Patent Application
20200283807
The present disclosure relates generally to production of phytocannabinoids and analogues of phytocannabinoids in yeast.
Phytocannabinoids are naturally produced in Cannabis sativa, other plants, and some fungi. Over 105 phytocannabinoids are known to be biosynthesized in C. sativa, or result from thermal or other decomposition from phytocannabinoids biosynthesized in C. sativa. While the C. sativa plant is also a valuable source of grain, fiber, and other material, growing C. sativa for phytocannabinoid production, particularly indoors, is costly in terms of energy and labour. Subsequent extraction, purification, and fractionation of phytocannabinoids from the C. sativa plant is also labour and energy intensive.
Phytocannabinoids are pharmacologically active molecules that contribute to the medical and psychotropic effects of C. sativa. Biosynthesis of phytocannabinoids in the C. sativa plant scales similarly to other agricultural projects. As with other agricultural projects, large scale production of phytocannabinoids by growing C. sativa requires a variety of inputs (e.g. nutrients, light, pest control, CO2, etc.). The inputs required for cultivating C. sativa must be provided. In addition, cultivation of C. sativa, where allowed, is currently subject to heavy regulation, taxes, and rigorous quality control where products prepared from the plant are for commercial use, further increasing costs. Phytocannabinoid analogues are pharmacologically active molecules that are structurally similar to phytocannabinoids. Phytocannabinoid analogues are often synthesized chemically, which can be labour intensive and costly. As a result, it may be economical to produce the phytocannabinoids and phytocannabinoid analogues in a robust and scalable, fermentable organism. Saccharomyces cerevisiae is an example of a fermentable organism that has been used to produce industrial scales of similar molecules.
The time, energy, and labour involved in growing C. sativa for production of naturally-occurring phytocannabinoids provides a motivation to produce transgenic cell lines for production of phytocannabinoids in yeast. One example of such efforts is provided in United States Patent Application Publication no. US 2016/0010126 to Poulos and Farnia.
It is an object of the present disclosure to obviate or mitigate at least one disadvantage of previous approaches to producing phytocannabinoids in yeast, and of previous approaches to producing phytocannabinoid analogues. Many of the 105 phytocannabinoids found in Cannabis sativa may be synthesized in yeast, and it may be desirable to improve yeast-based production. Similarly, an approach that allows for production of phytocannabinoid analogues without the need for labour-intensive synthesis may be desirable.
The methods and cells lines provided herein may apply and include transgenic Saccharomyces cerevisiae that have been transformed with a gene coding for the NphB prenyltransferase enzyme from Streptomyces coelicolor (“CL190”) (“AltPT”). AltPT is an αββα (“ABBA”) type prenyltransferase enzyme. AltPT catalyzes synthesis of cannabigerolic acid (“CBGa”) from olivetolic acid and geranyl pyrophosphate (“GPP”). AltPT also catalyzes synthesis of cannabigerol (“CBG”) from olivetol and GPP. In C. sativa, a prenyltransferase enzyme catalyzes synthesis of CBGa from olivetolic acid and GPP. The C. sativa prenyltransferase is membrane-bound, complicating expression in S. cerevisiae. In contrast, AltPT is cytosolic and expresses at greater levels than the C. sativa prenyltransferase in S. cerevisiae. AltPT may provide advantages over membrane-bound C. sativa prenyltransferase when expressed in S. cerevisiae to catalyze synthesis of CBGa from olivetolic acid and GPP or CBG from olivetol and GPP. The S. cerevisiae may have one or more mutations in Erg20, Maf1 or UPC2, or other genes for enzymes or other proteins that support metabolic pathways that deplete GPP, the one or more mutations being for increasing available GPP. Alternatively, other species of yeast, including Yarrowia lipolytica, Kluyveromyces marxianus, Kluyveromyces lactis, Rhodosporidium toruloides, Cryptococcus curvatus, Trichosporon pullulan and Lipomyces lipoferetc, may be applied.
In some methods and cell lines provided herein, the transgenic S. cerevisiae includes a gene for C. sativa polyketide synthase (also called olivetolic acid synthase or “OAS”). OAS catalyzes synthesis of olivetol from malonyl-CoA and hexanoyl-CoA. The reaction has a 2:1:1 stoichiometric ratio of malonyl-CoA to hexanoyl-CoA to olivetolic acid. In C. sativa, the olivetol is carboxylated in the presence of olivetolic acid cyclase (“OAC”) or another polyketide cyclase into olivetolic acid, which feeds into the CBGa synthesis metabolic pathway described above in relation to AltPT and other cytosolic prenyltransferase enzymes, catalyzed by in C. sativa by a membrane-bound prenyltransferase. The OAC enzyme from C. sativa may be excluded from the transgenic S. cerevisiae to drive synthesis of CBG rather than CBGa by AltPT.
In some methods and cell lines provided herein, the transgenic S. cerevisiae includes a gene for Dictyostelium discoideum polyketide synthase (“DiPKS”). DiPKS is a fusion protein consisting of both a type I fatty acid synthase (“FAS”) and a polyketide synthase and is referred to as a hybrid “FAS-PKS” protein. DiPKS catalyzes synthesis of methyl-olivetol from malonyl-CoA. The reaction has a 6:1 stoichiometric ratio of malonyl-CoA to methyl-olivetol. AltPT catalyzes synthesis of methyl cannabigerol (“meCBG”) from methyl-olivetol, similarly to synthesis of CBG from olivetol described above. Hexanoic acid is toxic to S. cerevisiae. When applying OAS, hexanoyl-CoA is a necessary precursor for synthesis of olivetol. When using DiPKS to produce methyl-olivetol rather than OAS to produce olivetol or olivetolic acid (if the, hexanoic acid need not be added to the growth media. The absence of hexanoic acid in growth media may result in increased growth of the S. cerevisiae cultures and greater yield of meCBG compared with yields of CBG when using OAS.
For some applications, meCBG and methylated downstream phytocannabinoid analogues that can be synthesized from meCBG (similarly to downstream phytocannabinoids being synthesized from CBGa in C. sativa) may be valuable. In other cases, phytocannabinoids structurally identical to the decarboxylated forms of naturally-occurring phytocannabinoids may be more desirable. For production of phytocannabinoids that are structurally identical to the decarboxylated forms of naturally-occurring phytocannabinoids, DiPKS may be modified relative to wild type DiPKS to reduce methylation of olivetol, resulting in synthesis of CBG rather than meCBG. The S. cerevisiae may include a co-factor loading enzyme to increase the activity of DiPKS.
Synthesis of olivetol and methyl-olivetol may be facilitated by increased levels of malonyl-CoA in the cytosol. The S. cerevisiae may have overexpression of native acetaldehyde dehydrogenase and expression of a mutant acetyl-CoA synthase or other gene, the mutations resulting in lowered mitochondrial acetaldehyde catabolism. Lowering mitochondrial acetaldehyde catabolism by diverting the acetaldehyde into acetyl-CoA production increases malonyl-CoA available for synthesizing olivetol. Acc1 is the native yeast malonyl CoA synthase. The S. cerevisiae may have over-expression of Acc1 or modification of Acc1 for increased activity and increased available malonyl-CoA. The S. cerevisiae may include modified expression of Maf1 or other regulators of tRNA biosynthesis. Overexpressing native Maf1 has been shown to reduce loss of isopentyl pyrophosphate (“IPP”) to tRNA biosynthesis and thereby improve monoterpene yields in yeast. IPP is an intermediate in the mevalonate pathway. Upc2 is an activator for sterol biosynthesis in S. cerevisiae, and a Glu888Asp mutation of Upc2 may increase monoterpene production in yeast.
In a first aspect, herein provided is a method and cell line for producing phytocannabinoids and phytocannabinoid analogues in yeast. The method applies, and the cell line includes, a yeast cell transformed with a polyketide synthase CDS and a cytosolic prenyltransferase CDS. The polyketide synthase enzyme catalyzes synthesis of olivetol or methyl-olivetol, and may include Cannabis sativa olivetolic acid synthase or Dictyostelium discoideum polyketide synthase (“DiPKS”). The yeast cell may be modified to include a phosphopantethienyl transferase for increased activity of DiPKS. The yeast cell may be modified to mitigate mitochondrial acetaldehyde catabolism for increasing malonyl-CoA available for synthesizing olivetol or methyl-olivetol. The prenyltransferase enzyme catalyzes synthesis of cannabigerol or a cannabigerol analogue, and may include an αββα cytosolic prenyltransferase enzyme from Streptomyces sp CL190. The yeast cell may be modified to mitigate depletion of geranyl pyrophosphate for increasing available geranyl pyrophosphate for prenylation.
In a further aspect, herein provided is a method of producing phytocannabinoids or phytocannabinoid analogues, the method comprising: providing a yeast cell comprising a first polynucleotide coding for a polyketide synthase enzyme and a second polynucleotide coding for a cytosolic prenyltransferase enzyme, and propagating the yeast cell for providing a yeast cell culture. The polyketide synthase enzyme is for producing at least one precursor chemical from malonyl-CoA, the precursor chemical having structure I:
On structure I, R1 is an alkyl group with a chain length of 1, 2, 3, 4, or 5 carbons, R2 is H, carboxyl, or methyl, and R3 is H, carboxyl, or methyl. The cytosolic prenyltransferase enzyme is for prenylating the at least one precursor chemical, providing at least one species of phytocannabinoid or phytocannabinoid analogue.
In some embodiments, the yeast cell comprises a third polynucleotide coding for a hexanoyl synthase enzyme; the polyketide synthase enzyme comprises an OAS enzyme from C. sativa; and propagating the yeast cell comprises propagating the yeast cell in a nutrient preparation comprising hexanoic acid. In some embodiments, the yeast cell does not include a C. sativa polyketide cyclase enzyme and the at least one species of phytocannabinoid or phytocannabinoid analogue comprises a decarboxylated phytocannabinoid or phytocannabinoid analogue. In some embodiments, the first polynucleotide comprises a coding sequence for the OAS enzyme from C. sativa with a primary structure having between 80% and 100% amino acid residue sequence homology with a protein coded for by a reading frame defined by bases 3841 to 4995 of SEQ ID NO: 45. In some embodiments the first polynucleotide has between 80% and 100% base sequence homology with bases 3841 to 4995 of SEQ ID NO: 45. In some embodiments, the first polynucleotide has between 80% and 100% base sequence homology with bases 3841 to 4995 of SEQ ID NO: 45.
In some embodiments, R1 is an alkyl group with a chain length of 3 carbons, R2 is H, and R3 is H.
In some embodiments, R1 is an alkyl group with a chain length of 3 carbons, R2 is carboxyl, and R3 is H.
In some embodiments, R1 is an alkyl group with a chain length of 3 carbons, R2 is methyl, and R3 is H.
In some embodiments, R1 is an alkyl group with a chain length of 3 carbons, R2 is carboxyl, and R3 is methyl.
In some embodiments, the polyketide synthase enzyme comprises a DiPKS polyketide synthase enzyme from D. discoideum. In some embodiments, the first polynucleotide comprises a coding sequence for the DiPKS polyketide synthase enzyme with a primary structure having between 80% and 100% amino acid residue sequence homology with a protein coded for by a reading frame defined by bases 535 to 9978 of SEQ ID NO: 46. In some embodiments, the first polynucleotide has between 80% and 100% base sequence homology with bases 535 to 9978 of SEQ ID NO: 46. In some embodiments, the at least one precursor chemical comprises a methyl group at R2 and the at least one species of phytocannabinoid or phytocannabinoid analogue comprises a methylated phytocannabinoid analogue. In some embodiments, the DiPKS polyketide synthase enzyme comprises a mutation affecting an active site of a C-Met domain for mitigating methylation of the at least one precursor chemical, resulting in the at least one precursor chemical comprising a first precursor chemical wherein R2 is methyl and R3 is H, and a second precursor chemical wherein R2 is H and R3 is H; and the at least one species of phytocannabinoid or phytocannabinoid analogue comprises a methylated phytocannabinoid analogue and an unmethylated phytocannabinoid. In some embodiments, the DiPKS polyketide synthase comprises a DiPKSG1516D; G1518A polyketide synthase enzyme. In some embodiments, the first polynucleotide comprises a coding sequence for the DiPKSG1516D; G1518A polyketide synthase enzyme with a primary structure having between 80% and 100% amino acid residue sequence homology with a protein coded for by a reading frame defined by bases 523 to 9966 of SEQ ID NO: 37. In some embodiments, the first polynucleotide has between 80% and 100% base sequence homology with bases 523 to 9966 of SEQ ID NO: 37. In some embodiments, the DiPKS polyketide synthase comprises a DiPKSG1516R polyketide synthase enzyme. In some embodiments, the first polynucleotide comprises a coding sequence for the DiPKSG1516R polyketide synthase enzyme with a primary structure having between 80% and 100% amino acid residue sequence homology with a protein coded for by a reading frame defined by bases 523 to 9966 of SEQ ID NO: 38. In some embodiments, the first polynucleotide has between 80% and 100% base sequence homology with bases 523 to 9966 of SEQ ID NO: 38. In some embodiments, the DiPKS polyketide synthase enzyme comprises a mutation reducing activity at an active site of a C-Met domain of the DiPKS polyketide synthase enzyme, for preventing methylation of the at least one precursor chemical, resulting in the at least one precursor chemical having a hydrogen R2 group and a hydrogen R3 group; and the at least one species of phytocannabinoid or phytocannabinoid analogue comprises a decarboxylated phytocannabinoid or phytocannabinoid analogue. In some embodiments, the yeast cell comprises a third polynucleotide coding for a phosphopantetheinyl transferase enzyme for increasing the activity of DiPKS. In some embodiments, the phosphopantetheinyl transferase comprises NpgA phosphopantetheinyl transferase enzyme from A. nidulans. In some embodiments, the third polynucleotide comprises a coding sequence for the NpgA phosphopantetheinyl transferase enzyme from A. nidulans with a primary structure having between 80% and 100% amino acid residue sequence homology with a protein coded for by a reading frame defined by bases 1170 to 2201 of SEQ ID NO: 10. In some embodiments, the third polynucleotide has between 80% and 100% base sequence homology with bases 1170 to 2201 of SEQ ID NO: 10.
In some embodiments, the polyketide synthase enzyme comprises an active site for synthesizing the at least one precursor chemical from malonyl-CoA without a longer chain ketyl-CoA. In some embodiments, the at least one precursor chemical comprises a pentyl group at R1 and the at least one species of phytocannabinoid or phytocannabinoid analogue comprises a pentyl-phytocannabinoid or methylated pentyl-phytocannabinoid analogue. In some embodiments, the at least one precursor chemical comprises at least one of olivetol olivetolic acid, methyl-olivetol, or methyl-olivetolic acid, and the at least one species of phytocannabinoid or phytocannabinoid analogue comprises at least one of CBG, CBGa, meCBG, or meCBGa.
In some embodiments, the cytosolic prenyltransferase enzyme comprises an NphB prenyltransferase enzyme from Streptomyces sp CL190. In some embodiments, the second polynucleotide comprises a coding sequence for NphB prenyltransferase enzyme from Streptomyces sp CL190 with a primary structure having between 80% and 100% amino acid residue sequence homology with a protein coded for by a reading frame defined by bases 987 to 1913 of SEQ ID NO: 44. In some embodiments, the second polynucleotide has between 80% and 100% base sequence homology with bases 987 to 1913 of SEQ ID NO: 44.
In some embodiments, R1 is an alkyl group with a chain length of 5 carbons, R2 is H, and R3 is H.
In some embodiments, R1 is an alkyl group with a chain length of 5 carbons, R2 is carboxyl, and R3 is H.
In some embodiments, R1 is an alkyl group with a chain length of 5 carbons, R2 is methyl, and R3 is H.
In some embodiments, R1 is an alkyl group with a chain length of 5 carbons, R2 is carboxyl, and R3 is methyl.
In some embodiments, the yeast cell comprises a genetic modification to increase available geranylpyrophosphate. In some embodiments, the genetic modification comprises an inactivation of the Erg20 enzyme. In some embodiments, the yeast cell comprises a third polynucleotide including a coding sequence for Erg20K197E with a primary structure having between 80% and 100% amino acid residue sequence homology with a protein coded for by a reading frame defined by SEQ ID NO: 3. In some embodiments, the third polynucleotide has between 80% and 100% base sequence homology with SEQ ID NO: 3.
In some embodiments, the yeast cell comprises a genetic modification to increase available malonyl-CoA. In some embodiments, the genetic modification comprises increased expression of Maf1. In some embodiments, the yeast cell comprises a third polynucleotide including a coding sequence for Maf1 with a primary structure having between 80% and 100% amino acid residue sequence homology with a protein coded for by a reading frame defined by bases 936 to 2123 of SEQ ID NO: 8. In some embodiments, the third polynucleotide further comprises a promoter sequence, a terminator sequence and integration sequences, and has between 80% and 100% base sequence homology with SEQ ID NO: 8. In some embodiments, the genetic modification comprises a modification for increasing cytosolic expression of an aldehyde dehydrogenase and an acetyl-CoA synthase. In some embodiments, the yeast cell comprises a third polynucleotide including a coding sequence for AcsL641P from S. enterica with a primary structure having between 80% and 100% amino acid residue sequence homology with a protein coded for by a reading frame defined by bases 3938 to 5893 of SEQ ID NO: 4, and a coding sequence for Ald6 from S. cerevisiae with a primary structure having between 80% and 100% amino acid residue sequence homology with a protein coded for by a reading frame defined by bases 1494 to 2999 of SEQ ID NO 4. In some embodiments, the third polynucleotide further comprises a promoter sequence, a terminator sequence and integration sequences, and has between 80% and 100% base sequence homology with bases 51 to 7114 SEQ ID NO: 4. In some embodiments, the genetic modification comprises a modification for increasing malonyl-CoA synthase activity. In some embodiments, the yeast cell comprises a third polynucleotide including a coding sequence for Acc1S659A; S1167A from S. cerevisiae. In some embodiments, the third polynucleotide includes a coding sequence for the Acc1S659A; S1167A enzyme, with a portion thereof having a primary structure with between 80% and 100% amino acid residue sequence homology with a protein portion coded for by a reading frame defined by bases 9 to 1716 of SEQ ID NO: 7. Acc1S659A; S1167A. In some embodiments, the third polynucleotide further comprises a promoter sequence, a terminator sequence and integration sequences, and has between 80% and 100% base sequence homology with SEQ ID NO: 7. In some embodiments, the yeast cell comprises a third polynucleotide including the coding sequence for Acc1 from S. cerevisiae under regulation of a constitutive promoter. In some embodiments, the constitutive promoter comprises a PGK1 promoter from S. cerevisiae. In some embodiments, the PGK1 promoter has between 80% and 100% nucleotide homology with bases 7 to 750 of SEQ ID NO: 6. In some embodiments, the genetic modification comprises increased expression of an activator for sterol biosynthesis. In some embodiments, the yeast cell comprises a third polynucleotide including a coding sequence for Upc2E888D from S. cerevisiae with a primary structure having between 80% and 100% amino acid residue sequence homology with a protein coded for by a reading frame defined by bases 975 to 3701 of SEQ ID NO: 9. In some embodiments, the third polynucleotide further comprises a promoter sequence, a terminator sequence and integration sequences, and has between 80% and 100% base sequence homology with SEQ ID NO: 9.
In some embodiments, the second polynucleotide comprises a coding sequence for a cytosolic prenyltransferase enzyme with a primary structure having between 80% and 100% amino acid residue sequence homology with any one of SEQ ID NO: 11, SEQ ID NO: 13, SEQ ID NO: 14, SEQ ID NO: 15, SEQ ID NO: 16, SEQ ID NO: 17, SEQ ID NO: 18, SEQ ID NO: 19, SEQ ID NO: 20, SEQ ID NO: 21, SEQ ID NO: 22, SEQ ID NO: 23, SEQ ID NO: 24, SEQ ID NO: 25, SEQ ID NO: 26, SEQ ID NO: 27, SEQ ID NO: 28, SEQ ID NO: 29, SEQ ID NO: 30, SEQ ID NO: 31, SEQ ID NO: 32, SEQ ID NO: 33, SEQ ID NO: 34, SEQ ID NO: 35 or SEQ ID NO: 36.
In some embodiments, the method includes extracting the at least one species of phytocannabinoid or phytocannabinoid analogue from the yeast cell culture.
In a further aspect, herein provided is yeast cell for producing phytocannabinoids or phytocannabinoid analogues, the yeast cell comprising: a first polynucleotide coding for a polyketide synthase enzyme; and a second polynucleotide coding for a cytosolic prenyltransferase enzyme.
In some embodiments, features of one or more of the yeast cell, the first polynucleotide, or the second polynucleotide described herein are included in the yeast cell.
In a further aspect, herein provided is a method of transforming a yeast cell for production of phytocannabinoids or phytocannabinoid analogues. The method comprises introducing a first polynucleotide coding for a polyketide synthase enzyme into the yeast cell line; and introducing a second polynucleotide coding for a cytosolic prenyltransferase enzyme into the yeast
In some embodiments, features of one or more of the yeast cell, the first polynucleotide, or the second polynucleotide described herein are applied in transforming the yeast cell.
In a further aspect, herein provided is a phytocannabinoid analogue having the following structure II:
On structure II, R1 is an alkyl group with a chain length of 1, 2, 3, 4, or 5 carbons. R2 is a methyl group. R3 is H, a carboxyl group, or a methyl group.
In some embodiments, R1 has a chain length of 5 carbons and R3 is H.
In some embodiments, the phytocannabinoid analogue is produced by biosynthesis in yeast.
In a further aspect, herein provided is a phytocannabinoid analogue having the following structure III:
On structure III, R1 is pentyl group; R2 is a methyl group; and R3 is H.
Other aspects and features of the present disclosure will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments in conjunction with the accompanying figures.
Embodiments of the present disclosure will now be described, by way of example only, with reference to the attached Figures.
Generally, the present disclosure provides methods and yeast cell lines for producing phytocannabinoids that are naturally biosynthesized in the Cannabis sativa plant and methylated phytocannabinoid analogues biosynthesized from methyl-olivetol. The phytocannabinoids and phytocannabinoid analogues are produced in transgenic yeast. The methods and cell lines provided herein include application of genes for enzymes absent from the C. sativa plant. Application of genes other than the complete set of genes in the C. sativa plant that code for enzymes in the biosynthetic pathway resulting in phytocannabinoids may provide one or more benefits including biosynthesis of decarboxylated phytocannabinoids, biosynthesis of methylated phytocannabinoid analogues, and biosynthesis production of phytocannabinoids without an input of hexanoic acid, which is toxic to Saccharomyces cerevisiae and other species of yeast.
The qualifier “decarboxylated” as used herein references a form of a phytocannabinoid or phytocannabinoid analogue lacking an acid group at, e.g. positions 2 or 4 of Δ9-tetrahydrocannabinol (“THC”), or an equivalent location in other phytocannabinoids or analogues corresponding to position 4 of olivetolic acid, which is the precursor to biosynthesis of cannabigerolic acid (“CBGa”) in C. sativa. Acid forms of phytocannabinoids are biosynthesized from olivetolic acid in C. sativa. When the acid forms of phytocannabinoids are heated, the bond between the aromatic ring of the phytocannabinoid and the carboxyl group is broken. Decarboxylation results from heating carboxylated phytocannabinoids produced in C. sativa, which occurs rapidly during combustion or heating to temperatures generally above about 110° C. For simplicity, as used herein, “decarboxylated” refers to phytocannabinoids lacking the acid groups whether or not the phytocannabinoid included an acid group that was lost during true decarboxylation, or was biosynthesized without the carboxyl group.
United States Publication No. 2016/0010126 to Poulos et al. describes expression of the five native C. sativa genes in S. cerevisiae and in K. marxianus. Expression of genes from the native C. sativa pathway in yeast for phytocannabinoid production may carry drawbacks. C. sativa OAS uses hexanoyl-CoA as a polyketide substrate. Hexanoic acid is toxic to S. cerevisiae and some other strains of yeast. In addition, synthesis of CBGa from olivetolic acid requires the membrane-bound C. sativa prenyltransferase enzyme, which may express poorly in fungi.
Methods and yeast cells as provided herein for production of phytocannabinoids and phytocannabinoid analogues may apply and include S. cerevisiae transformed with the gene for prenyltransferase NphB from Streptomyces sp CL 190. The Streptomyces sp CL 190 NphB prenyltransferase provides an alternative to the C. sativa prenyl transferase enzyme and is referred to below as “AltPT”. AltPT is an αββα (“ABBA”) type prenyltransferase enzyme. AltPT is highly promiscuous, accepting most polyketides as a substrate for prenylation. AltPT is specific for GPP as a terpenoid donor. AltPT is a cytosolic enzyme expressed in Streptomyces sp CL 190, a gram positive bacteria, in contrast with the membrane-bound prenyltransferase expressed in C. sativa, a plant. The bacterial cytosolic enzyme expresses at greater levels in yeast than the plant membrane bound enzyme. AltPT will prenylate olivetolic acid to CBGa, similarly to the reaction catalyzed by the membrane-bound prenyltransferase in C. sativa. AltPT will also prenylate olivetol to cannabigerol (“CBG”), or methyl-olivetol to methyl cannabigerol (“meCBG”). A synthetic sequence for AltPT that is codon optimized for yeast is included here at SEQ ID NO: 1. A complete coding DNA sequence (“CDS”) for AltPT is available at the NCBI GenBank online database under accession number NCBI-AB187169.
The pathway shown in
Conversion of hexanoyl-CoA to olivetol catalyzed by OAS at Reaction 2 of
Other than meCBD, a portion of the structure each of the downstream phytocannabinoid anaologues shown in
DiPKS includes a C-methyltransferase domain that methylates olivetol at position 4 on the aromatic ring. As a result, AltPT prenylates methyl-olivetol, resulting in meCBG, a phytocannabinoid analogue, rather than CBGa, which is known to be synthesized in C. sativa. Any downstream reactions that may produce phytocannabinoids when using CBGa or CBG as an input would correspondingly produce the decarboxylated species of methylated phytocannabinoid analogues shown in
An example of a yeast strain expressing a modified DiPKS with lowered activity in the C-Met domain is provided as “HB80A” in Example V below. HB80A includes a modification in a yeast-codon optimized gene coding for the wildtype DiPKS protein. HB80A includes modifications in the DiPKS gene such that the DiPKS protein is modified in the first motif of the C-Met domain. As a result of these modifications to the DiPKS gene, the DiPKS protein has substitutions of Gly1516Asp and Gly1518Ala. HB80A includes only the DiPKSG1516D; G1518A and not AltPT, and as a result catalyzes only steps 1A and 1B of
Examples of yeast strains expressing a modified DiPKS with essentially no activity in the C-Met domain are provided as “HB135”, “HB137”, “HB138” and “HB139” in Examples VIII, IX and X below. Each of HB135, HB137, HB138 and HB139 includes a modification in a yeast-codon optimized gene coding for the wildtype DiPKS protein. HB135, HB137, HB138 and HB139 each include a modification of the DiPKS gene such that the DiPKS protein is modified in the first motif of the C-Met domain. As a result of this modification to the DiPKS gene, the DiPKS protein has substitutions of Gly1516Arg.
DiPKSG1516R catalyzes reaction 1 in
Increasing Availability of Biosynthetic Precursors
The biosynthetic pathways shown in
The yeast cells may be modified for increasing available GPP. S. cerevisiae may have one or more other mutations in Erg20 or other genes for enzymes that support metabolic pathways that deplete GPP. Erg20 catalyzes GPP production in the yeast cell. Erg20 also adds one subunit of 3-isopentyl pyrophosphate (“IPP”) to GPP, resulting in farnesyl pyrophosphate (“FPP”), a metabolite used in downstream sesquiterpene and sterol biosynthesis. Some mutations in Erg20 have been demonstrated to reduce conversion of GPP to FPP, increasing available GPP in the cell. A substitution mutation Lys197Glu in Erg20 lowers conversion of GPP to FPP by Erg20. As shown in Table 4 below, all modified base strains express the Erg20K197E mutant protein (“HB42”, “HB82”, “HB100”, “HB106”, and “HB110”). Similarly, each modified yeast strain based on any of HB42, HB82, HB100, HB106, or HB110 includes a integrate polynucleotide coding for the Erg20K197E mutant integrated into the yeast genome. SEQ ID NO: 3 is a CDS coding for the Erg20K197E protein and flanking sequences for homologous recombination.
The yeast strain may be modified for increasing available malonyl-CoA. Lowered mitochondrial acetaldehyde catabolism results in diversion of the acetaldehyde from ethanol catabolism into acetyl-CoA production, which in turn drives production of malonyl-CoA and downstream polyketides and terpenoids. S. cerevisiae may be modified to express an acetyl-CoA synthase from Salmonella enterica with a substitution modification of Leucine to Proline at residue 641 (“AcsL641P”), and with aldehyde dehydrogenase 6 from S. cerevisiae (“Ald6”). The Leu641Pro mutation removes downstream regulation of Acs, providing greater activity with the ACSL641P mutant than the wild type Acs. Together, cytosolic expression of these two enzymes increases the concentration of acetyl-CoA in the cytosol. Greater acetyl-CoA concentrations in the cytosol result in lowered mitochondrial catabolism, bypassing mitochondrial pyruvate dehydrogenase (“PDH”), providing a PDH bypass. As a result, more acetyl-CoA is available for malonyl-CoA production. SEQ ID NO: 4 is plasmid based on the pGREG plasmid and including a DNA sequence coding for the genes for Ald6 and SeAcsL641P, promoters, terminators, and integration site homology sequences for integration into the S. cerevisiae genome at Flagfeldt-site 19 by recombination applying clustered regularly interspaced short palindromic repeats (“CRISPR”). As shown in Table 4 below (by the term “PDH bypass”), base strains HB82, HB100, HB106, and HB110 have a portion of SEQ ID NO: 4 from bases 1494 to 2999 that code for Ald6 under the TDH3 promoter, and a portion of SEQ ID NO: 4 from bases 3948 to 5893 that code for SeAcsL641P under the Tef1P promoter. Similarly, each modified yeast strain based on any of HB82, HB100, HB106, or HB110 includes a polynucleotide coding for Ald6 and SeAcsL641P.
Another approach to increasing cytosolic malonyl-CoA is to upregulate Acc1, which is the native yeast malonyl-CoA synthase. The promoter sequence of the Acc1 gene was replaced by a constitutive yeast promoter for the PGK1 gene. The promoter from the PGK1 gene allows multiple copies of Acc1 to be present in the cell. The native Acc1 promoter allows only a single copy of the protein to be present in the cell at a time. The native promoter region is shown in SEQ ID NO: 5. The modified promoter region is shown in SEQ ID NO: 6.
In addition to upregulating expression of Acc1, S. cerevisiae may include one or more modifications of Acc1 to increase Acc1 activity and cytosolic acetyl-CoA concentrations. Two mutations in regulatory sequences were identified in literature that remove repression of Acc1, resulting in greater Acc1 expression and higher malonyl-CoA production. SEQ ID NO: 7 is a polynucleotide that may be used to modify the S. cerevisiae genome at the native Acc1 gene by homologous recombination. SEQ ID NO: 7 includes a portion of the coding sequence for the Acc1 gene with Ser659Ala and Ser1167Ala modifications. As a result, the S. cerevisiae transformed with this sequence will express Acc1S659A; S1167A. A similar result may be achieved, for example, by integrating a sequence with the Tef1 promoter, the Acc1 with Ser659Ala and Ser1167Ala modifications, and the Prm9 terminator at any suitable site. The end result would be that Tef1, Acc1S659A; S1167A and Prm9 are flanked by genomic DNA sequences for promoting integration into the S. cerevisiae genome. This was attempted at Flagfeldt site 18 but due to the size of the construct, the approach with SEQ ID NO: 7 described above was followed instead.
S. cerevisiae may include modified expression of Maf1 or other regulators of tRNA biosynthesis. Overexpressing native Maf1 has been shown to reduce loss of IPP to tRNA biosynthesis and thereby improve monoterpene yields in yeast. IPP is an intermediate in the mevalonate pathway. SEQ ID NO: 8 is a polynucleotide that was integrated into the S. cerevisiae genome at Maf1-site 5 for genomic integration of Maf1 under the Tef1 promoter. SEQ ID NO: 8 includes the Tef1 promoter, the native Maf1 gene, and the Prm9 terminator. Together, Tef1, Maf1, and Prm9 are flanked by genomic DNA sequences for promoting integration into the S. cerevisiae genome. As shown in Table 4 below, base strains HB100, HB106, and HB110 express Maf1 under the Tef1 promoter. Similarly, each modified yeast strain based on any of HB100, HB106, or HB110 includes a polynucleotide including a coding sequence for Maf1 under the Tef1 promoter.
Upc2 is an activator for sterol biosynthesis in S. cerevisiae. A Glu888Asp mutation of Upc2 increases monoterpene production in yeast. SEQ ID NO: 9 is a polynucleotide that may be integrated into the genome to provide expression of Upc2E888D under the Tef1 promoter. SEQ ID NO: 9 includes the Tef1 promoter, the Upc2E888D gene, and the Prm9 terminator. Together, Tef1, Upc2E888D, and Prm9 are flanked by genomic DNA sequences for promoting integration into the S. cerevisiae genome.
Any of the above genes, Erg20K197E, AcsL641P, Ald6, Maf1, Acc1S659A; S1167A or Upc2E888D, may be expressed from a plasmid or integrated into the genome of S. cerevisiae. Genome integration may be through homologous recombination, including CRISPR recombination, or any suitable approach. The promoter of Acc1 may be similarly modified through recombination. The coding and regulatory sequences in each of SEQ ID NO: 3, SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 7, SEQ ID NO: 8, or SEQ ID NO: 9 may be included in a plasmid for expression (e.g. pYES, etc.) or a linear polynucleotide for integration into the S. cerevisiae genome. Each of base strains HB42, HB82, HB100, HB106, or HB110 includes one or more integrated SEQ ID NO: 3, SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 8, or SEQ ID NO: 10 (see below). Integration of SEQ ID NO: 7, or SEQ ID NO: 9 may be applied by similar approaches.
Increased DiPKS Function
As shown in
Expression of NpgA provides the A. nidulans phosphopantetheinyl transferase for greater catalysis of loading the phosphopantetheine group onto the ACP domain of DiPKS. As a result, the reaction catalyzed by DiPKS (reaction 1 in
Other Prenyltransferase Enzymes
NphB variants were defined based on a DELTA BLAST search for ABBA prenyltransferase structures. The list was refined by looking for a binding pocket appropriate for GPP and not IPP, dimethyl allyl pyrophosphate, or other prenyl groups. SEQ ID NO: 12 to SEQ ID NO: 33 provide primary structure amino acid residue sequences for cytosolic prenyltransferase enzymes from fungi and bacteria that were located in the DELTA BLAST search. DELTA BLAST searches of the C. sativa genome were also conducted and membrane-bound prenyltransferase enzymes were located in these searches. Some C. sativa membrane-bound prenyltransferase enzymes express poorly in some species of yeast and would not be introduced into the yeast strains provided herein to prepare phytocannabinoids or phytocannabinoid analogues.
SEQ ID NO: 33 to SEQ ID NO: 36 provide primary structure amino acid residue sequences for cytosolic prenyl transferase enzymes from fungi and bacteria that were located in a manual literature search. SEQ ID NO: 33 to SEQ ID NO: 36 are primary structure amino acid residue sequences for cytosolic prenyl transferase enzymes named FNQ26, FNQ28, FUR7, and NAPT9, respectively.
Any of SEQ ID NO: 11 to SEQ ID NO: 36 may be applied to the yeast strains described herein as the cytosolic prenyltransferase. Each of these prenyltransferases are summarized in Table 1.
cinnamonensis]
tendae]
cinnamonensis DSM 1042: AM384985]
Modification of DiPKS
DiPKS may be modified to reduce or eliminate the activity of C-Met.
SEQ ID NO: 37 is a modified form of a synthetic sequence for DIPKS that is codon optimized for yeast in which DiPKS includes a Gly1516Asp substitution and a Gly1518Ala substitution that together disrupt the activity of the C-met domain. Results of DiPKSG1516D, G1518A expression in S. cerevisiae cultures are provided below in relation to Example IV which includes strain HB80A. Other modifications may be introduced into DiPKS to disrupt or eliminate the entire active site of C-Met or all of C-Met. Each of these modified DiPKS enzymes may be introduced into S. cerevisiae as described for wild type DiPKS.
SEQ ID NO: 38 is a modified form of a synthetic sequence for DIPKS that is codon optimized for yeast in which DiPKS includes a Gly1516Arg substitution that disrupts the activity of the C-met domain. Results of DiPKSG1516R expression in S. cerevisiae cultures are provided below in relation to Example VIII, which includes strain HB135 and Example IX, which includes strains HB135, HB137 and HB138.
In addition to DiPKSG1516D,G1518A and DiPKSG1516R specifically, other modifications were introduced into DiPKS to disrupt or eliminate the entire active site of C-Met or all of C-Met: (a) substitution of motif 1 with GGGSGGGSG, (b) a Gly1516Arg substitution in motif 1 and substitution of motif 2 with GGGSGGGS, (c). a Glu1634Ala, which is just outside motif 3 and disrupts tertiary structure at an active site in the C-Met domain, and (d). disruption of an active site in the C-Met domain by a His1608Gln substitution. Codon optimized sequences for each of (a) to (d) were introduced into yeast on expression plasmids, similarly to expression of DiPKSG1516D,G1518A and DiPKSG1516R, into base strain HB100. In each case, no production of olivetol was observed. Substitution of either motif 1 or motif 2 with GGGSGGGS eliminated production of methyl-olivetol as well. A culture of yeast expressing the DiPKSG1634A mutant provided 2.67 mg methyl-olivetol per I of culture in one example batch. A culture of yeast expressing the DiPKSH1608N mutants provided 3.19 mg methyl-olivetol per I of culture in one example batch.
Transforming and Growing Yeast Cells
Details of specific examples of methods carried out and yeast cells produced in accordance with this description are provided below as Examples I, to X. Each of these ten specific examples applied similar approaches to plasmid construction, transformation of yeast, quantification of strain growth, and quantification of intracellular metabolites. These common features across the ten examples are described below, followed by results and other details relating to one or more of the ten examples.
Plasmid Construction
Plasmids assembled to apply and prepare examples of the methods and yeast cells provided herein are shown in Table 2. In Table 2, for the expression plasmids pYES, and pYES2, SEQ ID NOs 39 and 40 respectively provide the plasmids as a whole without an expression cassette. The expression cassettes of SEQ ID NOs: 10, 37, 38, and 41 to 47 can be included in to prepare the plasmids indicated in Table 2. SEQ ID NO: 4 is the pGREG plasmid including a cassette for the PDH bypass genes.
Plasmids for introduction into S. cerevisiae were amplified by polymerase chain reaction (“PCR”) with primers from Operon Eurofins and Phusion HF polymerase (ThermoFisher F-530S) according to the manufacturer's recommended protocols using an Eppendorf Mastercycler ep Gradient 5341.
All plasmids were assembled using overlapping DNA parts and transformation assisted recombination in S. cerevisiae. The plasmids were transformed into S. cerevisiae using the lithium acetate heat shock method as described by Gietz, R. D. and Schiestl, R. H., “High-efficiency yeast transformation using the LiAc/SS carrier DNA/PEG method.” Nat. Protoc. 2, 31-34 (2007). The base yeast strains used for assembling plasmids are shown in Table 3:
The pAltPT plasmid was assembled in the HB24 leucine auxotroph. The pNPGA, pDiPKSm1, pDiPKSm2, pGFP, pPTGFP, pAPTGFP, pH1OAS, pDiPKS, pCRISPR, and pPDH plasmids were assembled in the HB25 uracil auxotroph. Transformed S. cerevisiae cells were selected by auxotrophic selection on agar petri dishes. Colonies recovered from the petri dishes were grown up in liquid selective media for 16 hrs at 30° C. while being shaken at 250 RPM.
After growth in liquid selective media, the transformed S. cerevisiae cells were collected and the plasmid DNA was extracted. The extracted plasmid DNA was transformed into Escherichia coli. Transformed E. coli were selected for by growing on agar petri dishes including ampicillin. The E. coli were cultured to amplify the plasmid. The plasmid grown in the E. coli was extracted and sequenced with Sanger dideoxy sequencing to verify accurate construction. The sequence-verified plasmid was then used for genome modification or stable transformation of the S. cerevisiae.
Genome Modification of S. cerevisiae
The S. cerevisiae strains described herein may be prepared by stable transformation of plasmids or genome modification. Genome modification may be accomplished through homologous recombination, including by methods leveraging CRISPR.
Methods applying CRISPR were applied to delete DNA from the S. cerevisiae genome and introduce heterologous DNA into the S. cerevisiae genome. Guide RNA (“gRNA”) sequences for targeting the Cas9 endonuclease to the desired locations on the S. cerevisiae genome were designed with Benchling online DNA editing software. DNA splicing by overlap extension (“SOEing”) and PCR were applied to assemble the gRNA sequences and amplify a DNA sequence including a functional gRNA cassette.
The functional gRNA cassette, a Cas9-expressing gene cassette, and the pYes2 (URA) plasmid were assembled into the pCRISPR plasmid and transformed into S. cerevisiae for facilitating targeted DNA double-stranded cleavage. The resulting DNA cleavage was repaired by the addition of a linear fragment of target DNA.
The CDS for the Erg20K197E protein shown in SEQ ID NO: 3 was integrated into the genome of HB13 by homologous recombination, resulting in the HB42 base strain.
Bases 51 to 7114 of SEQ ID NO: 4 were integrated into the HB42 strain by CRISPR to provide the HB82 base strain with the PDH bypass genes in S. cerevisiae. The pPDH plasmid was sequence verified after assembly in S. cerevisiae. The sequence-verified pPDH plasmid was grown in E. coli, purified, and digested with BciV1 restriction enzymes. As in Table 2, digestion by BciV1 provided a polynucleotide including the genes for Ald6 and SeAcsL641P, promoters, terminators, and integration site homology sequences for integration into the S. cerevisiae genome at PDH-site 19 by Cas9. The resulting linear PDH bypass donor polynucleotide, shown in bases 51 to 7114 of SEQ ID NO: 4, was purified by gel separation.
With both PDH bypass genes (Ald6 and AcsL641P) on the single PDH bypass polynucleotide, the PDH bypass donor polynucleotide was co-tranformed into S. cerevisiae with pCRISPR. Transformation was by the lithium acetate heat shock method as described by Gietz. The pCRISPR plasmid expresses Cas9, which is targeted to a selected location of S. cerevisiae the genome by a gRNA molecule. At the location, the Cas9 protein creates a double stranded break in the DNA. The PDH bypass donor polynucleotide was used as a donor polynucleotide in the CRISPR reaction. The PDH bypass donor polynucleotide including Ald6, AcsL641P, promoters, and terminators was integrated into the genome at the site of the break, Site 19, by homologous recombination, resulting in strain HB82.
The NpgA donor polynucleotide shown in SEQ ID NO: 10 was prepared and amplified. DNA SOEing was used to create a single donor DNA fragment from three polynucleotides for NpgA integration. The first polynucleotide was the 5′ region of genomic homology that allows the donor to recombine into the genome at a specific locus. The second polynucleotide coded for the NpgA gene cassette. The NpgA gene cassette includes the Tef1 promoter, the NpgA coding sequence and the Prm9 terminator. The third polynucleotide included the 3′ region for genomic homology to facilitate targeted integration into the S. cerevisiae genome.
The NpgA donor polynucleotide was co-transformed with the pCRISPR plasmid into strain HB82. The pCRISPR plasmid was expressed and endonuclease Cas9 was targeted to a location on the S. cerevisiae genome by a gRNA molecule. At the location, the Cas9 protein created a double stranded break in the DNA and the NpgA donor polynucleotide was integrated into the genome at the break by homologous recombination to provide the HB100 base strain.
The Maf1 donor polynucleotide shown in SEQ ID NO: 8 was prepared and amplified. DNA SOEing was used to create a single donor DNA fragment from three polynucleotides for Maf1 integration. The first polynucleotide was the 5′ region of genomic homology that allows the donor to recombine into the genome at a specific locus. The second polynucleotide coded for the Maf1 gene cassette. The Maf1 gene cassette includes the Tef1 promoter, the Maf1 coding sequence and the Prm9 terminator. The third polynucleotide included the 3′ region for genomic homology to facilitate targeted integration into the S. cerevisiae genome.
The Maf1 donor polynucleotide was co-transformed with the pCRISPR plasmid into the HB100 strain. The pCRISPR plasmid may be expressed and endonuclease Cas9 was targeted to a location on the S. cerevisiae genome by a gRNA molecule. At the location, the Cas9 protein may create a double stranded break in the DNA and the Maf1 donor polynucleotide may be integrated into the genome at the break by homologous recombination. Stable transformation of the Maf1 donor polynucleotide into the HB100 strain provides the HB106 base strain.
The Acc1-PGK1p donor polynucleotide shown in SEQ ID NO: 6 was prepared and amplified. DNA SOEing was used to create a single donor DNA fragment from three polynucleotides for Acc1-PGK1 integration. The first polynucleotide was the 5′ region of genomic homology that allows the donor to recombine into the genome at a specific locus.
The second polynucleotide coded for the PGK1 promoter region. The third polynucleotide included the 3′ region for genomic homology to facilitate targeted integration into the S. cerevisiae genome.
The Acc1-PGK1 donor polynucleotide was co-transformed with the pCRISPR plasmid. The pCRISPR plasmid was expressed and endonuclease Cas9 was targeted to a location on the S. cerevisiae genome by a gRNA molecule. At the location, the Cas9 protein created a double stranded break in the DNA and the Acc1-PGK1 donor polynucleotide was integrated into the genome at the break by homologous recombination. Stable transformation of donor polynucleotide into the HB100 strain provides the HB110 base strain with Acc1 under regulation of the PGK1 promoter.
Table 4 provides a summary of the base strains that were prepared by genome modification of S. cerevisiae. Each base strain shown in Table 4 is a leucine and uracil auxotroph, and none of them include a plasmid.
Stable Transformation for Strain Construction
Plasmids were transformed into S. cerevisiae using the lithium acetate heat shock method as described by Gietz.
Transgenic S. cerevisiae strains HB1, HB6, and HB7 were prepared from the HB25 base strain by introducing the plasmids from Table 2 into HB25 as indicated below in Table 5. Strains HB1, HB6, and HB7 were used for comparing protein expression levels in S. cerevisiae of C. sativa prenyltransferase and AltPT.
Transgenic S. cerevisiae HB80, HB80A, HB98, HB102, HB135, HB137 and HB138 were prepared from the HB42, HB100, HB106 and HB110 bases strain by transformation of HB42 with expression plasmids, and HB80A was prepared by transformation of HB80, as shown below in Table 6. HB80, HB98 and HB102 each include and express DiPKS. HB80A includes and expresses DiPKSG1516D; G1518A. HB135, HB137 and HB138 each include and express DiPKSG1516R. HB98 includes and expresses DiPKS and NPGa from a plasmid.
Transgenic S. cerevisiae HB37, HB84, HB88, HB90, HB105 and HB130 were prepared from base strains indicated in Table 7 by transformation the base strains with the expression plasmids as shown below in Table 7. HB37 and HB88 each include and express AltPT and OAS. HB80, HB90 and HB105 each include and express AltPT and DiPKS. HB139 includes and expresses AltPT and DiPKSG1516R.
Yeast Growth and Feeding Conditions
Yeast cultures were grown in overnight cultures with selective media to provide starter cultures. The resulting starter cultures were then used to inoculate triplicate 50 ml cultures to an optical density at having an absorption at 600 nm (“A600”) of 0.1. Table 6 shows details of the media used to grow each strain.
In Table 8, “4DO*” refers to yeast synthetic dropout media supplement lacking leucine and uracil. With respect to strain HB13, “HB13-HA” refers to HB13 grown in the presence of 0.5 mM hexanoic acid and “HB13-No” refers to HB13 grown in the absence of hexanoic acid. In Table 8, “YNB” is a nutrient broth including the chemicals listed in the first two columns side of Table 9. The chemicals listed in the third and fourth columns of Table 9 are included in the 4DO* supplement.
Quantification of Metabolites
Intracellular metabolites were extracted from the S. cerevisiae cells using methanol extraction. One mL of liquid culture was spun down at 12,000×g for 3 minutes. 250 μL of the resulting supernatant was used for extracellular metabolite quantification. The resulting cell pellet was suspended in 200 μl of −40° C. 80% methanol. The mixture was vortexed and chilled on ice for 10 minutes. After chilling on ice for 10 minutes, the mixture was spun down at 15,000×g at 4° C. for 14 minutes. The resulting supernatant was collected. An additional 200 μl of −40° C. 80% methanol was added to the cell debris pellet and the mixture was vortexed and chilled for 10 minutes on ice. After chilling on ice for 10 minutes, the mixture was spun down at 15,000×g at 4° C. for 14 minutes. The resulting 200 μl of supernatant was added to the previously collected 200 μl of supernatant, providing a total of 400 μl of 80% methanol with intracellular metabolites.
Intracellular metabolites were quantified using high performance liquid chromatography (“HPLC”) and mass spectrometry (“MS”) methods. An Agilent 1260 autosampler and HPLC system connected to a ThermoFinnigan LTQ mass spectrometer was used. The HPLC system included a Zorbax Eclipse C18 2.1 μm×5.6 mm×100 mm column.
The metabolites were injected in 10 μl samples using the autosampler and separated on the HPLC using at a flow rate of 1 ml/min. The HPLC separation protocol was 20 mins total with (a) 0-2 mins of 98% Solvent A and 2% Solvent B; (b) 2-15 mins to get to 98% solvent B; (c) 15-16.5 minutes at 98% solvent B; (d) 16.5-17.5 minutes to get to 98% A; and (e) a final 2.5 minutes of equilibration at 98% Solvent A. Solvent A was acetonitrile+0.1% formic acid in MS water and solvent B was 0.1% formic acid in MS water.
After HPLC separation, samples were injected into the mass spectrometer by electrospray ionization and analyzed in positive mode. The capillary temperature was held at 380° C. The tube lens voltage was 30 V, the capillary voltage was 0 V, and the spray voltage was 5 kV. After HPLC-MS/MS, CBG was analyzed as a parent ion at 317.2 and a daughter ion at 193.1, while meCBG was analyzed as a parent ion of 331.2. Similarly, after HPLC-MS/MS, olivetol was analyzed as a parent ion at 181.2 and a daughter ion at 111, while methyl-olivetol analyzed as a parent ion at 193.2 and a daughter ion at 125.
Different concentrations of known standards were injected to create a linear standard curve. Standards for CBG and meCBG were purchased from Toronto Research Chemicals. The meCBG was custom prepared by request because Toronto Research Chemicals had not synthesized that chemical prior to being asked for the standard. Olivetol and methyl-olivetol standards were purchased from Sigma Aldrich.
Effects of Hexanoic Acid on S. cerevisiae Growth
The genes coding for enzymes required for hexanoic acid biosynthesis were not introduced into S. cerevisiae. Instead, in yeast cells including the OAS gene, such as HB37, hexanoic acid was included in the growth media.
In the presence of 0.5 mM hexanoic acid, HB13 and HB37 were grown for 96 hours with samples taken at the 24h, 36h, 48h, 60, 72h, 84h and 96h points. In the absence of hexanoic acid, HB13 and HB84 were grown and a single time point was taken at 72 hours. HB13 was used as a control in both experiments. The growth media are described above in relation to Tables 8 and 9.
As shown in Table 10, HB84, outgrew HB37. In addition, HB84 does not require hexanoic acid to produce meCBG, while HB37 requires hexanoic acid to produce CBG. Similarly, HB13 showed better growth at 72h in the absence of hexanoic acid compared with the presence of 0.5 mM hexanoic acid, consistent with the data shown in
Together,
Expression of Cytosolic and Membrane-Bound Prenyltransferase
C. sativa prenyltransferase is a membrane-bound plant protein while AltPT is a cytosolic bacterial protein. Application of AltPT in S. cerevisiae rather than C. sativa prenyltransferase provides greater protein expression levels in the yeast cells. Each of HB1, HB6, HB7, and HB13 as shown in Table 5 were grown in YNB, 2% glucose, and 1.6 g/L 4DO* overnight. The resulting culture, after being grown overnight, was normalized to 1.0 A600 and then grown for four hours in YNB, 2% glucose, and 1.6 g/L 4DO*. Fluorescence was measured from each culture suspension using a BD Acuri C6 flow cytometer.
HB1 expresses green fluorescent protein (“GFP”). Each of HB6 and HB7 express a GFP-prenyltransferase fusion protein. Neither HB6 nor HB7 include genes from the pDiPKS or pH1OAS plasmids. Correspondingly neither HB6 nor HB7 expresses a polyketide synthase gene or includes all the enzymes to complete the biosynthetic pathways in any of
The yeast strain HB37 as described above in Table 7 was cultured in the YNB+2% glucose+1.6 g/L 4DO*+0.5 mM hexanoic acid media. Production of CBG from glucose and hexanoic acid was observed, demonstrating direct production in yeast of CBG.
CBG was produced at a concentration of 10 μg/L with 0.85 mM hexanoic acid. After optimizing the hexanoic acid feeding and growth conditions, 50 μg/L of CBG was produced with 0.5 mM hexanoic acid.
The yeast strain HB84 as described above in Table 7 was cultured in the YNB+2% raffinose+2% galactose+1.6 g/L 4DO* media. Production of meCBG from raffinose and galactose was observed, demonstrating direct production in yeast of meCBG without hexanoic acid. The meCBG was produced at 42.63 mg/L. The yield of meCBG produced by HB84 represents a nearly 1,000× increase compared with the yield of CBG from HB37.
The yeast strain HB80 as described above in Table 6 was cultured in the YNB+2% raffinose+2% galactose+1.6 g/L 4DO* media. Production of methyl-olivetol from raffinose and galactose was observed, demonstrating direct production in yeast of methyl-olivetol without conversion to meCBG, as HB80 lacks AltPT. The methyl-olivetol was produced at concentrations of 3.259 mg/L Conversion to meCBG would be expected to follow in a strain that includes the features of HB80 and AltPT or another prenyltransferase, such as HB139.
The yeast strain HB80A as described above in Table 6 was cultured in the YNB+2% raffinose+2% galactose+1.6 g/L 4DO* media. Production of both olivetol and methyl-olivetol from raffinose and galactose, catalyzed by DiPKSG1516D; G1518A was observed. This data demonstrates direct production in yeast of both olivetol and methyl-olivetol without inclusion of hexanoic acid. Conversion to CBG and meCBG did not follow as HB80A lacks AltPT. Conversion to CBG and meCBG would be expected to following a strain that included the features of HB80A and AltPT or another prenyltransferase, such as by transforming HB80A with pAltPT.
The yeast strain HB98 as described above in Table 6 was cultured in the YNB+2% raffinose+2% galactose+1.6 g/L 4DO* media. Production of methyl-olivetol from raffinose and galactose, catalyzed by DiPKS, was observed. This data demonstrates increased methyl-olivetol production compared with HB80 as described in Example III, and also without inclusion of hexanoic acid. Conversion to meCBG did not follow as HB80A lacks AltPT. Conversion to meCBG would be expected to following a strain that included the features of HB98 and AltPT or another prenyltransferase, such as by transforming HB98 with pAltPT or by transforming HB84 with pNPGa.
The yeast strain HB102 as described above in Table 6 was cultured in the YNB+2% raffinose+2% galactose+1.6 g/L 4DO* media. Production of methyl-olivetol from raffinose and galactose was observed, demonstrating an increased production in yeast of methyl-olivetol at 42.44 mg/L as compared to strain HB98, which produced only 29.85 mg/L methyl-olivetol. This demonstrated that the genomically integrated version of NpgA is functional. Conversion to meCBG did not follow as HB102 lacks AltPT. Conversion to meCBG would be expected to following a strain that included the features of HB102 and AltPT or another prenyltransferase, such as HB105.
The yeast strain HB105 as described above in Table 7 was cultured in the YNB+2% raffinose+2% galactose+1.6 g/L 4DO* media. Production of meCBG from raffinose and galactose was observed at titres of 66.3 mg/L, demonstrating an increased production of meCBG compared with the yield of CBG from HB84. This demonstrates the positive effect of the PDH bypass and the integrated NpgA on meCBG titres.
The yeast strain HB135 as described above in Table 6 was cultured in the YNB+2% raffinose+2% galactose+1.6 g/L 4DO* media. Production of olivetol from raffinose and galactose was observed, demonstrating an production in yeast of olivetol without any hexanoic acid and at high titres of 49.24 mg/L and no production of methyl-olivetol. This is comparable to the production of methyl-olivetol by strain HB102 demonstrating that the mutation of DIPKS was effective in production of Olivetol as opposed to methyl-Olivetol. Conversion to CBG and meCBG did not follow as HB135 lacks AltPT. Conversion to CBG and meCBG would be expected to following a strain that includes the features of HB135 and AltPT or another prenyltransferase.
The yeast strains HB137 and HB138 as described above in Table 6 were cultured in the YNB+2% raffinose+2% galactose+1.6 g/L 4DO* media. Production of olivetol from raffinose and galactose was observed in both strains. Strain HB137 produced 61.26 mg/L of olivetol and strain HB138 produced 74.26 mg/L of olivetol demonstrating the positive effect of Maf1 integration and Acc1-promoter swap on olivetol titres. Conversion to CBG did not follow as HB137 and HB138 lack AltPT. Conversion to CBG would be expected to following strains that included the features of HB137 and HB138 and AltPT or another prenyltransferase.
The yeast strain HB139 as described above in Table 7 was cultured in the YNB+2% raffinose+2% galactose+1.6 g/L 4DO* media. Production of CBG from raffinose and galactose directly was observed at titres of 0.03 mg/L. This is much lower than the titre of meCBG produced by strain HB105.
The following sequences were filed electronically with this application but are also included here.
cerevisiae Acc1 promoter
In the preceding description, for purposes of explanation, numerous details are set forth in order to provide a thorough understanding of the embodiments. However, it will be apparent to one skilled in the art that these specific details are not required.
The above-described embodiments are intended to be examples only. Alterations, modifications and variations can be effected to the particular embodiments by those of skill in the art without departing from the scope, which is defined solely by the claims appended hereto.
This application claims the benefit of priority of United States Provisional Patent Application No. 62/460,526, entitled METHOD AND CELL LINE FOR PRODUCTION OF PHYTOCANNABINOIDS IN YEAST, filed Feb. 17, 2017, which is hereby incorporated by reference in its entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CA2018/050189 | 2/19/2018 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62460526 | Feb 2017 | US |
