Patent Application
20120288892
1. Field of the Invention
The present invention relates to methods of producing polypeptides in enzyme-deficient Trichoderma mutant strains, the enzyme-deficient Trichoderma mutant strains, and methods of obtaining the enzyme-deficient Trichoderma mutant strains.
2. Description of the Related Art
Trichoderma has been shown to be useful as a host cell for the recombinant production of polypeptides having biological activity (WO 96/00787, WO 97/26330). Trichoderma hosts with the desirable traits of increased protein expression and secretion may not necessarily have the most desirable characteristics for successful fermentation. The fermentation may not be optimal because of the production of biological substances, e.g., enzymes, detrimental to the production, recovery, or application of a particular polypeptide of interest.
Dienes et al., 2007, Enzyme and Microbial Technology 40: 1087-1094, disclose the identification of a trypsin-like serine protease from Trichoderma reesei QM9414. Eneyskaya et al., 1999, Appl. Microbiol. Biotechnol. 52: 226-231, describe acid protease from Trichoderma reesei. Haub et al., 1990, J. Biotechnology 16: 187-198, disclose the formation of extracellular proteases from Trichoderma reesei QM9414. Hagspiel et al., 1989, Appl. Microbiol. Biotechnol. 32: 61-67, disclose protease activity and proteolytic modification of cellulases from a Trichoderma reesei QM9414 selectant.
The present invention relates to improved Trichoderma hosts that combine the capacity for expression of commercial quantities of a polypeptide of interest while being deficient in the production of enzymes that can complicate recovery and downstream processing of the polypeptide.
The present invention relates to methods of producing a polypeptide, comprising:
(a) cultivating a mutant of a parent Trichoderma strain in a medium for the production of the polypeptide, wherein the mutant strain comprises a polynucleotide encoding the polypeptide and one or more (several) genes selected from the group consisting of a subtilisin-like serine protease gene, an aspartic protease gene, and a trypsin-like serine protease gene, wherein the one or more (several) genes are modified rendering the mutant strain deficient in the production of one or more (several) enzymes selected from the group consisting of a subtilisin-like serine protease, an aspartic protease, and a trypsin-like serine protease, respectively, compared to the parent Trichoderma strain when cultivated under identical conditions; and
(b) recovering the polypeptide from the cultivation medium.
The present invention also relates to mutants of a parent Trichoderma strain, comprising a polynucleotide encoding a polypeptide and one or more (several) genes selected from the group consisting of a subtilisin-like serine protease gene, an aspartic protease gene, and a trypsin-like serine protease gene, wherein the one or more (several) genes are modified rendering the mutant strain deficient in the production of one or more (several) enzymes selected from the group consisting of a subtilisin-like serine protease, an aspartic protease, and a trypsin-like serine protease, respectively, compared to the parent Trichoderma strain when cultivated under identical conditions.
The present invention also relates to methods of obtaining mutants of a parent Trichoderma strain, comprising:
(a) modifying one or more (several) genes selected from the group consisting of a subtilisin-like serine protease gene, an aspartic protease gene, and a trypsin-like serine protease gene; and
(b) identifying a mutant strain from step (a) wherein the one or more (several) genes selected from the group consisting of a subtilisin-like serine protease gene, an aspartic protease gene, and a trypsin-like serine protease gene are modified rendering the mutant strain deficient in the production of one or more (several) enzymes selected from the group consisting of a subtilisin-like serine protease, an aspartic protease, and a trypsin-like serine protease, respectively, compared to the parent Trichoderma strain when cultivated under identical conditions.
Subtilisin-like serine protease: The term “subtilisin-like serine protease” is defined herein as a protease with a substrate specificity similar to subtilisin that uses a serine residue for catalyzing the hydrolysis of peptide bonds in peptides and proteins. For purposes of the present invention, subtilisin-like serine protease activity is determined according to the procedure described in Example 13.
Aspartic protease: The term “aspartic protease” is defined herein as a protease (EC 3.4.23) that uses an aspartate residue for catalyzing the hydrolysis of peptide bonds in peptides and proteins. For purposes of the present invention, aspartic endopeptidase activity is determined according to the procedure described by Aikawa et al., 2001, J. Biochem. 129: 791-794.
Trypsin-like serine protease: The term “trypsin-like serine protease” is defined herein as a protease with a substrate specificity similar to trypsin that uses a serine residue for catalyzing the hydrolysis of peptide bonds in peptides and proteins. For purposes of the present invention, trypsin-like serine protease activity is determined according to the procedure described by Dienes et al., 2007, supra, or Example 20.
Deficient: The term “deficient” is defined herein as a Trichoderma mutant strain that produces no detectable activity of one or more (several) enzymes selected from the group consisting of a subtilisin-like serine protease, an aspartic protease, and a trypsin-like serine protease compared to the parent Trichoderma strain when cultivated under identical conditions, or, in the alternative, produces preferably at least 25% less, more preferably at least 50% less, even more preferably at least 75% less, and most preferably at least 95% less of one or more (several) enzymes selected from the group consisting of a subtilisin-like serine protease, an aspartic protease, and a trypsin-like serine protease than the parent Trichoderma strain when cultivated under identical conditions. The level of protease produced by a Trichoderma mutant strain of the present invention may be determined using methods described herein or known in the art.
Isolated polypeptide: The term “isolated polypeptide” as used herein refers to a polypeptide that is isolated from a source. In a preferred aspect, the polypeptide is at least 1% pure, preferably at least 5% pure, more preferably at least 10% pure, more preferably at least 20% pure, more preferably at least 40% pure, more preferably at least 60% pure, even more preferably at least 80% pure, and most preferably at least 90% pure, as determined by SDS-PAGE.
Substantially pure polypeptide: The term “substantially pure polypeptide” denotes herein a polypeptide preparation that contains at most 10%, preferably at most 8%, more preferably at most 6%, more preferably at most 5%, more preferably at most 4%, more preferably at most 3%, even more preferably at most 2%, most preferably at most 1%, and even most preferably at most 0.5% by weight of other polypeptide material with which it is natively or recombinantly associated. It is, therefore, preferred that the substantially pure polypeptide is at least 92% pure, preferably at least 94% pure, more preferably at least 95% pure, more preferably at least 96% pure, more preferably at least 97% pure, more preferably at least 98% pure, even more preferably at least 99% pure, most preferably at least 99.5% pure, and even most preferably 100% pure by weight of the total polypeptide material present in the preparation. The polypeptides of the present invention are preferably in a substantially pure form, i.e., that the polypeptide preparation is essentially free of other polypeptide material with which it is natively or recombinantly associated. This can be accomplished, for example, by preparing the polypeptide by well-known recombinant methods or by classical purification methods.
Mature polypeptide: The term “mature polypeptide” is defined herein as a polypeptide having enzyme activity that is in its final form following translation and any post-translational modifications, such as N-terminal processing, C-terminal truncation, glycosylation, phosphorylation, etc. In one aspect, the mature polypeptide is amino acids 20 to 882 of SEQ ID NO: 2 based on the SignalP program (Nielsen et al., 1997, Protein Engineering 10: 1-6) that predicts amino acids 1 to 19 of SEQ ID NO: 2 are a signal peptide. In another aspect, the mature polypeptide is amino acids 21 to 407 of SEQ ID NO: 4 based on the SignalP program (Nielsen et al., 1997, supra) that predicts amino acids 1 to 20 of SEQ ID NO: 4 are a signal peptide. In another aspect, the mature polypeptide is amino acids 20 to 259 of SEQ ID NO: 6 based on the SignalP program (Nielsen et al., 1997, supra) that predicts amino acids 1 to 19 of SEQ ID NO: 6 are a signal peptide.
Mature polypeptide coding sequence: The term “mature polypeptide coding sequence” is defined herein as a nucleotide sequence that encodes a mature polypeptide having enzyme activity. In one aspect, the mature polypeptide coding sequence is nucleotides 58 to 2774 of SEQ ID NO: 1 based on the SignalP program (Nielsen et al., 1997, supra) that predicts nucleotides 1 to 57 of SEQ ID NO: 3 encode a signal peptide. In another aspect, the mature polypeptide coding sequence is nucleotides 61 to 1299 of SEQ ID NO: 3 based on the SignalP program (Nielsen et al., 1997, supra) that predicts nucleotides 1 to 60 of SEQ ID NO: 1 encode a signal peptide. In another aspect, the mature polypeptide coding sequence is nucleotides 58 to 930 of SEQ ID NO: 5 based on the SignalP program (Nielsen et al., 1997, supra) that predicts nucleotides 1 to 57 of SEQ ID NO: 5 encode a signal peptide.
Identity: The relatedness between two amino acid sequences or between two nucleotide sequences is described by the parameter “identity”.
For purposes of the present invention, the degree of identity between two amino acid sequences is determined using the Needleman-Wunsch algorithm (Needleman and Wunsch, 1970, J. Mol. Biol. 48: 443-453) as implemented in the Needle program of the EMBOSS package (EMBOSS: The European Molecular Biology Open Software Suite, Rice et al., 2000, Trends in Genetics 16: 276-277), preferably version 3.0.0 or later. The optional parameters used are gap open penalty of 10, gap extension penalty of 0.5, and the EBLOSUM62 (EMBOSS version of BLOSUM62) substitution matrix. The output of Needle labeled “longest identity” (obtained using the—nobrief option) is used as the percent identity and is calculated as follows:
(Identical Residues×100)/(Length of Alignment−Total Number of Gaps in Alignment)
For purposes of the present invention, the degree of identity between two deoxyribonucleotide sequences is determined using the Needleman-Wunsch algorithm (Needleman and Wunsch, 1970, supra) as implemented in the Needle program of the EMBOSS package (EMBOSS: The European Molecular Biology Open Software Suite, Rice et al., 2000, supra), preferably version 3.0.0 or later. The optional parameters used are gap open penalty of 10, gap extension penalty of 0.5, and the EDNAFULL (EMBOSS version of NCBI NUC4.4) substitution matrix. The output of Needle labeled “longest identity” (obtained using the-nobrief option) is used as the percent identity and is calculated as follows:
(Identical Deoxyribonucleotides×100)/(Length of Alignment−Total Number of Gaps in Alignment)
Polypeptide fragment: The term “polypeptide fragment” is defined herein as a polypeptide having one or more (several) amino acids deleted from the amino and/or carboxyl terminus of a mature polypeptide or a homologous sequence thereof; wherein the fragment has enzyme activity, e.g., subtilisin-like serine protease, aspartic protease, or serine protease activity. In one aspect, a fragment contains at least 740 amino acid residues, more preferably at least 780 amino acid residues, and most preferably at least 820 amino acid residues of the mature polypeptide of SEQ ID NO: 2 or a homologous sequence thereof. In another aspect, a fragment contains at least 320 amino acid residues, more preferably at least 340 amino acid residues, and most preferably at least 360 amino acid residues of the mature polypeptide of SEQ ID NO: 4 or a homologous sequence thereof. In another aspect, a fragment contains at least 210 amino acid residues, more preferably at least 220 amino acid residues, and most preferably at least 230 amino acid residues of the mature polypeptide of SEQ ID NO: 6 or a homologous sequence thereof.
Subsequence: The term “subsequence” is defined herein as a nucleotide sequence having one or more (several) nucleotides deleted from the 5′ and/or 3′ end of a mature polypeptide coding sequence or a homologous sequence thereof; wherein the subsequence encodes a polypeptide fragment having enzyme activity, e.g., subtilisin-like serine protease, aspartic protease, or serine protease. In one aspect, a subsequence contains at least 2220 nucleotides, more preferably at least 2340 nucleotides, and most preferably at least 2460 nucleotides of the mature polypeptide coding sequence of SEQ ID NO: 1 or a homologous sequence thereof. In another aspect, a subsequence contains at least 960 nucleotides, more preferably at least 1020 nucleotides, and most preferably at least 1080 nucleotides of the mature polypeptide coding sequence of SEQ ID NO: 3 or a homologous sequence thereof. In another aspect, a subsequence contains at least 630 nucleotides, more preferably at least 660 nucleotides, and most preferably at least 690 nucleotides of the mature polypeptide coding sequence of SEQ ID NO: 5 or a homologous sequence thereof.
Allelic variant: The term “allelic variant” denotes herein any of two or more alternative forms of a gene occupying the same chromosomal locus. Allelic variation arises naturally through mutation, and may result in polymorphism within populations. Gene mutations can be silent (no change in the encoded polypeptide) or may encode polypeptides having altered amino acid sequences. An allelic variant of a polypeptide is a polypeptide encoded by an allelic variant of a gene.
Isolated polynucleotide: The term “isolated polynucleotide” as used herein refers to a polynucleotide that is isolated from a source. In a preferred aspect, the polynucleotide is at least 1% pure, preferably at least 5% pure, more preferably at least 10% pure, more preferably at least 20% pure, more preferably at least 40% pure, more preferably at least 60% pure, even more preferably at least 80% pure, and most preferably at least 90% pure, as determined by agarose electrophoresis.
Substantially pure polynucleotide: The term “substantially pure polynucleotide” as used herein refers to a polynucleotide preparation free of other extraneous or unwanted nucleotides and in a form suitable for use within genetically engineered protein production systems. Thus, a substantially pure polynucleotide contains at most 10%, preferably at most 8%, more preferably at most 6%, more preferably at most 5%, more preferably at most 4%, more preferably at most 3%, even more preferably at most 2%, most preferably at most 1%, and even most preferably at most 0.5% by weight of other polynucleotide material with which it is natively or recombinantly associated. A substantially pure polynucleotide may, however, include naturally occurring 5′ and 3′ untranslated regions, such as promoters and terminators. It is preferred that the substantially pure polynucleotide is at least 90% pure, preferably at least 92% pure, more preferably at least 94% pure, more preferably at least 95% pure, more preferably at least 96% pure, more preferably at least 97% pure, even more preferably at least 98% pure, most preferably at least 99% pure, and even most preferably at least 99.5% pure by weight. The polynucleotides of the present invention are preferably in a substantially pure form, i.e., that the polynucleotide preparation is essentially free of other polynucleotide material with which it is natively or recombinantly associated. The polynucleotides may be of genomic, cDNA, RNA, semisynthetic, synthetic origin, or any combinations thereof.
Coding sequence: When used herein the term “coding sequence” means a nucleotide sequence, which directly specifies the amino acid sequence of its protein product. The boundaries of the coding sequence are generally determined by an open reading frame, which begins with the ATG start codon or alternative start codons such as GTG and TTG and ends with a stop codon such as TAA, TAG, and TGA. The coding sequence may be a DNA, cDNA, synthetic, or recombinant nucleotide sequence.
cDNA: The term “cDNA” is defined herein as a DNA molecule that can be prepared by reverse transcription from a mature, spliced, mRNA molecule obtained from a eukaryotic cell. cDNA lacks intron sequences that are usually present in the corresponding genomic DNA. The initial, primary RNA transcript is a precursor to mRNA that is processed through a series of steps before appearing as mature spliced mRNA. These steps include the removal of intron sequences by a process called splicing. cDNA derived from mRNA lacks, therefore, any intron sequences.
Nucleic acid construct: The term “nucleic acid construct” as used herein refers to a nucleic acid molecule, either single- or double-stranded, which is isolated from a naturally occurring gene or modified to contain segments of nucleic acids in a manner that would not otherwise exist in nature or which is synthetic. The term nucleic acid construct is synonymous with the term “expression cassette” when the nucleic acid construct contains the control sequences required for expression of a coding sequence of the present invention.
Control sequences: The term “control sequences” is defined herein to include all components necessary for expression of a polynucleotide encoding a polypeptide of the present invention. Each control sequence may be native or foreign to the nucleotide sequence encoding the polypeptide or native or foreign to each other. Such control sequences include, but are not limited to, a leader, polyadenylation sequence, propeptide sequence, promoter, signal peptide sequence, and transcription terminator. At a minimum, the control sequences include a promoter, and transcriptional and translational stop signals. The control sequences may be provided with linkers for the purpose of introducing specific restriction sites facilitating ligation of the control sequences with the coding region of the nucleotide sequence encoding a polypeptide.
Operably linked: The term “operably linked” denotes herein a configuration in which a control sequence is placed at an appropriate position relative to the coding sequence of the polynucleotide sequence such that the control sequence directs expression of the coding sequence of a polypeptide.
Expression: The term “expression” includes any step involved in the production of the polypeptide including, but not limited to, transcription, post-transcriptional modification, translation, post-translational modification, and secretion.
Expression vector: The term “expression vector” is defined herein as a linear or circular DNA molecule that comprises a polynucleotide encoding a polypeptide of the present invention and is operably linked to additional nucleotides that provide for its expression.
Host cell: The term “host cell”, as used herein, includes any cell type that is susceptible to transformation, transfection, transduction, and the like with a nucleic acid construct or expression vector comprising a polynucleotide of the present invention.
Modification: The term “modification” is defined herein as an introduction, substitution, or removal of one or more nucleotides in a gene or a control sequence required for the transcription or translation thereof, or gene disruption, gene conversion, gene deletion, or random or specific mutagenesis of a subtilisin-like serine protease gene, an aspartic protease gene, a trypsin-like serine protease gene, or a combination thereof. The deletion of one or more (several) of the subtilisin-like serine protease gene, the aspartic protease gene, and/or the serine protease gene may be partial or complete. The modification results in a decrease in or elimination (inactivation) of expression of the subtilisin-like serine protease gene, the aspartic protease gene, the serine protease gene, or a combination thereof. In a preferred aspect, one or more (several) of the subtilisin-like serine protease gene, the aspartic protease gene, and the serine protease gene are inactivated.
The present invention relates to methods of producing a polypeptide, comprising: (a) cultivating a mutant of a parent Trichoderma strain in a medium for the production of the polypeptide, wherein the mutant strain comprises a polynucleotide encoding the polypeptide and one or more (several) genes selected from the group consisting of a subtilisin-like serine protease gene, an aspartic protease gene, and a trypsin-like serine protease gene, wherein the one or more (several) genes are modified rendering the mutant strain deficient in the production of one or more (several) enzymes selected from the group consisting of a subtilisin-like serine protease, an aspartic protease, and a trypsin-like serine protease, respectively, compared to the parent Trichoderma strain when cultivated under identical conditions; and (b) recovering the polypeptide from the cultivation medium.
An advantage of the present invention is elimination or reduction of one or more (several) enzyme activities, which may be detrimental to the production, downstream processing, e.g., recovery, and/or application of a particular polypeptide of interest
In the methods of the present invention, the parent Trichoderma strain may be any Trichoderma strain such as a wild-type Trichoderma strain or a mutant thereof. The parent Trichoderma strain may be Trichoderma harzianum, Trichoderma koningii, Trichoderma longibrachiatum, Trichoderma reesei, or Trichoderma viride; or the alternative sexual form thereof, i.e., Hypocrea.
In another aspect, the parent Trichoderma strain is Trichoderma harzianum. In another aspect, the parent Trichoderma strain is Trichoderma koningii. In another aspect, the parent Trichoderma strain is Trichoderma longibrachiatum. In another aspect, the parent Trichoderma strain is Trichoderma reesei. In another aspect, the parent Trichoderma strain is Trichoderma viride.
In another aspect, the parent Trichoderma reesei strain is Trichoderma reesei RutC30. In another aspect, the parent Trichoderma reesei strain is Trichoderma reesei TV10. In another aspect, the parent Trichoderma reesei strain is a mutant of Trichoderma reesei. In another aspect, the parent Trichoderma reesei strain is a morphological mutant of Trichoderma reesei (see WO 97/26330).
The enzyme-deficient Trichoderma mutant strain may be constructed by reducing or eliminating expression of one or more (several) genes selected from the group consisting of a subtilisin-like serine protease gene, an aspartic protease gene, and a trypsin-like serine protease gene using methods well known in the art, such as insertions, disruptions, replacements, or deletions. A portion of the gene can be modified such as the coding region or a control sequence required for expression of the coding region. Such a control sequence of a gene may be a promoter sequence or a functional part thereof, i.e., a part that is sufficient for affecting expression of the gene. For example, a promoter sequence may be inactivated resulting in no expression or a weaker promoter may be substituted for the native promoter sequence to reduce expression of the coding sequence. Other control sequences for possible modification include, but are not limited to, a leader, propeptide sequence, signal sequence, transcription terminator, and transcriptional activator.
The Trichoderma mutant strains may be constructed by gene deletion techniques to eliminate or reduce expression of a gene. Gene deletion techniques enable the partial or complete removal of the gene thereby eliminating their expression. In such methods, deletion of the gene(s) is accomplished by homologous recombination using a plasmid that has been constructed to contiguously contain the 5′ and 3′ regions flanking the gene.
The Trichoderma mutant strains may also be constructed by introducing, substituting, and/or removing one or more (several) nucleotides in the gene or a control sequence thereof required for the transcription or translation thereof. For example, nucleotides may be inserted or removed so as to result in the introduction of a stop codon, the removal of the start codon, or a frame-shift of the open reading frame. Such a modification may be accomplished by site-directed mutagenesis or PCR generated mutagenesis in accordance with methods known in the art. See, for example, Botstein and Shortle, 1985, Science 229: 4719; Lo et al., 1985, Proceedings of the National Academy of Sciences USA 81: 2285; Higuchi et al., 1988, Nucleic Acids Research 16: 7351; Shimada, 1996, Meth. Mol. Biol. 57: 157; Ho et al., 1989, Gene 77: 61; Horton et al., 1989, Gene 77: 61; and Sarkar and Sommer, 1990, BioTechniques 8: 404.
The Trichoderma mutant strains may also be constructed by gene disruption techniques by inserting into a gene a disruptive nucleic acid construct comprising a nucleic acid fragment(s) homologous to the gene that will create a duplication of the region of homology and incorporate construct DNA between the duplicated regions. Such gene disruption can eliminate gene expression if the inserted construct separates the promoter of the gene from the coding region or interrupts the coding sequence such that a non-functional gene product results. A disrupting construct may be simply a selectable marker gene accompanied by 5′ and 3′ regions homologous to the gene. The selectable marker enables identification of transformants containing the disrupted gene.
The Trichoderma mutant strains may also be constructed by the process of gene conversion (see, for example, Iglesias and Trautner, 1983, Molecular General Genetics 189: 73-76). For example, in the gene conversion method, a nucleotide sequence corresponding to the gene(s) is mutagenized in vitro to produce a defective nucleotide sequence, which is then transformed into the parent Trichoderma strain to produce a defective gene. By homologous recombination, the defective nucleotide sequence replaces the endogenous gene. It may be desirable that the defective nucleotide sequence also comprises a marker for selection of transformants containing the defective gene.
The Trichoderma mutant strains may also be constructed by established anti-sense techniques using a nucleotide sequence complementary to the nucleotide sequence of the gene (Parish and Stoker, 1997, FEMS Microbiology Letters 154: 151-157). More specifically, expression of the gene by a Trichoderma strain may be reduced or inactivated by introducing a nucleotide sequence complementary to the nucleotide sequence of the gene, which may be transcribed in the strain and is capable of hybridizing to the mRNA produced in the strain. Under conditions allowing the complementary anti-sense nucleotide sequence to hybridize to the mRNA, the amount of protein translated is thus reduced or eliminated.
The Trichoderma mutant strains may also be constructed by established RNA interference (RNAi) techniques (see, for example, WO 2005/056772 and WO 2008/080017).
The Trichoderma mutant strains may be further constructed by random or specific mutagenesis using methods well known in the art, including, but not limited to, chemical mutagenesis (see, for example, Hopwood, The Isolation of Mutants in Methods in Microbiology (J. R. Norris and D. W. Ribbons, eds.) pp 363-433, Academic Press, New York, 1970). Modification of the gene may be performed by subjecting the parent strain to mutagenesis and screening for mutant strains in which expression of the gene has been reduced or inactivated. The mutagenesis, which may be specific or random, may be performed, for example, by use of a suitable physical or chemical mutagenizing agent, use of a suitable oligonucleotide, or subjecting the DNA sequence to PCR generated mutagenesis. Furthermore, the mutagenesis may be performed by use of any combination of these mutagenizing methods.
Examples of a physical or chemical mutagenizing agent suitable for the present purpose include ultraviolet (UV) irradiation, hydroxylamine, N-methyl-N′-nitro-N-nitrosoguanidine (MNNG), N-methyl-N′-nitrosogaunidine (NTG) O-methyl hydroxylamine, nitrous acid, ethyl methane sulphonate (EMS), sodium bisulphite, formic acid, and nucleotide analogues. When such agents are used, the mutagenesis is typically performed by incubating the parent strain to be mutagenized in the presence of the mutagenizing agent of choice under suitable conditions, and selecting for mutants exhibiting reduced or no expression of a gene.
In one aspect, the modification results in the inactivation of one or more (several) genes selected from the group consisting of a subtilisin-like serine protease gene, an aspartic protease gene, and a trypsin-like serine protease gene. In another aspect, the modification results in a decrease in expression of one or more (several) genes selected from the group consisting of a subtilisin-like serine protease gene, an aspartic protease gene, and a trypsin-like serine protease gene. In another aspect, the modification results in expression of one or more (several) genes selected from the group consisting of a subtilisin-like serine protease gene, an aspartic protease gene, and a trypsin-like serine protease gene being decreased, inactivated, or a combination thereof.
In another aspect, the mutant comprises a modification of a subtilisin-like serine protease gene. In another aspect, the mutant comprises a modification of an aspartic protease gene. In another aspect, the mutant comprises a modification of a trypsin-like serine protease gene.
In another aspect, the mutant comprises a modification of a subtilisin-like serine protease gene and an aspartic protease gene. In another aspect, the mutant comprises a modification of a subtilisin-like serine protease gene and a trypsin-like serine protease gene. In another aspect, the mutant comprises a modification of an aspartic protease gene and a trypsin-like serine protease gene.
In another aspect, the mutant comprises a modification of a subtilisin-like serine protease gene, an aspartic protease gene, and a trypsin-like serine protease gene.
In one aspect, the subtilisin-like serine protease gene comprises a nucleotide sequence encoding a polypeptide having subtilisin-like serine protease activity comprising an amino acid sequence having preferably at least 60%, more preferably at least 65%, more preferably at least 70%, more preferably at least 75%, more preferably at least 80%, more preferably at least 85%, even more preferably at least 90%, most preferably at least 95%, and even most preferably at least 96%, at least 97%, at least 98%, or at least 99% identity to the amino acid sequence of SEQ ID NO: 2 or the mature polypeptide thereof. In another aspect, the subtilisin-like serine protease gene comprises a nucleotide sequence encoding a polypeptide having subtilisin-like serine protease activity comprising the amino acid sequence of SEQ ID NO: 2. In another aspect, the subtilisin-like serine protease gene comprises a nucleotide sequence encoding a polypeptide having subtilisin-like serine protease activity consisting of the amino acid sequence of SEQ ID NO: 2. In another aspect, the subtilisin-like serine protease gene comprises a nucleotide sequence encoding a polypeptide having subtilisin-like serine protease activity comprising the mature polypeptide of SEQ ID NO: 2. In another aspect, the subtilisin-like serine protease gene comprises a nucleotide sequence encoding a polypeptide having subtilisin-like serine protease activity consisting of the mature polypeptide of SEQ ID NO: 2.
In another aspect, the subtilisin-like serine protease gene comprises a nucleotide sequence having preferably at least 60%, more preferably at least 65%, more preferably at least 70%, more preferably at least 75%, more preferably at least 80%, more preferably at least 85%, even more preferably at least 90%, most preferably at least 95%, and even most preferably at least 96%, at least 97%, at least 98%, or at least 99% identity to the nucleotide sequence of SEQ ID NO: 1 or the mature polypeptide coding sequence thereof. In another aspect, the subtilisin-like serine protease gene comprises the nucleotide sequence of SEQ
ID NO: 1. In another aspect, the subtilisin-like serine protease gene consists of the nucleotide sequence of SEQ ID NO: 1. In another aspect, the subtilisin-like serine protease gene comprises the mature polypeptide coding sequence of SEQ ID NO: 1. In another aspect, the subtilisin-like serine protease gene consists of the mature polypeptide coding sequence of SEQ ID NO: 1.
In another aspect, the subtilisin-like serine protease gene comprises a nucleotide sequence that hybridizes under preferably very low stringency conditions, more preferably low stringency conditions, more preferably medium stringency conditions, more preferably medium-high stringency conditions, even more preferably high stringency conditions, and most preferably very high stringency conditions with (i) the nucleotide sequence of SEQ ID NO: 1; (ii) the mature polypeptide coding sequence of SEQ ID NO: 1, (iii) the cDNA sequence contained in (i) or (ii), or (iv) a full-length complementary strand of (i), (ii), or (iii).
In another aspect, the subtilisin-like serine protease comprises an amino acid sequence having preferably at least 60%, more preferably at least 65%, more preferably at least 70%, more preferably at least 75%, more preferably at least 80%, more preferably at least 85%, even more preferably at least 90%, most preferably at least 95%, and even most preferably at least 96%, at least 97%, at least 98%, or at least 99% identity to the amino acid sequence of SEQ ID NO: 2 or the mature polypeptide thereof. In another aspect, the subtilisin-like serine protease comprises the amino acid sequence of SEQ ID NO: 2. In another aspect, the subtilisin-like serine protease consists of the amino acid sequence of SEQ ID NO: 2 or the mature polypeptide thereof. In another aspect, the subtilisin-like serine protease comprises the mature polypeptide of SEQ ID NO: 2. In another aspect, the subtilisin-like serine protease consists of the mature polypeptide of SEQ ID NO: 2.
In another aspect, the subtilisin-like serine protease is encoded by a polynucleotide comprising a nucleotide sequence having preferably at least 60%, more preferably at least 65%, more preferably at least 70%, more preferably at least 75%, more preferably at least 80%, more preferably at least 85%, even more preferably at least 90%, most preferably at least 95%, and even most preferably at least 96%, at least 97%, at least 98%, or at least 99% identity to the nucleotide sequence of SEQ ID NO: 1 or the mature polypeptide coding sequence thereof. In another aspect, the subtilisin-like serine protease is encoded by a polynucleotide comprising the nucleotide sequence of SEQ ID NO: 1. In another aspect, the subtilisin-like serine protease is encoded by a polynucleotide consisting of the nucleotide sequence of SEQ ID NO: 1. In another aspect, the subtilisin-like serine protease is encoded by a polynucleotide comprising the mature polypeptide coding sequence of SEQ ID NO: 1. In another aspect, the subtilisin-like serine protease is encoded by a polynucleotide consisting of the mature polypeptide coding sequence of SEQ ID NO: 1.
In another aspect, the subtilisin-like serine protease is encoded by a polynucleotide comprising a nucleotide sequence that hybridizes under preferably very low stringency conditions, more preferably low stringency conditions, more preferably medium stringency conditions, more preferably medium-high stringency conditions, even more preferably high stringency conditions, and most preferably very high stringency conditions with (i) the nucleotide sequence of SEQ ID NO: 1; (ii) the mature polypeptide coding sequence of SEQ ID NO: 1, (iii) the cDNA sequence contained in (i) or (ii), or (iv) a full-length complementary strand of (i), (ii), or (iii).
In another aspect, the aspartic protease gene comprises a nucleotide sequence encoding a polypeptide having aspartic protease activity comprising an amino acid sequence having preferably at least 60%, more preferably at least 65%, more preferably at least 70%, more preferably at least 75%, more preferably at least 80%, more preferably at least 85%, even more preferably at least 90%, most preferably at least 95%, and even most preferably at least 96%, at least 97%, at least 98%, or at least 99% identity to the amino acid sequence of SEQ ID NO: 4 or the mature polypeptide thereof. In another aspect, the aspartic protease gene comprises a nucleotide sequence encoding a polypeptide having aspartic protease activity comprising the amino acid sequence of SEQ ID NO: 4 or the mature polypeptide thereof. In another aspect, the aspartic protease gene comprises a nucleotide sequence encoding a polypeptide having aspartic protease activity consisting of the amino acid sequence of SEQ ID NO: 4 or the mature polypeptide thereof. In another aspect, the aspartic protease gene comprises a nucleotide sequence encoding a polypeptide having aspartic protease activity comprising the mature polypeptide of SEQ ID NO: 4. In another aspect, the aspartic protease gene comprises a nucleotide sequence encoding a polypeptide having aspartic protease activity consisting of the mature polypeptide of SEQ ID NO: 4.
In another aspect, the aspartic protease gene comprises a nucleotide sequence having preferably at least 60%, more preferably at least 65%, more preferably at least 70%, more preferably at least 75%, more preferably at least 80%, more preferably at least 85%, even more preferably at least 90%, most preferably at least 95%, and even most preferably at least 96%, at least 97%, at least 98%, or at least 99% identity to the nucleotide sequence of SEQ ID NO: 3 or the mature polypeptide coding sequence thereof. In another aspect, the aspartic protease gene comprises the nucleotide sequence of SEQ ID NO: 3. In another aspect, the aspartic protease gene consists of the nucleotide sequence of SEQ ID NO: 3. In another aspect, the aspartic protease gene comprises the mature polypeptide coding sequence of SEQ ID NO: 3. In another aspect, the aspartic protease gene consists of the mature polypeptide coding sequence of SEQ ID NO: 3.
In another aspect, the aspartic protease gene comprises a nucleotide sequence that hybridizes under preferably very low stringency conditions, more preferably low stringency conditions, more preferably medium stringency conditions, more preferably medium-high stringency conditions, even more preferably high stringency conditions, and most preferably very high stringency conditions with (i) the nucleotide sequence of SEQ ID NO: 3; (ii) the mature polypeptide coding sequence of SEQ ID NO: 3, (iii) the cDNA sequence contained in (i) or (ii), or (iv) a full-length complementary strand of (i), (ii), or (iii).
In another aspect, the aspartic protease comprises an amino acid sequence having preferably at least 60%, more preferably at least 65%, more preferably at least 70%, more preferably at least 75%, more preferably at least 80%, more preferably at least 85%, even more preferably at least 90%, most preferably at least 95%, and even most preferably at least 96%, at least 97%, at least 98%, or at least 99% identity to the amino acid sequence of SEQ ID NO: 4 or the mature polypeptide thereof. In another aspect, the aspartic protease comprises the amino acid sequence of SEQ ID NO: 4. In another aspect, the aspartic protease consists of the amino acid sequence of SEQ ID NO: 4. In another aspect, the aspartic protease comprises the mature polypeptide of SEQ ID NO: 4. In another aspect, the aspartic protease consists of the mature polypeptide of SEQ ID NO: 4.
In another aspect, the aspartic protease is encoded by a polynucleotide comprising a nucleotide sequence having preferably at least 60%, more preferably at least 65%, more preferably at least 70%, more preferably at least 75%, more preferably at least 80%, more preferably at least 85%, even more preferably at least 90%, most preferably at least 95%, and even most preferably at least 96%, at least 97%, at least 98%, or at least 99% identity to the nucleotide sequence of SEQ ID NO: 3 or the mature polypeptide coding sequence thereof. In another aspect, the aspartic protease is encoded by a polynucleotide comprising the nucleotide sequence of SEQ ID NO: 3. In another aspect, the aspartic protease is encoded by a polynucleotide consisting of the nucleotide sequence of SEQ ID NO: 3. In another aspect, the aspartic protease is encoded by a polynucleotide comprising the mature polypeptide coding sequence of SEQ ID NO: 3. In another aspect, the aspartic protease is encoded by a polynucleotide consisting of the mature polypeptide coding sequence of SEQ ID NO: 3.
In another aspect, the aspartic protease is encoded by a polynucleotide comprising a nucleotide sequence that hybridizes under preferably very low stringency conditions, more preferably low stringency conditions, more preferably medium stringency conditions, more preferably medium-high stringency conditions, even more preferably high stringency conditions, and most preferably very high stringency conditions with (i) the nucleotide sequence of SEQ ID NO: 3; (ii) the mature polypeptide coding sequence of SEQ ID NO: 3, (iii) the cDNA sequence contained in (i) or (ii), or (iv) a full-length complementary strand of (i), (ii), or (iii).
In another aspect, the trypsin-like serine protease gene comprises a nucleotide sequence encoding a polypeptide having trypsin-like serine protease activity comprising an amino acid sequence having a preferably at least 60%, more preferably at least 65%, more preferably at least 70%, more preferably at least 75%, more preferably at least 80%, more preferably at least 85%, even more preferably at least 90%, most preferably at least 95%, and even most preferably at least 96%, at least 97%, at least 98%, or at least 99% identity to the amino acid sequence of SEQ ID NO: 6 or the mature polypeptide thereof. In another aspect, the trypsin-like serine protease gene comprises a nucleotide sequence encoding a polypeptide having trypsin-like serine protease activity comprising the amino acid sequence of SEQ ID NO: 6. In another aspect, the trypsin-like serine protease gene comprises a nucleotide sequence encoding a polypeptide having trypsin-like serine protease activity consisting of the amino acid sequence of SEQ ID NO: 6. In another aspect, the trypsin-like serine protease gene comprises a nucleotide sequence encoding a polypeptide having trypsin-like serine protease activity comprising the mature polypeptide of SEQ ID NO: 6. In another aspect, the trypsin-like serine protease gene comprises a nucleotide sequence encoding a polypeptide having trypsin-like serine protease activity consisting of the mature polypeptide of SEQ ID NO: 6.
In another aspect, the trypsin-like serine protease gene comprises a nucleotide sequence having preferably at least 60%, more preferably at least 65%, more preferably at least 70%, more preferably at least 75%, more preferably at least 80%, more preferably at least 85%, even more preferably at least 90%, most preferably at least 95%, and even most preferably at least 96%, at least 97%, at least 98%, or at least 99% identity to the nucleotide sequence of SEQ ID NO: 5 or the mature polypeptide coding sequence thereof. In another aspect, the trypsin-like serine protease gene comprises the nucleotide sequence of SEQ ID NO: 5. In another aspect, the trypsin-like serine protease gene consists of the nucleotide sequence of SEQ ID NO: 5. In another aspect, the trypsin-like serine protease gene comprises the mature polypeptide coding sequence of SEQ ID NO: 5. In another aspect, the trypsin-like serine protease gene consists of the mature polypeptide coding sequence of SEQ ID NO: 5.
In another aspect, the trypsin-like serine protease gene comprises a nucleotide sequence that hybridizes under preferably very low stringency conditions, more preferably low stringency conditions, more preferably medium stringency conditions, more preferably medium-high stringency conditions, even more preferably high stringency conditions, and most preferably very high stringency conditions with (i) the nucleotide sequence of SEQ ID NO: 5; (ii) the mature polypeptide coding sequence of SEQ ID NO: 5, (iii) the cDNA sequence contained in (i) or (ii), or (iv) a full-length complementary strand of (i), (ii), or (iii).
In another aspect, the trypsin-like serine protease comprises an amino acid sequence having preferably at least 60%, more preferably at least 65%, more preferably at least 70%, more preferably at least 75%, more preferably at least 80%, more preferably at least 85%, even more preferably at least 90%, most preferably at least 95%, and even most preferably at least 96%, at least 97%, at least 98%, or at least 99% identity to the amino acid sequence of SEQ ID NO: 6 or the mature polypeptide thereof. In another aspect, the aspartic protease comprises the amino acid sequence of SEQ ID NO: 6. In another aspect, the aspartic protease consists of the amino acid sequence of SEQ ID NO: 6. In another aspect, the aspartic protease comprises the mature polypeptide of SEQ ID NO: 6. In another aspect, the aspartic protease consists of the mature polypeptide of SEQ ID NO: 6.
In another aspect, the trypsin-like serine protease is encoded by a polynucleotide comprising a nucleotide sequence having preferably at least 60%, more preferably at least 65%, more preferably at least 70%, more preferably at least 75%, more preferably at least 80%, more preferably at least 85%, even more preferably at least 90%, most preferably at least 95%, and even most preferably at least 96%, at least 97%, at least 98%, or at least 99% identity to the nucleotide sequence of SEQ ID NO: 5 or the mature polypeptide coding sequence thereof. In another aspect, the trypsin-like serine protease is encoded by a polynucleotide comprising the nucleotide sequence of SEQ ID NO: 5. In another aspect, the trypsin-like serine protease is encoded by a polynucleotide consisting of the nucleotide sequence of SEQ ID NO: 5. In another aspect, the trypsin-like serine protease is encoded by a polynucleotide comprising the mature polypeptide coding sequence of SEQ ID NO: 5. In another aspect, the trypsin-like serine protease is encoded by a polynucleotide consisting of the mature polypeptide coding sequence of SEQ ID NO: 5.
In another aspect, the trypsin-like serine protease is encoded by a polynucleotide comprising a nucleotide sequence that hybridizes under preferably very low stringency conditions, more preferably low stringency conditions, more preferably medium stringency conditions, more preferably medium-high stringency conditions, even more preferably high stringency conditions, and most preferably very high stringency conditions with (i) the nucleotide sequence of SEQ ID NO: 5; (ii) the mature polypeptide coding sequence of SEQ ID NO: 5, (iii) the cDNA sequence contained in (i) or (ii), or (iv) a full-length complementary strand of (i), (ii), or (iii).
The nucleotide sequences disclosed herein or subsequences thereof, as well as the amino acid sequences thereof or fragments thereof, may be used to design nucleic acid probes to identify and clone homologous DNA of the genes described above from strains of different genera or species according to methods well known in the art. In particular, such probes can be used for hybridization with the genomic or cDNA of the genus or species of interest, following standard Southern blotting procedures, in order to identify and isolate the corresponding gene therein. Such probes can be considerably shorter than the entire sequence, but should be at least 15, preferably at least 25, and more preferably at least 35 nucleotides in length. Longer probes can also be used. Both DNA and RNA probes can be used. The probes are typically labeled for detecting the corresponding gene (for example, with 32P, 3H, 35S, biotin, or avidin).
Thus, a genomic DNA or cDNA library prepared from such other organisms may be screened for DNA that hybridizes with the probes described above. Genomic or other DNA from such other organisms may be separated by agarose or polyacrylamide gel electrophoresis, or other separation techniques. DNA from the libraries or the separated DNA may be transferred to and immobilized on nitrocellulose or other suitable carrier material. In order to identify a clone or DNA that is homologous with the nucleotide sequences disclosed herein or subsequences thereof, the carrier material is used in a Southern blot. For purposes of the present invention, hybridization indicates that the nucleic acid sequence hybridizes to a labeled nucleic acid probe corresponding to the nucleotide sequences disclosed herein, its complementary strand, or a subsequence thereof, under very low to very high stringency conditions. Molecules to which the nucleic acid probe hybridizes under these conditions are detected using X-ray film.
For long probes of at least 100 nucleotides in length, very low to very high stringency conditions are defined as prehybridization and hybridization at 42° C. in 5×SSPE, 0.3% SDS, 200 μg/ml sheared and denatured salmon sperm DNA, and either 25% formamide for very low and low stringencies, 35% formamide for medium and medium-high stringencies, or 50% formamide for high and very high stringencies, following standard Southern blotting procedures for 12 to 24 hours optimally.
For long probes of at least 100 nucleotides in length, the carrier material is finally washed three times each for 15 minutes using 2×SSC, 0.2% SDS preferably at 45° C. (very low stringency), more preferably at 50° C. (low stringency), more preferably at 55° C. (medium stringency), more preferably at 60° C. (medium-high stringency), even more preferably at 65° C. (high stringency), and most preferably at 70° C. (very high stringency).
For short probes of about 15 nucleotides to about 70 nucleotides in length, stringency conditions are defined as prehybridization, hybridization, and washing post-hybridization at about 5° C. to about 10° C. below the calculated Tm using the calculation according to Bolton and McCarthy (1962, Proceedings of the National Academy of Sciences USA 48:1390) in 0.9 M NaCl, 0.09 M Tris-HCl pH 7.6, 6 mM EDTA, 0.5% NP-40, 1×Denhardt's solution, 1 mM sodium pyrophosphate, 1 mM sodium monobasic phosphate, 0.1 mM ATP, and 0.2 mg of yeast RNA per ml following standard Southern blotting procedures for 12 to 24 hours optimally.
For short probes of about 15 nucleotides to about 70 nucleotides in length, the carrier material is washed once in 6×SCC plus 0.1% SDS for 15 minutes and twice each for 15 minutes using 6×SSC at 5° C. to 10° C. below the calculated Tm.
A nucleotide sequence homologous or complementary to a gene described herein may be used from other microbial sources to modify the corresponding gene in the Trichoderma strain of choice.
In another aspect, the modification of a gene in the Trichoderma mutant strain is unmarked with a selectable marker.
Removal of the selectable marker gene may be accomplished by culturing the mutants on a counter-selection medium. Where the selectable marker gene contains repeats flanking its 5′ and 3′ ends, the repeats will facilitate the looping out of the selectable marker gene by homologous recombination when the mutant strain is submitted to counter-selection. The selectable marker gene may also be removed by homologous recombination by introducing into the mutant strain a nucleic acid fragment comprising 5′ and 3′ regions of the defective gene, but lacking the selectable marker gene, followed by selecting on the counter-selection medium. By homologous recombination, the defective gene containing the selectable marker gene is replaced with the nucleic acid fragment lacking the selectable marker gene. Other methods known in the art may also be used.
It will be understood that the methods of the present invention are not limited to a particular order for obtaining the Trichoderma mutant strain. The modification of a gene may be introduced into the parent strain at any step in the construction of the strain for the production of a polypeptide of interest. It is preferred that the Trichoderma mutant strain has already been made enzyme-deficient prior to such a construction.
In a further aspect of the present invention, the mutants of Trichoderma strains may contain additional modifications, e.g., deletions or disruptions, of other genes, which may encode substances detrimental to the production, recovery, or application of a polypeptide of interest.
In one aspect, the Trichoderma strain further comprises a modification, e.g., disruption or deletion, of one or more (several) genes encoding a proteolytic activity selected from the group consisting of an aminopeptidase, dipeptidylaminopeptidase, tripeptidylaminopeptidase, carboxypeptidase, metalloprotease, cysteine protease, and vacuolar protease.
In another aspect, the Trichoderma strain further comprises a modification, e.g., disruption or deletion, of one or more (several) additional genes encoding an oxidoreductase, a transferase, a hydrolase, a lyase, an isomerase, or a ligase.
In another aspect, the Trichoderma strain further comprises a modification, e.g., disruption or deletion, of one or more (several) additional genes encoding an enzyme selected from the group consisting of an alpha-amylase, arabinofuranosidase, carbohydrase, catalase, cellobiohydrolase, cellulase, chitinase, cyclodextrin glycosyltransferase, cutinase, cyclodextrin glycosyltransferase, deoxyribonuclease, endoglucanase, esterase, alpha-galactosidase, beta-galactosidase, glucocerebrosidase, glucose oxidase, alpha-glucosidase, beta-glucosidase, glucuronidases, haloperoxidase, hemicellulase, invertase, isomerase, laccase, ligase, lipase, mannosidase, mutanase, oxidase, pectinolytic enzyme, peroxidase, phospholipase, phytase, phenoloxidase, polyphenoloxidase, ribonuclease, alpha-1,6-transglucosidase, transglutaminase, urokinase, xylanase, and beta-xylosidase.
In the methods of the present invention, the Trichoderma mutant strain preferably produces at least the same amount of the polypeptide of interest as the corresponding parent Trichoderma strain when cultured under identical production conditions. In another aspect, the mutant strain produces preferably at least 5% more, more preferably at least 10% more, more preferably at least 25% more, more preferably at least 50% more, even more preferably at least 75% more, and most preferably at least 100% more of the polypeptide than the corresponding parent Trichoderma strain when cultured under identical production conditions.
The Trichoderma mutant strains are cultivated in a nutrient medium for production of the polypeptide of interest using methods known in the art. For example, the strain may be cultivated by shake flask cultivation, small-scale or large-scale fermentation (including continuous, batch, fed-batch, or solid state fermentations) in laboratory or industrial fermentors performed in a suitable medium and under conditions allowing the polypeptide to be expressed and/or isolated. The cultivation takes place in a suitable nutrient medium comprising carbon and nitrogen sources and inorganic salts, using procedures known in the art. Suitable media are available from commercial suppliers or may be prepared according to published compositions (e.g., in catalogues of the American Type Culture Collection). The secreted polypeptide can be recovered directly from the medium. If the polypeptide is not secreted, it may be obtained from cell lysates.
The polypeptide of interest may be detected using methods known in the art that are specific for the polypeptide. These detection methods may include use of specific antibodies, high performance liquid chromatography, capillary chromatography, formation of an enzyme product, disappearance of an enzyme substrate, or SDS-PAGE. For example, an enzyme assay may be used to determine the activity of an enzyme. Procedures for determining enzyme activity are known in the art for many enzymes (see, for example, D. Schomburg and M. Salzmann (eds.), Enzyme Handbook, Springer-Verlag, New York, 1990).
The resulting polypeptide may be isolated by methods known in the art. For example, a polypeptide of interest may be isolated from the cultivation medium by conventional procedures including, but not limited to, centrifugation, filtration, extraction, spray-drying, evaporation, or precipitation. The isolated polypeptide may then be further purified by a variety of procedures known in the art including, but not limited to, chromatography (e.g., ion exchange, affinity, hydrophobic, chromatofocusing, and size exclusion), electrophoretic procedures (e.g., preparative isoelectric focusing (IEF), differential solubility (e.g., ammonium sulfate precipitation), or extraction (see, e.g., Protein Purification, J.-C. Janson and Lars Ryden, editors, VCH Publishers, New York, 1989).
The polypeptide of interest may be any polypeptide native or foreign (heterologous) to the Trichoderma strain. The polypeptide may be encoded by a single gene or two or more genes. The term “polynucleotide encoding the polypeptide” will be understood to encompass one or more (several) genes involved in the production of the polypeptide. The term “heterologous polypeptide” is defined herein as a polypeptide that is not native to the host strain; a native polypeptide in which structural modifications have been made to alter the native polypeptide, e.g., the protein sequence of a native polypeptide; or a native polypeptide whose expression is quantitatively altered as a result of a manipulation of the polynucleotide or host strain by recombinant DNA techniques, e.g., a stronger promoter. Thus, the present invention also encompasses, within the scope of the term “heterologous polypeptides,” such recombinant production of native polypeptides, to the extent that such expression involves the use of genetic elements not native to the Trichoderma strain, or use of native elements that have been manipulated to function in a manner that do not normally occur in the host strain. In one aspect, the polypeptide is a native polypeptide to the Trichoderma strain. In another aspect, the polypeptide is a heterologous polypeptide to the Trichoderma strain.
The polypeptide may be any polypeptide having a biological activity of interest. The term “polypeptide” is not meant herein to refer to a specific length of the encoded product and, therefore, encompasses peptides, oligopeptides, and proteins. The term “polypeptide” also encompasses two or more polypeptides combined to form the encoded product. Polypeptides also include fusion polypeptides, which comprise a combination of partial or complete polypeptide sequences obtained from at least two different polypeptides wherein one or more (several) may be heterologous to the Trichoderma strain. Polypeptides further include naturally occurring allelic and engineered variations of the above-mentioned polypeptides and hybrid polypeptides.
In one aspect, the polypeptide is an antibody, an antigen, an antimicrobial peptide, an enzyme, a growth factor, a hormone, an immunodilator, a neurotransmitter, a receptor, a reporter protein, a structural protein, or a transcription factor.
In another aspect, the polypeptide is an oxidoreductase, a transferase, a hydrolase, a lyase, an isomerase, or a ligase. In another aspect, the polypeptide is an aminopeptidase, alpha-amylase, arabinofuranosidase, carbohydrase, carboxypeptidase, catalase, cellobiohydrolase, cellulase, chitinase, cyclodextrin glycosyltransferase, cutinase, cyclodextrin glycosyltransferase, deoxyribonuclease, endoglucanase, esterase, alpha-galactosidase, beta-galactosidase, glucocerebrosidase, glucose oxidase, alpha-glucosidase, beta-glucosidase, glucuronidase, haloperoxidase, hemicellulase, invertase, isomerase, laccase, ligase, lipase, mannosidase, mutanase, oxidase, pectinolytic enzyme, peroxidase, phospholipase, phytase, phenoloxidase, polyphenoloxidase, proteolytic enzyme, ribonuclease, alpha-1,6-transglucosidase, transglutaminase, urokinase, xylanase, or beta-xylosidase.
In another aspect, the polypeptide is an albumin, a collagen, a tropoelastin, an elastin, or a gelatin.
In another aspect, the polypeptide is an endoglucanase. In another aspect, the polypeptide is a cellobiohydrolase. In another aspect, the polypeptide is a beta-glucosidase. In another aspect, the polypeptide is a polypeptide having cellulolytic enhancing activity. In another aspect, the polypeptide is a xylanase. In another aspect, the polypeptide is a beta-xylosidase. In another aspect, the polypeptide is an acetyxylan esterase. In another aspect, the polypeptide is a feruloyl esterase. In another aspect, the polypeptide is an arabinofuranosidase. In another aspect, the polypeptide is a glucuronidase.
In the methods of the present invention, the mutant of the Trichoderma strain is a recombinant strain, comprising a polynucleotide encoding a heterologous polypeptide, which is advantageously used in the recombinant production of the polypeptide. The strain is preferably transformed with a vector comprising the polynucleotide encoding the heterologous polypeptide followed by integration of the vector into the chromosome. “Transformation” means introducing a vector comprising the polynucleotide into a host strain so that the vector is maintained as a chromosomal integrant or as a self-replicating extra-chromosomal vector. Integration is generally considered to be an advantage as the polynucleotide is more likely to be stably maintained in the strain. Integration of the vector into the chromosome can occur by homologous recombination, non-homologous recombination, or transposition.
The polynucleotide encoding a heterologous polypeptide may be obtained from any prokaryotic, eukaryotic, or other source, e.g., archaeabacteria. For purposes of the present invention, the term “obtained from” as used herein in connection with a given source shall mean that the polypeptide is produced by the source or by a strain in which a gene from the source has been inserted.
In the methods of the present invention, a mutant Trichoderma strain of the present invention may also be used for the recombinant production of a polypeptide that is native to the Trichoderma strain. The native polypeptide may be produced by recombinant means by, for example, placing a gene encoding the polypeptide under the control of a different promoter to enhance expression of the substance, expediting its export outside the strain by use of, for example, a signal sequence, or increasing the copy number of a gene encoding the polypeptide normally produced by the Trichoderma strain.
The techniques used to isolate or clone a polynucleotide encoding a polypeptide of interest are known in the art and include isolation from genomic DNA, preparation from cDNA, or a combination thereof. The cloning of such a polynucleotide from such genomic DNA can be effected, e.g., by using the well known polymerase chain reaction (PCR). See, for example, Innis et al., 1990, PCR Protocols: A Guide to Methods and Application, Academic Press, New York. The cloning procedures may involve excision and isolation of a desired nucleic acid fragment comprising the polynucleotide encoding the polypeptide, insertion of the fragment into a vector molecule, and incorporation of the recombinant vector into a mutant Trichoderma strain of the present invention where multiple copies or clones of the polynucleotide will be replicated. The polynucleotide may be of genomic, cDNA, RNA, semisynthetic, synthetic origin, or any combinations thereof.
In the methods of the present invention, the polypeptide may also be a fused polypeptide or cleavable fusion polypeptide in which a polypeptide is fused at the N-terminus or the C-terminus of another polypeptide or fragment thereof. A fused polypeptide is produced by fusing a nucleotide sequence (or a portion thereof) encoding a polypeptide to another nucleotide sequence (or a portion thereof) encoding another polypeptide. Techniques for producing fusion polypeptides are known in the art, and include ligating the coding sequences encoding the polypeptides so that they are in frame and that expression of the fused polypeptide is under control of the same promoter(s) and terminator.
An isolated polynucleotide encoding a heterologous polypeptide may be manipulated in a variety of ways to provide for expression of the polypeptide in a mutant Trichoderma strain of the present invention. Manipulation of the polynucleotide's sequence prior to its insertion into a vector may be desirable or necessary depending on the expression vector. The techniques for modifying polynucleotide sequences utilizing recombinant DNA methods are well known in the art.
A nucleic acid construct comprising a polynucleotide encoding a polypeptide may be operably linked to one or more (several) control sequences capable of directing expression of the coding sequence in a mutant Trichoderma strain of the present invention under conditions compatible with the control sequences.
The control sequence may be an appropriate promoter sequence, a nucleotide sequence that is recognized by a mutant Trichoderma strain of the present invention for expression of the polynucleotide encoding the polypeptide. The promoter sequence contains transcriptional control sequences that mediate expression of the polypeptide. The promoter may be any nucleotide sequence that shows transcriptional activity in the mutant Trichoderma strain, including mutant, truncated, and hybrid promoters, and may be obtained from genes encoding extracellular or intracellular polypeptides either native or heterologous (foreign) to the mutant Trichoderma strain.
Examples of suitable promoters for directing the transcription of the nucleic acid constructs in the methods of the present invention are promoters obtained from the genes for Aspergillus oryzae TAKA amylase, Rhizomucor miehei aspartic proteinase, Aspergillus niger neutral alpha-amylase, Aspergillus niger acid stable alpha-amylase, Aspergillus niger or Aspergillus awamori glucoamylase (glaA), Rhizomucor miehei lipase, Aspergillus oryzae alkaline protease, Aspergillus oryzae triose phosphate isomerase, Aspergillus nidulans acetamidase, Fusarium venenatum amyloglucosidase (WO 00/56900), Fusarium venenatum Daria (WO 00/56900), Fusarium venenatum Quinn (WO 00/56900), Fusarium oxysporum trypsin-like protease (WO 96/00787), Trichoderma reesei beta-glucosidase, Trichoderma reesei cellobiohydrolase I, Trichoderma reesei cellobiohydrolase II, Trichoderma reesei endoglucanase I, Trichoderma reesei endoglucanase II, Trichoderma reesei endoglucanase III, Trichoderma reesei endoglucanase IV, Trichoderma reesei endoglucanase V, Trichoderma reesei xylanase I, Trichoderma reesei xylanase II, Trichoderma reesei beta-xylosidase, as well as the NA2-tpi promoter (a modified promoter including a gene encoding a neutral alpha-amylase in Aspergilli in which the untranslated leader has been replaced by an untranslated leader from a gene encoding triose phosphate isomerase in Aspergilli; non-limiting examples include modified promoters including the gene encoding neutral alpha-amylase in Aspergillus niger in which the untranslated leader has been replaced by an untranslated leader from the gene encoding triose phosphate isomerase in Aspergillus nidulans or Aspergillus oryzae); and mutant, truncated, and hybrid promoters thereof.
The control sequence may also be a suitable transcription terminator sequence, a sequence recognized by a mutant Trichoderma strain of the present invention to terminate transcription. The terminator sequence is operably linked to the 3′ terminus of the nucleotide sequence encoding the heterologous polypeptide. Any terminator that is functional in a Trichoderma strain may be used in the present invention.
Preferred terminators are obtained from the genes for Aspergillus oryzae TAKA amylase, Aspergillus niger glucoamylase, Aspergillus nidulans anthranilate synthase, Aspergillus niger alpha-glucosidase, and Fusarium oxysporum trypsin-like protease.
The control sequence may also be a suitable leader sequence, a nontranslated region of a mRNA that is important for translation by a mutant Trichoderma strain of the present invention. The leader sequence is operably linked to the 5′ terminus of the nucleotide sequence encoding the heterologous polypeptide. Any leader sequence that is functional in the mutant Trichoderma strain may be used in the present invention.
Preferred leaders for filamentous fungal host cells are obtained from the genes for Aspergillus oryzae TAKA amylase and Aspergillus nidulans triose phosphate isomerase.
The control sequence may also be a polyadenylation sequence, a sequence operably linked to the 3′ terminus of the nucleotide sequence and, when transcribed, is recognized by the mutant Trichoderma strain as a signal to add polyadenosine residues to transcribed mRNA. Any polyadenylation sequence that is functional in the mutant Trichoderma strain may be used in the present invention.
Preferred polyadenylation sequences for filamentous fungal host cells are obtained from the genes for Aspergillus oryzae TAKA amylase, Aspergillus niger glucoamylase, Aspergillus nidulans anthranilate synthase, Fusarium oxysporum trypsin-like protease, and Aspergillus niger alpha-glucosidase.
The control sequence may also be a signal peptide coding sequence that codes for an amino acid sequence linked to the amino terminus of a polypeptide and directs the encoded polypeptide into the cell's secretory pathway. The 5′ end of the coding sequence of the nucleotide sequence may inherently contain a signal peptide coding sequence naturally linked in translation reading frame with the segment of the coding sequence that encodes the secreted polypeptide. Alternatively, the 5′ end of the coding sequence may contain a signal peptide coding sequence that is foreign to the coding sequence. The foreign signal peptide coding sequence may be required where the coding sequence does not naturally contain a signal peptide coding sequence. Alternatively, the foreign signal peptide coding sequence may simply replace the natural signal peptide coding sequence in order to enhance secretion of the polypeptide. However, any signal peptide coding sequence that directs the expressed polypeptide into the secretory pathway of the mutant Trichoderma strain, i.e., secreted into a culture medium, may be used in the present invention.
Effective signal peptide coding regions for the mutant Trichoderma strains are the signal peptide coding regions obtained from the genes for Aspergillus oryzae TAKA amylase, Aspergillus niger neutral amylase, Aspergillus niger glucoamylase, Rhizomucor miehei aspartic proteinase, Humicola insolens cellulase, Humicola insolens endoglucanase V, and Humicola lanuginosa lipase.
The control sequence may also be a propeptide coding region, which codes for an amino acid sequence positioned at the amino terminus of a polypeptide. The resultant polypeptide is known as a proenzyme or propolypeptide (or a zymogen in some cases). A propolypeptide is generally inactive and can be converted to a mature, active polypeptide by catalytic or autocatalytic cleavage of the propeptide from the propolypeptide. The propeptide coding region may be obtained from genes for Saccharomyces cerevisiae alpha-factor, Rhizomucor miehei aspartic proteinase, and Myceliophthora thermophila laccase (WO 95/33836).
Where both signal peptide and propeptide sequences are present at the amino terminus of a polypeptide, the propeptide sequence is positioned next to the amino terminus of a polypeptide and the signal peptide sequence is positioned next to the amino terminus of the propeptide sequence.
The nucleic acid constructs may also comprise one or more (several) polynucleotides that encode one or more (several) factors that are advantageous for directing expression of the heterologous polypeptide, e.g., a transcriptional activator (e.g., a trans-acting factor), a chaperone, and a processing protease. Any factor that is functional in the mutant Trichoderma strain may be used in the present invention. The nucleic acids encoding one or more (several) of these factors are not necessarily in tandem with the nucleotide sequence encoding the heterologous polypeptide.
It may also be desirable to add regulatory or control sequences that allow regulation of expression of the polypeptide relative to the growth of the mutant Trichoderma strain. Examples of regulatory systems are those that cause expression of the gene to be turned on or off in response to a chemical or physical stimulus, including the presence of a regulatory compound. Regulatory systems in filamentous fungi such as the TAKA alpha-amylase promoter, Aspergillus niger glucoamylase promoter, and Aspergillus oryzae glucoamylase promoter may be used as regulatory sequences. Other examples of regulatory sequences are those that allow for gene amplification. In eukaryotic systems, these regulatory sequences include the dihydrofolate reductase gene that is amplified in the presence of methotrexate, and the metallothionein genes that are amplified with heavy metals. In these cases, the nucleotide sequence encoding the polypeptide would be operably linked with the regulatory sequence.
In the methods of the present invention, a recombinant expression vector comprising a nucleotide sequence, a promoter, and transcriptional and translational stop signals may be used for the recombinant production of a polypeptide of interest. The various nucleic acids and control sequences described herein may be joined together to produce a recombinant expression vector that may include one or more (several) convenient restriction sites to allow for insertion or substitution of the nucleotide sequence encoding the polypeptide at such sites. Alternatively, the nucleotide sequence may be expressed by inserting the nucleotide sequence or a nucleic acid construct comprising the sequence into an appropriate vector for expression. In creating the expression vector, the coding sequence is located in the vector so that the coding sequence is operably linked with the appropriate control sequences for expression.
The recombinant expression vector may be any vector (e.g., a plasmid or virus) that can be conveniently subjected to recombinant DNA procedures and can bring about expression of the nucleotide sequence. The choice of the vector will typically depend on its compatibility with the mutant Trichoderma strain into which the vector is to be introduced. The vector may be a linear or closed circular plasmid.
The vector may be an autonomously replicating vector, i.e., a vector that exists as an extrachromosomal entity, the replication of which is independent of chromosomal replication, e.g., a plasmid, an extrachromosomal element, a minichromosome, or an artificial chromosome. The vector may contain any means for assuring self-replication. Alternatively, the vector may be one that, when introduced into the mutant Trichoderma strain, is integrated into the genome and replicated together with the chromosome(s) into which it has been integrated. Furthermore, a single vector or plasmid or two or more vectors or plasmids that together contain the total DNA to be introduced into the genome of the mutant Trichoderma strain, or a transposon, may be used.
The vector preferably contains one or more (several) selectable markers that permit easy selection of transformed mutant Trichoderma strains. A selectable marker is a gene the product of which provides for biocide or viral resistance, resistance to heavy metals, prototrophy to auxotrophs, and the like.
Examples of selectable markers for use in the mutant Trichoderma strain include, but are not limited to, amdS (acetamidase), argB (ornithine carbamoyltransferase), bar (phosphinothricin acetyltransferase), hpt (hygromycin phosphotransferase), niaD (nitrate reductase), pyrG (orotidine-5′-phosphate decarboxylase), sC (sulfate adenyltransferase), and trpC (anthranilate synthase), as well as equivalents thereof. Preferred for use in the mutant Trichoderma strain are the amdS gene of Aspergillus nidulans and the bar gene of Streptomyces hygroscopicus.
The vectors preferably contain an element(s) that permits integration of the vector into the host cell's genome or autonomous replication of the vector in the cell independent of the genome.
For integration into the genome of the mutant Trichoderma strain, the vector may rely on the polynucleotide's sequence encoding the polypeptide or any other element of the vector for integration into the genome by homologous or nonhomologous recombination. Alternatively, the vector may contain additional nucleotide sequences for directing integration by homologous recombination into the genome of the mutant Trichoderma strain at a precise location(s) in the chromosome(s). To increase the likelihood of integration at a precise location, the integrational elements should preferably contain a sufficient number of nucleic acids, such as 100 to 10,000 base pairs, preferably 400 to 10,000 base pairs, and most preferably 800 to 10,000 base pairs, which have a high degree of identity to the corresponding target sequence to enhance the probability of homologous recombination. The integrational elements may be any sequence that is homologous with the target sequence in the genome of the mutant Trichoderma strain. Furthermore, the integrational elements may be non-encoding or encoding nucleotide sequences. On the other hand, the vector may be integrated into the genome of the mutant Trichoderma strain by non-homologous recombination.
For autonomous replication, the vector may further comprise an origin of replication enabling the vector to replicate autonomously in the mutant Trichoderma strain. The origin of replication may be any plasmid replicator mediating autonomous replication that functions in a cell. The term “origin of replication” or “plasmid replicator” is defined herein as a nucleotide sequence that enables a plasmid or vector to replicate in vivo.
Examples of origins of replication useful in the mutant Trichoderma strain are AMA1 and ANSI (Gems et al., 1991, Gene 98: 61-67; Cullen et al., 1987, Nucleic Acids Research 15: 9163-9175; WO 00/24883). Isolation of the AMA1 gene and construction of plasmids or vectors comprising the gene can be accomplished according to the methods disclosed in WO 00/24883.
The procedures used to ligate the elements described herein to construct the recombinant expression vectors are well known to one skilled in the art (see, e.g., J. Sambrook, E. F. Fritsch, and T. Maniatus, 1989, Molecular Cloning, A Laboratory Manual, 2d edition, Cold Spring Harbor, N.Y.).
A vector comprising the nucleotide sequence can be introduced, e.g., by transformation, into the mutant Trichoderma strain so that the vector is maintained as a chromosomal integrant or as a self-replicating extra-chromosomal vector. Integration is generally considered to be an advantage as the nucleotide sequence is more likely to be stably maintained in the strain. Integration of the vector into the chromosome occurs by homologous recombination, non-homologous recombination, or transposition.
The introduction of an expression vector into the mutant Trichoderma strain may involve a process consisting of protoplast formation, transformation of the protoplasts, and regeneration of the strain wall in a manner known per se. Suitable procedures for transformation of Trichoderma strains are described in Malardier et al., 1989, Gene 78: 147-156, and WO 96/00787.
The present invention also relates to methods of obtaining mutants of a parent Trichoderma strain, comprising: (a) modifying one or more (several) genes selected from the group consisting of a subtilisin-like serine protease gene, an aspartic protease gene, and a trypsin-like serine protease gene; and (b) identifying a mutant strain from step (a) wherein the one or more (several) genes are modified rendering the mutant strain deficient in the production of one or more (several) enzymes selected from the group consisting of subtilisin-like serine protease, aspartic protease, and trypsin-like serine protease, respectively, compared to the parent Trichoderma strain when cultivated under identical conditions.
The present invention also relates to mutants of a parent Trichoderma strain, comprising a polynucleotide encoding a polypeptide and one or more (several) genes selected from the group consisting of a subtilisin-like serine protease gene, an aspartic protease gene, and a trypsin-like serine protease gene, wherein the one or more (several) genes are modified rendering the mutant strain deficient in the production of one or more to (several) enzymes selected from the group consisting of subtilisin-like serine protease, aspartic protease, and trypsin-like serine protease, respectively, compared to the parent Trichoderma strain when cultivated under identical conditions.
The present invention is further described by the following examples that should not be construed as limiting the scope of the invention.
Trichoderma reesei strain 981-O-8 (D4) is a mutagenized strain of Trichoderma reesei RutC30 (ATCC 56765; Montenecourt and Eveleigh, 1979, Adv. Chem. Ser. 181: 289-301).
LB plates were composed of 10 g of tryptone, 5 g of yeast extract, 5 g of NaCl, 15 g of Bacto agar, and deionized water to 1 liter.
NZY top agarose was composed of 5 g of NaCl, 5 g of yeast extract, 10 g of NZ amine, 2 g of MgSO4, 7 g of agarose, and deionized water to 1 liter.
YEG medium was composed of 5 g of yeast extract, 20 g of glucose, and deionized water to 1 liter
COVE selection plates were composed of 342.3 g of sucrose, 20 ml of COVE salt solution, 10 mM acetamide, 15 mM CsCl2, 25 g or 30 g of Noble agar, and deionized water to 1 liter.
COVE2 plates were composed of 30 g of sucrose, 20 ml of COVE salt solution, 10 mM acetamide, 25 g or 30 g of Noble agar, and deionized water to 1 liter.
COVE salt solution was composed of 26 g of KCl, 26 g of MgSO4.7H2O, 76 g of KH2PO4, 50 ml of COVE trace metals solution, and deionized water to 1 liter.
COVE trace metals solution was composed of 0.04 g of NaB4O7.10H2O, 0.4 g of CuSO4.5H2O, 1.2 g of FeSO4.7H2O, 0.7 g or 1 g of MnSO4.H2O, 0.8 g of Na2MoO2.2H2O, 10 g of ZnSO4.7H2O, and deionized water to 1 liter.
COVE top agarose was composed of 342.3 g of sucrose, 20 ml of COVE salt solution, 10 mM acetamide, 10 g of low melt agarose, and deionized water to 1 liter.
Cellulase-inducing medium was composed of 20 g of Arbocel-natural cellulose fibers (J. Rettenmaier USA LP, Schoolcraft, Mich., USA), 10 g of corn steep solids (Sigma Chemical Co., St. Louis, Mo., USA), 1.45 g of (NH4)2SO4, 2.08 g of KH2PO4, 0.28 g of CaCl2, 0.42 g of MgSO4.7H2O, 0.42 ml of Trichoderma reesei trace metals solution, 2 drops of pluronic acid, and deionized water to 1 liter. The pH was adjusted to 6.0 with 10 N NaOH before autoclaving.
Trichoderma reesei trace metals solution was composed of 216 g of FeCl3.6H2O, 58 g of ZnSO4.7H2O, 27 g of MnSO4.H2O, 10 g of CuSO4.5H2O, 2.4 g of H3BO3, 336 g of citric acid, and deionized water to 1 liter.
YP medium was composed of 10 g of yeast extract, 20 g of Bacto peptone, and deionized water to 1 liter.
YPG medium was composed of 4 g of yeast extract, 1 g of K2HPO4, 0.5 g of MgSO4, 15.0 g of glucose, and deionized water to 1 liter (pH 6.0).
PEG buffer was composed of 500 g of PEG 4000, 10 mM CaCl2, 10 mM Tris-HCl pH 7.5, and deionized water to 1 liter; filter sterilized.
STC was composed of 0.8 M or 1 M sorbitol, 10 mM or 25 mM CaCl2, and 10 mM or 25 mM Tris-HCl, pH 7.5 or pH 8; filter sterilized.
PDA plates were composed of 39 g of Potato Dextrose Agar (Difco) and deionized water to 1 liter.
TE Buffer was composed of 1 M Tris pH 8.0 and 0.5 M EDTA pH 8.0
20×SSC was composed of 175.3 g NaCl, 88.2 g of sodium citrate, and deionized water to 1 liter.
A probe of a Neurospora crassa orotidine-5′-monophosphate decarboxylase (pyr-4) gene (SEQ ID NO: 7 for the DNA sequence and SEQ ID NO: 8 for the deduced amino acid sequence) was prepared by PCR incorporating digoxigenin-labeled deoxyuridine-triphosphate (dUTP) using the primers described below.
Plasmid pFB6 (Buxton et al, 1983, Molecular and General Genetics 190: 403-405) was digested with Hind III and the digestion purified by 1% agarose gel electrophoresis using 40 mM Tris base-20 mM sodium acetate-1 mM disodium EDTA (TAE) buffer. A 1.1 kb pyr-4 fragment was excised from the gel and extracted using a QIAQUICK® Gel Extraction Kit (QIAGEN Inc., Valencia Calif., USA) according to the manufacturer's suggested protocols.
The amplification reaction (50 μl) was composed of 1×Taq DNA Polymerase Buffer (New England Biolabs Inc., Ipswich, Mass., USA), 5 pl of PCR DIG Labeling Mix (Boehringer
Mannheim, Manheim, Germany), 10 ng of the 1.1 kb Hind III pyr-4 fragment, 10 pmol of the sense primer, 10 pmol of the anti-sense primer, and 1 unit of Taq DNA polymerase (New England Biolabs Inc., Ipswich, Mass., USA). The reaction was incubated in a ROBOCYCLER® (Stratagene, La Jolla, Calif., USA) programmed for 1 cycle at 95° C. for 3 minutes followed by 35 cycles each at 95° C. for 30 seconds, 55° C. for 1 minute, and 72° C. for 1 minute. A final extension was performed for 5 minutes at 72° C.
The amplification reaction products were purified by 1% agarose gel electrophoresis using TAE buffer. A digoxigenin (DIG) labeled probe of approximately 0.78 kb was excised from the gel and extracted using a QIAQUICK® Gel Extraction Kit.
A genomic DNA library of Fusarium venenatum strain A3/5 was generated and cloned into lambda vector EMBL4 as described in WO 99/60137.
The DIG-labeled probe was used to screen the genomic library of Fusarium venenatum A3/5 DNA cloned into lambda vector EMBL4. Lambda phages were plated with E. coli K802 cells (New England Biolabs, Ipswich, Mass., USA) onto LB plates with NZY top agarose. Plaque lifts were made to HYBOND™ N nylon membranes (Amersham Biosciences, Buckinghamshire, UK) using the technique of Sambrook et al. (Molecular Cloning, A Laboratory Manual, Second Edition; J. Sambrook, E. F. Fritsch, and T. Maniatis; Cold Spring Harbor Laboratory Press, 1989). DNA was bound to the membranes by UV cross-linking using a UV STRATALINKER™ (Stratagene, La Jolla, Calif., USA). Filters were then hybridized with the 0.78 kb DIG-labeled N. crassa pyr-4 probe. Hybridization and detection of pyrG clones were performed according to the GENIUS™ System User's Guide (Boehringer Hammheim, Manheim, Germany) at 42° C. with a hybridization solution composed of 5×SSC, 35% formamide, 0.1% L-lauroylsarcosine, 0.02% SDS, and 1% blocking reagent (Boehringer Hammheim, Manheim, Germany). The concentration of DIG-labeled probe used was 2.5 ng per ml of the hybridization solution. Hybridizing DNA was immuno-detected with an alkaline-phosphatase-conjugated anti-digoxigenin antibody (Boehringer Hammheim, Manheim, Germany) and visualized with Lumiphos 530, a chemiluminescent substrate (Boehringer Hammheim, Manheim, Germany). DNA preparations were made from putative positive lambda clones using a Lambda Midi Kit (QIAGEN Inc., Valencia, Calif., USA).
Lambda DNA from a clone identified above was digested with Eco RI and subjected to 1% agarose gel electrophoresis in TAE buffer. A 3.9 kb fragment was excised and extracted using a QIAEX® Gel Extraction Kit (QIAGEN Inc., Valencia, Calif., USA). The fragment was then cloned into the Eco RI site of pUC18 (Viera and Messing, 1987, Methods to in Enzymology 153: 3-11) and ONE SHOT® TOP10 competent cells (Invitrogen, Carlsbad, Calif., USA) were transformed with 2 μl of the cloning reaction. Plasmid DNA from eight of the resulting transformants was analyzed by DNA sequencing. One clone with the desired sequence was selected and designated pDM156.2 (
An E. coli hygromycin phosphotransferase (hpt) gene (SEQ ID NO: 11 for the DNA sequence and SEQ ID NO: 12 for the deduced amino acid sequence) was amplified from plasmid pPHTI (Cummings et al., 1999, Current Genetics 36: 371-382) using the following primers:
The restriction enzyme sites Bst BI (forward primer) and Eco 47111 (reverse primer) were engineered into the primers, represented by the underlined sequence, for cloning.
The PCR reaction (to amplify the hpt gene) was composed of 1×ThermoPol reaction buffer (New England Biolabs, Inc, Ipswich, Mass., USA), 200 μM dNTPs, 50 pmol of the forward and reverse primers, 100 pg of pPHT1, 1 unit of VENT® DNA polymerase (New England Biolabs Inc., Ipswich, Mass. USA), and sterile distilled water in a total volume of 100 μl. The amplification reaction was performed using a ROBOCYCLER® programmed for 1 cycle at 95° C. for 2 minutes; 25 cycles each at 95° C. for 1 minute, 51° C. for 1 minute, and 72° C. for 2 minutes; and 1 cycle at 72° C. for 7 minutes.
PCR products were separated by 1% agarose gel electrophoresis in TAE buffer. A 1.8 kb fragment was excised from the gel and extracted using a QIAQUICK® Gel Extraction Kit. The gel purified fragment was then cloned into pCR®-Bluntll-TOPO® (Invitrogen, Carlsbad, Calif., USA) using a TOPO® Blunt Cloning Kit (Invitrogen, Carlsbad, Calif., USA). The resulting plasmid was designated pEmY10.
The Eco RI site was then removed from the coding sequence of the hpt gene in pEmY10 using a QUIKCHANGE® Site-Directed Mutagenesis Kit (Stratagene, La Jolla, Calif., USA) according to the manufacturer's instructions using the primers shown below, where the lower case letters represent the non-mutated nucleotides of the target Eco RI site and the underlined case letters represent the mutated nucleotides. The resulting plasmid was designated pBK3.
The resulting hpt gene without the Eco RI site was PCR amplified from pBK3 using forward and reverse primers shown below.
The underlined portions represent introduced Kpn I sites for cloning.
Portions of the Aspergillus oryzae pyrG gene were used to generate direct repeats and were PCR amplified from pSO2 (WO 98/12300) using the following primers:
The underlined portions represent introduced restriction sites Sma I (cccggg) or Kpn I (ggtacc) for cloning.
The three fragments (hpt, repeat #1 and repeat #2) were amplified in separate reactions (50 μl each) composed of 1×ThermoPol reaction buffer, 200 μM dNTPs, 0.25 μM each primer, 50 ng of template DNA, and 1 unit of VENT® DNA polymerase. The amplification reaction was performed using a ROBOCYCLER® programmed for 1 cycle at 95° C. for 2 minutes; 30 cycles each at 95° C. for 1 minute, 61° C. for 1 minute, and 72° C. for 2 minutes; and 1 cycle at 72° C. for 7 minutes.
The PCR products were separated by 1.5% agarose gel electrophoresis in TAE buffer. The approximately 2 kb amplified hpt fragment and the approximately 0.2 kb repeat fragments were excised from the gels and extracted using a MINELUTE® Gel Extraction Kit. The two pyrG repeat fragments were digested with Kpn I, dephosphorylated with calf intestine phosphatase (New England Biolabs Inc., Ipswich, Mass., USA), and treated with a MINELUTE® Reaction Cleanup Kit (QIAGEN Inc., Valencia, Calif., USA) according to the manufacturer's instructions. The fragments harboring repeat #1 and hpt were then ligated together using a QUICK LIGATION™ Kit (New England Biolabs Inc., Ipswich, Mass., USA) according to the manufacturer's instructions, and treated with a MINELUTE® Reaction Cleanup Kit, and the resulting ligation cloned into pCR®ll Blunt using a TOPO® Blunt Cloning Kit. Sequence analysis confirmed one clone in which repeat #1 and the hpt fragment were ligated together in pCR®II Blunt. This plasmid was designated pEmY18.
In order to clone the second repeat into pEmY18, pEmyl8 was digested with Eco RV and the digestion purified by 1% agarose gel electrophoresis in TAE buffer. A 5.6 kb fragment was excised from the gel and extracted using a QIAQUICK® Gel Extraction Kit. The 0.2 kb Repeat 2 fragment (described above) and digested pEmY18 were ligated together using a QUICK LIGATION™ Kit. The ligation mixture was used to transform SOLOPACK® Gold Supercompetent Cells (Stratagene, La Jolla, Calif., USA). Sequence analysis identified a plasmid in which the three components (repeat #1, hpt and repeat #2) were in the desired order and orientation and lacked PCR errors. The resulting plasmid was designated pEmY20.
To insure that subsequent digestion of pEmY20 with Eco RI would liberate a single fragment, an Eco RI site was removed using a QUIKCHANGE® Site-Directed Mutagenesis Kit according to the manufacturer's instructions and forward and reverse primers shown below. The resulting plasmid was designated pEmY21 (
The Fusarium venenatum pyrG coding sequence (2,678 bp) was excised from pDM156.2 (Example 1) by digestion with Eco RV and Stu I restriction endonucleases, and the remaining 4,398 bp vector was gel-purified using a QIAQUICK® Gel Extraction Kit according to the manufacturer's directions. The Sma I fragment of pEmY21 was isolated and gel-purified using a QIAQUICK® Gel Extraction Kit and the two gel-purified fragments were ligated together. They were screened for insert orientation, sequenced for the absence of errors, and one of the clones with the correct insert sequence was selected and designated pEmY23 (
Plasmid pJRoy40 (U.S. Pat. No. 7,332,341), which harbors 5′ and 3′ flanking sequences of a Fusarium venenatum trichodiene synthase (tri5) gene (SEQ ID NO: 25 for the DNA sequence and SEQ ID NO: 26 for the deduced amino acid sequence), was used as template for amplification of a portion of the 5′ tri5 gene flanking sequence. The PCR reaction contained 200 μM dNTPs, 1×Taq DNA polymerase buffer, 125 pg of pJRoy40 DNA, 50 pmol of each primer shown below, and 1 unit of Taq DNA polymerase in a final volume of 50 μl.
(Underlined nucleotides indicate introduced Bgl II sites).
The amplification reaction was incubated in a ROBOCYCLER® programmed for 1 cycle at 95° C. for 3 minutes; 10 cycles each at 95° C. for 30 seconds, 52° C. for 45 seconds, and 7° C. for 2 minutes; 20 cycles each at 95° C. for 30 seconds, 52° C. for 45 seconds, and 72° C. for 5 minutes; and 1 cycle at 72° C. for 7 minutes.
PCR products were separated by 1.5% agarose gel electrophoresis using TBE buffer. A fragment of approximately 600 bp was excised from the gel and extracted using a MINELUTE® Gel Extraction Kit. The fragment was inserted into pCR®2.1 (Invitrogen, Carlsbad, Calif., USA) using a TOPO® TA Cloning Kit (Invitrogen, Carlsbad, Calif., USA) and ONE SHOT® TOP10 competent cells (Invitrogen, Carlsbad, Calif., USA) were transformed with 2 μl of the TOPO® TA cloning reaction. Plasmid DNA from eight of the resulting transformants was digested with Eco RI and Bgl II in separate reactions and the inserts for three transformants with the correct restriction digestion patterns were confirmed by DNA sequencing. One clone with the desired sequence was selected and designated pWTY1470-09-05.
A 608 bp Bgl II fragment harboring the tri5 gene 5′ repeat was liberated from pWTY1470-09-05 bp digestion with Bgl II, purified by 1.0% agarose gel electrophoresis using TBE buffer, excised from the gel, and extracted using a MINELUTE® Gel Extraction Kit.
Plasmid pJRoy40 was linearized by digestion with Bgl II, after which it was dephosphorylated using shrimp alkaline phosphatase (Roche Diagnostics Corporation, Indianapolis, Ind., USA) according to the manufacturer's instructions, and purified using a QIAQUICK® PCR Purification Kit (QIAGEN Inc., Valencia, Calif., USA). Linearized pJRoy40 and the gel-purified Bgl II fragment were ligated together using T4 DNA ligase (New England Biolabs Inc., Ipswich, Mass., USA) according to the manufacturer's instructions. Transformation of E. coli SURE® chemically competent cells (Stratagene, La Jolla, Calif.,
USA) was performed according to the manufacturer's directions. One transformant was confirmed by DNA sequencing to contain the desired vector, i.e., harboring the tri5 5′ and 3′ flanking sequences and a repeat of a portion of the 5′ flanking sequence. The resulting plasmid was designated pWTY1470-19-07 (
Plasmid pWTY1470-19-07 was subjected to in vitro mutagenesis using a QUIKCHANGE® Site-Directed Mutagenesis Kit according to the manufacturer's instructions and forward and reverse primers shown below.
The mutagenesis removed the Bgl II site at 1779 bp and rendered the Bgl II site at 2386 bp unique and usable in subsequent manipulations to insert fragments harboring thymidine kinase (tk) and hygromycin phosphotransferase (hpt) gene cassettes. The mutagenesis reaction was used to transform the kit-supplied E. coli XL10-GOLD® Ultra-competent cells (Stratagene, La Jolla, Calif., USA) according to the manufacturer's suggested protocol.
One transformant harboring the mutations indicated above, as verified by sequence analysis, was designated pWTY1515-2-01 (
Plasmid pDV8 (U.S. Pat. No. 6,806,062) harbors the Herpes simplex virus type 1 thymidine kinase (HSV1-TK; tk) gene (SEQ ID NO: 31 for the DNA sequence and SEQ ID NO: 32 for the deduced amino acid sequence) as a 1.2 kb Bgl II/Bam HI fragment inserted between a 1.0 kb Xho I/Bgl II fragment of the Aspergillus nidulans glyceraldehyde-3-phosphate dehydrogenase (gpdA) promoter and a 1.8 kb Bam HI/Hind III fragment harboring the tri-functional Aspergillus nidulans indoleglycerolphosphate synthase, phosphoribosylanthranilate isomerase, and glutamine amidotransferase (trpC) transcriptional terminator. Plasmid pDV8 was digested with Bam HI, extracted with phenol-chloroform, ethanol precipitated, and then filled in using Klenow polymerase (Stratagene, La Jolla, Calif., USA). The digested plasmid was re-ligated using a QUICK LIGATION™ Kit following the manufacturer's protocol, treated with a MINELUTE® Gel Extraction Kit, and the resulting ligation products cloned into pCR®4Blunt-TOPO® (Invitrogen, Carlsbad, Calif., USA) using a TOPO® Blunt Cloning Kit according to the manufacturer's instructions. The cloning reaction was transformed into ONE SHOT® chemically competent TOP10 cells (Invitrogen, Carlsbad, Calif., USA) according to the manufacturer's directions. Plasmid DNA was extracted from eight of the resulting transformants using a BIOROBOT® 9600 (QIAGEN Inc, Valencia, Calif., USA) and screened by restriction digestion using Xho I/Bam HI and Xho I/Hind III. DNA sequencing of plasmid DNA from two transformants with the correct restriction digestion pattern confirmed that both harbored the desired sequence. One was named pJaL504-[Bam HI] (
Plasmid pJaL504-[Bam HI] was digested with Bgl II, extracted with phenol-chloroform, ethanol precipitated, and then filled in using Klenow polymerase. The digested plasmid was re-ligated using a QUICK LIGATION™ Kit following the manufacturer's protocol, treated with a MINELUTE® Reaction Cleanup Kit, and the resulting ligation cloned into pCR®4Blunt-TOPO® using a TOPO® Blunt Cloning Kit according to the manufacturer's instructions. The cloning reaction was transformed into ONE SHOT® chemically competent E. coli TOP10 cells according to the manufacturer's directions. Plasmid DNA was extracted from eight of the resulting transformants using a BIOROBOT® 9600 and screened by restriction digestion using Xho I/Bgl II and Xho I/Hind III. DNA sequencing of plasmid DNA from two transformants with the correct restriction digestion pattern confirmed that both harbored the desired sequence. One was named pJaL504-[Bgl II] (
GTGACCGGTGACTC-3′
The underlined sequence corresponds to gpdA promoter sequence. The remaining sequence is a handle harboring the following restriction sites: Eco RI, Xba I, Bgl II, Xho I, and Hind III.
For truncating the Aspergillus nidulans trpC terminator (again to reduce vector size), primer #172499, shown below, was designed harboring an Eco RI handle.
The underlined sequence corresponds to the trpC terminator sequence. Amplification using primers 172499 and 172450 truncates the promoter by 364 bp and the trpC terminator sequence by 239 bp.
PCR was performed with the above two primers using pJaL504-[Bg/ II] as template to generate a 2,522 bp fragment composed of a truncated version of the A. nidulans gpdA promoter, the coding sequence of the HSV1-TK gene, and a truncated version of the A. nidulans trpC terminator.
The amplification reaction consisted of 5 pl of 10×Buffer (Promega Corporation, Madison, Wisc., USA), 0.4 μl of 25 mM dNTPs, 1.25 μl of primer 172450 (100 ng/μl), 1.25 μl of primer 172499 (100 ng/μl), 0.5 μl of pJaL504-[Bgl II] (100 ng/μl), 2 μl of Pfu DNA polymerase (Promega Corporation, Madison, Wisc., USA) (2.5 U/μl), and 39.6 μl of sterile distilled water. The amplification reaction was incubated in a ROBOCYCLER® programmed for 1 cycle at 95° C. for 45 seconds; and 28 cycles each at 95° C. for 45 seconds, 57° C. for 45 seconds, and 72° C. for 5 minutes. A final extension was performed for 10 minutes at 72° C.
The amplification reaction was subjected to 1% agarose gel electrophoresis using low melting temperature agarose gel in 50 mM Tris-50 mM boric acid-1 mM disodium EDTA (TBE) buffer. A 2,522 bp fragment was excised from the gel and extracted using a QIAQUICK® Gel Extraction Kit. The gel-purified DNA was then inserted into pCR®4Blunt-TOPO® using a TOPO® Blunt Cloning Kit according to the manufacturer's instructions. The cloning reaction was transformed into ONE SHOT® chemically competent TOP10 cells according to the manufacturer's directions. Plasmid DNA was extracted from eight of the resulting transformants using a BIOROBOT® 9600 and screened by restriction digestion using Eco RI and Bgl II. DNA sequencing of plasmid DNA from two transformants with the correct restriction digestion pattern confirmed that both harbored the desired sequence. One was designated pJaL574 (
Plasmid pJaL574 was transformed into competent E. coli SCS110 cells (Stratagene, La Jolla, Calif., USA) following the manufacturer's recommended protocol. Plasmid DNA was extracted from twenty-four of the resulting transformants using a BIOROBOT® 9600, and then subjected to analytical digestion using Eco RI and Bgl II. Subsequent DNA sequence analysis resulted in the identification of a clone with the correct sequence, which was designated pWTY1449-02-01 (
An E. coli hygromycin phosphotransferase (hpt) gene cassette was PCR amplified from plasmid pEmY23 using an ADVANTAGE® GC Genomic PCR Kit (Clontech, Palo Alto, Calif., USA) and gene-specific forward and reverse primers shown below. The underlined portion in the reverse primer is a Bgl II site for cloning.
The amplification reaction contained 362 ng of pEmY23 as DNA template, 200 μm dNTP's, 1.1 mM magnesium acetate, 0.4 μM primers, 1×GC Reaction Buffer (Clontech, Palo Alto, Calif., USA), 0.5 M GC Melt (Clontech, Palo Alto, Calif., USA), and 1×GC Genomic Polymerase Mix (Clontech, Palo Alto, Calif., USA) in a final volume of 50 μl.
The amplification reaction was incubated in an EPPENDORF® MASTERCYCLER® (Eppendorf, Munich, Germany) programmed for 1 cycle at 95° C. for 2 minutes; 25 cycles each at 94° C. for 30 seconds and 66° C. for 3 minutes; and 1 cycle at 66° C. for 3 minutes; and hold at 4° C.
PCR products were separated by 1% agarose gel electrophoresis using TAE buffer. A fragment of approximately 1.9 kb was excised from the gel and extracted using a MINIELUTE® Gel Extraction Kit. The fragment was cloned into pCR®2.1 using a TOPO® TA Cloning Kit according to the manufacturer's instructions. ONE SHOT® TOP10 competent cells (Invitrogen, Carlsbad, Calif., USA) were transformed with 2 μl of the TOPO® TA reaction. Sequence analysis of plasmid DNA from 8 transformants confirmed that there were no deviations from the expected sequence and the plasmid was designated pJfyS1540-75-5 (
The hpt insert was liberated from pJfyS1540-75-5 by digestion with Bam HI and Bgl II and purified by 1% agarose gel electrophoresis in TAE buffer. A fragment of 1.9 kb was excised and extracted using a MINIELUTE® Gel Extraction Kit. A Rapid DNA Ligation Kit was used to ligate the fragment to Bgl II-linearized empty tri5 deletion vector pWTY1515-2-01 (Example 5) which had been dephosphorylated using calf intestine phosphatase. E. coli SURE® chemically competent cells were transformed with the ligation reaction and plasmid DNA from 24 of the resulting transformants was analyzed by restriction digestion with Eco RI to confirm the orientation of the insert. One of the transformants harboring the insert in the desired orientation was selected and designated pJfyS1579-1-13 (
A Herpes simplex virus thymidine kinase (tk) gene (SEQ ID NO: 31 for the DNA sequence and SEQ ID NO: 32 for the deduced amino acid sequence) was PCR amplified using pWTY1449-02-01 as template and gene specific forward and reverse primers shown below. The bold sequence represents the introduced Bgl II site.
The amplification reaction contained 1×HERCULASE® reaction buffer (Stratagene, La Jolla, Calif., USA), 200 μM dNTPs, 55 ng of pWTY1449-02-01, 0.2 μM primers, 2% DMSO, and 2.5 units of HERCULASE® DNA polymerase (Stratagene, La Jolla, Calif., USA) in a final volume of 50 μl. The amplification reaction was incubated in an EPPENDORF® MASTERCYCLER® programmed for 1 cycle at 95° C. for 1 minute; 25 cycles each at 94° C. for 30 seconds, 60° C. for 30 seconds, and 68° C. for 2 minutes and 45 seconds; and 1 cycle at 68° C. for 2 minutes and 45 seconds; and a hold at 4° C.
PCR products were separated by 1% agarose gel electrophoresis using TAE buffer. A fragment of approximately 2.8 kb was excised from the gel and purified using a MINIELUTE® Gel Extraction Kit. The fragment was cloned into pCR®2.1 using a TOPO® TA Cloning Kit. ONE SHOT® TOP10 competent cells (Invitrogen, Carlsbad, Calif., USA) were transformed with 2 μl of the TOPO® TA reaction. Sequence analysis of plasmid DNA from one of the transformants identified a mutation in the tk coding sequence (C1621G) resulting in an amino acid change of glycine to alanine. This mutation was corrected using a QUIKCHANGE® II XL Site-Directed Mutagenesis Kit (Stratagene, La Jolla, Calif., USA) according to the manufacturer's instructions and forward and reverse primers shown below. The lower case letter indicates the desired change. Sequence analysis of 16 clones resulted in the selection of one which was designated pJfyS1579-8-6 (
Plasmid pJfyS1579-8-6 was digested with Barn HI and Bgl II to liberate the 2.8 kb tk fragment and the fragment was purified as described above. This fragment was ligated to pJfyS1579-1-13, which had been linearized with Bgl II and treated with calf intestine phosphatase, using a QUICK LIGATION™ Kit and used to transform E. coli SURE® chemically competent cells according to the manufacturer's protocol. The resulting plasmid was designated pJfyS1579-21-16 (
A universal deletion vector harboring both the thymidine kinase (tk) and hygromycin phosphotransferase (hpt) markers was constructed to facilitate assembly of subsequent deletion plasmids. Flanking sequences for 5′ and 3′ regions of the gene targeted for deletion can be easily ligated to the vector following digestion of the latter with Pme I or Asc I (for 5′ flanking sequences) and Sbf I or Swa I (for 3′ flanking sequences).
In order to PCR-amplify the direct repeats derived from the 5′ flanking region of the Fusarium venenatum pyrG gene, 50 picomoles of the primers shown below were used in two PCR reactions containing 50 ng of pDM156.2, 1×Pfx Amplification Buffer (Invitrogen, Carlsbad, Calif., USA), 6 μl of a 10 mM blend of dNTPs, 2.5 units of PLATINUM® Pfx DNA polymerase (Invitrogen, Carlsbad, Calif., USA), and 1 μl of 50 mM MgSO4 in a total volume of 50 μl.
Primers:
The amplification reactions were incubated in an EPPENDORF® MASTERCYCLER® programmed as follows. For repeat #1: 1 cycle at 98° C. for 2 minutes; and 5 cycles each at 94° C. for 30 seconds, 55° C. for 30 seconds, and 68° C. for 1 minute. This was followed by 35 cycles each at 94° C. for 30 seconds, 59° C. for 30 seconds, and 68° C. for 1 minute. For repeat #2 the cycling parameters were: 1 cycle at 98° C. for 2 minutes; and 5 cycles each at 94° C. for 30 seconds, 55° C. for 30 seconds, and 68° C. for 1 minute. This was followed by 35 cycles each at 94° C. for 30 seconds, 56° C. for 30 seconds, and 68° C. for 1 minute. After the 35 cycles both reactions (i.e., repeats # 1 and #2) were incubated at 68° C. for 10 minutes and then cooled at 10° C. until being further processed.
PCR products from both reactions were separated by 0.8% GTG-agarose (Cambrex Bioproducts, East Rutherford, N.J., USA) gel electrophoresis using TAE buffer. For repeat #1 and repeat #2, fragments of approximately 0.26 kb were excised from the gels and purified using Ultrafree®-DA spin cups (Millipore, Billerica, Mass., USA) according to the manufacturer's instructions. Ten microliters of each purified repeat were then used in a single overlapping PCR reaction containing 1×Pfx Amplification Buffer, 6 μl of a 10 mM blend of dATP, dTTP, dGTP, and dCTP, 2.5 units of PLATINUM® Pfx DNA polymerase, and 1 μl of 50 mM MgSO4 in a total volume of 50 μl. The amplification reaction was incubated in an EPPENDORF® MASTERCYCLER® programmed for 1 cycle at 98° C. for 2 minutes; and 5 cycles each at 94° C. for 30 seconds, 50° C. for 30 seconds, and 68° C. for 1 minute. The reaction was then mixed with a pre-warmed solution containing 50 picomoles of the sense primer for repeat #1 and 50 picomoles of the anti-sense primer for repeat #2, 1×Pfx Amplification Buffer, 6 μl of a 10 mM dNTPs, 2.5 units of PLATINUM® Pfx DNA polymerase, and 1 μl of 50 mM MgSO4 in a final volume of 50 μl.
The new 100 μl amplification reaction was incubated in an EPPENDORF® MASTERCYCLER® programmed for 35 cycles each at 94° C. for 30 seconds, 58° C. for 30 seconds, and 68° C. for 1 minute. After 35 cycles, the reaction was incubated at 68° C. for 10 minutes and then cooled at 10° C. until being further processed. A 0.5 kb PCR product (harboring the repeat assembly) was isolated by 0.8% GTG-agarose gel electrophoresis as described above.
Plasmid pCR4 (Invitrogen, Carlsbad, Calif., USA) was used as the source of the vector backbone for the construction of the universal deletion vector. To remove the non-essential portions of the pCR4 DNA, 2.5 μg of plasmid pTter61C (WO 2005/074647) were digested sequentially with Bsp LU11 I and Bst XI. The digested vector was then treated with Antarctic phosphatase (New England Biolabs Inc., Ipswich, Mass., USA). The 3.1 kb digested backbone was isolated by 0.8% GTG-agarose gel electrophoresis as described above. The purified repeat assembly was then ligated to the purified vector backbone with a Rapid Ligation Kit (Roche Diagnostics Corporation, Indianapolis, Ind., USA). The ligation reaction consisted of: 75 ng of purified vector backbone and 3 μl of the purified repeat assembly. One microliter of this ligation reaction was used to transform chemically competent SOLOPACK® Supercompetent cells (Stratagene, Carlsbad, Calif., USA) using the manufacturer's suggested protocols. Twenty-four transformants were analyzed by Nco I/Pme I restriction digestion. Twenty-three out of twenty four transformants had the expected restriction digestion pattern. Clone pFvRs #10 was selected at random for sequencing to confirm that there were no PCR-induced errors. Sequencing analysis showed that the repeat assembly in clone pFvRs #10 had the expected sequence, and was designated pAlLo1492-24 (
The cassette harboring the hygromycin phosphotransferase (hpt) gene was PCR amplified from pEmY23 using the gene-specific forward and reverse primers shown below. The underlined sequence represents a Xma I site and the bold letters represent a Bgl II site. The four “a”s at each 5′ end allow for subsequent digestion of the terminal ends of the PCR product.
The amplification reaction contained 60 ng of pEmY23, 200 μm dNTPs, 1 mM magnesium acetate, 0.4 μM primers, 1×Pfx Amplification Buffer, 0.5 M GC Melt, and 2.5 units of PLATINUM® Pfx polymerase in a final volume of 50 μl. The reaction was incubated in an EPPENDORF® MASTERCYCLER® programmed for 1 cycle at 95° C. for 2 minutes; 10 cycles each at 94° C. for 30 seconds, 60° C. for 30 seconds, and 68° C. for 1 minute 50 seconds; and 1 cycle at 68° C. for 7 minutes followed by holding at 4° C.
PCR products were separated by 1% agarose gel electrophoresis using TAE buffer. A fragment of approximately 1.8 kb was excised from the gel and extracted using a MINIELUTE® Gel Extraction Kit. The gel-purified PCR product was subsequently digested with Xma I and run on a 1% agarose gel and gel-purified again as above. A QUICK LIGATION™ Kit was used to ligate the hpt PCR product to Xma I-linearized pAlLo1492-24, which had been treated with calf intestine phosphatase. The resulting plasmid was designated pJfyS1579-35-2 (
The source of the Herpes simplex virus tk cassette was plasmid pJfyS1579-8-6 (Example 8), from which the insert was liberated by digestion with Bam HI and Bgl II. The digestion products were separated by 1% agarose gel electrophoresis using TAE buffer, and a fragment corresponding to the 2.8 kb tk gene insert was excised and extracted using a MINELUTE® Gel Extraction Kit. A QUICK LIGATION™ Kit was used to ligate the tk gene cassette to Bgl II-linearized pJfyS1579-35-2, which had been treated with calf intestine phosphatase. The resulting plasmid was designated pJfyS1579-41-11 (
Trichoderma reesei strain 981-O-8 was grown in 50 ml of YEG medium in a baffled shake flask at 28° C. for 2 days with agitation at 200 rpm. Mycelia were harvested by filtration using MIRACLOTH® (Calbiochem, La Jolla, Calif., USA), washed twice in deionized water, and frozen under liquid nitrogen. Frozen mycelia were ground, by mortar and pestle, to a fine powder, and total DNA was isolated using a DNEASY® Plant Maxi Kit (QIAGEN Inc., Valencia, Calif., USA).
To construct a Trichoderma reesei subtilisin-like serine protease gene deletion cassette, a 1.4 kb fragment of the downstream non-coding region of the Trichoderma reesei subtilisin-like serine protease gene (SEQ ID NO: 1 for the DNA sequence and SEQ ID NO: 2 for the deduced amino acid sequence) was PCR amplified using oligonucleotides 067375 and 067376 shown below.
Underlined letters represent a Sbf I site added to the sense and antisense primers to facilitate cloning of the amplified fragment and the bold region represents a Not I site introduced for later restriction digestion to remove a β-lactamase gene for fungal transformation.
The amplification reaction was composed of 300 ng of the Trichoderma reesei strain 981-O-8 genomic DNA (Example 10), 300 μM dNTPs, 50 pmol of primer 067375, 50 pmol of primer 067376, 1×reaction buffer, 1 mM MgSO4 and 2.5 units of PLATINUM® Pfx DNA polymerase (Invitrogen Corp., Carlsbad, Calif., USA). The reaction was incubated in an EPPENDORF® MASTERCYCLER® 5333 (Eppendorf Scientific, Inc., Westbury, N.Y., USA) programmed for 1 cycle at 98° C. for 5 minutes; 30 cycles each at 98° C. for 30 seconds, 58° C. for 30 seconds, and 72° C. for 1.6 minutes; and 1 cycle at 72° C. for 15 minutes. A 1442 bp PCR fragment was isolated by 1% agarose gel electrophoresis using TAE buffer, excised from the gel, and extracted using a MinElute Gel Extraction Kit (QIAGEN Inc., Valencia, Calif., USA). The 1442 bp PCR product was cloned into pCR®2.1 TOPO® (Invitrogen Corp., Carlsbad, Calif., USA) and transformed into Chemically Competent E. coli cells according to the manufacturer's instructions. Transformants were selected on 2×YT agar plates supplemented with 100 μg of ampicillin per ml and incubated at 37° C. for 16 hours. The DNA sequence of the cloned fragment was verified by DNA sequencing with M13 forward and reverse primers. The resulting plasmid was designated pClone10.
Similarly, a 1.5 kb fragment of the upstream non-coding region of the Trichoderma reesei subtilisin-like serine protease gene (SEQ ID NO: 1 for the DNA sequence and SEQ ID NO: 2 for the deduced amino acid sequence) was PCR amplified using primers 067377 and 067374 shown below.
Underlined letters represent an Asc I site added to the sense and antisense primers to facilitate the cloning of the amplified fragment and the bold region represents a Not I site
The PCR amplification was performed under the same conditions described above except primers 067377 and 067374 were used. A 1530 bp PCR fragment was isolated by 1% agarose gel electrophoresis using TAE buffer, excised from the gel, and extracted using a MinElute Gel Extraction Kit. The 1530 bp amplified fragment was cloned into pCR®2.1 TOPO® vector and transformed into Chemically CompetentE. coli cells according to the manufacturer's instructions. Transformants were selected on 2×YT agar plates supplemented with 100 μg of ampicillin per ml and incubated at 37° C. for 16 hours. The DNA sequence of the cloned fragment was verified by DNA sequencing with M13 forward and reverse primers. The resulting plasmid was designated pClone1.
Plasmid pClone1 was digested with Asc I and the digestion purified by 1% agarose gel electrophoresis in TAE buffer. A 1415 bp fragment containing the upstream non-coding region of the Trichoderma reesei subtilisin-like serine protease gene fragment was excised from the gel and extracted using a MinElute Gel Extraction Kit (QIAGEN Inc., Valencia, Calif., USA). This insert was ligated to Asc I digested and calf intestinal phosphatase (CIP) dephosphorylated pJfyS1579-41-11 (Example 9) using a QUICK LIGATION™ Kit (New England Biolabs, Beverly, Mass., USA) according to the manufacturer's suggested protocol. Restriction analysis was used to identify transformants containing the insert in the desired orientation and sequence analysis was performed to confirm the absence of PCR errors. The resulting plasmid was designated pClone14.
The final Trichoderma reesei subtilisin-like serine protease gene deletion cassette, pDAtw18 (
Protoplast preparation and transformation were performed using a modified protocol by Penttila et al., 1987, Gene 61: 155-164. Briefly, Trichoderma reesei strain 981-O-8 was cultivated in 25 ml of YP medium supplemented with 2% (w/v) glucose and 10 mM uridine at 27° C. for 17 hours with gentle agitation at 90 rpm. Mycelia were collected by filtration using a Millipore Vacuum Driven Disposable Filtration System (Millipore, Bedford, Mass., USA) and washed twice with deionized water and twice with 1.2 M sorbitol. Protoplasts were generated by suspending the washed mycelia in 20 ml of 1.2 M sorbitol containing 15 mg of GLUCANEX® 200 G (Novozymes A/S, Bagsvaerd, Denmark) per ml and 0.36 units of chitinase (Sigma Chemical Co., St. Louis, Mo., USA) per ml for 15-25 minutes at 34° C. with gentle shaking at 90 rpm. Protoplasts were collected by centrifuging for 7 minutes at 400×g and washed twice with cold 1.2 M sorbitol. The protoplasts were counted using a haemacytometer and re-suspended to a final concentration of 1×108 protoplasts/ml in STC. Excess protoplasts were stored in a Cryo 1° C. Freezing Container (Nalgene, Rochester, N.Y., USA) at −80° C.
Approximately 10 μg of each of the deletion cassettes described in the following examples were digested with either Not I (Examples 13 and 20) or Hind III/Bgl II (Example 17). Each digestion reaction was purified by 1% agarose gel electrophoresis in TAE buffer, a DNA band was excised from the gel, and extracted using a QIAQUICK® Gel Extraction Kit. The resulting purified DNA was added to 100 μl of the protoplast solution and mixed gently. PEG buffer (250 μl) was added, mixed, and incubated at 34° C. for 30 minutes. STC (3 ml) was then added, mixed, and plated onto PDA medium supplemented with 1 M sucrose. After incubation at 28° C. for 16 hours, 15 ml of an overlay PDA medium supplemented with 100 μg of hygromycin B per ml was added to each plate. The plates were incubated at 28° C. for 4-6 days.
Trichoderma reesei strain 981-O-8 protoplasts were transformed with Not I-linearized pDAtw18 using the method described in Example 12 to delete the subtilisin-like serine protease gene. One hundred and sixty-six transformants were selected on PDA plates containing 25 μg of hygromycin B per ml. The transformants were sub-cultured to PDA plates to generate spores. Each transformant was cultured in a 125 ml baffled shake flask containing 25 ml of cellulase-inducing medium at pH 6.0 and incubated at 28° C. for 7 days with agitation at 200 rpm. Trichoderma reesei strain 981-O-8 was run as a control. Culture broth samples were removed 7 days post-inoculation, centrifuged at 15,700×g for 5 minutes in a micro-centrifuge, and the supernatants transferred to new tubes.
A protease assay using a synthetic substrate, N-Succinyl-L-Ala-L-Ala-L-Pro-L-Phe-p-nitroanilide (AAPF) (Bachem AG, Bubendorf, Switzerland), was performed on the supernatants above to determine whether any of the transformants were deleted for the subtilisin-like serine protease gene. The substrate was initially dissolved in dimethyl sulfoxide at a concentration of 100 mg/ml. The dissolved substrate was then diluted 50-fold into 100 mM NaCl-100 mM MOPS pH 7.0. The reaction was initiated by adding 10 μl of each transformant supernatant to 100 μl of the diluted substrate in a flat-bottomed 96-well plate (Corning Inc., Acton, Mass., USA). The reaction plate was incubated at 50° C. for 3 hours and then the absorbance at 405 nm was measured using a SPECTRAMAX® Microplate Reader (Molecular Devices, Sunnyvale, Calif., USA). Protease activities of the Trichoderma reesei DAtw18 transformants were compared to that of parent strain Trichoderma reesei strain 981-O-8.
Fifteen transformants displaying lower extracellular protease activities compared to Trichoderma reesei strain 981-O-8 were then analyzed by Southern analysis. Genomic DNA from each of the 15 transformants was extracted as described in Example 11 and 2 μg of each were digested with 20 units of Ncol-HF™ (New England Biolabs, Inc., Ipswich, Mass., USA) for 16 hours at 37° C. Digested DNA was fractionated by 0.7% agarose gel electrophoresis using TAE buffer for 4 hours and blotted onto a NYTRAN™ SuperCharge membrane (Schleicher & Schuell BioScience, Keene, N.H., USA) using a TURBOBLOTTER™ (Schleicher & Schuell BioScience, Keene, N.H., USA) for 16 hours following the manufacturer's recommendations. The membrane was hybridized with a 502 by digoxigenin-labeled subtilisin-like serine protease gene probe, which was synthesized by incorporation of digoxigenin-11-dUTP by PCR using primers 067911 (sense) and 067912 (antisense) shown below.
The amplification reaction (50 μl) was composed of 1×ThermoPol Reaction Buffer, 5 μl of PCR DIG Labeling Mix (Roche Molecular Biochemicals, Indianapolis, Ind., USA), 10 ng of pDAtw18, 0.3 μM primer 067911, 0.3 μM primer 067912, and 2.5 units of Taq DNA polymerase (New England Biolabs, Inc., Ipswich, Mass., USA). The reactions were incubated in an EPPENDORF® MASTERCYCLER® 5333 programmed for 30 cycles each at 95° C. for 30 seconds, 56° C. for 30 seconds, and 72° C. for 40 seconds (15 minute final extension). Five microliters of the PCR product was size-selected by 1.5% agarose gel electrophoresis using TAE buffer, stained with ethidium bromide, and visualized under a UV transilluminator. Incorporation of digoxigenin was indicated by increase in molecular mass.
Hybridization was performed in DIG Easy Hyb buffer (Roche Molecular Biochemicals, Indianapolis, Ind., USA) at 42° C. for 17 hours. The membrane was then washed under high stringency conditions in 2×SSC plus 0.1% SDS for 5 minutes at room temperature followed by two washes in 0.5×SSC plus 0.1% SDS for 15 minutes each at 65° C. The probe-target hybrids were detected by chemiluminescent assay (Roche Molecular Biochemicals, Indianapolis, Ind., USA) following the manufacturer's instructions. Southern analysis indicated that all 15 transformants contained a single integration of the deletion cassette at the subtilisin-like serine protease gene locus without any further integration of the deletion fragment at other loci. One strain designated Trichoderma reesei DAtw18-97 was chosen for subsequent transformations.
Plasmid pSaMe-AaXYL was constructed to comprise the Trichoderma reesei cellobiohydrolase I gene promoter and terminator and the Aspergillus aculeatus GH10 xylanase coding sequence.
Cloning of the Aspergillus aculeatus xylanase followed the overall expression cloning protocol as outlined in H. Dalbøge et al., 1994, Mol. Gen. Genet. 243: 253-260.
RNA was isolated from Aspergillus aculeatus CBS 101.43 mycelium. Poly(A)+ RNA was isolated from total RNA by chromatography on oligo(dT)-cellulose. Double-stranded cDNA was synthesized as described by Maniatis et al. (Molecular cloning: a laboratory manual. Cold Spring Harbor Laboratory Press, 1982). After synthesis the cDNA was treated with mung bean nuclease, blunt-ended with T4 DNA polymerase, and ligated to non-palindromic Bst XI adaptors (Invitrogen, Carlsbad, Calif., USA). The cDNA was size fractionated by 1% agarose gel electrophoresis using TAE buffer where fragments ranging from 600 bp to 4000 bp were used in the library construction. The DNA was ligated into Bst XI-digested pYES 2.0 between the GAL1 promoter and the iso-1-cytochrome c terminator and transformed into Escherichia coli MC1061 cells (Stratagene, La Jolla, Calif., USA. The library was plated onto LB plates and incubated overnight at 37° C. The colonies were scraped from the plates and resuspended in LB medium supplemented with 100 μg of ampicillin per ml. Plasmid DNA was isolated using a Plasmid Midi Kit (QIAGEN Inc., Valenicia, Calif., USA). The purified plasmid DNA was pooled.
The purified plasmid DNA mixture was transformed into Saccharomyces cerevisiae W3124 cells (MATa; ura 3-52; leu 2-3, 112; his 3-D200; pep 4-1137; prcl::HIS3; prbl:: LEU2; cir+; van den Hazel et al., 1992, Eur. J. Biochem. 207: 277-283). Cultivation, transformation and media were as described by Guthrie et al., 1991, Meth. Enzymol. Vol 194, Academic Press. The transformed cells were plated onto synthetic complete agar containing 2% glucose for 3 days at 30° C. After 3 days the colonies were replica plated to SC medium with 2% galactose and incubated for 4 days at 30° C. Xylanase expressing colonies were identified by 1% agarose overlay with 0.1% AZCL-Birch-Xylan at pH 4.5 (Dalbøge, 2006, FEMS Microbiology Reviews 21: 29-42). Colonies expressing xylanase activity were surrounded by a blue zone. Plasmid DNA, rescued from the positive colonies, contained a DNA insert of approximately 1.3 kb. Sequencing of the isolated gene fragment revealed a 1218 bp open reading frame encoding a polypeptide with a theoretical molecular weight of 43.0 kDa. The cDNA fragment was subcloned into the Aspergillus expression vector pHD464 (Dalbøge and Heldt-Hansen, 1994, Mol. Gen. Genet. 243, 253-260) digested with Bam Hi and Xho I by cutting the clone with Bam HI and Xho I and isolating the 1.2 kb cDNA insert (Christgau et al., 1996. Biochem. J. 319: 705-712) to generate plasmid pA2×2.
The Aspergillus aculeatus GH10 xylanase coding sequence was PCR amplified using plasmid pA2×2 as template and primers 153505 and 153506 shown below using standard methods to yield an approximately 1.2 kb fragment. The 1.2 kb fragment was digested with Bam HI and Xho I (introduced in the PCR primers) and cloned into vector pCaHj527 (WO 2004/099228). The resulting plasmid was designated pMT2155 in which the cDNA was under transcriptional control of the neutral amylase II (NA2) promoter from A. niger and the AMG terminator from A. niger.
Two synthetic oligonucleotide primers shown below were designed to PCR amplify the Aspergillus aculeatus GH10 gene from plasmid pMT2155 and introduce flanking regions for insertion into expression vector pMJ09 (WO 2005/056772). Bold letters represent coding sequence and the remaining sequence is homologous to the insertion sites of pMJ09.
The amplification reaction was composed of 50 picomoles of each of the primers above, 50 ng of pMT2155, 1 μl of 10 mM blend of dATP, dTTP, dGTP, and dCTP, 5 μl of 10×ACCUTAQ™ DNA Polymerase Buffer, and 5 units of ACCUTAQ™ DNA Polymerase, in a final volume of 50 μl. An EPPENDORF® MASTERCYCLER® 5333 was used to amplify the DNA fragment programmed for 1 cycle at 95° C. for 3 minutes; and 30 cycles each at 94° C. for 45 seconds, 55° C. for 60 seconds, and 72° C. for 1 minute 30 seconds. After the 30 cycles, the reaction was incubated at 72° C. for 10 minutes and then cooled to 4° C. until further processing.
The reaction products were isolated by 1.0% agarose gel electrophoresis using TAE buffer where a 1.2 kb product band was excised from the gel and purified using a QIAQUICK® Gel Extraction Kit according to the manufacturer's instructions.
The fragment was then cloned into pMJ09 using an IN-FUSION™ Cloning Kit. The vector was digested with Nco I and Pac I and purified by agarose gel electrophoresis as described above. The 1.2 kb gene fragment and the digested vector were ligated together in a reaction resulting in the expression plasmid pSaMe-AaXYL in which transcription of the Family GH10 gene was under the control of the T. reesei cbh1 promoter. The ligation reaction (50 μl) was composed of 1×IN-FUSION™ Buffer, 1×BSA, 1 μl of IN-FUSION™ enzyme (diluted 1:10), 100 ng of pAlLo2 digested with Nco I and Pac I, and 100 ng of the Aspergillus aculeatus GH10 xylanase purified PCR product. The reaction was incubated at room temperature for 30 minutes. One μl of the reaction was used to transform E. coli XL10 SOLOPACK® Gold cells according to the manufacturer. An E. coli transformant containing pSaMe-AaXYL (
Protoplasts were generated from subtilisin-like serine protease deficient strain Trichoderma reesei DAtw18-97 according to the procedure described in Example 12 and transformed with Trichoderma reesei expression construct pSaMe-AaXYL (Example 14) containing the Aspergillus aculeatus GH10 xylanase coding sequence to determine the stability of A. aculeatus xylanase GH10 expressed by T. reesei DAtw18-97. Transformation was performed by adding approximately 3 μg of Pme I digested and gel-purified pSaMe-AaXYL to 100 μl of protoplast solution and mixing gently. PEG buffer (250 μl) was added, mixed, and incubated at 37° C. for 30 minutes. STC (3 ml) was then added, mixed, and plated onto COVE plates. The plates were incubated at 28° C. for 7-10 days. After a single round of spore purification on COVE2 plates, 20 transformants were grown in small-scale shake flasks containing 25 ml of cellulase-inducing medium for 5 days at 28° C., after which supernatant were collected by centrifugation at 15,700 ×g for 10 minutes in a micro-centrifuge.
Expression of the Aspergillus aculeatus GH10 xylanase was analyzed using 8-16% CRITERION™ Tris-HCl gels (Bio-Rad Laboratories, Hercules, Calif., USA) with a CRITERION™ Cell (Bio-Rad Laboratories, Hercules, Calif., USA). Five μl of day 5 samples were suspended in 2×concentration of Laemmli Sample Buffer (Bio-Rad Laboratories, Hercules, Calif., USA) and heated at 95° C. for 5 minutes in the presence of 5% β-mercaptoethanol. All samples were loaded onto the CRITERION™ Tris-HCl gels and subjected to electrophoresis in 1×Tris/Glycine/SDS running buffer (Bio-Rad Laboratories, Hercules, Calif., USA). The resulting gels were stained with BIO-SAFE™ Coomassie Stain (Bio-Rad Laboratories, Hercules, Calif., USA). SDS-PAGE profiles of the cultures showed the presence of predominately the full-length Aspergillus aculeatus GH10 xylanase protein but also a smaller fragment present in lower quantities. The results suggested that deletion of the subtilisin-like serine protease gene for the production of Aspergillus aculeatus GH10 xylanase did not completely prevent proteolysis of the protein.
The deletion vector pAgJg111 was constructed to disrupt expression of a Trichoderma reesei 42 kDa aspartic protease (SEQ ID NO: 3 for the DNA sequence and SEQ ID NO: 4 for the deduced amino acid sequence) in Trichoderma reesei strain 981-O-8. Plasmid pAgJg110 was generated first by amplifying the aspartic protease coding region plus and minus 600 bp upstream and downstream of the coding region using primers 066694 (sense) and 066695 (antisense) shown below.
The aspartic protease region was amplified by PCR in a reaction composed of 316 ng of Trichoderma reesei strain 981-O-8 genomic DNA (Example 10), 1 μl of Herculase II Fusion DNA Polymerase (Stratagene, LaJolla, Calif., USA), 50 pmol of primer 066694, 50 pmol of primer 066695, 5 μl of 10 mM dNTPs, 5 μl of 5×Herculase II reaction buffer (Stratagene, LaJolla, Calif., USA), and 35 μl of water. The reaction was incubated in an EPPENDORF® MASTERCYCLER® 5333 programmed for 1 cycle at 95° C. for 2 minutes; 30 cycles each at 95° C. for 20 seconds, 60° C. for 20 seconds, and 72° C. for 1 minute 30 seconds; 1 cycle at 72° C. for 3 minutes; and a 4° C. hold. A 2.5 kb PCR fragment was purified by 1% agarose gel electrophoresis using TAE buffer, excised from the gel, and extracted using a QIAQUICK® Gel Extraction Kit according to the manufacturer's instructions.
The gel purified PCR fragment was treated with Taq DNA polymerase to add 3′ A-overhangs to the fragment in a reaction composed of 5 μl of the purified PCR fragment, 1 μl of the 10×Thermopol Buffer, 0.5 μl of 10 mM dNTPs, 0.5 μl of Taq DNA polymerase, and 3 μl of water. The reaction was incubated at 72° C. for 15 minutes. The aspartic protease gene fragment was cloned into pCR®2.1-TOPO® according to the manufacturer's instruction to generate pAgJg110. The cloning reaction was composed of 2 μl of the aspartic protease PCR fragment, 1 μl of Salt Solution, 2 μl of water, and 1 μl of pCR2.1-TOPO.
To construct plasmid pAgJg111, pAgJg110 was digested with Bmg I and BstE II in a reaction composed of 5 μg of pAgJg110 DNA, 3 μl of Bmg I, 3 μl of BstE II, 10 μl 10×NEB Buffer 3 (New England Biolabs, Inc, Ipswich, Mass., USA), 1 μl 100×BSA, and 53 μl of water. The digestion of pAgJg110 was incubated at 37° C. for 1 hour, and then at 60° C. for 1 hour. The digested pAgJg110 was then blunt ended by adding 10 μl of 10 mM dNTPs, and 12.5 units of DNA Polymerase I, Large (Klenow) Fragment (New England Biolabs, Inc, Ipswich, Mass., USA). The reaction was incubated at 37° C. for 15 minutes. The digested blunt ended pAgJg110 was purified by 1% agarose gel electrophoresis using TAE buffer, excised from the gel, and extracted using a QIAQUICK® Gel Extraction Kit according to the manufacturer's instructions.
Plasmid pHT (Cummings et al., 1999, Current Genetics 36: 371-382) was digested with Hind III and Ava I in a reaction composed of 1.86 μg of pHT DNA, 3 μl of Hind III, 3 μl of Ava I, 10 μl of 10×NEB Buffer 2 (New England Biolabs, Inc, Ipswich, Mass., USA), and 51 μl of water at 37° C. for 2.5 hours and then blunt ended by adding 10 μl of 10 mM dNTPs and 12.5 μl units of DNA Polymerase I, Large (Klenow) Fragment and incubating at 37° C. for 15 minutes. The digested blunt ended pHT was purified by 1% agarose gel electrophoresis using TAE buffer and a 1.9 kb fragment was excised from the gel and extracted using a QIAQUICK® Gel Extraction Kit according to the manufacturer's instructions.
The resulting fragments from pAgJg110 and pHT were ligated together to form pAgJg111 (
Trichoderma reesei strain 981-O-8 protoplasts were transformed with Hind III/Bgl I-linearized pAgJg111 using the method described in Example 12 to delete the aspartic protease gene. Ninety transformants were selected on PDA plates containing 25 μg of hygromycin B per ml. The transformants were sub-cultured to PDA plates to generate spores.
Possible candidates of Trichoderma reesei strain 981-O-8 containing the pAgJg111 deletion vector in the aspartic protease locus, thereby disrupting the expression of the aspartic protease, were screened by Fungal Colony PCR using a modified protocol by Suzuki et al., 2006, J. Bioscience and Bioengineering 102: 572-574. A small amount of spores from each candidate was suspended in 25 μl of TE buffer and heated on high in a microwave oven for 1 minute. The microwaved spore suspension was used as a template in a PCR reaction to screen for the aspartic protease deletion. The reaction was composed of 1 μl of the spore suspension, 1 μl of 10 mM dNTPs, 12.5 μl of 2×Advantage GC-Melt LA Buffer (Clontech, Mountain View, Calif., USA), 25 pmol of primer 066694 (16), 25 pmol of primer 066695 (Example 16), 1.25 units of Advantage GC Genomic LA Polymerase Mix (Clontech, Mountain View, Calif., USA), and 9.25 μl water. The reaction was incubated in an EPPENDORF® MASTERCYCLER® programmed for 1 cycle at 95° C. for 10 minutes; 35 cycles each at 95° C. for 30 seconds, 60° C. for 30 seconds, and 72° C. for 4 minutes 30 seconds; 1 cycle at 72° C. for 5 minutes; and a 4° C. hold. The primers used in this screen were originally used to amplify the aspartic protease region. If the deletion vector was inserted into the aspartic protease locus, the amplified PCR fragment should be larger than the wild-type fragment since it contains the hph cassette used to disrupt the aspartic protease gene. The candidates that exhibited one larger band in the first Fungal Colony PCR screen were subjected to a second PCR screen using the primers shown below.
Primer 068331 is upstream of the 5′ region of the aspartic protease gene that is contained in the deletion strain, and primer 067947 is in the hph cassette. Only those candidates that contain the aspartic protease disruption would produce a PCR fragment. The amplification reaction was composed of 1 μl of genomic DNA from the candidate (extracted according to Example 10), 1 μl of 10 mM dNTPs, 12.5 μl of 2×Advantage GC-Melt LA Buffer, 25 pmol of primer 068331, 25 pmol of primer 067947, 0.25 μl 1.25 units of Advantage GC Genomic LA Polymerase Mix, and 9.25 μl of water. The reaction was incubated in an EPPENDORF® MASTERCYCLER® programmed for 1 cycle at 95° C. for 2 minutes; 30 cycles each at 95° C. for 30 seconds, 55° C. for 30 seconds, and 72° C. for 2 minutes; 1 cycle at 72° C. for 5 minutes; and a 4° C. hold.
Southern blot analysis was performed to confirm the disruption of the aspartic protease gene by plasmid pAgJg111. Genomic DNA was extracted from the deletion strain and Trichoderma reesei strain 981-O-8 as described in Example 10. Two μg of genomic DNA from the deletion strain and Trichoderma reesei strain 981-O-8, as well as 1 ng of plasmid DNA from pAgJg111, were digested with Nco I and Pvu II. T. reesei strain 981-O-8 and pAgJg111 were included in the Southern blot as controls. The genomic DNA digestion reaction was composed of 2 μg of genomic DNA, 1 μl of Nco I, 1 μl of Pvu II, 5 μl of 10×NEB Buffer 2, and water to 50 μl. Both genomic DNA digestions were incubated at 37° C. for approximately 14-16 hours. Plasmid pAgJg111 was digested in a reaction composed of 1 ng of pAgJg111 DNA, 0.5 μl of Nco I, 0.5 μl of Pvu II, 2 μl of 10×NEB Buffer 2, and water to 20 μl. The digestion was incubated at 37 ° C. for approximately 1 hour.
The digestions were submitted to 0.7% agarose gel electrophoresis using TAE buffer and blotted onto NYTRAN® SuperCharge blotting membrane using a TURBOBLOTTER® for 14-16 hours following the manufacturer's recommendations. The membrane was hybridized with a 500 bp digoxigenin-labeled Trichoderma reesei 42 kDa aspartic protease probe, which was synthesized by incorporation of digoxigenin-11-dUTP by PCR using primers 068128 (sense) and 068129 (antisense) shown below.
The amplification reaction was composed of 5 μl of 10×ThermoPol Reaction Buffer, 2.5 μl of PCR DIG Labeling Mix, 2 ng of pAgJg111, 50 pmol of primer 068128, 50 pmol of primer 068129, 2.5 μl of 10 mM dNTPs, 5 units of Taq DNA polymerase, and 35.5 μl of water. The reactions were incubated in an EPPENDORF® MASTERCYCLER® 5333 programmed for 1 cycle at 95° C. for 2 minutes; 30 cycles each at 95° C. for 30 seconds, 60° C. for 30 seconds, and 72° C. for 40 seconds; 1 cycle at 72° C. for 15 minutes; and a 4° C. hold. The PCR reaction product was purified by 1% agarose gel electrophoresis using TAE buffer, excised from the gel, and extracted using a QIAQUICK® Gel Extraction Kit according to the manufacturer's instructions. Incorporation of digoxigenin was indicated by increase in molecular mass.
Hybridization was performed in DIG Easy Hyb buffer at 42° C. for 15-17 hours. The membrane was then washed under high stringency conditions in 2×SSC plus 0.1% SDS for 5 minutes at room temperature followed by two washes in 0.5×SSC plus 0.1% SDS for 15 minutes each at 65° C. The probe-target hybrids were detected by chemiluminescent assay (Roche Molecular Biochemicals, Indianapolis, Ind., USA) following the manufacturer's instructions. The strain containing the aspartic protease deletion was designated Trichoderma reesei AgJg 111-50.
To determine whether deletion of the 42 kDa aspartic protease was effective in eliminating degradation of the Aspergillus aculeatus GH10 xylanase, plasmid pSaMe-AaXYL (Example 14), which contains the Aspergillus aculeatus GH10 xylanase coding sequence, was transformed into Trichoderma reesei AgJg111-50. Protoplasts of T. reesei AgJg111-50 were generated as described in Example 12 and transformed with plasmid pSaMe-AaXYL. Twenty transformants containing the Aspergillus aculeatus GH10 xylanase were randomly selected from COVE plates and cultured in 125 ml shake flasks containing 25 ml of cellulase-inducing medium at pH 6.0 inoculated with spores of the transformants and incubated at 28° C. for 5 days with agitation at 200 rpm. Trichoderma reesei strain 981-O-8 and Trichoderma reesei AgJg111-50 were both run as controls. Culture broth samples were removed 5 days post-inoculation, centrifuged at 15,700 ×g for 10 minutes in a micro-centrifuge, and the supernatants transferred to new tubes.
The supernatants were analyzed by SDS-PAGE using an 8-16% CRITERION™ Tris-HCl gels with a CRITERION™ Cell. Five μl of day 5 samples were suspended in 2×concentration of Laemmli Sample Buffer and heated at 95° C. for 5 minutes in the presence of 5% 3-mercaptoethanol. All samples were loaded onto the SDS-PAGE gels and subjected to electrophoresis in 1×Tris/Glycine/SDS running buffer. The resulting gels were stained with BIO-SAFE™ Coomassie Stain. SDS-PAGE analysis suggested that deletion of the aspartic protease gene for the production of Aspergillus aculeatus GH10 xylanase did not completely prevent proteolysis of the protein. The aspartic protease deletion strain T. reesei AgJg111-50 did not exhibit any unusual expression patterns of any protein and behaved similarly to the parent strain, Trichoderma reesei strain 981-O-8.
The deletion vector pAgJg116 was constructed to disrupt expression of a Trichoderma reesei 25 kDa trypsin-like serine protease gene (SEQ ID NO: 5 for the DNA sequence and SEQ ID NO: 6 for the deduced amino acid sequence). Plasmid pAgJg116 was generated by first amplifying 5′ and 3′ flanking regions and cloning them into the vector pCR®2.1-TOPO®. The 5′ flanking region contains a region upstream of the 25 kDa serine protease coding region and part of the 25 kDa trypsin-like serine protease coding region. The 5′ flanking region was amplified using the primers 067518 (sense) and 067519 (antisense) shown below. Primer 067518 was engineered to contain Asc I and Not I sites on the 5′ end of the primer. Primer 067519 was engineered to contain an Asc I site on the 5′ end of the primer.
The 5′ region of the trypsin-like serine protease was amplified by PCR in a reaction composed of 175 μg of T. reesei genomic DNA (Example 10), 1 μl of Herculase II Fusion DNA Polymerase (Stratagene, LaJolla, Calif., USA), 50 pmol of primer 067518, 50 pmol of primer 067519, 5 μl of 10 mM dNTPs, 5 μl of 5×Herculase II reaction buffer (Stratagene, LaJolla, Calif., USA), and 31 μl of water. The reaction was incubated in an EPPENDORF® MASTERCYCLER® programmed for 1 cycle at 95° C. for 2 minutes; 30 cycles each at 95° C. for 20 seconds, 60° C. for 20 seconds, and 72° C. for 45 seconds; 1 cycle at 72° C. for 3 minutes; and a 4° C. hold. A 1.5 kb PCR fragment was purified by 1% agarose gel electrophoresis using TAE buffer, excised from the gel, and extracted using QIAQUICK® Gel Extraction Kit according to the manufacturer's instructions. The gel purified PCR fragment was treated with Taq DNA polymerase to add 3′ A-overhangs to the fragment in a reaction composed of 5 pl of the purified PCR fragment, 1 μl of the 10×Thermopol Buffer, 0.5 μl of 10 mM dNTPs, 0.5 pl of Taq DNA polymerase, and 3 pl of water. The reaction was incubated at 72° C. for 15 minutes. The 5′ region of the trypsin-like serine protease fragment was cloned into pCR®2.1-TOPO® in a reaction composed of 2.5 pl of the 5′ trypsin-like serine protease region PCR fragment, 1 pl of Salt Solution, 1.5 pl of water, and 1 pl of pCR®2.1-TOPO®. The resulting plasmid was designated 5′SP-TOPO.
The 3′ region of the trypsin-like serine protease fragment was cloned into pCR®2.1-TOPO® using primers 067520 (sense) and 067521 (antisense) shown below. Primer 067520 was engineered to contain a Sbf I site on the 5′ end of the primer. Primer 067521 was engineered to contain Sbf I and Not I sites on the 5′ end of the primer.
The 3′ region of the trypsin-like serine protease gene was amplified by PCR in a reaction composed of 175 μg of T. reesei genomic DNA (Example 10), 1 μl of Herculase II Fusion DNA Polymerase, 50 pmol of primer 067520, 50 pmol of primer 067521, 5 μl of 10 mM dNTPs, 5 μl of 5×Herculase II reaction buffer, and 31 μl of water. The reaction was incubated in an EPPENDORF® MASTERCYCLER® programmed for 1 cycle at 95° C. for 2 minutes; 30 cycles each at 95° C. for 20 seconds, 60° C. for 20 seconds, and 72° C. for 45 seconds; 1 cycle at 72° C. for 3 minutes; and a 4° C. hold. A 1.5 kb PCR fragment was purified by 1% agarose gel electrophoresis using TAE buffer, excised from the gel, and extracted using a QIAQUICK® Gel Extraction Kit according to the manufacturer's instructions. The gel purified PCR fragment was treated with Taq DNA polymerase to add 3′ A-overhangs to the fragment in a reaction composed of 5 μl of the purified PCR fragment, 1 μl of the 10×Thermopol Buffer, 0.5 μl of 10 mM dNTPs, 0.5 μl of Taq DNA polymerase, and 3 μl of water. The reaction was incubated at 72° C. for 15 minutes. The 5′ region of the trypsin-like serine protease fragment was cloned into pCR®2.1-TOPO® according to the manufacturer's instruction in a reaction composed of 2.5 μl of the 5′ trypsin-like serine protease region PCR fragment, 1 μl of Salt Solution, 1.5 μl of water, and 1 μl of pCR®2.1-TOPO®. The resulting plasmid was designated 3′SP-TOPO.
Plasmid 5′SP-TOPO was digested with Asc I and cloned into Asc I digested plasmid pJfyS1579-41-11 (Example 9) in a reaction composed of 12.4 μg of digested 5′SP-TOPO plasmid DNA, 5 μl of Asc I, 10 μl of 10×NEB Buffer 4 (New England Biolabs, Inc, Ipswich, Mass., USA), and 55 μl of water. The restriction enzyme digestion was incubated at 37° C. for 2 hours. The digestion was purified by 1% agarose gel electrophoresis using TAE buffer, where a 1.5 kb fragment was excised from the gel and extracted using a QIAQUICK® Gel Extraction Kit according to the manufacturer's instructions. The Asc I digested 5′SP-TOPO fragment was ligated to the Asc I digested pJfyS1579-49-11 in a reaction composed of 282 ng of Asc I digested 5′SP-TOPO, 120 ng of Asc I digested pJfyS1579-49-11, 2 μl of Quick Ligase (New England Biolabs, Inc, Ipswich, Mass., USA), 15 μl of 2×Quick Ligase Buffer (New England Biolabs, Inc, Ipswich, Mass., USA), and 2 μl of water. The ligation reaction was incubated at room temperature for 15 minutes. The resulting plasmid was designated pJfyS1579+5′S P.
To construct plasmid pAgJg116, plasmids 3′SP-TOPO and pJfyS1579+5′SP were digested with Sbf I. The digestions were composed of 7.5 μg of pJfyS1579+5′SP or 12.5 μg of 3′SP-TOPO, 5 μl of Sbf I, 10 μl of 10×NEB Buffer 4, and 55 μl of water. Both digestion reactions were incubated at 37° C. overnight. Two μl of calf intestinal alkaline phosphatase (CIP) was added to the pJfyS1579+5′SP digestion reaction and incubated at 37° C. for an additional hour. A 9.5 kb fragment from pJfyS1579+5SP/Sbf I and a 1.5 kb fragment from 3SP-TOPO/Sbf I were purified by 0.8% agarose gel electrophoresis using TAE buffer, excised from the gel, and extracted using a QIAQUICK® Gel Extraction Kit according to the manufacturer's instructions. The Sbf I digested 3′SP-TOPO fragment was ligated to the Sbf I digested pJfyS1579+5′SP fragment in a reaction composed of 767 ng of Sbf I digested 3′SP-TOPO, 380 ng of Sbf I digested pJfyS1579+5′SP, 2 μl of Quick Ligase, 15 μl of 2×Quick Ligase Buffer, and 1 μl of water. The ligation reaction incubated at room temperature for 20 minutes. The resulting plasmid was designated pAgJg116 (
Trichoderma reesei strain 981-O-8 protoplasts were transformed with Not I-linearized pAgJg116 using the method described in Example 12 to delete the trypsin-like serine protease gene. Ninety transformants were selected on PDA plates containing 25 μg of hygromycin B per ml. The transformants were sub-cultured to PDA plates to generate spores.
Transformants of Trichoderma reesei strain 981-O-8 containing the deletion vector pAgJg116 were cultured in 125 ml shake flasks containing 25 ml of cellulase-inducing medium at pH 6.0 inoculated with spores of the transformants and incubated at 28° C. for 5 days with agitation at 200 rpm. Trichoderma reesei strain 981-O-8 was run as a control. Culture broth samples were removed 5 days post-inoculation, centrifuged at 15,700 ×g for 10 minutes in a micro-centrifuge, and the supernatants transferred to new tubes.
The supernatants of each transformant were assayed for protease activity using the synthetic substrate Val-Leu-Lys 4-nitroanilide (Bachem AG, Bubendorf, Switzerland). The substrate was initially dissolved in dimethyl sulfoxide at a concentration of 100 mg/ml. The dissolved substrate was then diluted 200-fold into 100 mM NaCl-100 mM MOPS pH 7.0. The reaction was initiated by adding 10 μl of each transformant supernatant to 100 μl of the diluted substrate in a flat-bottomed 96-well plate. The reaction plate was incubated at 50° C. for 30 minutes and then the absorbance at 405 nm was measured using a SPECTRAMAX® Microplate Reader. Transformants exhibiting little to no protease activity were subjected to a PCR screen using the primers shown below.
Primer 068155 is upstream of the 5′ region of the trypsin-like serine protease gene contained in the deletion strain, and primer 067947 is in the hph cassette. Only those candidates that contain the trypsin-like serine protease disruption would produce a PCR fragment. The PCR screen was performed by Fungal Colony PCR according to the modified protocol described in Example 17. A small amount of spores from each candidate was suspended in 25 μl of TE buffer and heated on high in a microwave oven for 1 minute. The microwaved spore suspension was used as a template in a PCR reaction to screen for the aspartic protease deletion. The reaction was composed of 1 μl of the spore suspension, 1 μl of 10 mM dNTPs, 12.5 μl of 2×Advantage GC-Melt LA Buffer, 25 pmol of primer 068155, 25 pmol of primer 067947, 1.25 units of Advantage GC Genomic LA Polymerase Mix, and 9.25 μl water. The reaction was incubated in an EPPENDORF® MASTERCYCLER® programmed for 1 cycle at 95° C. for 10 minutes; 35 cycles each at 95° C. for 30 seconds, 60° C. for 30 seconds, and 72° C. for 2 minutes 30 seconds; 1 cycle at 72° C. for 5 minutes; and a 4° C. hold.
Southern blot analysis was performed to confirm the disruption of the 25 kDa trypsin-like serine protease gene by the vector pAgJg116. Genomic DNA was extracted from the deletion strain and Trichoderma reesei strain 981-O-8 according to Example 10. Two μg of genomic DNA from the deletion strains and Trichoderma reesei strain 981-O-8, along with 1 ng of plasmid DNA from pAgJg116 were digested with Nco I and Sac I. Trichoderma reesei strain 981-O-8 and pAgJg116 were included in the Southern blot as controls. The genomic DNA was digested in a reaction composed of 2 μg of genomic DNA, 1 μl of Nco I, 1 μl of Sac I, 5 μl of 10×NEB Buffer 1 (New England Biolabs, Inc, Ipswich, Mass., USA), 0.5 μl of 100×BSA, and water in a 50 μl reaction. Both digests were incubated at 37° C. for approximately 14-16 hours. Plasmid pAgJg116 was digested in a reaction composed of 1 ng of pAgJg116 DNA, 0.5 μl of Nco I, 0.5 μl of Sac I, 2 μl of 10×NEB Buffer 1, 0.2 μl of 100×BSA, and water in a 20 μl reaction. The digestion was incubated at 37 ° C. for approximately 1 hour and 30 minutes.
The digests were submitted to 0.7% agarose gel electrophoresis using TAE buffer and blotted onto NYTRAN® SuperCharge blotting membrane using a TURBOBLOTTER® for 14-16 hours following the manufacturer's recommendations. The membrane was hybridized with a 500 bp digoxigenin-labeled Trichoderma reesei 25 kDa trypsin-like serine protease probe, which was synthesized by incorporation of digoxigenin-11-dUTP during PCR using primers 068128 (sense) and 068129 (antisense) shown below.
The amplification reaction was composed of 5 μl of 10×ThermoPol Reaction Buffer, 2.5 μl of PCR DIG Labeling Mix, 2 ng of pAgJg116, 50 pmol of primer 068233, 50 pmol of primer 068234, 2.5 μl of 10 mM dNTPs, 5 units of Taq DNA polymerase, and 35.5 μl water. The reaction was incubated in an EPPENDORF® MASTERCYCLER® programmed for 1 cycle at 95° C. for 2 minutes; 30 cycles each 95° C. for 30 seconds, 60° C. for 30 seconds, and 72° C. for 40 seconds; 1 cycle at 72 ° C. for 15 minutes; and a 4° C. hold. The PCR product was size-selected by 1.5% agarose gel electrophoresis using TAE buffer, excised from the gel, and extracted using a QIAQUICK® Gel Extraction Kit according to the manufacturer's instructions. Incorporation of digoxigenin was indicated by increase in molecular mass.
Hybridization was performed in DIG Easy Hyb buffer at 42° C. for 15-17 hours. The membrane was then washed under high stringency conditions in 2×SSC plus 0.1% SDS for 5 minutes at room temperature followed by two washes in 0.5×SSC plus 0.1% SDS for 15 minutes each at 65° C. The probe-target hybrids were detected by chemiluminescent assay following the manufacturer's instructions. Several transformants were confirmed to contain the trypsin-like serine protease deletion. One transformant was selected and designated Trichoderma reesei AgJg116-19.
To determine whether deletion of the 25 kDa trypsin-like serine protease was effective in preventing degradation of recombinantly expressed Aspergillus aculeatus GH10 xylanase, plasmid pSaMe-AaXYL (Example 14), which contains the Aspergillus aculeatus GH10 xylanase coding sequence, was transformed into the Trichoderma reesei AgJg116-19 strain. Protoplasts of Trichoderma reesei AgJg116-19 were generated as described in Example 12 and transformed with plasmid pSaMe-AaXYL. Thirty-six transformants containing the Aspergillus aculeatus GH10 xylanase were randomly selected from COVE plates and cultured in 125 ml shake flasks containing 25 ml of cellulase-inducing medium at pH 6.0 inoculated with spores of the transformants and incubated at 28° C. for 5 days with agitation at 200 rpm. Trichoderma reesei strain 981-O-8 and Trichoderma reesei AgJg116-19 were both run as controls. Culture broth samples were removed 5 days post-inoculation, centrifuged at 15,700 ×g for 10 minutes in a micro-centrifuge, and the supernatants transferred to new tubes.
The supernatants were analyzed by SDS-PAGE using an 8-16% CRITERION™ Tris-HCl gels with a CRITERION™ Cell. Five μl of day 5 samples were suspended in 2×concentration of Laemmli Sample Buffer and heated at 95° C. for 5 minutes in the presence of 5% β-mercaptoethanol. All samples were loaded onto the SDS-PAGE gels and subjected to electrophoresis in 1×Tris/Glycine/SDS running buffer. The resulting gels were stained with BIO-SAFE™ Coomassie Stain. SDS-PAGE analysis indicated that none of the transformants expressing the Aspergillus aculeatus GH10 xylanase produced any trace of degradation of the xylanase. Also, the trypsin-like serine protease deletion strain Trichoderma reesei AgJg116-19 did not exhibit any unusual expression patterns of any protein and behaved similarly to the parent strain, Trichoderma reesei strain 981-O-8. The deletion of the 25 kDa trypsin-like serine protease gene in Trichoderma reesei strain 981-O-8 appeared effective in eliminating degradation of the Aspergillus aculeatus GH10 xylanase.
The invention described and claimed herein is not to be limited in scope by the specific aspects herein disclosed, since these aspects are intended as illustrations of several aspects of the invention. Any equivalent aspects are intended to be within the scope of this invention. Indeed, various modifications of the invention in addition to those shown and described herein will become apparent to those skilled in the art from the foregoing description. Such modifications are also intended to fall within the scope of the appended claims. In the case of conflict, the present disclosure including definitions will control. Various references are cited herein, the disclosures of which are incorporated by reference in their entireties.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US10/61105 | 12/17/2010 | WO | 00 | 6/15/2012 |
| Number | Date | Country | |
|---|---|---|---|
| 61287844 | Dec 2009 | US |
