants. Examples of such selections may include rescue of growth of o-fluoro-D,L-phenylalanine or growth of aro3 mutant yeast strains in media with excess tyrosine as described by Fukuda et al. ((1990) Breeding of Brewing Yeast Producing a Large Amount of Beta-Phenylethyl Alcohol and Beta-Phenylethyl Acetate. Agr Biol Chem Tokyo 54(1):269-271).
In certain embodiments, the engineered host cells of the present invention may include 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, 11 or more, 12 or more, 13 or more, 14 or more, or even 15 or more feedback inhibition alleviating mutations, such as 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15 feedback inhibition alleviating mutations in one or more biosynthetic enzyme genes within the engineered host cell.
Transcriptional Modulation Modifications
The host cells may include one or more transcriptional modulation modifications (such as two or more, three or more, four or more, five or more, or even more modifications) of one or more biosynthetic enzyme genes of the cell. In some examples, the one or more biosynthetic enzyme genes are native to the cell. In some examples, the one or more biosynthetic enzyme genes are non-native to the cell. Any convenient biosynthetic enzyme genes of the cell may be targeted for transcription modulation. By transcription modulation is meant that the expression of a gene of interest in a modified cell is modulated, e.g., increased or decreased, enhanced or repressed, relative to a control cell (e.g., an unmodified cell). In some cases, transcriptional modulation of the gene of interest includes increasing or enhancing expression. By increasing or enhancing expression is meant that the expression level of the gene of interest is increased by 2-fold or more, such as by 5-fold or more and sometimes by 25-, 50-, or 100-fold or more and in certain embodiments 300-fold or more or higher, as compared to a control, i.e., expression in the same cell not modified (e.g., by using any convenient gene expression assay). Alternatively, in cases where expression of the gene of interest in a cell is so low that it is undetectable, the expression level of the gene of interest is considered to be increased if expression is increased to a level that is easily detectable. In certain instances, transcriptional modulation of the gene of interest includes decreasing or repressing expression. By decreasing or repressing expression is meant that the expression level of the gene of interest is decreased by 2-fold or more, such as by 5-fold or more and sometimes by 25-, 50-, or 100-fold or more and in certain embodiments 300-fold or more or higher, as compared to a control. In some cases, expression is decreased to a level that is undetectable. Modifications of host cell processes of interest that may be adapted for use in the subject host cells are described in U.S. Publication No. 20140273109 (Ser. No. 14/211,611) by Smolke et al., the disclosure of which is herein incorporated by reference in its entirety.
Any convenient biosynthetic enzyme genes may be transcriptionally modulated, and include but are not limited to, those biosynthetic enzymes described in
In some embodiments, the transcriptional modulation modification may include a substitution of a strong promoter for a native promoter of the one or more biosynthetic enzyme genes or the expression of an additional copy(ies) of the gene or genes under the control of a strong promoter. The promoters driving expression of the genes of interest may be constitutive promoters or inducible promoters, provided that the promoters may be active in the host cells. The genes of interest may be expressed from their native promoters. Additionally or alternatively, the genes of interest may be expressed from non-native promoters. Although not a requirement, such promoters may be medium to high strength in the host in which they are used. Promoters may be regulated or constitutive. In some embodiments, promoters that are not glucose repressed, or repressed only mildly by the presence of glucose in the culture medium, may be used. There are numerous suitable promoters, examples of which include promoters of glycolytic genes such as the promoter of the B. subtilis tsr gene (encoding fructose biphosphate aldolase) or GAPDH promoter from yeast S. cerevisiae (coding for glyceraldehyde-phosphate dehydrogenase) (Bitter G. A., Meth. Enzymol. 152:673 684 (1987)). Other strong promoters of interest include, but are not limited to, the ADHI promoter of baker's yeast (Ruohonen L., et al, J. Biotechnol. 39:193 203 (1995)), the phosphate-starvation induced promoters such as the PHO5 promoter of yeast (Hinnen, A., et al, in Yeast Genetic Engineering, Barr, P. J., et al. eds, Butterworths (1989), the alkaline phosphatase promoter from B. licheniformis (Lee. J. W. K., et al., J. Gen. Microbiol. 137:1127 1133 (1991)), GPD1, and TEF1. Yeast promoters of interest include, but are not limited to, inducible promoters such as Gall-10, Gall, GalL, GalS, repressible promoter Met25, tetO, and constitutive promoters such as glyceraldehyde 3-phosphate dehydrogenase promoter (GPD), alcohol dehydrogenase promoter (ADH), translation-elongation factor-1-alpha promoter (TEF), cytochrome c-oxidase promoter (CYC1), MRP7 promoter, etc. In some instances, the strong promoter is GPD1. In certain instances, the strong promoter is TEF1. Autonomously replicating yeast expression vectors containing promoters inducible by hormones such as glucocorticoids, steroids, and thyroid hormones are also known and include, but are not limited to, the glucorticoid responsive element (GRE) and thyroid hormone responsive element (TRE), see e.g., those promoters described in U.S. Pat. No. 7,045,290. Vectors containing constitutive or inducible promoters such as alpha factor, alcohol oxidase, and PGH may be used. Additionally any promoter/enhancer combination (as per the Eukaryotic Promoter Data Base EPDB) could also be used to drive expression of genes of interest. It is understood that any convenient promoters specific to the host cell may be selected, e.g., E. coli. In some cases, promoter selection may be used to optimize transcription, and hence, enzyme levels to maximize production while minimizing energy resources.
Inactivating Mutations
The engineered host cells may include one or more inactivating mutations to an enzyme of the cell (such as two or more, three or more, four or more, five or more, or even more). The inclusion of one or more inactivating mutations may modify the flux of a synthetic pathway of an engineered host cell to increase the levels of a BIA of interest or a desirable enzyme or precursor leading to the same. In some examples, the one or more inactivating mutations are to an enzyme native to the cell. Additionally or alternatively, the one or more inactivating mutations are to an enzyme non-native to the cell. As used herein, by “inactivating mutation” is meant one or more mutations to a gene or regulatory DNA sequence of the cell, where the mutation(s) inactivates a biological activity of the protein expressed by that gene of interest. In some cases, the gene is native to the cell. In some instances, the gene encodes an enzyme that is inactivated and is part of or connected to the synthetic pathway of a BIA of interest produced by the host cell. In some instances, an inactivating mutation is located in a regulatory DNA sequence that controls a gene of interest. In certain cases, the inactivating mutation is to a promoter of a gene. Any convenient mutations (e.g., as described herein) may be utilized to inactivate a gene or regulatory DNA sequence of interest. By “inactivated” or “inactivates” is meant that a biological activity of the protein expressed by the mutated gene is reduced by 10% or more, such as by 20% or more, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, 90% or more, 95% or more, 97% or more, or 99% or more, relative to a control protein expressed by a non-mutated control gene. In some cases, the protein is an enzyme and the inactivating mutation reduces the activity of the enzyme.
In some examples, the engineered host cell includes an inactivating mutation in an enzyme native to the cell. Any convenient enzymes may be targeted for inactivation. Enzymes of interest may include, but are not limited to those enzymes, described in Table 3 whose action in the synthetic pathway of the engineered host cell tends to reduce the levels of a BIA of interest. In some cases, the enzyme has glucose-6-phosphate dehydrogenase activity. In certain embodiments, the enzyme that includes an inactivating mutation is ZWF1. In some cases, the enzyme has alcohol dehydrogenase activity. In some embodiments, the enzyme that includes an inactivating mutation is selected from ADH2, ADH3, ADH4, ADH5, ADH6, ADH7, and SFA1. In certain embodiments, the enzyme that includes an inactivating mutation(s) is ADH2. In certain embodiments, the enzyme that includes an inactivating mutation(s) is ADH3. In certain embodiments, the enzyme that includes an inactivating mutation(s) is ADH4. In certain embodiments, the enzyme that includes an inactivating mutation(s) is ADH5. In certain embodiments, the enzyme that includes an inactivating mutation(s) is ADH6. In certain embodiments, the enzyme that includes an inactivating mutation(s) is ADH7. In some cases, the enzyme has aldehyde oxidoreductase activity. In certain embodiments, the enzyme that includes an inactivating mutation is selected from ALD2, ALD3, ALD4, ALD5, and ALD6. In certain embodiments, the enzyme that includes an inactivating mutation(s) is ALD2. In certain embodiments, the enzyme that includes an inactivating mutation(s) is ALD3. In certain embodiments, the enzyme that includes an inactivating mutation(s) is ALD4. In certain embodiments, the enzyme that includes an inactivating mutation(s) is ALD5. In certain embodiments, the enzyme that includes an inactivating mutation(s) is ALD6. In some embodiments, the host cell includes one or more inactivating mutations to one or more genes described in Table 3.
Epimerization Modifications
Some methods, processes, and systems provided herein describe the conversion of (S)-1-benzylisoquinoline alkaloids to (R)-1-benzylisoquinoline alkaloids. Some of these methods, processes, and systems may comprise an engineered host cell. In some examples, the conversion of (S)-1-benzylisoquinoline alkaloids to (R)-1-benzylisoquinoline alkaloids is a key step in the conversion of a substrate to a diverse range of alkaloids. In some examples, the conversion of (S)-1-benzylisoquinoline alkaloids to (R)-1-benzylisoquinoline alkaloids comprises an epimerization reaction. In some examples, the conversion of (S)-1-benzylisoquinoline alkaloids to (R)-1-benzylisoquinoline alkaloids comprises an epimerization reaction via an engineered epimerase. In some cases, epimerization of a substrate alkaloid may be performed by oxidizing an (S)-substrate to the corresponding Schiff base or imine intermediate, then stereospecifically reducing this intermediate to an (R)-product as provided in
In some examples, the conversion of the (S)-substrate to the (R)-product may involve at least one oxidation reaction and at least one reduction reaction. In some cases, an oxidation reaction is optionally followed by a reduction reaction. In some cases, at least one of the oxidation and reduction reactions is carried out in the presence of an enzyme. In some cases, at least one of the oxidation and reduction reactions is catalyzed by an enzyme. In some cases, the oxidation and reduction reactions are both carried out in the presence of at least one enzyme. In some cases, at least one enzyme is useful to catalyze the oxidation and reduction reactions. The oxidation and reduction reactions may be catalyzed by the same enzyme. In some cases, at least one of the oxidation and reduction reactions is catalyzed by an engineered epimerase. In some cases, the oxidation and reduction reactions are both carried out in the presence of an engineered fused epimerase. In some cases, the oxidation and reduction reactions are both carried out in the presence of an engineered split epimerase having a separately expressed oxidase component and reductase component, respectively. In some cases, an engineered epimerase is useful to catalyze the oxidation and reduction reactions. The oxidation and reduction reactions may be catalyzed by the same engineered epimerase.
In some methods, processes and systems described herein, an oxidation reaction may be performed in the presence of an enzyme. In some examples, the enzyme may be an oxidase. In some examples, the enzyme may be part of an engineered epimerase. In some examples, the engineered epimerase may have an oxidase component. In some cases, the oxidase component may be a component of an engineered fused epimerase. In some cases, the oxidase component may be independently expressed as part of an engineered split epimerase. The oxidase may use an (S)-1-benzylisoquinoline as a substrate. The oxidase may convert the (S)-substrate to a corresponding imine or Schiff base derivative. The oxidase may be referred to as 1,2-dehydroreticuline synthase (DRS). Non-limiting examples of enzymes suitable for oxidation of (S)-1-benzylisoquinoline alkaloids in this disclosure include a cytochrome P450 oxidase, a 2-oxoglutarate-dependent oxidase, and a flavoprotein oxidase. For example, (S)-tetrahydroprotoberberine oxidase (STOX, E.C 1.3.3.8) may oxidize (S)-norreticuline and other (S)-1-benzylisoquinoline alkaloids to 1,2-dehydronorreticuline and other corresponding 1,2-dehydro products. In some examples, a protein that comprises an oxidase domain of any one of the preceding examples may perform the oxidation. In some examples, the oxidase may catalyze the oxidation reaction within a host cell, such as an engineered host cell, as described herein.
In some examples, a reduction reaction may follow the oxidation reaction. In some examples, the reduction reaction may be performed by an enzyme. In some examples, the reduction reaction may be performed by an enzyme that is part of an engineered epimerase. In some examples, the reductase may use an imine or Schiff base derived from a 1-benzylisoquinoline as a substrate. The reductase may convert the imine or Schiff base derivative to an (R)-1-benzylisoquinoline. The reductase may be referred to as 1,2-dehydroreticuline reductase (DRR). Non-limiting examples of enzymes suitable for reduction of an imine or Schiff base derived from an (S)-1-benzylisoquinoline alkaloid include an aldo-keto reductase (e.g., a codeinone reductase-like enzyme (EC 1.1.1.247)) and a short chain dehydrogenase (e.g., a salutaridine reductase-like enzyme (EC 1.1.1.248)). In some examples, a protein that comprises a reductase domain of any one of the preceding examples may perform the reduction. In a further embodiment, the reduction is stereospecific. In some examples, the reductase may catalyze the reduction reaction within a host cell, such as an engineered host cell, as described herein.
An example of an enzyme that can perform an epimerization reaction that converts (S)-1-benzylisoquinoline alkaloids to (R)-1-benzylisoquinoline alkaloids includes an epimerase having an oxidase domain and a reductase domain. In particular, the epimerase may have a cytochrome P450 oxidase 82Y2-like domain. Additionally, the epimerase may have a codeinone reductase-like domain. Further, an epimerase having a cytochrome P450 oxidase 82Y2-like domain and also having a codeinone reductase-like domain may be referred to as a DRS-DRR enzyme. In particular, a DRS-DRR enzyme may be a fusion enzyme that is a fusion epimerase. Further, when a DRS-DRR enzyme is modified by at least one activity-increasing modification, the fusion enzyme may be an engineered fusion epimerase.
An example of an amino acid sequence of a DRS-DRR enzyme that may be used to perform the conversion of (S)-1-benzylisoquinoline alkaloids to (R)-1-benzylisoquinoline alkaloids is provided in
An engineered host cell may be provided that produces an epimerase that converts (S)-1-benzylisoquinoline alkaloid to (R)-1-benzylisoquinoline alkaloid, wherein the epimerase comprises an amino acid sequence selected from the group consisting of: SEQ ID NOs: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, and 15. The epimerase that is produced within the engineered host cell may be recovered and purified so as to form a biocatalyst. In some cases, the epimerase may be split into one or more enzymes. Additionally, one or more enzymes that are produced by splitting the epimerase may be recovered from the engineered host cell. These one or more enzymes that result from splitting the epimerase may also be used to catalyze the conversion of (S)-1-benzylisoquinoline alkaloids to (R)-1-benzylisoquinoline alkaloids. In particular, the one or more enzymes that are recovered from the engineered host cell that produces the epimerase may be used in a process for converting an (S)-1-benzylisoquinoline alkaloid to an (R)-1-benzylisoquinoline alkaloid. The process may include contacting the (S)-1-benzylisoquinoline alkaloid with an epimerase in an amount sufficient to convert said (S)-1-benzylisoquinoline alkaloid to (R)-1-benzylisoquinoline alkaloid. In examples, the (S)-1-benzylisoquinoline alkaloid may be contacted with a sufficient amount of the one or more enzymes such that at least 5% of said (S)-1-benzylisoquinoline alkaloid is converted to (R)-1-benzylisoquinoline alkaloid. In further examples, the (S)-1-benzylisoquinoline alkaloid may be contacted with a sufficient amount of the one or more enzymes such that at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 82%, at least 84%, at least 86%, at least 88%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5%, at least 99.7%, or 100% of said (S)-1-benzylisoquinoline alkaloid is converted to (R)-1-benzylisoquinoline alkaloid.
An example of an amino acid sequence of a DRS-DRR enzyme that may be used to perform the conversion of (S)-1-benzylisoquinoline alkaloids to (R)-1-benzylisoquinoline alkaloids is provided in
Amino acid residues of homologous epimerases may be referenced according to the numbering scheme of SEQ ID NO. 16, and this numbering system is used throughout the disclosure to refer to specific amino acid residues of epimerases which are homologous to SEQ ID NO. 16. Epimerases homologous to SEQ ID NO. 16 may have at least about 70%, 75%, 80%, 85%, 90%, 95%, 97%, 98%, or 99% sequence identity to SEQ ID NO. 16. In some cases, an amino acid referred to as position 50 in a homologous epimerase may not be the 50th amino acid in the homologous epimerase, but would be the amino acid which corresponds to the amino acid at position 50 in SEQ ID NO. 16 in a protein alignment of the homologous epimerase with SEQ ID NO. 16. In some cases, homologous enzymes may be aligned with SEQ ID NO. 16 either according to primary sequence, secondary structure, or tertiary structure.
An engineered host cell may be provided that produces an engineered epimerase that converts (S)-1-benzylisoquinoline alkaloid to (R)-1-benzylisoquinoline alkaloid, wherein the epimerase comprises an amino acid sequence selected from the group consisting of: SEQ ID NOs: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, and 18, and having one or more activity-enhancing modifications. The epimerase that is produced within the engineered host cell may be recovered and purified so as to form a biocatalyst. In some cases, the epimerase may be split into one or more enzymes. Additionally, one or more enzymes that are produced by splitting the epimerase may be recovered from the engineered host cell. These one or more enzymes that result from splitting the epimerase may also be used to catalyze the conversion of (S)-1-benzylisoquinoline alkaloids to (R)-1-benzylisoquinoline alkaloids. Additionally, the use of an engineered split epimerase may be used to increase the production of benzylisoquinoline alkaloid products within a cell when compared to the production of benzylisoquinoline alkaloid products within a cell utilizing a fused epimerase.
In additional cases, the one or more enzymes that are recovered from the engineered host cell that produces the epimerase may be used in a process for converting an (S)-1-benzylisoquinoline alkaloid to an (R)-1-benzylisoquinoline alkaloid. The process may include contacting the (S)-1-benzylisoquinoline alkaloid with an epimerase in an amount sufficient to convert said (S)-1-benzylisoquinoline alkaloid to (R)-1-benzylisoquinoline alkaloid. In examples, the (S)-1-benzylisoquinoline alkaloid may be contacted with a sufficient amount of the one or more enzymes such that at least 5% of said (S)-1-benzylisoquinoline alkaloid is converted to (R)-1-benzylisoquinoline alkaloid. In further examples, the (S)-1-benzylisoquinoline alkaloid may be contacted with a sufficient amount of the one or more enzymes such that at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 82%, at least 84%, at least 86%, at least 88%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5%, at least 99.7%, or 100% of said (S)-1-benzylisoquinoline alkaloid is converted to (R)-1-benzylisoquinoline alkaloid.
The one or more enzymes that may be used to convert an (S)-1-benzylisoquinoline alkaloid to an (R)-1-benzylisoquinoline alkaloid may contact the (S)-1-benzylisoquinoline alkaloid in vitro. Additionally, or alternatively, the one or more enzymes that may be used to convert an (S)-1-benzylisoquinoline alkaloid to an (R)-1-benzylisoquinoline alkaloid may contact the (S)-1-benzylisoquinoline alkaloid in vivo. Additionally, the one or more enzymes that may be used to convert an (S)-1-benzylisoquinoline alkaloid to an (R)-1-benzylisoquinoline alkaloid may be provided to a cell having the (S)-1-benzylisoquinoline alkaloid within, or may be produced within an engineered host cell.
In some examples, the methods provide for engineered host cells that produce an alkaloid product, wherein the epimerization of an (S)-substrate to an (R)-product may comprise a key step in the production of an alkaloid product. In some examples, the alkaloid produced is an (R)-1-benzylisoquinoline alkaloid. In still other embodiments, the alkaloid produced is derived from an (R)-1-benzylisoquinoline alkaloid, including, for example, 4-ring promorphinan and 5-ring morphinan alkaloids. In another embodiment, an (S)-1-benzylisoquinoline alkaloid is an intermediate toward the product of the engineered host cell. In still other embodiments, the alkaloid product is selected from the group consisting of 1-benzylisoquinoline, morphinan, promorphinan, nor-opioid, or nal-opioid alkaloids.
In some examples, the (S)-substrate is an (S)-1-benzylisoquinoline alkaloid selected from the group consisting of (S)-norreticuline, (S)-reticuline, (S)-tetrahydropapaverine, (S)-norcoclaurine, (S)-coclaurine, (S)—N-methylcoclaurine, (S)-3′-hydroxy-N-methylcoclaurine, (S)-norisoorientaline, (S)-orientaline, (S)-isoorientaline, (S)-norprotosinomenine, (S)-protosinomenine, (S)-norlaudanosoline, (S)-laudanosoline, (S)-4′-O-methyllaudanosoline, (S)-6-O-methylnorlaudanosoline, (S)-4′-O-methylnorlaudanosoline.
In some examples, the (S)-substrate is a compound of Formula I:
In some other examples, at least one of R1, R2, R3, R4, and R5 is hydrogen.
In still other examples, the (S)-substrate is a compound of Formula II:
When a bond is drawn across a ring, it means substitution may occur at a non-specific ring atom or position. For example, in Formula II shown above, the hydrogen of any —CH— in the 6-membered ring may be replaced with R7 to form —CR′—.
In some examples, R6 and R7 are independently methyl or methoxy. In some other examples, n and n′ are independently 1 or 2. In still other embodiments, R3 is hydrogen or methyl.
In some examples, the methods provide for engineered host cells that produce alkaloid products from (S)-reticuline. The epimerization of (S)-reticuline to (R)-reticuline may comprise a key step in the production of diverse alkaloid products from a precursor. In some examples, the precursor is L-tyrosine or a sugar (e.g., glucose). The diverse alkaloid products can include, without limitation, 1-benzylisoquinoline, morphinan, promorphinan, nor-opioid, or nal-opioid.alkaloids.
Any suitable carbon source may be used as a precursor toward an epimerized 1-benzylisoquinoline alkaloid. Suitable precursors can include, without limitation, monosaccharides (e.g., glucose, fructose, galactose, xylose), oligosaccharides (e.g., lactose, sucrose, raffinose), polysaccharides (e.g., starch, cellulose), or a combination thereof. In some examples, unpurified mixtures from renewable feedstocks can be used (e.g., cornsteep liquor, sugar beet molasses, barley malt, biomass hydrolysate). In still other embodiments, the carbon precursor can be a one-carbon compound (e.g., methanol, carbon dioxide) or a two-carbon compound (e.g., ethanol). In yet other embodiments, other carbon-containing compounds can be utilized, for example, methylamine, glucosamine, and amino acids (e.g., L-tyrosine). In some examples, a 1-benzylisoquinoline alkaloid may be added directly to an engineered host cell of the invention, including, for example, norlaudanosoline, laudanosoline, norreticuline, and reticuline. In still further embodiments, a 1-benzylisoquinoline alkaloid may be added to the engineered host cell as a single enantiomer (e.g., an (S)-1-benzylisoquinoline alkaloid), or a mixture of enantiomers, including, for example, a racemic mixture.
In some examples, the methods provide for the epimerization of a stereocenter of a 1-benzylisoquinoline alkaloid, or a derivative thereof. In a further embodiment, the method comprises contacting the 1-benzylisoquinoline alkaloid with at least one enzyme. The at least one enzyme may invert the stereochemistry of a stereocenter of a 1-benzylisoquinoline alkaloid, or derivative thereof, to the opposite stereochemistry. In some examples, the at least one enzyme converts an (S)-1-benzylisoquinoline alkaloid to an (R)-1-benzylisoquinoline alkaloid. In some examples of this conversion of an (S)-1-benzylisoquinoline alkaloid to an (R)-1-benzylisoquinoline alkaloid utilizing the at least one enzyme, the (S)-1-benzylisoquinoline alkaloid is selected from the group consisting of (S)-norreticuline, (S)-reticuline, (S)-tetrahydropapaverine, (S)-norcoclaurine, (S)-coclaurine, (S)—N-methylcoclaurine, (S)-3′-hydroxy-N-methylcoclaurine, (S)-norisoorientaline, (S)-orientaline, (S)-isoorientaline, (S)-norprotosinomenine, (S)-protosinomenine, (S)-norlaudanosoline, (S)-laudanosoline, (S)-4′-O-methyllaudanosoline, (S)-6-O-methylnorlaudanosoline, and (S)-4′-O-methylnorlaudanosoline.
In still other embodiments, the 1-benzylisoquinoline alkaloid that is epimerized may comprise two or more stereocenters, wherein only one of the two or more stereocenters is inverted to produce a diastereomer of the substrate (e.g., (S, R)-1-benzylisoquinoline alkaloid converted to (R, R)-1-benzylisoquinoline alkaloid). In examples where only one stereocenter of a 1-benzylisoquinoline alkaloid is inverted when contacted with the at least one enzyme, the product is referred to as an epimer of the 1-benzylisoquinoline alkaloid.
In some examples, the 1-benzylisoquinoline alkaloid is presented to the enzyme as a single stereoisomer. In some other examples, the 1-benzylisoquinoline alkaloid is presented to the enzyme as a mixture of stereoisomers. In still further embodiments, the mixture of stereoisomers may be a racemic mixture. In some other examples, the mixture of stereoisomers may be enriched in one stereoisomer as compared to another stereoisomer.
In some examples, an 1-benzylisoquinoline alkaloid, or a derivative thereof, is recovered. In some examples, the 1-benzylisoquinoline alkaloid is recovered from a cell culture. In still further embodiments, the recovered 1-benzylisoquinoline alkaloid is enantiomerically enriched in one stereoisomer as compared to the original mixture of 1-benzylisoquinoline alkaloids presented to the enzyme. In still further embodiments, the recovered 1-benzylisoquinoline alkaloid has an enantiomeric excess of at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 82%, at least 84%, at least 86%, at least 88%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5%, at least 99.7%, or 100%.
In some examples, a promorphinan, or a derivative thereof, is recovered. In some examples, the promorphinan is recovered from a cell culture.
In some examples, a morphinan, or a derivative thereof, is recovered. In some examples, the morphinan is recovered from a cell culture.
In some examples, a nal-opioid, or a derivative thereof, is recovered. In some examples, the nal-opioid is recovered from a cell culture.
In some examples, a nor-opioid, or a derivative thereof, is recovered. In some examples, the nor-opioid is recovered from a cell culture.
“Isomers” are different compounds that have the same molecular formula. “Stereoisomers” are isomers that differ only in the way the atoms are arranged in space. “Enantiomers” are a pair of stereoisomers that are non superimposable mirror images of each other. A 1:1 mixture of a pair of enantiomers is a “racemic” mixture. “Diastereoisomers” or “diastereomers” are stereoisomers that have at least two asymmetric atoms but are not mirror images of each other. The term “epimer” as used herein refers to a compound having the identical chemical formula but a different optical configuration at a particular position. For example, the (R,S) and (S,S) stereoisomers of a compound are epimers of one another. In some examples, a 1-benzylisoquinoline alkaloid is converted to its epimer (e.g., epi-1-benzylisoquinoline alkaloid). The absolute stereochemistry is specified according to the Cahn-Ingold-Prelog R-S system. When a compound is a pure enantiomer, the stereochemistry at each chiral carbon can be specified by either R or S. Resolved compounds whose absolute configuration is unknown can be designated (+) or (−) depending on the direction (dextro- or levorotatory) in which they rotate plane polarized light at the wavelength of the sodium D line. Certain compounds described herein contain one or more asymmetric centers and can thus give rise to enantiomers, diastereomers, and other stereoisomeric forms that can be defined, in terms of absolute stereochemistry, as (R)- or (S)-.
P. somniferum
P. somniferum
P. somniferum
P. somniferum
P. setigerum
P. setigerum
P. bracteatum
P. bracteatum
P. bracteatum
P. bracteatum
P. bracteatum
P. bracteatum
P. bracteatum
P. bracteatum
C. majus plant
P. bracteatum
P. bracteatum
P. bracteatum
Morphinan Alkaloid Generating Modifications
Some methods, processes, and systems provided herein describe the conversion of promorphinan alkaloids to morphinan alkaloids. Some of the methods, processes, and systems describe the conversion of a tetracyclic scaffold to a pentacyclic scaffold (
In some examples, the tetracyclic precursor may be salutaridine, salutaridinol, or salutaridinol-7-O-acetate. The tetracyclic precursor may be converted to pentacyclic thebaine by closure of an oxide bridge between C-4 and C-5. In some examples, the tetracyclic precursor salutaridine may be prepared for ring closure by stepwise hydroxylation and O-acetylation at C-7. Ring closure may be activated by elimination of an acetate leaving group. In some examples, the allylic elimination and oxide ring closure that generates thebaine occurs spontaneously. In other examples, the ring closure reaction that generates pentacyclic thebaine is promoted by factors such as pH or solvent. In other examples, the thebaine-generating ring closure reaction is promoted by contact with a protein or enzyme. These conversion steps are provided in
In some examples, the first enzyme that prepares the tetracyclic precursor is salutaridine reductase (SalR). In some cases, SalR hydroxylates the substrate salutaridine at the C-7 position (see Formula III). The product of this reaction may be one or more salutaridinol epimers. In some examples, the product is (7S)-salutaridinol. In some examples, the salutaridine reductase may catalyze the reduction reaction within a host cell, such as an engineered host, as described herein.
In some examples, the second enzyme that prepares the tetracyclic precursor is salutaridinol 7-O-acetyltransferase (SalAT). In some cases, SalAT transfers the acetyl from acetyl-CoA to the 7-OH of salutaridinol (see Formula IV). In other cases, SalAT may utilize a novel cofactor such as n-propionyl-CoA and transfer the propionyl to the 7-OH of salutaridinol. In some examples, the product of SalAT is (7S)-salutaridinol-7-O-acetate. In some examples, the salutaridinol 7-O-acetyltransferase may catalyze the acetyl transfer reaction within a host cell, such as an engineered host, as described herein.
In some examples, the tetracyclic precursor of thebaine is (7S)-salutaridinol-7-O-acetate. In some examples (7S)-salutaridinol-7-O-acetate is unstable and spontaneously eliminates the acetate at C-7 and closes the oxide bridge between C-4 and C-5 to form thebaine (see Formula V). In some examples, the rate of elimination of the acetate leaving group is promoted by pH. In some examples, the allylic elimination and oxide bridge closure is catalyzed by an enzyme with thebaine synthase activity, or a thebaine synthase. In some examples, this enzyme is a Bet v 1-fold protein. In some examples, this enzyme is an engineered thebaine synthase, an engineered SalAT, a dirigent (DIR) protein, or a chalcone isomerase (CHI). In some examples, the enzyme encoding thebaine synthase activity may catalyze the ring closure reaction within a host cell, such as an engineered host, as described herein.
In some examples, the salutaridine reductase enzyme may be SalR or a SalR-like enzyme from plants in the Ranunculales order that biosynthesize thebaine, for example Papaver somniferum. In other examples, the enzyme with salutaridine reductase activity may be from mammals or any other vertebrate or invertebrate that biosynthesizes endogenous morphine.
In some examples, the salutaridinol 7-O-acetyltransferase enzyme may be SalAT or a SalAT-like enzyme from plants in the Ranunculales order that biosynthesize thebaine, for example P. somniferum. In other examples, the enzyme with salutaridinol 7-O-acetyltransferase activity may be from mammals or any other vertebrate or invertebrate that biosynthesizes endogenous morphine.
In some examples, the thebaine synthase enzyme may be a Bet v 1 fold protein from plants in the Ranunculales order that biosynthesize thebaine, for example P. somniferum. In some examples, the Bet v 1 protein includes the following domains in order from the N-terminus to C-terminus: a β-strand, one or two α-helices, six β-strands, and one or two α-helices. The protein is organized such that it has a Bet v 1 fold and an active site that accepts large, bulky, hydrophobic molecules, such as morphinan alkaloids. This protein may be any plant Bet v 1 protein, pathogenesis-related 10 protein (PR-10), a major latex protein (MLP), fruit or pollen allergen, plant hormone binding protein (e.g., binding to cytokinin or brassinosteroids), plant polyketide cyclase-like protein, or norcoclaurine synthase (NCS)-related protein that has a Bet v 1 fold. Other non-plant examples of the Bet v 1 fold protein are polyketide cyclases, activator of Hsp90 ATPase homolog 1 (AHA1) proteins, SMU440-like proteins (e.g., from Streptococcus mutans), PA1206-related proteins (e.g., from Pseudomonas aeruginosa), CalC calicheamicin resistance protein (e.g., from Micromonospora echinospora), and the CoxG protein from carbon monoxide metabolizing Oligotropha carboxidovorans. Further examples from Bet v 1-related families include START lipid transfer proteins, phosphatidylinositol transfer proteins, and ring hydroxylases.
In some examples, the thebaine synthase enzyme may be a dirigent protein from plants in the Ranunculales order that biosynthesize thebaine, for example P. somniferum. In other examples, the enzyme may be any dirigent protein from plants.
In some examples, the thebaine synthase enzyme may be a chalcone isomerase protein from plants in the Ranunculales order that biosynthesize thebaine, for example P. somniferum. In other examples, the enzyme may be any chalcone isomerase protein from plants.
In some examples, the thebaine synthase enzyme may be a SalAT-like enzyme from plants in the Ranunculales order that biosynthesize thebaine, for example P. somniferum. In other examples, the enzyme may be any SalAT-like protein from plants.
In some examples, the enzyme with thebaine synthase activity may be from mammals or any other vertebrate or invertebrate that biosynthesizes endogenous morphine.
In some examples, any combination of the above enzymes together with additional accessory proteins may function to convert any tetracyclic precursor into thebaine. In some examples, these enzymes catalyze the reactions within a host cell, such as an engineered host, as described herein.
Examples of amino acid sequences for thebaine synthase activity are set forth in Table 2. An amino acid sequence for a thebaine synthase that is utilized in a tetracyclic precursor to thebaine may be 45% or more identical to a given amino acid sequence as listed in Table 2. For example, an amino acid sequence for such a thebaine synthase may comprise an amino acid sequence that is at least 45% or more, 46% or more, 47% or more, 48% or more, 49% or more, 50% or more, 51% or more, 52% or more, 53% or more, 54% or more, 55% or more, 56% or more, 57% or more, 58% or more, 59% or more, 60% or more, 61% or more, 62% or more, 63% or more, 64% or more, 65% or more, 66% or more, 67% or more, 68% or more, 69% or more, 70% or more, 71% or more, 72% or more, 73% or more, 74% or more, 75% or more, 76% or more, 77% or more, 78% or more, 79% or more, 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more identical to an amino acid sequence as provided herein. Additionally, in certain embodiments, an “identical” amino acid sequence contains at least 80%-99% identity at the amino acid level to the specific amino acid sequence. In some cases an “identical” amino acid sequence contains at least about 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94% and more in certain cases, at least 95%, 96%, 97%, 98% and 99% identity, at the amino acid level. In some cases, the amino acid sequence may be identical but the DNA sequence is altered such as to optimize codon usage for the host organism, for example.
An engineered host cell may be provided that produces a salutaridine reductase, salutaridinol 7-O-acetyltransferase, and thebaine synthase that converts a tetracyclic precursor into thebaine, wherein the thebaine synthase comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 30, 31, 32, 33, 34, 35, 36, and 37. In some cases, the thebaine synthase may form a fusion protein with other enzymes. The enzymes that are produced within the engineered host cell may be recovered and purified so as to form a biocatalyst. These one or more enzymes may also be used to catalyze the conversion of a tetracyclic promorphinan precursor to thebaine.
In other examples, the thebaine synthase comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, and 61.
In additional cases, the one or more enzymes that are recovered from the engineered host cell may be used in a process for converting a tetracyclic promorphinan precursor to a thebaine. The process may include contacting the tetracyclic promorphinan precursor with the recovered enzymes in an amount sufficient to convert said tetracyclic promorphinan precursor to thebaine. In examples, the tetracyclic promorphinan precursor may be contacted with a sufficient amount of the one or more enzymes such that at least 5% of said tetracyclic promorphinan precursor is converted to thebaine. In further examples, the tetracyclic promorphinan precursor may be contacted with a sufficient amount of the one or more enzymes such that at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 80%, at least 82%, at least 84%, at least 86%, at least 88%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5%, at least 99.7%, or 100% of said tetracyclic promorphinan precursor is converted to thebaine.
In some examples, process conditions are implemented to support the formation of thebaine in engineered host cells. In some cases, engineered host cells are grown at pH 3.3, and once high cell density is reached the pH is adjusted to pH 8.0 to support continued production of thebaine at higher pH. In some cases, the engineered host cells produce additional enzymes to convert sugar and other simple precursors, such as tyrosine, to thebaine. In some cases, the SalAT enzyme has been engineered to exhibit higher activity at pH 8.0 and is expressed from a late stage promoter.
In some examples, one or more of the enzymes converting a tetracyclic promorphinan precursor to a thebaine are localized to cellular compartments. In some examples, SalR, SalAT, and Bet v 1 may be modified such that they encode targeting sequences that localize them to the endoplasmic reticulum membrane of the engineered host cell (see for example WO2014143744). In other examples, SalAT and Bet v 1 may be co-localized in to a single protein fusion. In some examples, the fusion is created between SalAT and Bet v 1 by one of several methods, including, direct fusion, co-localization to a yeast organelle, or by enzyme co-localization tools such as leucine zippers, protein scaffolds that utilize adaptor domains, or RNA scaffolds that utilize aptamers. Co-localizing the thebaine synthesis enzyme may facilitate substrate channeling between the active sites of the enzymes and limit the diffusion of unstable intermediates such as salutaridinol-7-O-acetate.
In some examples, an engineered salutaridinol 7-O-acetyltransferase (SalAT) enzyme is used in converting a tetracyclic promorphinan precursor to a thebaine. In some examples, a SalAT enzyme is engineered to combine two functions: (1) the transfer of an acyl group from acetyl-CoA to the 7-OH of salutaridinol, and (2) the subsequent elimination of the acetyl group and closure of an oxide bridge between carbons C4 and C5 to form thebaine.
In some examples, an enzyme with salutaridinol 7-O-acetyltransferase activity is fused to a peptide with a Bet v 1 fold. In some examples, salutaridinol 7-O-acetyltransferase enzyme and the Bet v 1 fold protein may be fused in any order from N-terminus to C-terminus, C-terminus to N-terminus, N-terminus to N-terminus, or C-terminus to C-terminus. In some examples, the two protein sequences may be fused directly or fused through a peptide linker region.
In some examples, an enzyme with salutaridinol 7-O-acetyltransferase activity is fused to a peptide with a Bet v 1 fold by circular permutation. In some cases, the N- and C-termini of SalAT are fused and the Bet v 1 sequence is then inserted randomly within this sequence. In some cases, the resulting fusion protein library is screened for thebaine production. In other cases, a circular permutation SalAT library is first screened for activity in the absence of Bet v 1. In other cases, the N- and C-termini of SalAT are fused and the enzyme is digested and blunt end cloned. In other cases, this library of circularly permuted SalAT is screened for salutaridinol 7-O-acetyltransferase activity. In other cases, active variants from the circularly permuted SalAT library are then used to design protein fusions with a peptide with a Bet v 1 fold.
The one or more enzymes that may be used to convert a tetracyclic promorphinan precursor to a thebaine may contact the tetracyclic promorphinan precursor in vitro. Additionally, or alternatively, the one or more enzymes that may be used to convert a tetracyclic promorphinan precursor to thebaine may contact the tetracyclic promorphinan precursor in vivo. Additionally, the one or more enzymes that may be used to convert a tetracyclic promorphinan precursor to thebaine may be provided to a cell having the tetracyclic promorphinan precursor within, or may be produced within an engineered host cell.
In some examples, the methods provide for engineered host cells that produce an alkaloid product, wherein the conversion of a tetracyclic promorphinan precursor to a thebaine may comprise a key step in the production of an alkaloid product. In some examples, the alkaloid product is a thebaine. In still other embodiments, the alkaloid product is derived from a thebaine, including for example, downstream morphinan alkaloids. In another embodiment, a tetracyclic promorphinan precursor is an intermediate toward the product in of the engineered host cell. In still other embodiments, the alkaloid product is selected from the group consisting of morphinan, nor-opioid, or nal-opioid alkaloids.
In some examples, the substrate of the reduction reaction is a compound of Formula III:
In some other examples, R1, R2, and R3 are methyl, and the reduction reaction is catalyzed by a salutaridine reductase.
In some examples, the substrate of the carbon chain transfer reaction is a compound of Formula IV:
In some other examples, R1, R2, and R3 are methyl, and the carbon chain transfer reaction is catalyzed by a salutaridinol 7-O-acetyltransferase.
In some examples, the substrate of thebaine synthase is a compound of Formula V:
In some other examples, R1, R2, R3, and R4 are methyl, and the ring closure reaction is catalyzed by a thebaine synthase. In some examples, the thebaine synthase is a Bet v 1 protein.
In some examples, the methods provide for engineered host cells that produce alkaloid products from salutaridine. The conversion of salutardine to thebaine may comprise a key step in the production of diverse alkaloid products from a precursor. In some examples, the precursor is L-tyrosine or a sugar (e.g., glucose). The diverse alkaloid products can include, without limitation, morphinan, nor-opioid, or nal-opioid alkaloids.
Any suitable carbon source may be used as a precursor toward a pentacyclic morphinan alkaloid. Suitable precursors can include, without limitation, monosaccharides (e.g., glucose, fructose, galactose, xylose), oligosaccharides (e.g., lactose, sucrose, raffinose), polysaccharides (e.g., starch, cellulose), or a combination thereof. In some examples, unpurified mixtures from renewable feedstocks can be used (e.g., cornsteep liquor, sugar beet molasses, barley malt, biomass hydrolysate). In still other embodiments, the carbon precursor can be a one-carbon compound (e.g., methanol, carbon dioxide) or a two-carbon compound (e.g., ethanol). In yet other embodiments, other carbon-containing compounds can be utilized, for example, methylamine, glucosamine, and amino acids (e.g., L-tyrosine). In some examples, a 1-benzylisoquinoline alkaloid may be added directly to an engineered host cell of the invention, including, for example, norlaudanosoline, laudanosoline, norreticuline, and reticuline.
In some examples, the benzylisoquinoline alkaloid product, or a derivative thereof, is recovered. In some examples, the benzylisoquinoline alkaloid product is recovered from a cell culture. In some examples, the benzylisoquinoline alkaloid product is a morphinan, nor-opioid, or nal-opioid alkaloid.
P.
bracteatum
P. setigerum
P. setigerum
P. setigerum
P. setigerum
P.
somniferum
P.
somniferum
P.
somniferum
P.
somniferum
P.
somniferum
P. setigerum
P.
somniferum
P. setigerum
P. setigerum
P. setigerum
P.
somniferum
P.
somniferum
P. setigerum
P.
somniferum
P.
somniferum
P. setigerum
P. rhoeas
P.
bracteatum
P.
bracteatum
P. ginseng
A. hypogaea
H.
perforatum
L. luteus
ananassa)
A. deliciosa
T. flavum
V. radiata
BIA Generating Modifications
Once BIAs are formed, the BIAs may be further derivatized or modified. The BIAs may be derivatized or modified utilizing one or more enzymes that are produced by the engineered host cell. In particular, the BIAs may be derivatized or modified by contacting the BIAs with one or more enzymes that are produced by the engineered host cell. Additionally or alternatively, the BIAs may be derivatized or modified by contacting the BIAs with one or more enzymes that are provided to the BIAs from a source that is external to the engineered host cell. The one or more enzymes that may be used to derivatize or modify the BIAs may be used to perform tailoring reactions. Examples of tailoring reactions include oxidation, reduction, O-methylation, N-methylation, O-demethylation, acetylation, methylenedioxybridge formation, and O,O-demethylenation. A BIA may be derivatized or modified using one or more tailoring reactions.
Examples of tailoring reactions are provided in Table 9. In some examples, tailoring enzymes may be used to catalyze carbon-carbon coupling reactions performed on a BIA, or a derivative thereof. Examples of tailoring enzymes that may be used to catalyze carbon-carbon coupling reactions include a Berberine bridge enzyme (BBE) from Papaver somniferum, Eschscholzia californica, Coptis japonica, Berberis stolonifer, Thalictrum flavum, or another species; Salutaridine synthase (SalSyn) from Papaver somniferum or another species; and Corytuberine synthase (CorSyn) from Coptis japonica or another species. Non-limiting examples of reactions that can be catalyzed by tailoring enzymes are shown in Scheme 3, wherein Ra, Rb, Rc, and Rd are independently selected from hydrogen, hydroxy, fluoro, chloro, bromo, carboxaldehyde, C1-C4 acyl, C1-C4 alkyl, and C1-C4 alkoxy. In some examples, Ra, Rb, and the carbon atoms to which they are attached optionally form a carbocycle or heterocycle. In some examples, Rc, Rd, and the carbon atoms to which they are attached optionally form a carbocycle or heterocycle.
In some examples, tailoring enzymes may be used to catalyze oxidation reactions performed on a BIA, or a derivative thereof. Examples of tailoring enzymes that may be used to catalyze oxidation reactions include a Tetrahydroprotoberberine oxidase (STOX) from Coptis japonica, Argemone mexicana, Berberis wilsonae, or another species; Dihydrobenzophenanthridine oxidase (DBOX) from Papaver somniferum or another species; Methylstylopine hydroxylase (MSH) from Papaver somniferum or another species; and Protopine 6-hydroxylase (P6H) from Papaver somniferum, Eschscholzia californica, or another species.
Tailoring enzymes may also be used to catalyze methylenedioxy bridge formation reactions performed on a BIA, or a derivative thereof. Examples of tailoring enzymes that may be used to catalyze methylenedioxy bridge formation reactions include a Stylopine synthase (StySyn) from Papaver somniferum, Eschscholzia californica, Argemone mexicana, or another species; Cheilanthifoline synthase (CheSyn) from Papaver somniferum, Eschscholzia californica, Argemone mexicana, or another species; and Canadine synthase (CAS) from Thalictrum flavum, Coptis chinensis, or another species.
In other examples, tailoring enzymes may be used to catalyze O-methylation reactions performed on a BIA, or a derivative thereof. Examples of tailoring enzymes that may be used to catalyze O-methylation reactions include a Norcoclaurine 6-O-methyltransferase (6OMT) from Papaver somniferum, Thalictrum flavum, Coptis japonica, Papaver bracteatum, or another species; 3′hydroxy-N-methylcoclaurine 4′-O-methyltransferase (4′OMT) from Papaver somniferum, Thalictrum flavum, Coptis japonica, Coptis chinensis, or another species; Reticuline 7-O-methyltransferase (7OMT) from Papaver somniferum, Eschscholzia californica, or another species; and Scoulerine 9-O-methyltransferase (9OMT) from Papaver somniferum, Thalictrum flavum, Coptis japonica, Coptis chinensis, or another species.
Additionally, tailoring enzymes may be used to catalyze N-methylation reactions performed on a BIA, or a derivative thereof. Examples of tailoring enzymes that may be used to catalyze N-methylation reactions include Coclaurine N-methyltransferase (CNMT) from Papaver somniferum, Thalictrum flavum, Coptis japonica, or another species; Tetrahydroprotoberberine N-methyltransferase (TNMT) from Papaver somniferum, Eschscholzia californica, Papaver bracteatum, or another species.
Further, tailoring enzymes may be used to catalyze O-demethylation reactions performed on a BIA, or a derivative thereof. Examples of tailoring enzymes that may be used to catalyze O-demethylation reactions include Thebaine demethylase (T6ODM) from Papaver somniferum or another species; and Codeine demethylase (CODM) from Papaver somniferum, or another species.
Tailoring enzymes may also be used to catalyze reduction reactions performed on a BIA, or a derivative thereof. Examples of tailoring enzymes that may be used to catalyze reduction reactions include Salutaridine reductase (SalR) from Papaver somniferum, Papaver bracteatum, or another species; Codeinone reductase (COR) from Papaver somniferum or another species; and Sanguinarine reductase (SanR) from Eschscholzia californica or another species. In other examples, tailoring enzymes may be used to catalyze acetylation reactions performed on a BIA, or a derivative thereof. An example of a tailoring enzyme that may be used to catalyze acetylation reactions includes Salutaridine acetyltransferase (SalAT) from Papaver somniferum or another species.
O-Demethylation Modifications
Some methods, processes, and systems provided herein describe the conversion of a first benzylisoquinoline alkaloid to a second benzylisoquinoline alkaloid by the removal of an 0-linked methyl group. Some of these methods, processes, and systems may comprise an engineered host cell. In some examples, the conversion of a first benzylisoquinoline alkaloid to a second benzylisoquinoline alkaloid is a key step in the conversion of a substrate to a nor-opioids or nal-opioids. In some examples, the conversion of a first alkaloid to a second alkaloid comprises a demethylase reaction.
Examples of amino acid sequences of ODM enzymes are set forth in Table 4. An amino acid sequence for an ODM that is utilized in converting a first alkaloid to a second alkaloid may be 75% or more identical to a given amino acid sequence as listed in Table 4. For example, an amino acid sequence for such an epimerase may comprise an amino acid sequence that is at least 75% or more, 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more identical to an amino acid sequence as provided herein. Additionally, in certain embodiments, an “identical” amino acid sequence contains at least 80%-99% identity at the amino acid level to the specific amino acid sequence. In some cases an “identical” amino acid sequence contains at least about 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94% and more in certain cases, at least 95%, 96%, 97%, 98% and 99% identity, at the amino acid level. In some cases, the amino acid sequence may be identical but the DNA sequence is altered such as to optimize codon usage for the host organism, for example.
An engineered host cell may be provided that produces an ODM that converts a first alkaloid to a second alkaloid, wherein the ODM comprises a given amino acid sequence as listed in Table 4. An engineered host cell may be provided that produces one or more ODM enzymes. The ODM that is produced within the engineered host cell may be recovered and purified so as to form a biocatalyst. The process may include contacting the first alkaloid with an ODM in an amount sufficient to convert said first alkaloid to a second alkaloid. In examples, the first alkaloid may be contacted with a sufficient amount of the one or more enzymes such that at least 5% of said first alkaloid is converted to a second alkaloid. In further examples, the first alkaloid may be contacted with a sufficient amount of the one or more enzymes such that at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 82%, at least 84%, at least 86%, at least 88%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5%, at least 99.7%, or 100% of said first alkaloid is converted to a second alkaloid.
The one or more enzymes that may be used to convert a first alkaloid to a second alkaloid may contact the first alkaloid in vitro. Additionally, or alternatively, the one or more enzymes that may be used to convert a first alkaloid to a second alkaloid may contact the first alkaloid in vivo. In some examples, the one or more enzymes that may be used to convert a first alkaloid to a second alkaloid may be provided to a cell having the first alkaloid within. In some examples, the one or more enzymes that may be used to convert a first alkaloid to a second alkaloid may be produced within an engineered host cell.
In some examples, the methods provide for engineered host cells that produce an alkaloid product, wherein the O-demethylation of a substrate to a product may comprise a key step in the production of an alkaloid product. In some examples, the alkaloid produced is a nor-opioid or a nal-opioid. In still other embodiments, the alkaloid produced is derived from a nor-opioid or a nal-opioid. In another embodiment, a first alkaloid is an intermediate toward the product of the engineered host cell. In still other embodiments, the alkaloid product is selected from the group consisting of morphine, oxymorphine, oripavine, hydromorphone, dihydromorphine, 14-hydroxymorphine, morphinone, and 14-hydroxymorphinone.
In some examples, the substrate alkaloid is an opioid selected from the group consisting of codeine, oxycodone, thebaine, hydrocodone, dihydrocodeine, 14-hydroxycodeine, codeinone, and 14-hydroxycodeinone.
N-Demethylation Modifications
Some methods, processes, and systems provided herein describe the conversion of a first alkaloid to a second alkaloid by the removal of an N-linked methyl group. Some of these methods, processes, and systems may comprise an engineered host cell. In some examples, the conversion of a first alkaloid to a second alkaloid is a key step in the conversion of a substrate to a nor-opioids or nal-opioids. In some examples, the conversion of a first alkaloid to a second alkaloid comprises a demethylase reaction.
Examples of an amino acid sequence of an N-demethylase enzyme that may be used to perform the conversion a first alkaloid to a second alkaloid are provided in Table 5. An amino acid sequence for an NDM that is utilized in converting a first alkaloid to a second alkaloid may be 75% or more identical to a given amino acid sequence as listed in Table 5. For example, an amino acid sequence for such an epimerase may comprise an amino acid sequence that is at least 75% or more, 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more identical to an amino acid sequence as provided herein. Additionally, in certain embodiments, an “identical” amino acid sequence contains at least 80%-99% identity at the amino acid level to the specific amino acid sequence. In some cases an “identical” amino acid sequence contains at least about 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94% and more in certain cases, at least 95%, 96%, 97%, 98% and 99% identity, at the amino acid level. In some cases, the amino acid sequence may be identical but the DNA sequence is altered such as to optimize codon usage for the host organism, for example.
An engineered host cell may be provided that produces an NDM that converts a first alkaloid to a second alkaloid, wherein the NDM comprises an amino acid sequence as listed in Table 5. An engineered host cell may be provided that produces one or more NDM enzymes. The NDM that is produced within the engineered host cell may be recovered and purified so as to form a biocatalyst. The process may include contacting the first alkaloid with an NDM in an amount sufficient to convert said first alkaloid to a second alkaloid. In examples, the first alkaloid may be contacted with a sufficient amount of the one or more enzymes such that at least 5% of said first alkaloid is converted to a second alkaloid. In further examples, the first alkaloid may be contacted with a sufficient amount of the one or more enzymes such that at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 82%, at least 84%, at least 86%, at least 88%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5%, at least 99.7%, or 100% of said first alkaloid is converted to a second alkaloid.
The one or more enzymes that may be used to convert a first alkaloid to a second alkaloid may contact the first alkaloid in vitro. Additionally, or alternatively, the one or more enzymes that may be used to convert a first alkaloid to a second alkaloid may contact the first alkaloid in vivo. In some examples, the one or more enzymes that may be used to convert a first alkaloid to a second alkaloid may be provided to a cell having the first alkaloid within. In some examples, the one or more enzymes that may be used to convert a first alkaloid to a second alkaloid may be produced within an engineered host cell.
In some examples, the methods provide for engineered host cells that produce an alkaloid product, wherein the N-demethylation of a substrate to a product may comprise a key step in the production of an alkaloid product. In some examples, the alkaloid produced is a nor-opioid or a nal-opioid. In still other embodiments, the alkaloid produced is derived from a nor-opioid or a nal-opioid. In another embodiment, a first alkaloid is an intermediate toward the product of the engineered host cell. In still other embodiments, the alkaloid product is selected from the group consisting of norcodeine, noroxycodone, northebaine, norhydrocodone, nordihydro-codeine, nor-14-hydroxy-codeine, norcodeinone, nor-14-hydroxy-codeinone, normorphine, noroxymorphone, nororipavine, norhydro-morphone, nordihydro-morphine, nor-14-hydroxy-morphine, normorphinone, and nor-14-hydroxy-morphinone.
In some examples, the substrate alkaloid is an opioid selected from the group consisting of codeine, oxycodone, thebaine, hydrocodone, dihydrocodeine, 14-hydroxycodeine, codeinone, and 14-hydroxycodeinone, morphine, oxymorphone, oripavine, hydromorphone, dihydromorphine, 14-hydroxy-morphine, morphinone, or 14-hydroxy-morphinone.
N-Linked Modifications
Some methods, processes, and systems provided herein describe the conversion of a first alkaloid to a second alkaloid by the addition of an N-linked sidechain group. Some methods, processes, and systems provided herein describe the conversion of a first alkaloid to a second alkaloid by the transfer of a sidechain group from a cosubstrate to the first alkaloid. Some of these methods, processes, and systems may comprise an engineered host cell. In some examples, the conversion of a first alkaloid to a second alkaloid is a key step in the conversion of a substrate to a nal-opioid. In some examples, the conversion of a first alkaloid to a second alkaloid comprises a methyltransferase reaction.
Examples of amino acid sequences of NMT enzymes are set forth in Table 6. An amino acid sequence for an NMT that is utilized in converting a first alkaloid to a second alkaloid may be 75% or more identical to a given amino acid sequence as listed in Table 6. For example, an amino acid sequence for such an epimerase may comprise an amino acid sequence that is at least 75% or more, 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more identical to an amino acid sequence as provided herein. Additionally, in certain embodiments, an “identical” amino acid sequence contains at least 80%-99% identity at the amino acid level to the specific amino acid sequence. In some cases an “identical” amino acid sequence contains at least about 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94% and more in certain cases, at least 95%, 96%, 97%, 98% and 99% identity, at the amino acid level. In some cases, the amino acid sequence may be identical but the DNA sequence is altered such as to optimize codon usage for the host organism, for example.
An engineered host cell may be provided that produces an NMT that converts a first alkaloid to a second alkaloid, wherein the NMT comprises an amino acid sequence as provided in Table 6. An engineered host cell may be provided that produces one or more NMT enzymes. The NMT that is produced within the engineered host cell may be recovered and purified so as to form a biocatalyst. The process may include contacting the first alkaloid with an NMT in an amount sufficient to convert said first alkaloid to a second alkaloid. In examples, the first alkaloid may be contacted with a sufficient amount of the one or more enzymes such that at least 5% of said first alkaloid is converted to a second alkaloid. In further examples, the first alkaloid may be contacted with a sufficient amount of the one or more enzymes such that at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 82%, at least 84%, at least 86%, at least 88%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5%, at least 99.7%, or 100% of said first alkaloid is converted to a second alkaloid.
The one or more enzymes that may be used to convert a first alkaloid to a second alkaloid may contact the first alkaloid in vitro. Additionally, or alternatively, the one or more enzymes that may be used to convert a first alkaloid to a second alkaloid may contact the first alkaloid in vivo. In some examples, the one or more enzymes that may be used to convert a first alkaloid to a second alkaloid may be provided to a cell having the first alkaloid within. In some examples, the one or more enzymes that may be used to convert a first alkaloid to a second alkaloid may be produced within an engineered host cell.
In some examples, the methods provide for engineered host cells that produce an alkaloid product, wherein the N-methyltransferase of a substrate to a product may comprise a key step in the production of an alkaloid product. In some examples, the alkaloid produced is a nal-opioid. In still other embodiments, the alkaloid produced is derived from a nor-opioid or a nal-opioid. In another embodiment, a first alkaloid is an intermediate toward the product of the engineered host cell. In still other embodiments, the alkaloid product is selected from the group including naloxone, naltrexone, and nalmefene.
In some examples, the substrate alkaloid is an opioid selected from the group consisting of norcodeine, noroxycodone, northebaine, norhydrocodone, nordihydro-codeine, nor-14-hydroxy-codeine, norcodeinone, nor-14-hydroxy-codeinone, normorphine, noroxymorphone, nororipavine, norhydro-morphone, nordihydro-morphine, nor-14-hydroxy-morphine, normorphinone, and nor-14-hydroxy-morphinone. In some examples, the cosubstrate is S-adenosylmethionine, Allyl-S-adenosylmethionine, or cyclopropylmethyl-S-adenosylmethionine.
Heterologous Coding Sequences
In some instances, the engineered host cells harbor one or more heterologous coding sequences (such as two or more, three or more, four or more, five or more) which encode activity(ies) that enable the engineered host cells to produce desired enzymes of interest and/or BIAs of interest, e.g., as described herein. As used herein, the term “heterologous coding sequence” is used to indicate any polynucleotide that codes for, or ultimately codes for, a peptide or protein or its equivalent amino acid sequence, e.g., an enzyme, that is not normally present in the host organism and may be expressed in the host cell under proper conditions. As such, “heterologous coding sequences” includes multiple copies of coding sequences that are normally present in the host cell, such that the cell is expressing additional copies of a coding sequence that are not normally present in the cells. The heterologous coding sequences may be RNA or any type thereof, e.g., mRNA, DNA or any type thereof, e.g., cDNA, or a hybrid of RNA/DNA. Coding sequences of interest include, but are not limited to, full-length transcription units that include such features as the coding sequence, introns, promoter regions, 3′-UTRs, and enhancer regions.
In examples, the engineered host cells may comprise a plurality of heterologous coding sequences each encoding an enzyme, such as an enzyme listed in Table 3. In some examples, the plurality of enzymes encoded by the plurality of heterologous coding sequences may be distinct from each other. In some examples, some of the plurality of enzymes encoded by the plurality of heterologous coding sequences may be distinct from each other and some of the plurality of enzymes encoded by the plurality of heterologous coding sequences may be duplicate copies.
In some examples, the heterologous coding sequences may be operably connected. Heterologous coding sequences that are operably connected may be within the same pathway of producing a particular benzylisoquinoline alkaloid product and/or thebaine synthase product. In some examples, the operably connected heterologous coding sequences may be directly sequential along the pathway of producing a particular benzylisoquinoline alkaloid product and/or thebaine synthase product. In some examples, the operably connected heterologous coding sequences may have one or more native enzymes between one or more of the enzymes encoded by the plurality of heterologous coding sequences. In some examples, the heterologous coding sequences may have one or more heterologous enzymes between one or more of the enzymes encoded by the plurality of heterologous coding sequences. In some examples, the heterologous coding sequences may have one or more non-native enzymes between one or more of the enzymes encoded by the plurality of heterologous coding sequences.
The engineered host cells may also be modified to possess one or more genetic alterations to accommodate the heterologous coding sequences. Alterations of the native host genome include, but are not limited to, modifying the genome to reduce or ablate expression of a specific protein that may interfere with the desired pathway. The presence of such native proteins may rapidly convert one of the intermediates or final products of the pathway into a metabolite or other compound that is not usable in the desired pathway. Thus, if the activity of the native enzyme were reduced or altogether absent, the produced intermediates would be more readily available for incorporation into the desired product.
Heterologous coding sequences include but are not limited to sequences that encode enzymes, either wild-type or equivalent sequences, that are normally responsible for the production of BIAs of interest in plants. In some cases, the enzymes for which the heterologous sequences code may be any of the enzymes in the 1-BIA pathway, and may be from any convenient source. The choice and number of enzymes encoded by the heterologous coding sequences for the particular synthetic pathway may be selected based upon the desired product. In certain embodiments, the host cells of the invention may include 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, 11 or more, 12 or more, 13 or more, 14 or more, or even 15 or more heterologous coding sequences, such as 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 heterologous coding sequences.
As used herein, the term “heterologous coding sequences” also includes the coding portion of the peptide or enzyme, i.e., the cDNA or mRNA sequence, of the peptide or enzyme, as well as the coding portion of the full-length transcriptional unit, i.e., the gene including introns and exons, as well as “codon optimized” sequences, truncated sequences or other forms of altered sequences that code for the enzyme or code for its equivalent amino acid sequence, provided that the equivalent amino acid sequence produces a functional protein. Such equivalent amino acid sequences may have a deletion of one or more amino acids, with the deletion being N-terminal, C-terminal, or internal. Truncated forms are envisioned as long as they have the catalytic capability indicated herein. Fusions of two or more enzymes are also envisioned to facilitate the transfer of metabolites in the pathway, provided that catalytic activities are maintained.
Operable fragments, mutants, or truncated forms may be identified by modeling and/or screening. In some cases, this is achieved by deletion of, for example, N-terminal, C-terminal, or internal regions of the protein in a step-wise fashion, followed by analysis of the resulting derivative with regard to its activity for the desired reaction compared to the original sequence. If the derivative in question operates in this capacity, it is considered to constitute an equivalent derivative of the enzyme proper.
In examples, some heterologous proteins may show occurrences where they are incorrectly processed when expressed in a recombinant host. For example, plant proteins such as cytochrome P450 enzymes expressed in microbial production hosts may have occurrences of incorrect processing. In particular, salutaridine synthase may undergo N-linked glycosylation when heterologously expressed in yeast. This N-linked glycosylation may not be observed in plants, which may be indicative of incorrect N-terminal sorting of the nascent SalSyn transcript so as to reduce the activity of the enzyme in the heterologous microbial host. In such examples, protein engineering directed at correcting N-terminal sorting of the nascent transcript so as to remove the N-linked glycosylation pattern may result in improved activity of the salutaridine synthase enzyme in the recombinant production host, see for example WO2016183023A1.
Some aspects of the invention also relate to heterologous coding sequences that code for amino acid sequences that are equivalent to the native amino acid sequences for the various enzymes. An amino acid sequence that is “equivalent” is defined as an amino acid sequence that is not identical to the specific amino acid sequence, but rather contains at least some amino acid changes (deletions, substitutions, inversions, insertions, etc.) that do not essentially affect the biological activity of the protein as compared to a similar activity of the specific amino acid sequence, when used for a desired purpose. The biological activity refers to, in the example of a thebaine synthase, its catalytic activity. Equivalent sequences are also meant to include those which have been engineered and/or evolved to have properties different from the original amino acid sequence. Mutable properties of interest include catalytic activity, substrate specificity, selectivity, stability, solubility, localization, etc.
In some instances, the expression of each type of enzyme is increased through additional gene copies (i.e., multiple copies), which increases intermediate accumulation and/or BIA of interest production. Some embodiments of the invention include increased BIA of interest production in a host cell through simultaneous expression of multiple species variants of a single or multiple enzymes. In some cases, additional gene copies of a single or multiple enzymes are included in the host cell. Any convenient methods may be utilized including multiple copies of a heterologous coding sequence for an enzyme in the host cell.
In some examples, the engineered host cell includes multiple copies of a heterologous coding sequence for an enzyme, such as 2 or more, 3 or more, 4 or more, 5 or more, or even 10 or more copies. In certain embodiments, the engineered host cell includes multiple copies of heterologous coding sequences for one or more enzymes, such as multiple copies of two or more, three or more, four or more, etc. In some cases, the multiple copies of the heterologous coding sequence for an enzyme are derived from two or more different source organisms as compared to the host cell. For example, the engineered host cell may include multiple copies of one heterologous coding sequence, where each of the copies is derived from a different source organism. As such, each copy may include some variations in explicit sequences based on inter-species differences of the enzyme of interest that is encoded by the heterologous coding sequence.
In certain embodiments, the engineered host cell includes multiple copies of heterologous coding sequences for one or more enzymes, such as multiple copies of two or more, three or more, four or more, etc. In some cases, the multiple copies of the heterologous coding sequence for an enzyme are derived from two or more different source organisms as compared to the host cell. For example, the engineered host cell may include multiple copies of one heterologous coding sequence, where each of the copies is derived from a different source organism. As such, each copy may include some variations in explicit sequences based on inter-species differences of the enzyme of interest that is encoded by the heterologous coding sequence.
The engineered host cell medium may be sampled and monitored for the production of BIAs of interest. The BIAs of interest may be observed and measured using any convenient methods. Methods of interest include, but are not limited to, LC-MS methods (e.g., as described herein) where a sample of interest is analyzed by comparison with a known amount of a standard compound. Additionally, there are other ways that BIAs of interest may be observed and/or measured. Examples of alternative ways of observing and/or measuring BIAs include GC-MS, UV-vis spectroscopy, NMR, LC-NMR, LC-UV, TLC, capillary electrophoresis, among others. Identity may be confirmed, e.g., by m/z and MS/MS fragmentation patterns, and quantitation or measurement of the compound may be achieved via LC trace peaks of know retention time and/or EIC MS peak analysis by reference to corresponding LC-MS analysis of a known amount of a standard of the compound.
Additionally, a culture of the engineered host cell may be sampled and monitored for the production of enzymes of interest, such as a thebaine synthase enzyme. The enzymes of interest may be observed and measured using any convenient methods. Methods of interest include enzyme activity assays, polyacrylamide gel electrophoresis, carbon monoxide spectroscopy, and western blot analysis.
Methods
Methods for Culturing Host Cells for BIA production
As summarized above, some aspects of the invention include methods of preparing benzylisoquinoline alkaloids (BIAs) of interest. Additionally, some aspects of the invention include methods of preparing enzymes of interest. As such, some aspects of the invention include culturing an engineered host cell under conditions in which the one or more host cell modifications (e.g., as described herein) are functionally expressed such that the cell converts starting compounds of interest into product enzymes and/or BIAs of interest. Also provided are methods that include culturing an engineered host cell under conditions suitable for protein production such that one or more heterologous coding sequences are functionally expressed and convert starting compounds of interest into product enzymes or BIAs of interest. In examples, the method is a method of preparing a benzylisoquinoline alkaloid (BIA) that includes culturing an engineered host cell (e.g., as described herein); adding a starting compound to the cell culture; and recovering the BIA from the cell culture. In some examples, the method is a method of preparing an enzyme that includes culturing an engineered host cell (e.g., as described herein); adding a starting compound to the cell culture; and recovering the enzyme from the cell culture.
Fermentation media may contain suitable carbon substrates. The source of carbon suitable to perform the methods of this disclosure may encompass a wide variety of carbon containing substrates. Suitable substrates may include, without limitation, monosaccharides (e.g., glucose, fructose, galactose, xylose), oligosaccharides (e.g., lactose, sucrose, raffinose), polysaccharides (e.g., starch, cellulose), or a combination thereof. In some cases, unpurified mixtures from renewable feedstocks may be used (e.g., cornsteep liquor, sugar beet molasses, barley malt). In some cases, the carbon substrate may be a one-carbon substrate (e.g., methanol, carbon dioxide) or a two-carbon substrate (e.g., ethanol). In other cases, other carbon containing compounds may be utilized, for example, methylamine, glucosamine, and amino acids.
Any convenient methods of culturing engineered host cells may be employed for producing the enzymes and/or BIAs of interest. The particular protocol that is employed may vary, e.g., depending on the engineered host cell, the heterologous coding sequences, the enzymes of interest, the BIAs of interest, etc. The cells may be present in any convenient environment, such as an environment in which the cells are capable of expressing one or more functional heterologous enzymes. In some embodiments, the cells are cultured under conditions that are conducive to enzyme expression and with appropriate substrates available to allow production of enzymes and/or BIAs of interest in vivo. In some embodiments, the functional enzymes are extracted from the engineered host for production of enzymes and/or BIAs of interest under in vitro conditions. In some instances, the engineered host cells are placed back into a multicellular host organism. The engineered host cells are in any phase of growth, including, but not limited to, stationary phase and log-growth phase, etc. In addition, the cultures themselves may be continuous cultures or they may be batch cultures.
Cells may be grown in an appropriate fermentation medium at a temperature between 14-40° C. Cells may be grown with shaking at any convenient speed (e.g., 200 rpm). Cells may be grown at a suitable pH. Suitable pH ranges for the fermentation may be between pH 5-9. Fermentations may be performed under aerobic, anaerobic, or microaerobic conditions. Any suitable growth medium may be used. Suitable growth media may include, without limitation, common commercially prepared media such as synthetic defined (SD) minimal media or yeast extract peptone dextrose (YEPD) rich media. Any other rich, defined, or synthetic growth media appropriate to the microorganism may be used.
Cells may be cultured in a vessel of essentially any size and shape. Examples of vessels suitable to perform the methods of this disclosure may include, without limitation, multi-well shake plates, test tubes, flasks (baffled and non-baffled), and bioreactors. The volume of the culture may range from 10 microliters to greater than 10,000 liters.
The addition of agents to the growth media that are known to modulate metabolism in a manner desirable for the production of alkaloids may be included. In a non-limiting example, cyclic adenosine 2′3′-monophosphate may be added to the growth media to modulate catabolite repression.
Any convenient cell culture conditions for a particular cell type may be utilized. In certain embodiments, the host cells that include one or more modifications are cultured under standard or readily optimized conditions, with standard cell culture media and supplements. As one example, standard growth media when selective pressure for plasmid maintenance is not required may contain 20 g/L yeast extract, 10 g/L peptone, and 20 g/L dextrose (YPD). Host cells containing plasmids are grown in synthetic complete (SC) media containing 1.7 g/L yeast nitrogen base, 5 g/L ammonium sulfate, and 20 g/L dextrose supplemented with the appropriate amino acids required for growth and selection. Alternative carbon sources which may be useful for inducible enzyme expression include, but are not limited to, sucrose, raffinose, and galactose. Cells are grown at any convenient temperature (e.g., 30° C.) with shaking at any convenient rate (e.g., 200 rpm) in a vessel, e.g., in test tubes or flasks in volumes ranging from 1-1000 mL, or larger, in the laboratory.
Culture volumes may be scaled up for growth in larger fermentation vessels, for example, as part of an industrial process. The industrial fermentation process may be carried out under closed-batch, fed-batch, or continuous chemostat conditions, or any suitable mode of fermentation. In some cases, the cells may be immobilized on a substrate as whole cell catalysts and subjected to fermentation conditions for alkaloid production.
A batch fermentation is a closed system, in which the composition of the medium is set at the beginning of the fermentation and not altered during the fermentation process. The desired organism(s) are inoculated into the medium at the beginning of the fermentation. In some instances, the batch fermentation is run with alterations made to the system to control factors such as pH and oxygen concentration (but not carbon). In this type of fermentation system, the biomass and metabolite compositions of the system change continuously over the course of the fermentation. Cells typically proceed through a lag phase, then to a log phase (high growth rate), then to a stationary phase (growth rate reduced or halted), and eventually to a death phase (if left untreated).
A continuous fermentation is an open system, in which a defined fermentation medium is added continuously to the bioreactor and an equal amount of fermentation media is continuously removed from the vessel for processing. Continuous fermentation systems are generally operated to maintain steady state growth conditions, such that cell loss due to medium being removed must be balanced by the growth rate in the fermentation. Continuous fermentations are generally operated at conditions where cells are at a constant high cell density. Continuous fermentations allow for the modulation of one or more factors that affect target product concentration and/or cell growth.
The liquid medium may include, but is not limited to, a rich or synthetic defined medium having an additive component described above. Media components may be dissolved in water and sterilized by heat, pressure, filtration, radiation, chemicals, or any combination thereof. Several media components may be prepared separately and sterilized, and then combined in the fermentation vessel. The culture medium may be buffered to aid in maintaining a constant pH throughout the fermentation.
Process parameters including temperature, dissolved oxygen, pH, stirring, aeration rate, and cell density may be monitored or controlled over the course of the fermentation. For example, temperature of a fermentation process may be monitored by a temperature probe immersed in the culture medium. The culture temperature may be controlled at the set point by regulating the jacket temperature. Water may be cooled in an external chiller and then flowed into the bioreactor control tower and circulated to the jacket at the temperature required to maintain the set point temperature in the vessel.
Additionally, a gas flow parameter may be monitored in a fermentation process. For example, gases may be flowed into the medium through a sparger. Gases suitable for the methods of this disclosure may include compressed air, oxygen, and nitrogen. Gas flow may be at a fixed rate or regulated to maintain a dissolved oxygen set point.
The pH of a culture medium may also be monitored. In examples, the pH may be monitored by a pH probe that is immersed in the culture medium inside the vessel. If pH control is in effect, the pH may be adjusted by acid and base pumps which add each solution to the medium at the required rate. The acid solutions used to control pH may be sulfuric acid or hydrochloric acid. The base solutions used to control pH may be sodium hydroxide, potassium hydroxide, or ammonium hydroxide.
Further, dissolved oxygen may be monitored in a culture medium by a dissolved oxygen probe immersed in the culture medium. If dissolved oxygen regulation is in effect, the oxygen level may be adjusted by increasing or decreasing the stirring speed. The dissolved oxygen level may also be adjusted by increasing or decreasing the gas flow rate. The gas may be compressed air, oxygen, or nitrogen.
Stir speed may also be monitored in a fermentation process. In examples, the stirrer motor may drive an agitator. The stirrer speed may be set at a consistent rpm throughout the fermentation or may be regulated dynamically to maintain a set dissolved oxygen level.
Additionally, turbidity may be monitored in a fermentation process. In examples, cell density may be measured using a turbidity probe. Alternatively, cell density may be measured by taking samples from the bioreactor and analyzing them in a spectrophotometer. Further, samples may be removed from the bioreactor at time intervals through a sterile sampling apparatus. The samples may be analyzed for alkaloids produced by the host cells. The samples may also be analyzed for other metabolites and sugars, the depletion of culture medium components, or the density of cells.
In another example, a feed stock parameter may be monitored during a fermentation process. In particular, feed stocks including sugars and other carbon sources, nutrients, and cofactors that may be added into the fermentation using an external pump. Other components may also be added during the fermentation including, without limitation, anti-foam, salts, chelating agents, surfactants, and organic liquids.
Any convenient codon optimization techniques for optimizing the expression of heterologous polynucleotides in host cells may be adapted for use in the subject host cells and methods, see e.g., Gustafsson, C. et al. (2004) Trends Biotechnol, 22, 346-353, which is incorporated by reference in its entirety.
The subject method may also include adding a starting compound to the cell culture. Any convenient methods of addition may be adapted for use in the subject methods. The cell culture may be supplemented with a sufficient amount of the starting materials of interest (e.g., as described herein), e.g., a mM to μM amount such as between about 1-5 mM of a starting compound. It is understood that the amount of starting material added, the timing and rate of addition, the form of material added, etc., may vary according to a variety of factors. The starting material may be added neat or pre-dissolved in a suitable solvent (e.g., cell culture media, water, or an organic solvent). The starting material may be added in concentrated form (e.g., 10× over desired concentration) to minimize dilution of the cell culture medium upon addition. The starting material may be added in one or more batches, or by continuous addition over an extended period of time (e.g., hours or days).
Methods for Isolating Products from the Fermentation Medium
The subject methods may also include recovering the enzymes and/or BIAs of interest from the cell culture. Any convenient methods of separation and isolation (e.g., chromatography methods or precipitation methods) may be adapted for use in the subject methods to recover the enzymes and/or BIAs of interest from the cell culture. Filtration methods may be used to separate soluble from insoluble fractions of the cell culture. In some cases, liquid chromatography methods (e.g., reverse phase HPLC, size exclusion, normal phase chromatography) may be used to separate the BIA of interest from other soluble components of the cell culture. In some cases, extraction methods (e.g., liquid extraction, pH based purification, solid phase extraction, affinity chromatography, ion exchange, etc.) may be used to separate the enzymes and/or BIAs of interest from other components of the cell culture.
The produced alkaloids may be isolated from the fermentation medium using methods known in the art. A number of recovery steps may be performed immediately after (or in some instances, during) the fermentation for initial recovery of the desired product. Through these steps, the alkaloids (e.g., BIAs) may be separated from the cells, cellular debris and waste, and other nutrients, sugars, and organic molecules may remain in the spent culture medium. This process may be used to yield a BIA-enriched product.
In an example, a product stream having a benzylisoquinoline alkaloid (BIA) product is formed by providing engineered yeast cells and a feedstock including nutrients and water to a batch reactor. In particular, the engineered yeast cells may be subjected to fermentation by incubating the engineered yeast cells for a time period of at least about 5 minutes to produce a solution comprising the BIA product and cellular material. Once the engineered yeast cells have been subjected to fermentation, at least one separation unit may be used to separate the BIA product from the cellular material to provide the product stream comprising the BIA product. In particular, the product stream may include the BIA product as well as additional components, such as a clarified yeast culture medium. Additionally, a BIA product may comprise one or more BIAs of interest, such as one or more BIA compounds.
Different methods may be used to remove cells from a bioreactor medium that include an enzyme and/or BIA of interest. In examples, cells may be removed by sedimentation over time. This process of sedimentation may be accelerated by chilling or by the addition of fining agents such as silica. The spent culture medium may then be siphoned from the top of the reactor or the cells may be decanted from the base of the reactor. Alternatively, cells may be removed by filtration through a filter, a membrane, or other porous material. Cells may also be removed by centrifugation, for example, by continuous flow centrifugation or by using a continuous extractor.
If some valuable enzymes and/or BIAs of interest are present inside the cells, the cells may be permeabilized or lysed and the cell debris may be removed by any of the methods described above. Agents used to permeabilize the cells may include, without limitation, organic solvents (e.g., DMSO) or salts (e.g., lithium acetate). Methods to lyse the cells may include the addition of surfactants such as sodium dodecyl sulfate, or mechanical disruption by bead milling or sonication.
Enzymes and/or BIAs of interest may be extracted from the clarified spent culture medium through liquid-liquid extraction by the addition of an organic liquid that is immiscible with the aqueous culture medium. In examples, the use of liquid-liquid extraction may be used in addition to other processing steps. Examples of suitable organic liquids include, but are not limited to, isopropyl myristate, ethyl acetate, chloroform, butyl acetate, methylisobutyl ketone, methyl oleate, toluene, oleyl alcohol, ethyl butyrate. The organic liquid may be added to as little as 10% or as much as 100% of the volume of aqueous medium.
In some cases, the organic liquid may be added at the start of the fermentation or at any time during the fermentation. This process of extractive fermentation may increase the yield of enzymes and/or BIAs of interest from the host cells by continuously removing enzymes and/or BIAs to the organic phase.
Agitation may cause the organic phase to form an emulsion with the aqueous culture medium. Methods to encourage the separation of the two phases into distinct layers may include, without limitation, the addition of a demulsifier or a nucleating agent, or an adjustment of the pH. The emulsion may also be centrifuged to separate the two phases, for example, by continuous conical plate centrifugation.
Alternatively, the organic phase may be isolated from the aqueous culture medium so that it may be physically removed after extraction. For example, the solvent may be encapsulated in a membrane.
In examples, enzymes and/or BIAs of interest may be extracted from a fermentation medium using adsorption methods. In examples, BIAs of interest may be extracted from clarified spent culture medium by the addition of a resin such as Amberlite® XAD4 or another agent that removes BIAs by adsorption. The BIAs of interest may then be released from the resin using an organic solvent. Examples of suitable organic solvents include, but are not limited to, methanol, ethanol, ethyl acetate, or acetone.
BIAs of interest may also be extracted from a fermentation medium using filtration. At high pH, the BIAS of interest may form a crystalline-like precipitate in the bioreactor. This precipitate may be removed directly by filtration through a filter, membrane, or other porous material. The precipitate may also be collected by centrifugation and/or decantation.
The extraction methods described above may be carried out either in situ (in the bioreactor) or ex situ (e.g., in an external loop through which media flows out of the bioreactor and contacts the extraction agent, then is recirculated back into the vessel). Alternatively, the extraction methods may be performed after the fermentation is terminated using the clarified medium removed from the bioreactor vessel.
Methods for Purifying Products from Alkaloid-Enriched Solutions
Subsequent purification steps may involve treating the post-fermentation solution enriched with BIA product(s) of interest using methods known in the art to recover individual product species of interest to high purity.
In one example, BIAs of interest extracted in an organic phase may be transferred to an aqueous solution. In some cases, the organic solvent may be evaporated by heat and/or vacuum, and the resulting powder may be dissolved in an aqueous solution of suitable pH. In a further example, the BIAs of interest may be extracted from the organic phase by addition of an aqueous solution at a suitable pH that promotes extraction of the BIAs of interest into the aqueous phase. The aqueous phase may then be removed by decantation, centrifugation, or another method.
The BIA-containing solution may be further treated to remove metals, for example, by treating with a suitable chelating agent. The BIA of interest-containing solution may be further treated to remove other impurities, such as proteins and DNA, by precipitation. In one example, the BIA of interest-containing solution is treated with an appropriate precipitation agent such as ethanol, methanol, acetone, or isopropanol. In an alternative example, DNA and protein may be removed by dialysis or by other methods of size exclusion that separate the smaller alkaloids from contaminating biological macromolecules.
In further examples, the solution containing BIAs of interest may be extracted to high purity by continuous cross-flow filtration using methods known in the art.
If the solution contains a mixture of BIAs of interest, it may be subjected to acid-base treatment to yield individual BIA of interest species using methods known in the art. In this process, the pH of the aqueous solution is adjusted to precipitate individual BIAs.
For high purity, small-scale preparations, the BIAs may be purified in a single step by liquid chromatography.
Liquid Chromatography Mass Spectrometry (LCMS) Method
The BIA compounds of interest, including morphinan, nal-opioids, and nor-opioids, may be separated using liquid chromatography, and detected and quantified using mass spectrometry. Compound identity may be confirmed by characteristic elution time, mass-to-charge ratio (m/z) and fragmentation patterns (MS/MS). Quantitation may be performed by comparison of compound peak area to a standard curve of a known reference standard compound. Additionally, BIAs of interest may be detected by alternative methods such as GC-MS, UV-vis spectroscopy, NMR, LC-NMR, LC-UV, TLC, and capillary electrophoresis.
Purpald Assay Method
For high throughput screening of demethylation reactions a purpald assay may be used. For example, demethylation catalyzed by 2-oxoglutarate dependent dioxygenases produces formaldehyde a as product as shown in the generalized chemical equation: [substrate]+2-oxoglutarate+O2⇄[product]+formaldehyde+succinate+CO2. Purpald reagent in alkaline conditions undergoes a color change in the presence of formaldehyde that can be quantified to concentrations as low as 1 nM with a spectrophotometer at 510 nm.
Yeast-Derived Alkaloid APIs Versus Plant-Derived APIs
The clarified yeast culture medium (CYCM) may contain a plurality of impurities. The clarified yeast culture medium may be dehydrated by vacuum and/or heat to yield an alkaloid-rich powder. This product is analogous to the concentrate of poppy straw (CPS) or opium, which is exported from poppy-growing countries and purchased by API manufacturers. For the purposes of this invention, CPS is a representative example of any type of purified plant extract from which the desired alkaloids product(s) may ultimately be further purified. Table 10 and Table 11 highlight the impurities in these two products that may be specific to either CYCM or CPS or may be present in both. While some BIAs may have a pigment as an impurity, other BIAs may be categorized as pigments themselves. Accordingly, these BIAs may be assessed for impurities based on non-pigment impurities. By analyzing a product of unknown origin for a subset of these impurities, a person of skill in the art could determine whether the product originated from a yeast or plant production host.
API-grade pharmaceutical ingredients are highly purified molecules. As such, impurities that could indicate the plant- or yeast-origin of an API (such as those listed in Table 10 and Table 11) may not be present at the API stage of the product. Indeed, many of the API products derived from yeast strains of the present invention may be largely indistinguishable from the traditional plant-derived APIs. In some cases, however, conventional alkaloid compounds may be subjected to chemical modification using chemical synthesis approaches, which may show up as chemical impurities in plant-based products that require such chemical modifications. For example, chemical derivatization may often result in a set of impurities related to the chemical synthesis processes. In certain situations, these modifications may be performed biologically in the yeast production platform, thereby avoiding some of the impurities associated with chemical derivation from being present in the yeast-derived product. In particular, these impurities from the chemical derivation product may be present in an API product that is produced using chemical synthesis processes but may be absent from an API product that is produced using a yeast-derived product. Alternatively, if a yeast-derived product is mixed with a chemically-derived product, the resulting impurities may be present but in a lesser amount than would be expected in an API that only or primarily contains chemically-derived products. In this example, by analyzing the API product for a subset of these impurities, a person of skill in the art could determine whether the product originated from a yeast production host or the traditional chemical derivatization route.
Non-limiting examples of impurities that may be present in chemically-derivatized morphinan APIs but not in biosynthesized APIs include a codeine-O(6)-methyl ether impurity in API codeine; 8,14-dihydroxy-7,8-dihydrocodeinone in API oxycodone; and tetrahydrothebaine in API hydrocodone. The codeine-O(6)-methyl ether may be formed by chemical over-methylation of morphine. The 8,14-dihydroxy-7,8-dihydrocodeinone in API oxycodone may be formed by chemical over-oxidation of thebaine. Additionally, the tetrahydrothebaine in API hydrocodone may be formed by chemical over-reduction of thebaine.
However, in the case where the yeast-derived compound and the plant-derived compound are both subjected to chemical modification through chemical synthesis approaches, the same impurities associated with the chemical synthesis process may be expected in the products. In such a situation, the starting material (e.g., CYCM or CPS) may be analyzed as described above.
Host Cell Derived Nal-Opioids Vs Chemically Derived Nal-Opioids
Nal-opioids produced by chemical synthesis may contain a plurality of impurities. These impurities may arise from many different causes, for example, unreacted starting materials, incomplete reactions, the formation of byproducts, persistence of intermediates, dimerization, or degradation. An example of an unreacted starting material could be oxymorphone remaining in a preparation of naltrexone. An example of an impurity arising from an incomplete reaction could be 3-O-Methylbuprenorphine resulting from the incomplete 3-O-demethylation of thebaine. Chemical modification can result in the addition or removal of functional groups at off-target sites. For example, the oxidation of C10 to create 10-hydroxynaltrexone and 10-ketonaltrexone during naltrexone synthesis, or the removal of the 6-O-methyl group to give 6-O-desmethylbuprenorphine during buprenorphine synthesis. Impurites may arise from the persistence of reaction intermediates, for example the persistence of N-oxides like oxymorphone N-oxide formed during the N-demethylation process. Another source of impurities is dimerization, the conjugation of two opioid molecules, for example two buprenorphine molecules (2,2′-bisbuprenorphine), two naltrexone molecules (2,2′-bisnaltrexone), or two naloxone molecules (2,2′-bisnaloxone). Impurities may arise from degradation of starting materials, reaction intermediates, or reaction products. The extreme physical conditions used in chemical syntheses may make the presence of degradation more likely. An example of an impurity that may arise from degradation is dehydrobuprenorphine produced by oxidizing conditions during buprenorphine synthesis.
Nal-opioids produced by enzyme catalysis in a host cell may contain different impurities than nal-opioids produced by chemical synthesis. Nal-opioids produced by enzyme catalysis in a host cell may contain fewer impurities than nal-opioids produced by chemical synthesis. Nal-opioids produced by enzyme catalysis in a host cell may lack certain impurities that are found in nal-opioids produced by chemical synthesis. In examples, key features of enzyme synthesis may include, (1) enzymes target a specific substrate and residue with high fidelity; (2) enzymes perform reactions in the mild physiological conditions within the cell which do not compromise the stability of the molecules; and (3) enzymes are engineered to be efficient catalysts that drive reactions to completion.
Table 12 highlights some of the impurities that may be specific to chemically produced nal-opioids. Accordingly, nal-opioids may be assessed for impurities to determine the presence or absence of any impurity from Table 12. By analyzing a product of unknown origin for a subset of these impurities, a person of skill in the art could determine whether the product originated from a chemical or enzymatic synthesis.
Methods of Engineering Host Cells
Also included are methods of engineering host cells for the purpose of producing enzymes and/or BIAs of interest. Inserting DNA into host cells may be achieved using any convenient methods. The methods are used to insert the heterologous coding sequences into the engineered host cells such that the host cells functionally express the enzymes and convert starting compounds of interest into product enzymes and/or BIAs of interest.
Any convenient promoters may be utilized in the subject engineered host cells and methods. The promoters driving expression of the heterologous coding sequences may be constitutive promoters or inducible promoters, provided that the promoters are active in the engineered host cells. The heterologous coding sequences may be expressed from their native promoters, or non-native promoters may be used. Such promoters may be low to high strength in the host in which they are used. Promoters may be regulated or constitutive. In certain embodiments, promoters that are not glucose repressed, or repressed only mildly by the presence of glucose in the culture medium, are used. Promoters of interest include but are not limited to, promoters of glycolytic genes such as the promoter of the B. subtilis tsr gene (encoding the promoter region of the fructose bisphosphate aldolase gene) or the promoter from yeast S. cerevisiae gene coding for glyceraldehyde 3-phosphate dehydrogenase (GPD, GAPDH, or TDH3), the ADH1 promoter of baker's yeast, the phosphate-starvation induced promoters such as the PHO5 promoter of yeast, the alkaline phosphatase promoter from B. licheniformis, yeast inducible promoters such as Gall-10, Gall, GalL, GalS, repressible promoter Met25, tetO, and constitutive promoters such as glyceraldehyde 3-phosphate dehydrogenase promoter (GPD), alcohol dehydrogenase promoter (ADH), translation-elongation factor-1-α promoter (TEF), cytochrome c-oxidase promoter (CYC1), MRP7 promoter, etc. Autonomously replicating yeast expression vectors containing promoters inducible by hormones such as glucocorticoids, steroids, and thyroid hormones may also be used and include, but are not limited to, the glucorticoid responsive element (GRE) and thyroid hormone responsive element (TRE). These and other examples are described U.S. Pat. No. 7,045,290, which is incorporated by reference, including the references cited therein. Additional vectors containing constitutive or inducible promoters such as a factor, alcohol oxidase, and PGH may be used. Additionally any promoter/enhancer combination (as per the Eukaryotic Promoter Data Base EPDB) could also be used to drive expression of genes. Any convenient appropriate promoters may be selected for the host cell, e.g., E. coli. One may also use promoter selection to optimize transcript, and hence, enzyme levels to maximize production while minimizing energy resources.
Any convenient vectors may be utilized in the subject engineered host cells and methods. Vectors of interest include vectors for use in yeast and other cells. The types of yeast vectors may be broken up into 4 general categories: integrative vectors (YIp), autonomously replicating high copy-number vectors (YEp or 2μ plasmids), autonomously replicating low copy-number vectors (YCp or centromeric plasmids) and vectors for cloning large fragments (YACs). Vector DNA is introduced into prokaryotic or eukaryotic cells via any convenient transformation or transfection techniques. DNA of another source (e.g. PCR-generated double stranded DNA product, or synthesized double stranded or single stranded oligonucleotides) may be used to engineer the yeast by integration into the genome. Any single transformation event may include one or several nucleic acids (vectors, double stranded or single stranded DNA fragments) to genetically modify the host cell.
Utility
The engineered host cells and methods of the invention, e.g., as described above, find use in a variety of applications. Applications of interest include, but are not limited to: research applications and therapeutic applications. Methods of the invention find use in a variety of different applications including any convenient application where the production of enzymes and/or BIAs is of interest.
The subject engineered host cells and methods find use in a variety of therapeutic applications. Therapeutic applications of interest include those applications in which the preparation of pharmaceutical products that include BIAs is of interest. The engineered host cells described herein produce BIAs of interest and enzymes of interest. Reticuline is a major branch point intermediate of interest in the synthesis of BIAs including engineering efforts to produce end products such as opioid products. The subject host cells may be utilized to produce BIAs of interest from simple and inexpensive starting materials that may find use in the production of BIAs of interest, including reticuline, and BIA end products. As such, the subject host cells find use in the supply of therapeutically active BIAs of interest.
In some instances, the engineered host cells and methods find use in the production of commercial scale amounts of BIAs thereof where chemical synthesis of these compounds is low yielding and not a viable means for large-scale production. In certain cases, the host cells and methods are utilized in a fermentation facility that would include bioreactors (fermenters) of e.g., 5,000-200,000 liter capacity allowing for rapid production of BIAs of interest thereof for therapeutic products. Such applications may include the industrial-scale production of BIAs of interest from fermentable carbon sources such as cellulose, starch, and free sugars.
The subject engineered host cells and methods find use in a variety of research applications. The subject host cells and methods may be used to analyze the effects of a variety of enzymes on the biosynthetic pathways of a variety of enzymes and/or BIAs of interest. In addition, the engineered host cells may be engineered to produce enzymes and/or BIAs of interest that find use in testing for bioactivity of interest in as yet unproven therapeutic functions. In some cases, the engineering of host cells to include a variety of heterologous coding sequences that encode for a variety of enzymes elucidates the high yielding biosynthetic pathways towards enzymes and/or BIAs of interest. In certain cases, research applications include the production of enzymes and/or BIAs of interest for therapeutic molecules of interest that may then be further chemically modified or derivatized to desired products or for screening for increased therapeutic activities of interest. In some instances, host cell strains are used to screen for enzyme activities that are of interest in such pathways, which may lead to enzyme discovery via conversion of BIA metabolites produced in these strains.
The subject engineered host cells and methods may be used as a production platform for plant specialized metabolites. The subject host cells and methods may be used as a platform for drug library development as well as plant enzyme discovery. For example, the subject engineered host cells and methods may find use in the development of natural product based drug libraries by taking yeast strains producing interesting scaffold molecules, such as protopine, and further functionalizing the compound structure through combinatorial biosynthesis or by chemical means. By producing drug libraries in this way, any potential drug hits are already associated with a production host that is amenable to large-scale culture and production. As another example, these subject engineered host cells and methods may find use in plant enzyme discovery. The subject host cells provide a clean background of defined metabolites to express plant EST libraries to identify new enzyme activities. The subject host cells and methods provide expression methods and culture conditions for the functional expression and increased activity of plant enzymes in yeast.
Kits and Systems
Aspects of the invention further include kits and systems, where the kits and systems may include one or more components employed in methods of the invention, e.g., engineered host cells, starting compounds, heterologous coding sequences, vectors, culture medium, etc., as described herein. In some embodiments, the subject kit includes an engineered host cell (e.g., as described herein), and one or more components selected from the following: starting compounds, a heterologous coding sequence and/or a vector including the same, vectors, growth feedstock, components suitable for use in expression systems (e.g., cells, cloning vectors, multiple cloning sites (MCS), bi-directional promoters, an internal ribosome entry site (IRES), etc.), and a culture medium.
Any of the components described herein may be provided in the kits, e.g., host cells including one or more modifications, starting compounds, culture medium, etc. A variety of components suitable for use in making and using heterologous coding sequences, cloning vectors and expression systems may find use in the subject kits. Kits may also include tubes, buffers, etc., and instructions for use. The various reagent components of the kits may be present in separate containers, or some or all of them may be pre-combined into a reagent mixture in a single container, as desired.
Also provided are systems for producing enzymes and/or BIAs of interest, where the systems may include engineered host cells including one or more modifications (e.g., as described herein), starting compounds, culture medium, a fermenter and fermentation equipment, e.g., an apparatus suitable for maintaining growth conditions for the host cells, sampling and monitoring equipment and components, and the like. A variety of components suitable for use in large scale fermentation of yeast cells may find use in the subject systems.
In some cases, the system includes components for the large scale fermentation of engineered host cells, and the monitoring and purification of enzymes and/or BIA compounds produced by the fermented host cells. In certain embodiments, one or more starting compounds (e.g., as described herein) are added to the system, under conditions by which the engineered host cells in the fermenter produce one or more desired BIA products of interest. In some instances, the host cells produce a BIA of interest (e.g., as described herein). In certain cases, the BIA products of interest are opioid products, such as thebaine, codeine, neopine, morphine, neomorphine, hydrocodone, oxycodone, hydromorphone, dihydrocodeine, 14-hydroxycodeine, dihydromorphine, or oxymorphone.
In some cases, the system includes processes for monitoring and or analyzing one or more enzymes and/or BIAs of interest compounds produced by the subject host cells. For example, a LC-MS analysis system as described herein, a chromatography system, or any convenient system where the sample may be analyzed and compared to a standard, e.g., as described herein. The fermentation medium may be monitored at any convenient times before and during fermentation by sampling and analysis. When the conversion of starting compounds to enzymes and/or BIA products of interest is complete, the fermentation may be halted and purification of the BIA products may be done. As such, in some cases, the subject system includes a purification component suitable for purifying the enzymes and/or BIA products of interest from the host cell medium into which it is produced. The purification component may include any convenient means that may be used to purify the enzymes and/or BIA products of interest produced by fermentation, including but not limited to, silica chromatography, reverse-phase chromatography, ion exchange chromatography, HIC chromatography, size exclusion chromatography, liquid extraction, and pH extraction methods. In some cases, the subject system provides for the production and isolation of enzyme and/or BIA fermentation products of interest following the input of one or more starting compounds to the system.
The following examples are put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how to make and use the present invention, and are not intended to limit the scope of what the inventors regard as their invention nor are they intended to represent that the experiments below are all or the only experiments performed. Efforts have been made to ensure accuracy with respect to numbers used (e.g. amounts, temperature, etc.), but some experimental errors and deviations should be accounted for. Unless indicated otherwise, parts are parts by weight, molecular weight is weight average molecular weight, temperature is in degrees Centigrade, and pressure is at or near atmospheric.
Discussion of Enzyme List
The host cells may be engineered to include one or more modifications (such as two or more, three or more, four or more, five or more, or even more modifications) that provide for the production of BIAs of interest and/or enzymes of interest. Table 3 provides a list of exemplary genes that may be acted upon by one or more modifications so as to provide for the production of BIAs of interest and/or enzymes of interest in an engineered host cell.
Modifications of genes as provided in Table 3 may be used to produce BIAs of interest from engineered host cells that are supplied with a medium containing the minimal nutrients required for growth. This minimal medium may contain a carbon source, a nitrogen source, amino acids, vitamins, and salts. For example, modifications of genes as provided in Table 3 may be used to produce BIAs of interest from engineered host cells that are fed sugar. Additionally, modifications of one or more genes as provided in Table 3 may be used to augment the biosynthetic processes of host cells that may be engineered for drug production.
Additionally, the use of these modifications to provide for the production of BIAs of interest and/or enzymes of interest in engineered host cells is not readily apparent from the mere identification of enzymes that may be produced by the genes. In particular, synthetic pathways that have been reconstructed in host cells, such as yeast cells, as described herein comprise a variety of enzymes that do not act together in nature within a single organism. Additionally, some of the enzymes discussed herein do not act for BIA biosynthesis in their natural context. Further, some of the enzymes described herein are not evolved to function in particular host cells, such as yeast cells, and are not evolved to function together. In these cases, it would not be obvious that the enzymes would exhibit sufficient activity in the context of the synthetic BIA pathway in a host cell, such as yeast, to have sufficient flux through the pathway to produce downstream BIA end products.
For example, plant enzymes are often difficult to functionally express in heterologous microbial hosts, such as yeast. In many cases the enzymes may be misfolded, not correctly localized within the host cell, and/or incorrectly processed. The differences in protein translation and processing between yeast and plants can lead to these enzymes exhibiting substantially reduced to no detectable activities in the yeast host. These challenges arise commonly for endomembrane localized enzymes, such as cytochrome P450s, which are strongly represented in the BIA pathways. Even reduced enzyme activities may pose a substantial challenge to engineering yeast to produce complex BIAs, which requires sufficient activity at each step to ensure high-level accumulation of the desired BIA products.
Additionally, there are endogenous enzymes/pathways in some host cells, such as yeast, that may act on many of the early precursors in the BIA pathway (i.e., intermediates from tyrosine to norcoclaurine), and thus it may not be readily apparent that there would be sufficient flux through the heterologous pathway to achieve substantial BIA production given these competing endogenous pathways. For example, the Erlich pathway (Hazelwood, et al. 2008. Appl. Environ. Microbiol. 74: 2259-66; Larroy, et al. 2003. Chem. Biol. Interact. 143-144: 229-38; Larroy, et al. 2002. Eur. J. Biochem. 269: 5738-45) in yeast is the main endogenous pathway that would act to convert many of the intermediates in the early BIA pathway to undesired products and divert flux from the synthetic pathway.
Further, many of the enzymes as discussed herein, and as provided in Table 3, may function under very specific regulation strategies, including spatial regulation, in the native plant hosts, which may be lost upon transfer to the heterologous yeast host. In addition, plants present very different biochemical environments than yeast cells under which the enzymes are evolved to function, including pH, redox state, and substrate, cosubstrate, coenzyme, and cofactor availabilities. Given the differences in biochemical environments and regulatory strategies between the native hosts and the heterologous yeast hosts, it is not obvious that the enzymes would exhibit substantial activities when in the context of the yeast environment and further not obvious that they would work together to direct simple precursors such as sugar to complex BIA compounds. Maintaining the activities of the enzymes in the yeast host is particularly important as many of the pathways have many reaction steps (>10), such that if these steps are not efficient then one would not expect accumulation of desired downstream products.
In addition, in the native plant hosts, the associated metabolites in these pathways may be localized across different cell and tissue types. In several examples, there are cell types that may be specialized for biosynthesis and cell types that may be synthesized for metabolite accumulation. This type of cell specialization may be lost when expressing the pathways within a heterologous yeast host, and may play an important role in controlling the toxicity of these metabolites on the cells. Thus, it is not obvious that yeast could be successfully engineered to biosynthesize and accumulate these metabolites without being harmed by the toxicity of these compounds.
As one example, in the native plant hosts, the enzyme BBE is reported to have dynamic subcellular localization. In particular, the enzyme BBE initially starts in the ER and then is sorted to the vacuole (Bird and Facchini. 2001. Planta. 213: 888-97). It has been suggested that the ER-association of BBE in plants (Alcantara, et al. 2005. Plant Physiol. 138: 173-83) provides the optimal basic pH (pH˜8.8) for BBE activity (Ziegler and Facchini. 2008. Annu. Rev. Plant Biol. 59: 735-69). As another example, there is evidence that sanguinarine biosynthesis occurs in specialized vesicles within plant cells (Amann, et al. 1986. Planta. 167: 310-20), but only some of the intermediates accumulate in the vesicles. This may occur so as to sequester them from other enzyme activities and/or toxic effects.
As another example, the biosynthetic enzymes in the morphinan pathway branch are all localized to the phloem, which is part of the vascular tissue in plants. In the phloem, the pathway enzymes may be further divided between two cell types: the sieve elements common to all plants, and the laticifer which is a specialized cell type present only in certain plants which make specialized secondary metabolites. The upstream enzymes (i.e., from NCS through to SalAT) are predominantly in the sieve elements, and the downstream enzymes (i.e., T6ODM, COR, CODM) are mostly in the laticifer (Onoyovwe, et al. 2013. Plant Cell. 25: 4110-22). Additionally, it was discovered that the final steps in the noscapine biosynthetic pathway take place in the laticifer (Chen and Facchini. 2014. Plant J. 77: 173-84). This compartmentalization is thought to be highly important for regulating biosynthesis by isolating or trafficking intermediates, providing optimal pH, enhancing supply of cofactors, although the nature of the poppy laticifer microenvironment is still under investigation (Ziegler and Facchini. 2008. Annu. Rev. Plant Biol. 59: 735-69). Further, it is predicted that several of the enzymes may function as multi-enzyme complexes or metabolic channels common to plant secondary metabolism (Kempe, et al. 2009. Phytochemistry. 70: 579-89; Allen, et al. 2004. Nat. Biotechnol. 22: 1559-66). When biosynthetic enzymes are combined from different hosts and/or expressed recombinantly in a heterologous yeast cell it is not clear that these complexes or channels will form as they would in the native host. In an additional example, in Coptis japonica, berberine is biosynthesized in root tissues and then accumulated within the rhizome via the action of specialized ATP-binding cassette transport proteins (Shitan, et al. 2013. Phytochemistry. 91: 109-16). In opium poppy, morphinan alkaloids are accumulated within the latex (cytoplasm of laticifer cells) (Martin, et al. 1967. Biochemistry. 6: 2355-63).
Further, even without these considerations, it is also the case that the plant enzymes for several of the steps in the pathways described herein have not yet been characterized. For example, the conversion of tyrosine to the early benzylisoquinoline alkaloid scaffold norcoclaurine has not yet been characterized. Additionally, the conversion of (S)-reticuline to (R)-reticuline has only recently been characterized as described herein. Thus, for several of the steps in the pathways described herein, alternative biosynthetic scheme were produced by bringing together enzyme activities that do not normally occur together in nature for the biosynthesis of BIAs or identifying new enzyme activities from genome sequence information to use in the reconstructed pathways.
For example, the two-step conversion of tyrosine to dopamine may be achieved by combining at least 5 mammalian enzymes and 1 bacterial enzyme, which do not naturally occur together and were not evolved to function in the context of this pathway or with plant enzymes. In these instances, it may not be obvious to utilize these enzymes for the biosynthesis of compounds they were not evolved for in nature and that they would function effectively in the context of a heterologous microbial host and this pathway. In these instances, it may not be obvious to utilize these enzymes for the biosynthesis of compounds they were not evolved for in nature and that they would function effectively in the context of a heterologous microbial host and this pathway.
As another example, until recent years the enzyme responsible for the conversion of (S)-reticuline to (R)-reticuline was unknown. Even when a fused epimerase enzyme was discovered, evolutionary analysis suggested that morphine-producing poppies evolved a fusion enzyme between the oxidase and reductase for an epimerase reaction, which was in contrast to non-morphine producing poppies where the epimerase enzymes were non-fused. Based on this analysis, some scholars believed the fusion of the oxidase and reductase portions was necessary to efficiently catalyze the conversion of (S)-Reticuline to (R)-Reticuline. Novel methods of using engineered split epimerases as discussed herein may perform this epimerization reaction in yeast and in the context of the synthetic BIA pathway, and may perform this epimerization with greater efficiency than performing an epimerization with a wild-type epimerase.
Examples of the genes that are the object of modifications so as to produce BIAs of interest and/or enzymes of interest are discussed below. Additionally, the genes are discussed in the context of a series of Figures that illustrate pathways that are used in generating BIAs of interest and/or enzymes of interest.
[TKL1] In some examples, the engineered host cell may modify the expression of the enzyme transketolase. Transketolase is encoded by the TKL1 gene. In examples, transketolase catalyzes the reaction of fructose-6-phosphate+glyceraldehyde-3-phosphate↔xylulose-5-phosphate+erythrose-4-phosphate, as referenced in
[ZWF1] In some examples, the engineered host cell may modify the expression of the enzyme glucose-6-phosphate dehydrogenase. Glucose-6-phosphate dehydrogenase is encoded by the ZWF1 gene. In examples, glucose-6-phosphate dehydrogenase catalyzes the reaction of glucose-6-phosphate→6-phosphogluconolactone, as referenced in
[ARO4] In some examples, the engineered host cell may modify the expression of the enzyme 3-deoxy-D-arabino-heptulosonate-7-phosphate (DAHP) synthase. DAHP synthase is encoded by the ARO4 gene. In examples, DAHP synthase catalyzes the reaction of erythrose-4-phosphate+phosphoenolpyruvic acid→DAHP, as referenced in
[ARO7] In some examples, the engineered host cell may modify the expression of the enzyme chorismate mutase. Chorismate mutase is encoded by the ARO7 gene. In examples, chorismate mutase catalyzes the reaction of chorismate→prephenate, as referenced in
[ARO10] In some examples, the engineered host cell may modify the expression of the enzyme phenylpyruvate decarboxylase. Phenylpyruvate decarboxylase is encoded by the ARO10 gene. In examples, phenylpyruvate decarboxylase catalyzes the reaction of hydroxyphenylpyruvate→4-hydroxyphenylacetate (4HPA), as referenced in
[ADH2-7, SFA1] In some examples, the engineered host cell may modify the expression of alcohol dehydrogenase enzymes. Alcohol dehydrogenase enzymes may be encoded by one or more of the ADH2, ADH3, ADH4, ADH5, ADH6, ADH7, and SFA1 genes. In examples, alcohol dehydrogenase catalyzes the reaction of 4HPA→tyrosol. An engineered host cell may be modified to delete the coding region of one or more of the ADH2, ADH3, ADH4, ADH5, ADH6, ADH7, and SFA1 genes in the engineered host cell. Alternatively, the engineered host cell may be modified to disable the functionality of one or more of the ADH2, ADH3, ADH4, ADH5, ADH6, ADH7, and SFA1 genes, such as by introducing an inactivating mutation.
[ALD2-6] In some examples, the engineered host cell may modify the expression of aldehyde oxidase enzymes. Aldehyde oxidase enzymes may be encoded by one or more of the ALD2, ALD3, ALD4, ALD5, and ALD6 genes. In examples, aldehyde oxidase catalyzes the reaction of 4HPA→4 hydroxyphenylacetic acid. An engineered host cell may be modified to delete the coding region of one or more of the ALD2, ALD3, ALD4, ALD5, and ALD6 genes in the engineered host cell. Alternatively, the engineered host cell may be modified to disable the functionality of one or more of the ALD2, ALD3, ALD4, ALD5, and ALD6 genes, such as by introducing an inactivating mutation.
[ARO9] In some examples, the engineered host cell may modify the expression of the enzyme aromatic aminotransferase. Aromatic aminotransferase is encoded by the ARO9 gene. In examples, aromatic aminotransferase catalyzes the reaction of hydroxyphenylpyruvate+L-alanine↔tyrosine↔pyruvate, as referenced in
[ARO8] In some examples, the engineered host cell may modify the expression of the enzyme aromatic aminotransferase. Aromatic aminotransferase is encoded by the ARO8 gene. In examples, aromatic aminotransferase catalyzes the reaction of hydroxyphenylpyruvate+glutamate↔tyrosine+alpha-ketogluterate, as referenced in
[TYR1] In some examples, the engineered host cell may modify the expression of the enzyme prephenate dehydrogenase. Prephenate dehydrogenase is encoded by the TYR1 gene. In examples, prephenate dehydrogenase catalyzes the reaction of prephenate+NADP+→4-hydroxyphenylpyruvate+CO2+NADPH, as referenced in
[TYR] In some examples, the engineered host cell may modify the expression of the enzyme tyrosinase. Tyrosinase is encoded by the TYR gene. In examples, tyrosinase catalyzes the reaction of tyrosine→L-DOPA, as referenced in
[TyrH] In some examples, the engineered host cell may modify the expression of the enzyme tyrosine hydroxylase. Tyrosine hydroxylase is encoded by the TyrH gene. In examples, tyrosine hydroxylase catalyzes the reaction of tyrosine→L-DOPA, as referenced in
[DODC] In some examples, the engineered host cell may modify the expression of the enzyme L-DOPA decarboxylase. L-DOPA decarboxylase is encoded by the DODC gene. In examples, L-DOPA decarboxylase catalyzes the reaction of L-DOPA→dopamine, as referenced in
[TYDC] In some examples, the engineered host cell may modify the expression of the enzyme tyrosine/DOPA decarboxylase. Tyrosine/DOPA decarboxylase is encoded by the TYDC gene. In examples, tyrosine/DOPA decarboxylase catalyzes the reaction of L-DOPA→dopamine, as referenced in
[MAO] In some examples, the engineered host cell may modify the expression of the enzyme monoamine oxidase. Monoamine oxidase is encoded by the MAO gene. In examples, monoamine oxidase catalyzes the reaction of dopamine 3,4-DHPA, as referenced in
[NCS] In some examples, the engineered host cell may modify the expression of the enzyme norcoclaurine synthase. Norcoclaurine synthase is encoded by the NCS gene. In examples, norcoclaurine synthase catalyzes the reaction of 4HPA+dopamine→(S)-norcoclaurine, as referenced in
Additionally, norcoclaurine synthase catalyzes the reaction of 3,4-DHPA+dopamine→(S)-norlaudanosoline, as referenced in
An engineered host cell may be modified to include constitutive expression of the NCS gene in the engineered host cell. Additionally or alternatively, the engineered host cell may be modified to synthetically regulate the expression of the NCS gene in the engineered host cell. In examples, the engineered host cell may be modified to incorporate a copy, copies, or additional copies, of the NCS gene. Additionally or alternatively, the engineered host cell may be modified to incorporate the introduction of a strong promoter element for the overexpression of the NCS gene within the engineered host cell. Additionally, the norcoclaurine synthase may have an N-terminal truncation. In some cases, the NCS gene may be codon optimized for expression in Saccharomyces cerevisiae. The NCS gene may be derived from Coptis japonica, Papaver somniferum, Papver bracteatum, Thalicitum flavum, Corydalis saxicola, or another species. In some examples, the NCS gene may be 80% similar to the naturally occurring gene.
[6OMT] In some examples, the engineered host cell may modify the expression of the enzyme norcoclaurine 6-O-methyltransferase. Norcoclaurine 6-O-methyltransferase is encoded by the 6OMT gene. In some examples, norcoclaurine 6-O-methyltransferase catalyzes the reaction of norcoclaurine→coclaurine, as referenced in
[CNMT] In some examples, the engineered host cell may modify the expression of the enzyme coclaurine-N-methyltransferase. Coclaurine-N-methyltransferase is encoded by the CNMT gene. In some examples, coclaurine-N-methyltransferase catalyzes the reaction of coclaurine→N-methylcoclaurine, as referenced in
[4′OMT] In some examples, the engineered host cell may modify the expression of the enzyme 4′-O-methyltransferase. 4′-O-methyltransferase is encoded by the 4′OMT gene. In some examples, 4′-O-methyltransferase catalyzes the reaction of 3′-hydroxy-N-methylcoclaurine→reticuline, as referenced in
[CYP80B1] In some examples, the engineered host cell may modify the expression of the enzyme cytochrome P450 80B1. Cytochrome P450 80B1 is encoded by the CYP80B1 gene. In examples, cytochrome P450 80B1 catalyzes the reaction of N-methylcoclaurine→3′-hydroxy-N-methylcoclaurine, as referenced in
[FOL2] In some examples, the engineered host cell may modify the expression of the enzyme GTP cyclohydrolase. GTP cyclohydrolase is encoded by the FOL2 gene. In some examples, GTP cyclohydrolase catalyzes the reaction of GTP→dihydroneopterin triphosphate, as referenced in
[PTPS] In some examples, the engineered host cell may modify the expression of the enzyme 6-pyruvoyl tetrahydrobiopterin (PTP) synthase. Pyruvoyl tetrahydrobiopterin synthase is encoded by the PTPS gene. In some examples, 6-pyruvoyl tetrahydrobiopterin synthase catalyzes the reaction of dihydroneopterin triphosphate→PTP, as referenced in
[SepR] In some examples, the engineered host cell may modify the expression of the enzyme sepiapterin reductase. Sepiapterin reductase is encoded by the SepR gene. In some examples, sepiapterin reductase catalyzes the reaction of PTP→BH4, as referenced in
[PCD] In some examples, the engineered host cell may modify the expression of the enzyme 4a-hydroxytetrahydrobiopterin (pterin-4α-carbinolamine) dehydratase. 4a-hydroxytetrahydrobiopterin dehydratase is encoded by the PCD gene. In some examples, 4a-hydroxytetrahydrobiopterin dehydratase catalyzes the reaction of 4a-hydroxytetrahydrobiopterin→H2O+quinonoid dihydropteridine, as referenced in
[QDHPR] In some examples, the engineered host cell may modify the expression of the enzyme quinonoid dihydropteridine reductase. Quinonoid dihydropteridine reductase is encoded by the QDHPR gene. In some examples, quinonoid dihydropteridine reductase catalyzes the reaction of quinonoid dihydropteridine→BH4, as referenced in
[DHFR] In some examples, the engineered host cell may modify the expression of the enzyme dihydrofolate reductase. Dihydrofolate reductase is encoded by the DHFR gene. In some examples, dihydrofolate reductase catalyzes the reaction of 7,8-dihydrobiopterin (BH2)→5,6,7,8-tetrahydrobiopterin (BH4), as referenced in
[DRS-DRR] As discussed above with regard to epimerizing 1-BIAs, the engineered host cell may modify the expression of a BIA epimerase. The BIA epimerase is encoded by the DRS-DRR gene. In some examples, DRS-DRR may also be referred to as CYP-COR. In some examples, the BIA epimerase, or an engineered split version or an engineered fused version of the BIA epimerase, catalyzes the conversion of (S)-1-BIA→(R)-1-BIA, as referenced in
The engineered host cell may be modified to include constitutive expression of the DRS-DRR gene or the engineered DRS-DRR gene in the engineered host cell. In some cases, the engineered DRS-DRR gene may encode an engineered fusion epimerase. In some cases, the engineered DRS-DRR gene may encode an engineered split epimerase. Additionally or alternatively, the engineered host cell may be modified to synthetically regulate the expression of the DRS-DRR gene in the engineered host cell. In examples, the engineered host cell may be modified to incorporate a copy, copies, or additional copies, of the DRS-DRR gene. Additionally or alternatively, the engineered host cell may be modified to incorporate the introduction of a strong promoter element for the overexpression of the DRS-DRR gene within the engineered host cell. The DRS-DRR gene may be derived from Papaver bracteatum, Papaver somniferum, Papaver setigerum, Chelidonium majus, or another species. In some examples, the DRS-DRR gene may be 77% similar to the naturally occurring gene.
[CPR] In some examples, the engineered host cell may modify the expression of the enzyme cytochrome P450 reductase. The cytochrome P450 reductase is encoded by the CPR gene. In some examples, the cytochrome P450 reductase catalyzes the reaction of (R)-reticuline salutaridine, as referenced in
[SalSyn] In some examples, the engineered host cell may modify the expression of the enzyme salutaridine synthase. The salutaridine synthase is encoded by the SalSyn gene. In some examples, the salutaridine synthase catalyzes the reaction of (R)-reticuline salutaridine, as referenced in
[SalR] In some examples, the engineered host cell may modify the expression of the enzyme salutaridine reductase. Salutaridine reductase is encoded by the SalR gene. In some examples, salutaridine reductase reversibly catalyzes the reaction of salutaridinol→salutaridine, as referenced in
[SalAT] In some examples, the engineered host cell may modify the expression of the enzyme acetyl-CoA:salutaridinol 7-O-acetyltransferase. Acetyl-CoA:salutaridinol 7-O-acetyltransferase is encoded by the SalAT gene. In some examples, acetyl-CoA:salutaridinol 7-O-acetyltransferase catalyzes the reaction of acetyl-CoA+salutaridinol→CoA+7-O-acetylsalutaridinol, as referenced in
[TS] In some examples, the engineered host cell may modify the expression of the enzyme thebaine synthase. Thebaine synthase is encoded by the TS gene. In some examples, a thebaine synthase or an engineered thebaine synthase catalyzes the reaction of 7-O-acetylsalutaridinol→thebaine+acetate, as referenced in
The engineered host cell may be modified to include constitutive expression of the TS gene or the engineering TS gene in the engineered host cell. In some cases, the engineered TS gene may encode an engineered fusion enzyme. Additionally or alternatively, the engineered host cell may be modified to synthetically regulate the expression of the TS gene in the engineered host cell. In examples, the engineered host cell may be modified to incorporate a copy, copies, or additional copies, of the TS gene. Additionally or alternatively, the engineered host cell may be modified to incorporate the introduction of a strong promoter element for the overexpression of the TS gene within the engineered host cell. In some cases, the TS gene may be codon optimized for expression in Saccharomyces cerevisiae. The TS gene may be derived from Papaver somniferum, Papaver bracteatum, Papaver orientale, Papaver spp., or another species. In some examples, the TS gene may be 75-80% similar to the naturally occurring gene.
[T6ODM] In some examples, the engineered host cell may modify the expression of the enzyme thebaine 6-O-demethylase. Thebaine 6-0 demethylase is encoded by the T6ODM gene. In some examples, thebaine 6-O-demethylase catalyzes the reaction of thebaine→neopinone, as referenced in
[COR] In some examples, the engineered host cell may modify the expression of the enzyme codeinone reductase. Codeinone reductase is encoded by the COR gene. In some examples, codeinone reductase catalyzes the reaction of codeinone to codeine, as referenced in
[CODM] In some examples, the engineered host cell may modify the expression of the enzyme codeine O-demethylase. Codeine O-demethylase is encoded by the CODM gene. In some examples, codeine O-demethylase catalyzes the reaction of codeine to morphine, as referenced in
[BBE] In some examples, the engineered host cell may modify the expression of the enzyme berberine bridge enzyme. The berberine bridge enzyme is encoded by the BBE gene. In some examples, berberine bridge enzyme catalyzes the reaction of (S)-reticuline (S)-scoulerine. The engineered host cell may be modified to include constitutive expression of the BBE gene in the engineered host cell. Additionally or alternatively, the engineered host cell may be modified to synthetically regulate the expression of the BBE gene in the engineered host cell. In examples, the engineered host cell may be modified to incorporate a copy, copies, or additional copies, of the BBE gene. Additionally or alternatively, the engineered host cell may be modified to incorporate the introduction of a strong promoter element for the overexpression of the BBE gene within the engineered host cell. The BBE gene may be derived from Papaver somniferum, Argemone mexicana, Eschscholzia californica, Berberis stolonifera, Thalictrum flavum subsp. glaucum, Coptis japonica, Papaver spp., or another species. In some examples, the BBE gene may be 99% similar to the naturally occurring gene.
[S9OMT] In some examples, the engineered host cell may modify the expression of the enzyme S-adenosyl-L-methionine:(S)-scoulerine 9-O-methyltransferase. S-adenosyl-L-methionine:(S)-scoulerine 9-O-methyltransferase is encoded by the S9OMT gene. In some examples, S-adenosyl-L-methionine:(S)-scoulerine 9-O-methyltransferase catalyzes the reaction of S-adenosyl-L-methionine+(S)-scoulerine→S-adenosyl-L-homocysteine+(S)-tetrahydrocolumbamine. The engineered host cell may be modified to include constitutive expression of the S9OMT gene in the engineered host cell. Additionally or alternatively, the engineered host cell may be modified to synthetically regulate the expression of the S9OMT gene in the engineered host cell. In examples, the engineered host cell may be modified to incorporate a copy, copies, or additional copies, of the S9OMT gene. Additionally or alternatively, the engineered host cell may be modified to incorporate the introduction of a strong promoter element for the overexpression of the S9OMT gene within the engineered host cell. In some cases, the S9OMT gene may be codon optimized for expression in Saccharomyces cerevisiae. The S9OMT gene may be derived from Thalictrum flavum subsp. glaucum, Coptis japonica, Coptis chinensis, Papaver somniferum, Thalictrum spp., Coptis spp., Papaver spp., or another species. In some examples, the S9OMT gene may be 100% similar to the naturally occurring gene. In examples, the S9OMT gene may be 80% similar to the naturally occurring gene.
[CAS] In some examples, the engineered host cell may modify the expression of the enzyme (S)-canadine synthase. (S)-canadine synthase is encoded by the CAS gene. In some examples, (S)-canadine synthase catalyzes the reaction of (S)-tetrahydrocolumbamine→(S)-canadine. The engineered host cell may be modified to express the CAS gene in the engineered host cell. The engineered host cell may be modified to include constitutive expression of the CAS gene in the engineered host cell. Additionally or alternatively, the engineered host cell may be modified to synthetically regulate the expression of the CAS gene in the engineered host cell. In examples, the engineered host cell may be modified to incorporate a copy, copies, or additional copies, of the CAS gene. Additionally or alternatively, the engineered host cell may be modified to incorporate the introduction of a strong promoter element for the overexpression of the CAS gene within the engineered host cell. The CAS gene may be derived from Thalictrum flavum subsp. glaucum, Coptis japonica, Thalictrum spp., Coptis spp., or another species. In some examples, the CAS gene may be 100% similar to the naturally occurring gene.
[STOX] In some examples, the engineered host cell may modify the expression of the enzyme (S)-tetrahydroprotoberberine oxidase. (S)-tetrahydroprotoberberine oxidase is encoded by the STOX gene. In some examples, (S)-tetrahydroprotoberberine oxidase catalyzes the reaction of (S)-tetrahydroberberine+2 O2→berberine+2 H2O2. The engineered host cell may be modified to include constitutive expression of the STOX gene in the engineered host cell. Additionally or alternatively, the engineered host cell may be modified to synthetically regulate the expression of the STOX gene in the engineered host cell. In examples, the engineered host cell may be modified to incorporate a copy, copies, or additional copies, of the STOX gene. Additionally or alternatively, the engineered host cell may be modified to incorporate the introduction of a strong promoter element for the overexpression of the STOX gene within the engineered host cell. In some examples the STOX may be modified at the N-terminus. In some cases, the STOX gene may be codon optimized for expression in Saccharomyces cerevisiae. The STOX gene may be derived from Berberis wilsonae, Coptis japonica, Berberis spp., Coptis spp., or another species. In some examples, the STOX gene may be 78% similar to the naturally occurring gene.
[TNMT] In some examples, the engineered host cell may modify the expression of the enzyme tetrahydroprotoberberine-N-methyltransferase. Tetrahydroprotoberberine-N-methyltransferase is encoded by the TNMT gene. In some examples, tetrahydroprotoberberine-N-methyltransferase catalyzes the reaction of canadine→N-methylcanadine. In some examples, tetrahydroprotoberberine-N-methyltransferase catalyzes the reaction of noroxymorphone→naloxone.
In other examples, tetrahydroprotoberberine-N-methyltransferase catalyzes the reaction of stylopine→cis-N-methylstylopine. The engineered host cell may be modified to include constitutive expression of the TNMT gene in the engineered host cell. Additionally or alternatively, the engineered host cell may be modified to synthetically regulate the expression of the TNMT gene in the engineered host cell. In examples, the engineered host cell may be modified to incorporate a copy, copies, or additional copies, of the TNMT gene. Additionally or alternatively, the engineered host cell may be modified to incorporate the introduction of a strong promoter element for the overexpression of the TNMT gene within the engineered host cell. In some cases, the TNMT gene may be codon optimized for expression in Saccharomyces cerevisiae. The TNMT gene may be derived from Papaver somniferum, Eschscholzia californica, Papaver bracteatuin, Argemone mexicana, or another species. In some examples, the TNMT gene may be 100% similar to the naturally occurring gene. In examples, the TNMT gene may be 81% similar to the naturally occurring gene.
[CFS] In some examples, the engineered host cell may modify the expression of the enzyme cheilanthifoline synthase. Cheilanthifoline synthase is encoded by the CFS gene. In examples, cheilanthifoline synthase catalyzes the reaction of scoulerine→cheilanthifoline. An engineered host cell may be modified to include constitutive expression of the CFS gene in the engineered host cell. Additionally or alternatively, the engineered host cell may be modified to synthetically regulate the expression of the CFS gene in the engineered host cell. In examples, the engineered host cell may be modified to incorporate a copy, copies, or additional copies, of the CFS gene. Additionally or alternatively, the engineered host cell may be modified to incorporate the introduction of a strong promotor element for the overexpression of the CFS gene within the engineered host cell. The CFS gene may be derived from P. somniferum, E. californica, A. mexicana, or another species. In some examples, the CFS gene may be 77%, 78%, or 79% similar to the naturally occurring gene. Additionally, the CFS gene may be codon optimized for expression in Saccharomyces cerevisiae.
In some examples, the engineered host cell may modify the expression of the enzyme stylopine synthase. Stylopine synthase is encoded by the STS gene. In examples, stylopine synthase catalyzes the reaction of cheilanthifoline→stylopine. An engineered host cell may be modified to include constitutive expression of the STS gene in the engineered host cell. Additionally or alternatively, the engineered host cell may be modified to synthetically regulate the expression of the STS gene in the engineered host cell. In examples, the engineered host cell may be modified to incorporate a copy, copies, or additional copies, of the STS gene. Additionally or alternatively, the engineered host cell may be modified to incorporate the introduction of a strong promotor element for the overexpression of the STS gene within the engineered host cell. The STS gene may be derived from P. somniferum, E. californica, A. mexicana, or another species. In some examples, the STS gene may be 76%, 78%, or 79% similar to the naturally occurring gene. Additionally, the STS gene may be codon optimized for expression in Saccharomyces cerevisiae.
[MSH] In some examples, the engineered host cell may modify the expression of the enzyme cis-N-methylstylopine 14-hydroxylase. Cis-N-methylstylopine 14-hydroxylase is encoded by the MSH gene. In examples, cis-N-methylstylopine 14-hydroxylase catalyzes the reaction of cis-N-methylstylopine→protopine. An engineered host cell may be modified to include constitutive expression of the MSH gene in the engineered host cell. Additionally or alternatively, the engineered host cell may be modified to synthetically regulate the expression of the MSH gene in the engineered host cell. In examples, the engineered host cell may be modified to incorporate a copy, copies, or additional copies, of the MSH gene. Additionally or alternatively, the engineered host cell may be modified to incorporate the introduction of a strong promotor element for the overexpression of the MSH gene within the engineered host cell. The MSH gene may be derived from P. somniferum or another species. In some examples, the MSH gene may be 79% similar to the naturally occurring gene. Additionally, the MSH gene may be codon optimized for expression in Saccharomyces cerevisiae.
[P6H] In some examples, the engineered host cell may modify the expression of the enzyme protopine-6-hydroxylase. Protopine-6-hydroxylase is encoded by the P6H gene. In examples, protopine-6-hydroxylase catalyzes the reaction of Protopine→6-hydroxyprotopine. An engineered host cell may be modified to include constitutive expression of the P6H gene in the engineered host cell. Additionally or alternatively, the engineered host cell may be modified to synthetically regulate the expression of the P6H gene in the engineered host cell. In examples, the engineered host cell may be modified to incorporate a copy, copies, or additional copies, of the P6H gene. Additionally or alternatively, the engineered host cell may be modified to incorporate the introduction of a strong promotor element for the overexpression of the CFS gene within the engineered host cell. The P6H gene may be derived from P. somniferum, E. californica, or another species. In some examples, the P6H gene may be 79% similar to the naturally occurring gene. Additionally, the P6H gene may be codon optimized for expression in Saccharomyces cerevisiae.
[DBOX] In some examples, the engineered host cell may modify the expression of the enzyme dihydrobenzophenanthridine oxidase. Dihydrobenzophenanthridine oxidase is encoded by the DBOX gene. In examples, dihydrobenzophenanthridine oxidase catalyzes the reaction of dihydrosanguinarine→sanguinarine. An engineered host cell may be modified to include constitutive expression of the DBOX gene in the engineered host cell. Additionally or alternatively, the engineered host cell may be modified to synthetically regulate the expression of the DBOX gene in the engineered host cell. In examples, the engineered host cell may be modified to incorporate a copy, copies, or additional copies, of the DBOX gene. Additionally or alternatively, the engineered host cell may be modified to incorporate the introduction of a strong promotor element for the overexpression of the DBOX gene within the engineered host cell. The DBOX gene may be derived from P. somniferum or another species. In some examples, the DBOX gene may be 100% similar to the naturally occurring gene. Additionally, the DBOX gene may be codon optimized for expression in Saccharomyces cerevisiae.
[morA] In some examples, the engineered host cell may modify the expression of the enzyme morphine dehydrogenase. Morphine dehydrogenase is encoded by the morA gene. In some examples, morphine dehydrogenase catalyzes the reaction of morphine→morphinone, as referenced in
The engineered host cell may be modified to include constitutive expression of the morA gene in the engineered host cell. Additionally or alternatively, the engineered host cell may be modified to synthetically regulate the expression of the morA gene in the engineered host cell. In examples, the engineered host cell may be modified to incorporate a copy, copies, or additional copies, of the morA gene. Additionally or alternatively, the engineered host cell may be modified to incorporate the introduction of a strong promoter element for the overexpression of the morA gene within the engineered host cell. In some cases, the morA gene may be codon optimized for expression in Saccharomyces cerevisiae. The morA gene may be derived from Pseudomonas putida or another species. In some examples, the morA gene may be 73.7% similar to the naturally occurring gene.
[morB] In some examples, the engineered host cell may modify the expression of the enzyme morphinone reductase. Morphinone reductase is encoded by the morB gene. In some examples, morphinone reductase catalyzes the reaction of codeinone hydrocodone, as referenced in
[CYP80A1] In some examples, the engineered host cell may express the enzyme berbamunine synthase. Berbamunine synthase is encoded by the gene for cytochrome P450 enzyme 80A1 (CYP80A1). In some examples, CYP80A1 catalyzes the reaction (S)—N-methylcoclaurine+(R)—N-methylcoclaurine→berbamunine. In other examples, CYP80A1 catalyzes the reaction (R)—N-methylcoclaurine+(R)—N-methylcoclaurine→guattegaumerine. In other examples, CYP80A1 catalyzes the reaction (R)—N-methylcoclaurine+(S)-coclaurine→2′norberbamunine. The engineered host cell may be modified to include constitutive expression of the CYP80A1 gene in the engineered host cell. Additionally or alternatively, the engineered host cell may be modified to synthetically regulate the expression of the CYP80A1 gene in the engineered host cell. In examples, the engineered host cell may be modified to incorporate a copy, copies, or additional copies, of the CYP80A1 gene. Additionally or alternatively, the engineered host cell may be modified to incorporate the introduction of a strong promoter element for the overexpression of the CYP80A1 gene within the engineered host cell. In some cases, the CYP80A1 gene may be codon optimized for expression in Saccharomyces cerevisiae. The CYP80A1 gene may be derived from Berber's stolonifera or another species. In some examples, the CYP80A1 gene may be 76% similar to the naturally occurring gene.
[PODA] In some example, the engineered host cell may express the enzyme protopine O-dealkylase. Protopine O-dealkylase is encoded by the gene PODA. In some examples, PODA catalyzes the 0, O-demethylenation of protoberberines and protopines such as canadine, stylopine, berberine, cryptopine, allocryptopine, and protopine. In some examples, PODA catalyzes the O-demethylation of BIAs including tetrahydropapaverine, tetrahydropalmatine, and cryptopine. The engineered host cell may be modified to include constitutive expression of the PODA gene in the engineered host cell. Additionally or alternatively, the engineered host cell may be modified to synthetically regulate the expression of the PODA gene in the engineered host cell. In examples, the engineered host cell may be modified to incorporate a copy, copies, or additional copies, of the PODA gene. Additionally or alternatively, the engineered host cell may be modified to incorporate the introduction of a strong promoter element for the overexpression of the PODA gene within the engineered host cell. In some cases, the PODA gene may be codon optimized for expression in Saccharomyces cerevisiae. The PODA gene may be derived from Papaver somniferum or other species. In some examples, the PODA gene may be 70-100% similar to the naturally occurring gene.
[BM3] In some examples, the engineered host cell may express the enzyme BM3. BM3 is a Bacillus megaterium cytochrome P450 involved in fatty acid monooxygenation in its native host. In some cases BM3 N-demethylates an opioid to produce a nor-opioid, as referenced in
Examples of the aforementioned genes can be expressed from a number of different platforms in the host cell, including plasmid (2μ, ARS/CEN), YAC, or genome. In addition, examples of the aforementioned gene sequences can either be native or codon optimized for expression in the desired heterologous host (e.g., Saccharomyces cerevisiae).
The following examples are given for the purpose of illustrating various embodiments of the invention and are not meant to limit the invention in any fashion. Where indicated, expression constructs are understood to incorporate a suitable promoter, gene, and terminator, even if the exact terminator sequence used is not specified. The present examples, along with the methods described herein are presently representative of preferred embodiments, are exemplary, and are not intended as limitations on the scope of the invention. Changes therein and other uses which are encompassed within the spirit of the invention as defined by the scope of the claims will occur to those skilled in the art.
The OneKP (Matasci N et al. 2014. Data access for the 1,000 Plants (1KP) project. Gigascience 3:17) and Phytometasyn (Xiao M et al. 2013. Transcriptome analysis based on next-generation sequencing of non-model plants producing specialized metabolites of biotechnological interest. J Biotechnol 166:122-34) plant transcriptome databases were queried with amino acid sequences of representative variants from each of the hypothesized classes of enzymes. In particular, the basal eudicot Glade, which includes many plant species that produce benzylisoquinoline alkaloids of interest, were searched. A large number of sequences were identified from these searches and the list of candidate sequences were narrowed down by building phylogenetic trees. In building the trees, sequences were included from similar known and characterized enzymes from plant species that produce morphinan alkaloids. These reference sequences helped to develop an understanding of the relationships between sequences and further constrain the sequence space for identifying the candidates most likely to exhibit desired activities. An example of a phylogenetic tree generated for the Bet v 1/PR10/major latex protein class of enzymes using this approach is show in
An alignment of the primary amino acid sequence of PbDRS-DRR versus dehydroreticuline synthase (DRS) and dehydroreticuline reductase (DRR) from P. rhoeas was generated using the Clustal Omega (http://www.ebi.ac.uk/Tools/msa/clustalo/). Based on the alignment with DRR from P. rhoeas, we identified a truncation point at which to separate PbDRS-DRR into DRS and DRR enzymes, where a conserved methionine residue at position M569 is found (SEQ ID NO. 16). This residue corresponds to position 1 of SEQ ID NO. 18. In
For propagation of yeast strains harboring engineered DRS-DRR (or separate DRS and DRR) enzymes, the reporter strain was transformed with expression plasmids using standard molecular biology techniques, and single colonies of yeast were isolated from solid agar medium plates under selective conditions (such as synthetic complete 2% dextrose without tryptophan). Colonies were inoculated into liquid culture medium and grown for 2 days at 30° C. Cultures were then subcultured into fresh medium of the same composition, or in some cases into synthetic complete liquid medium containing 8% maltodextrin. To release monosaccharide from the maltodextrin polymer, amyloglucosidase from A. niger (Sigma) was added at a concentration of approximately 3 U/L. Yeast strains were grown for an additional 3 or 4 days at 30° C., cultures were separated by centrifugation, and salutaridine concentration was measured directly in the supernatant by LC-MS.
Plasmids and Strains
S. cerevisiae Cen. PK, BIA pathway = CjNCS,
A platform yeast strain that produces the key branch point BIA intermediate (S)-reticuline from L-tyrosine was constructed (
In the first integration construct, four heterologous genes from Rattus norvegicus are integrated into the YBR197C locus together with a G418 selection marker (KanMX). RnPTPS, RnSepR, RnPCD, and RnQDHPR are required to synthesize and regenerate tetrahydrobiopterin (BH4) from the yeast endogenous folate synthesis pathway as indicated in
In the second integration construct, four heterologous genes are integrated into the HISS locus together with the HISS selection marker. Rattus norvegicus tyrosine hydroxylase (RnTyrH) converts tyrosine to L-DOPA using the cosubstrate BH4 generated by the preceding integration construct. The RnTyrH gene can be any of the wild-type or improved mutants which confer enhanced activity (e.g., W166Y, R37E, and R38E). A second Rattus norvegicus gene, RnDHFR, encodes an enzyme that reduces dihydrobiopterin (an oxidation product of BH4) to BH4, in this way increasing the availability of this cosubstrate. Also included in the third construct is PpDODC from Pseudomonas putida, an enzyme that converts L-DOPA to dopamine. The fourth enzyme is CjNCS from Coptis japonica, which condenses 4-HPA and dopamine to make norcoclaurine. Each gene is codon optimized for expression in yeast.
In the third integration construct, five heterologous genes from plants and the LEU2 selection marker are integrated into the locus YDR514C. Ps6OMT, Ps4′OMT, and PsCNMT are methyltransferases from Papaver somniferum and are expressed as native plant nucleotide sequences. A fourth P. somniferum gene, yPsCPRv2, is codon optimized for yeast and encodes a reductase that supports the activity of a cytochrome P450 from Eschscholzia californica, EcCYP80A1. The enzymes encoded in this construct perform two O-methylations, an N-methylation, and a hydroxylation to produce reticuline from the norcoclaurine produced by the preceding integration construct. Each gene is codon optimized for expression in yeast.
In the final integration construct, additional copies of Saccharomyces cerevisiae endogenous genes ARO4Q166K, ARO7T226I, TYR1, and ARO10 are integrated into the ARO4 locus together with a hygromycin resistance selection marker. ARO4Q166K and ARO7T226I are feedback-resistant mutants of ARO4 and ARO10 which each encode a single base pair substitution relative to the wild-type sequence. TYR1 and ARO10 are identical to the native yeast genes, but are expressed behind strong promoters. Aro4p and Aro7p are enzymes in the biosynthesis of aromatic amino acids including tyrosine. Removing feedback inhibition from these enzymes results in upregulation of endogenous tyrosine biosynthesis. Overexpression of Tyr1p upregulates tyrosine biosynthesis and thus production of tyrosine. Overexpression of Aro10p increases the production of 4-HPA.
Platform yeast strains can be constructed with any number of the four expression cassettes. Specifically, platform yeast strains were constructed with integration constructs 1-4 and integration constructs 1-3. In the latter strain in which the tyrosine over-production construct (construct 4) is excluded, additional tyrosine may be supplied in the culture medium to support the biosynthesis of reticuline. Additional genetic modifications may be incorporated into the platform strains to support production of downstream BIAs and increased flux to BIA biosynthesis.
The yeast strains were grown in synthetic complete media with the appropriated amino acid drop out solution at 30° C. BIA metabolites in the media supernatant were analyzed after 48 and 96 hours of growth by LC-MS/MS analysis.
Yeast strains can be engineered for the production of the morphinan alkaloid thebaine from early precursors such as tyrosine. As an example, the platform yeast strains described in Example 3 can be further engineered to produce the morphinan alkaloid products from L-tyrosine (
The platform yeast strain producing (S)-reticuline from L-tyrosine (see description in Example 3) was further engineered to incorporate an engineered split epimerase DRS-DRR, an engineered salutaridine synthase, salutaridine reductase, salutaridinol acetyltransferase, and thebaine synthase to convert the biosynthesized (S)-reticuline to the first morphinan alkaloid thebaine (
The yeast strains harboring the integrated cassettes were grown in synthetic complete media with the appropriated drop out solution at 30° C. After 96 hours of growth, the media was analyzed for BIA metabolites by LC-MS/MS analysis.
Yeast strains were engineered as described in Examples 3 and 4 to produce the pentacyclic morphinan alkaloid thebaine directly from simple sugars (e.g., glucose) and nitrogen sources present in standard growth media. Specifically, a CEN.PK strain of Saccharomyces cerevisiae was engineered to express the following heterologous enzymes via integration into the yeast chromosome: TyrH, DODC, PTPS, SepR, PCD, QDHPR, NCS, 6OMT, CNMT, CYP80B1, CPR, 4OMT, DRS, DRR, SalSyn, SalR, SalAT, and TS. In this example, the SalSyn enzyme is engineered to have its leader sequence replaced with 83 amino acids from the N-terminus of Eschscholzia californica chelanthifoline synthase (EcCFS). Additional modifications were made to the strain to increase BIA precursor accumulation, including: overexpression of ARO10, overexpression of TYR1, expression of a feedback resistant ARO4 (ARO4Q166K) and expression of a feedback resistant ARO7 (ARO7T226I). Separate engineered yeast strains were made as described, harboring different variants of enzymes encoding thebaine synthase activity (TS), including SEQ ID NOs. 35 (i.e., TS1), 37 (i.e., TS2), and a variant of 35 with a N-terminal truncation of the first 22 amino acids (i.e., tTS1), and no thebaine synthase enzyme (YA397). The sequences of the enzyme variants are provided in Table 2.
The described yeast strains were inoculated into 2 ml of synthetic complete media (yeast nitrogen base and amino acids) with 2% glucose and grown for approximately 4 hours at 30° C. Then, 10 uL of each culture was transferred to 400 uL of fresh media in a 96-well plate in replicates of 4 and grown for an additional 48 hours at 30° C. The production media contains 1× yeast nitrogen broth and amino acids, 20 mM ascorbic acid, 300 mg/L tyrosine, 40 g/L maltodextrin, and 2 units/L amylase. The amylase is used to mimic a fed-batch process and gradually releases glucose from maltodextrin polymer so that the yeast can use it as a carbon source. The cells were separated from the media by centrifugation, and thebaine concentration was measured directly in the supernatant by LC-MS/MS analysis. All engineered yeast strains produced thebaine from glucose and simple nitrogen sources present in the growth media (
Yeast strains can be engineered for the production of the downstream morphinan alkaloids from early precursors such as tyrosine. As an example, the platform yeast strains described in Example 4 can be further engineered to produce the downstream morphinan alkaloid products from L-tyrosine (
The platform yeast strain producing thebaine from L-tyrosine (see description in Example 5) was further engineered to incorporate thebaine 6-O-demethylase, codeinone reductase, and codeinone-O-demethylase to convert the biosynthesized thebaine to the downstream morphinan alkaloids including morphine (
The yeast strains harboring the integrated cassettes were grown in synthetic complete media with the appropriated drop out solution at 30° C. After 96 hours of growth, the media was analyzed for BIA metabolites by LC-MS/MS analysis.
Yeast strains can be engineered for the production of the downstream morphinan alkaloids from early precursors such as tyrosine. As an example, the yeast strains described in Examples 4 and 5 can be further engineered to produce the semi-synthetic opioid products from L-tyrosine (
The yeast strains producing downstream morphinan alkaloids from L-tyrosine (see description in Example 4) were further engineered to incorporate morphine dehydrogenase and morphinone reductase to convert the biosynthesized thebaine to the downstream morphinan alkaloids including morphine (
The yeast strains harboring the integrated cassettes were grown in synthetic complete media with the appropriated drop out solution at 30° C. After 96 hours of growth, the media was analyzed for BIA metabolites by LC-MS/MS analysis.
Enzymes listed in Table 4 that displayed O-demethylase activity on morphinan alkaloids, were incorporated into a microbial strain (either Saccharomyces cerevisiae or Escherichia coli) which biosynthesizes morphinan alkaloids de novo (as described in Example 5). The complete BIA biosynthetic pathway uses L-tyrosine produced by the host cell and/or supplemented in the culture medium. Two molecules of tyrosine are modified and condensed to form the first benzylisoquinoline structure, which may be either norcoclaurine or norlaudanosoline. The benzylisoquinoline is further modified to form (S)-reticuline and then stereochemically inverted by the activity of an epimerase enzyme to yield (R)-reticuline. (R)-reticuline undergoes a carbon-carbon coupling reaction to form the first promorphinan, salutaridine, and is further modified before undergoing an oxygen-carbon coupling reaction catalyzed by a thebaine synthase to arrive at the first morphinan alkaloid structure, thebaine (see
To detect O-demethylase activity in strains producing morphinan alkaloid molecules, cells expressing candidate enzymes, either from plasmid vectors or chromosomally-integrated cassettes, were propagated by fermentation and cell supernatants were collected to analyze the total opioid profile (as described above). O-demethylation of opioid molecules in strains harboring the complete BIA pathway was detected by LC-MS (as described above). Specifically, the conversion of oxycodone to oxymorphone was detected. To detect 0-demethylation activity via biocatalysis, strains were cultured in selective medium and then lysed by glass bead disruption. Cell lysates were supplied exogenously with opioid substrates (see
Enzymes listed in Table 5, that displayed N-demethylase activity on morphinan alkaloids, were incorporated into a microbial strain (either Saccharomyces cerevisiae or Escherichia coli) which biosynthesizes morphinan alkaloids de novo (as described in Example 6). The complete BIA biosynthetic pathway uses L-tyrosine produced by the host cell and/or supplemented in the culture medium. Two molecules of tyrosine are modified and condensed to form the first benzylisoquinoline structure which may be either norcoclaurine or norlaudanosoline. The benzylisoquinoline is further modified to form (S)-reticuline and then stereochemically inverted by the activity of an epimerase enzyme to yield (R)-reticuline. (R)-reticuline undergoes a carbon-carbon coupling reaction to form the first promorphinan, salutaridine, and is further modified before undergoing an oxygen-carbon coupling reaction catalyzed by a thebaine synthase to arrive at the first morphinan alkaloid structure, thebaine (see
To detect N-demethylase activity in strains producing morphinan alkaloid molecules, cells expressing candidate enzymes, either from plasmid vectors or chromosomally-integrated cassettes, were propagated by fermentation and cell supernatants were collected to analyze the total opioid profile (as described above). N-demethylation of opioid molecules in strains harboring the complete BIA pathway was detected by LC-MS (as described above). Specifically, the conversion of oxymorphone to noroxymorphone was detected. To detect N-demethylation activity via biocatalysis, strains were cultured in selective medium and then lysed by glass bead disruption. Cell lysates were supplied exogenously with opioid substrates (see
Enzymes listed in Table 6, that displayed N-methylase activity on morphinan alkaloids, were incorporated into a microbial strain (either Saccharomyces cerevisiae or Escherichia coli) which biosynthesizes morphinan alkaloids de novo (as described in Example 6).
To detect N-modifying activity in strains with the complete BIA pathway to nor-opioids (see
Saccharomyces
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Saccharomyces
cerevisiae,
Homo sapiens,
Mus musculus
Rattus
norvegicus,
Homo sapiens,
Mus musculus
Rattus
norvegicus,
Homo sapiens,
Mus musculus
Rattus
norvegicus,
Homo sapiens,
Mus musculus
Rattus
norvegicus,
Homo sapiens,
Mus musculus
Pseudomonas
putida, Rattus
norvegicus
Papaver
somniferum
E. coli, Homo
sapiens,
Micrococcus
luteus
Rattus
norvegicus,
Homo sapiens
P. somniferum
T. flovum
Coptis japonica*
P. somniferum
T. flovum
Coptis japonica*
P. somniferum
T. flovum
Coptis japonica*
Coptis japonica,
Papaver
somniferum,
Papver
bracteatum,
Thalicitum
flavum, Corydalis
saxicola
P. somniferum,
E. californica,
T. flavum
P. somniferum
E. californica
A. mexicana
P. somniferum
E. californica
A. mexicana
P. somniferum
E. californica
P. bracteatum
A. mexicana
P. somniferum
E. californica
P. somniferum
P. somniferum
Berberis
wilsonae, Coptis
japonica,
Berberis spp,
Coptis spp
Thalictrum
flavum subsp.
glaucum, Coptis
japonica, Coptis
chinensis,
Papaver
somniferum,
Thalictrum spp,
Coptis spp,
Papaver spp
Thalictrum
flavum subsp.
glaucum, Coptis
japonica,
Thalictrum spp,
Coptis spp
Papaver
somniferum,
Argemone
mexicana,
Eschscholzia
californica,
Berberis
stolonifera,
Thalictrum
flavum subsp.
glaucum, Coptis
japonica,
Papaver spp,
Eschscholzia spp,
Berberis spp,
Thalictrum spp,
Coptis spp
Arabidopsis
thaliana,
Eschscholzia
californica,
Papaver
somniferum,
Homo sapiens,
Saccharomyces
cerevisiae,
Papaver
bracteatum,
Papaver spp, all
Papaver
somniferum,
Papaver
bracteatum,
Papaver spp
Chelidonium
majus
Papaver
somniferum,
Papaver
bracteatum,
Papaver
orientale,
Papaver spp
Papaver
somniferum,
Papaver
bracteatum,
Papaver
orientale,
Papaver spp
Papaver
somniferum,
Papaver spp
Chelidonium
majus
Papaver
bracteatum,
Papaver
somniferum,
Papaver
setigerum,
Chelidonium
majus
Homo sapiens
Papaver
neopinone
somniferium,
Papaver spp.
Papaver
codeine
somniferium,
Papaver spp.
neopine
Papaver
morphine
somniferium,
Papaver spp.
neomorphine
Pseudomonas
morphinone
putida
codeine
Pseudomonas
hydrocodone
putida
hydromorphone
Papaver
somniferum,
Papaver spp.
Papaver
somniferum,
Papaver spp.
Papaver
somniferum,
Papaver
bracteatum,
Papaver rhoeas,
Papaver spp.
Bacillus
megaterium,
Homo sapiens,
Papaver
somniferum,
Papaver spp.,
Chelidonium
majus,
Stylophorum
diphyllum,
Nigella sativa,
Hydrastis
canadensis,
Glaucium
flavum,
Eschscholzia
californica,
Menispermum
canadense,
Papaver
bracteatum
Papaver
Chelidonium
majus,
Thalictrum
flavum,
Coptis
japonica,
Papaver
somniferum,
Eschscholzia
californica,
Papaver
bracteatum,
Argenome
mexicana,
Glaucium
flavum,
Sanguinaria
canadensis,
Corydalis
chelanthifolia,
Nigella
saliva,
Jeffersonia
diphylla,
Berberis
thunbergii,
Mahonia
aquifolium,
Menispermum
canadense,
Tinospora
cordifolia,
Cissampelos
mucronata,
Cocculus
trilobus
Papaver spp.,
Chelidonium
majus,
Thalictrum
flavum, Coptis
japonica,
Papaver
somniferum,
Eschscholzia
californica,
Papaver
bracteatum,
Argenome
mexicana,
Glaucium
flavum,
Sanguinaria
canadensis,
Corydalis
chelanthifolia,
Nigella sativa,
Jeffersonia
diphylla,
Berberis
thunbergii,
Mahonia
aquifolium,
Menispermum
canadense,
Tinospora
cordifolia,
Cissampelos
mucronata,
Cocculus trilobus
Papaver spp.,
Chelidonium
majus,
Thalictrum
flavum, Coptis
japonica,
Papaver
somniferum,
Eschscholzia
californica,
Papaver
bracteatum,
Argenome
mexicana,
Glaucium
flavum,
Sanguinaria
canadensis,
Corydalis
chelanthifolia,
Nigella sativa,
Jeffersonia
diphylla,
Berberis
thunbergii,
Mahonia
aquifolium,
Menispermum
canadense,
Tinospora
cordifolia,
Cissampelos
mucronata,
Cocculus trilobus
While preferred embodiments of the invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention. It is intended that the following claims define the scope of the invention and that methods and structures within the scope of these claims and their equivalents be covered thereby.
This application is continuation application of International Application No. PCT/US19/17357, filed Feb. 8, 2019, which claims the benefit of U.S. Provisional Application No. 62/628,264, which was filed Feb. 8, 2018. This application is related to: U.S. patent application Ser. No. 14/211,611 now published as US 2014-0273109, which application was filed on Mar. 14, 2014; PCT Application Serial No. PCT/US2014/027833 now published as WO 2014/143744, which application was filed on Mar. 14, 2014; U.S. patent application Ser. No. 15/031,618, which application was filed on Apr. 22, 2016; Application Serial No. PCT/US2014/063738 now published as WO 2015/066642, which application was filed on Nov. 3, 2014; U.S. Provisional Patent Application Ser. No. 62/080,610, which was filed Nov. 17, 2014; U.S. Provisional Patent Application Ser. No. 62/107,238, which was filed Jan. 23, 2015; Application Serial No. PCT/US2015/060891 which application was filed on Nov. 16, 2015; U.S. Provisional Patent Application Ser. No. 62/156,701, which was filed May 4, 2015; Application Serial No. PCT/US2016/030808 which application was filed on May 4, 2016; Application Serial No. PCT/US2016/031506 which application was filed on May 9, 2016; Application Serial No. PCT/US2017/057237 which application was filed Oct. 18, 2017; Application Ser. No. 62/541,038 which application was filed on Aug. 3, 2017; and Application Serial No. PCT/US2018/045222 which application was filed on Aug. 3, 2018; and application Ser. No. 16/149,025 which application was filed on Oct. 1, 2018; the disclosures of which applications are herein incorporated by reference. The instant application contains a Sequence Listing which has been submitted electronically in ASCII format and is hereby incorporated by reference in its entirety. Said ASCII copy, created on Aug. 3, 2020, is named 47840-708_301_SL.txt and is 620,839 bytes in size.
| Number | Name | Date | Kind |
|---|---|---|---|
| 6573428 | Vodkin et al. | Jun 2003 | B1 |
| 10544420 | Smolke | Jan 2020 | B2 |
| 11142780 | Facchini et al. | Oct 2021 | B2 |
| 11479586 | Facchini et al. | Oct 2022 | B2 |
| 20090156815 | Wang et al. | Jul 2009 | A1 |
| 20160208269 | Smolke et al. | Jul 2016 | A1 |
| 20200325509 | Enquist-Newman | Oct 2020 | A1 |
| 20210062235 | Smolke | Mar 2021 | A1 |
| 20220205004 | Facchini et al. | Jun 2022 | A1 |
| Number | Date | Country |
|---|---|---|
| 2011058446 | May 2011 | WO |
| 2015081437 | Jun 2015 | WO |
| 2015173590 | Nov 2015 | WO |
| 2018000089 | Jan 2018 | WO |
| 2018005553 | Jan 2018 | WO |
| Entry |
|---|
| Facchini, P.J., “GenBank Accession No. FE967184”. Mar. 31, 2008, [online] [retrieved on Sep. 19, 2017]. Retrieved from the internet: <https://www.ncbi.nlm.nih.gov/nucest/FE967184>. |
| Shitan et al., “Alkaloid Transporters in Plants”, Plant Biotechnology, 31:453-463 (2014), DOI 10.5511/plantbiotechnology.14.1002a. |
| Fossati et al., “Synthesis of Morphinan Alkaloids in Saccharomyces cerevisiae”, PLOS ONE, DOI: 10.1371/journal.pone.0124453 (2015). |
| Sabarna, “Approaches to isolating a cDNA encoding thebaine synthase or morphine biosynthesis from opium poppy Papaver somniferum L.”, Internet Citation, [Online], Retrieved from the Internet: URL:http://sundoc.bibliothek.uni-halle.de/ Jun. 22, 2007 (Jun. 22, 2007). |
| Fisinger et al., “Thebaine synthase: A new enzyme in the morphone pathway in Papaver somniferum”, Natural Product Communications, 2: 249-253 (2007). |
| Beaudoin et al., “Benzylisoquinoline alkaloid biosynthesis in opium poppy”, Planta, 240: 19-32 (2014), DOI 10.1007/S00425-014-2056-8. |
| Database EMBL [Online] Jul. 2, 2015 (Jul. 2, 2015), “Papaver somniferum (opium poppy) reticuline epimerase ID-AKO60181 ; SV 1 ; linearl; genomic DNA; STD; PLN; 2703 BP.”, retrieved from EBI accession No. EM_CDS: AKO60181. |
| Database Geneseq [Online] Apr. 9, 2015 (Apr. 9, 2015), “Papaver somniferum OMT protein, SEQ ID 543.”, retrieved from EBI accession No. GSP:BBU80692 Database accession No. BBU80692. |
| Winzer et al., “A Papaver somniferum 10-Gene Cluster for Synthesis of the Anticancer Alkaloid Noscapine”, Science, 336:1704-1708 (2012), DOI: 10.1126/science.1220757. |
| Hagel et al., “Dioxygenases catalyze the O-demethylation steps of morphine biosynthesis in opium poppy”, Nature Chemical Biology, 6:273-275 (2010). |
| Morris et al., “Plug-and-Play Benzylisoquinoline Alkaloid Biosynthetic Gene Discovery in Engineered Yeast” in Methods in Enzymology, 144-178 (Elsevier 2016). |
| Galanie et al., “Complete biosynthesis of opioids in yeast”, Science, 349:1095-1100 (2015). |
| Glenn, W.S. et al., “Recent progress in the metabolic engineering of alkaloids in plant 1-49 systems”, Curr. Opin. Biotechnol., Apr. 2013 (Apr. 2013), vol. 24(2), pp. 354-365. |
| Chen et al, “A pathogenesis-related 10 protein catalyzes the final step in thebaine biosynthesis”, 2018, Nature Chemical Biology, 14:738-743. |
| Zulak et al, “Gene transcript and metabolite profiling of elicitor-induced opium poppy cell cultures reveals the coordinate regulation of primary and secondary metabolism”, 2007, Planta, 225:1085-1106, DOI: 10.1007/s00425-006-0419-5. |
| Dastmalchi et al, “Purine Permease-Type Benzylisoquinoline Alkaloid Transporters in Opium Poppy”, 2019, Plant Psychology, 181:916-933. |
| Grothe et al, “Molecular Characterization of the Salutaridinol 7-O-Acetyltransferase Involved in Morphine Biosynthesis in Opium Poppy Papaver somniferum”, 2001, The Journal of Biological Chemistry, 276:30717-30723. |
| Choe et al., “Genetic and chemical components analysis of Papaver setigerum naturalized in Korea”, Forensic Science International, 222:387-393 (2012). |
| Samanani et al., “The role of phloem sieve elements and laticifers in the biosynthesis and accumulation of alkaloids in opium poppy”, Plant Journal, 47:547-563 (2006), DOI: 10.111/j.1365-313X.2006.02801.x. |
| Facchini et al., “Developmental and inducible accumulation of gene transcripts involved in alkaloid biosynthesis in opium poppy”, Phytochemistry, 64:177-186 (2003). |
| Kisselev L., “Polypeptide Release Factors in Prokaryotes and Eukaryotes: Same Function, Different Structure”, Structure, 2002, vol. 10: 8-9. |
| Witkowski et al., “Conversion of a B-Ketoacyl Synthase to a Malonyl Decazrboxylase by Replacement of the Active-Site Cysteine with Glutamine”, Biochemistry 38:11643-11650, 1999. |
| Whisstock et al., Quarterly Reviews of Biophysics 2003, vol. 36 (3): 307-340. |
| Devos et al., “Practical Limits of Function Prediction”, Proteins: Structure, Function and Genetics, 2000, vol. 41: 98-107. |
| U.S. Non-Final Office Action dated May 20, 2020 in U.S. Appl. No. 16/312,895. |
| U.S. Final Office Action dated Nov. 25, 2020 in U.S. Appl. No. 16/312,895. |
| U.S. Non-Final Office Action dated Aug. 28, 2020 in U.S. Appl. No. 16/312,776. |
| U.S. Notice of Allowance dated Mar. 15, 2021 in U.S. Appl. No. 16/312,776. |
| Farrow et al. “Stereochemical inversion of (S)-reticuline by a cytochrome P450 fusion in opium poppy” Nature Chemical Biology, vol. 11, Sep. 2015, p. 728-732; abstract. |
| U.S. Office Action dated Apr. 23, 2021 in U.S. Appl. No. 16/312,895. |
| Number | Date | Country | |
|---|---|---|---|
| 20210062235 A1 | Mar 2021 | US |
| Number | Date | Country | |
|---|---|---|---|
| 62628264 | Feb 2018 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/US2019/017357 | Feb 2019 | US |
| Child | 16984900 | US |
