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Zhu Z, Zou G, Chai S, Xiao M, Wang Y, Wang P, Zhou Z. The protein methyltransferase TrSAM inhibits cellulase gene expression by interacting with the negative regulator ACE1 in Trichoderma reesei. Commun Biol 2024; 7:375. [PMID: 38548869 PMCID: PMC10978942 DOI: 10.1038/s42003-024-06072-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Accepted: 03/19/2024] [Indexed: 04/01/2024] Open
Abstract
Protein methylation is a commonly posttranslational modification of transcriptional regulators to fine-tune protein function, however, whether this regulation strategy participates in the regulation of lignocellulase synthesis and secretion in Trichoderma reesei remains unexplored. Here, a putative protein methyltransferase (TrSAM) is screened from a T. reesei mutant with the ability to express heterologous β-glucosidase efficiently even under glucose repression. The deletion of its encoding gene trsam causes a significant increase of cellulase activities in all tested T. reesei strains, including transformants of expressing heterologous genes using cbh1 promotor. Further investigation confirms that TrSAM interacts with the cellulase negative regulator ACE1 via its amino acid residue Arg383, which causes a decrease in the ACE1-DNA binding affinity. The enzyme activity of a T. reesei strain harboring ACE1R383Q increases by 85.8%, whereas that of the strains with trsam or ace1 deletion increases by more than 100%. By contrast, the strain with ACE1R383K shows no difference to the parent strain. Taken together, our results demonstrate that TrSAM plays an important role in regulating the expression of cellulase and heterologous proteins initiated by cbh1 promotor through interacting with ACE1R383. Elimination and mutation of TrSAM and its downstream ACE1 alleviate the carbon catabolite repression (CCR) in expressing cellulase and heterologous protein in varying degrees. This provides a new solution for the exquisite modification of T. reesei chassis.
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Affiliation(s)
- Zhihua Zhu
- CAS-Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, 300 FengLin Rd, Shanghai, 200032, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Gen Zou
- CAS-Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, 300 FengLin Rd, Shanghai, 200032, China
- Shanghai Key Laboratory of Agricultural Genetics and Breeding, Institute of Edible Fungi, Shanghai Academy of Agricultural Science, 1000 Jinqi Rd, Shanghai, 201403, China
| | - Shunxing Chai
- CAS-Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, 300 FengLin Rd, Shanghai, 200032, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Meili Xiao
- CAS-Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, 300 FengLin Rd, Shanghai, 200032, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yinmei Wang
- CAS-Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, 300 FengLin Rd, Shanghai, 200032, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Pingping Wang
- CAS-Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, 300 FengLin Rd, Shanghai, 200032, China
| | - Zhihua Zhou
- CAS-Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, 300 FengLin Rd, Shanghai, 200032, China.
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Liu R, Yang Z, Yang T, Wang Z, Chen X, Zhu J, Ren A, Shi L, Yu H, Zhao M. PRMT5 regulates the polysaccharide content by controlling the splicing of thaumatin-like protein in Ganoderma lucidum. Microbiol Spectr 2023; 11:e0290623. [PMID: 37882562 PMCID: PMC10715077 DOI: 10.1128/spectrum.02906-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Accepted: 09/07/2023] [Indexed: 10/27/2023] Open
Abstract
IMPORTANCE PRMT5 contributes to secondary metabolite biosynthesis in Ganoderma lucidum. However, the mechanism through which PRMT5 regulates the biosynthesis of secondary metabolites remains unclear. In the current study, PRMT5 silencing led to a significant decrease in the biosynthesis of polysaccharides from G. lucidum through the action of the alternative splicing of TLP. A shorter TLP2 isoform can directly bind to PGI and regulated polysaccharide biosynthesis. These results suggest that PRMT5 enhances PGI activity by regulating TLP binding to PGI. The results of the current study reveal a novel target gene for PRMT5-mediated alternative splicing and provide a reference for the identification of PRMT5 regulatory target genes.
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Affiliation(s)
- Rui Liu
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture; Microbiology Department, College of Life Sciences, Nanjing Agricultural University, Nanjing, China
| | - Zhengyan Yang
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture; Microbiology Department, College of Life Sciences, Nanjing Agricultural University, Nanjing, China
| | - Tao Yang
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture; Microbiology Department, College of Life Sciences, Nanjing Agricultural University, Nanjing, China
| | - Zi Wang
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture; Microbiology Department, College of Life Sciences, Nanjing Agricultural University, Nanjing, China
| | - Xin Chen
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture; Microbiology Department, College of Life Sciences, Nanjing Agricultural University, Nanjing, China
| | - Jing Zhu
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture; Microbiology Department, College of Life Sciences, Nanjing Agricultural University, Nanjing, China
| | - Ang Ren
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture; Microbiology Department, College of Life Sciences, Nanjing Agricultural University, Nanjing, China
| | - Liang Shi
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture; Microbiology Department, College of Life Sciences, Nanjing Agricultural University, Nanjing, China
| | - Hanshou Yu
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture; Microbiology Department, College of Life Sciences, Nanjing Agricultural University, Nanjing, China
| | - Mingwen Zhao
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture; Microbiology Department, College of Life Sciences, Nanjing Agricultural University, Nanjing, China
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Zhou Y, Du C, Odiba AS, He R, Ahamefule CS, Wang B, Jin C, Fang W. Phosphoglucose Isomerase Plays a Key Role in Sugar Homeostasis, Stress Response, and Pathogenicity in Aspergillus flavus. Front Cell Infect Microbiol 2022; 11:777266. [PMID: 34976860 PMCID: PMC8715936 DOI: 10.3389/fcimb.2021.777266] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Accepted: 11/17/2021] [Indexed: 01/22/2023] Open
Abstract
Aspergillus flavus is one of the important human and plant pathogens causing not only invasive aspergillosis in immunocompromised patients but also crop contamination resulting from carcinogenic aflatoxins (AFs). Investigation of the targeting factors that are involved in pathogenicity is of unmet need to dismiss the hazard. Phosphoglucose isomerase (PGI) catalyzes the reversible conversion between glucose-6-phosphate and fructose-6-phosphate, thus acting as a key node for glycolysis, pentose phosphate pathway, and cell wall biosynthesis in fungi. In this study, we constructed an A. flavus pgi deletion mutant, which exhibited specific carbon requirement for survival, reduced conidiation, and slowed germination even under optimal experimental conditions. The Δpgi mutant lost the ability to form sclerotium and displayed hypersusceptibility to osmotic, oxidative, and temperature stresses. Furthermore, significant attenuated virulence of the Δpgi mutant was documented in the Caenorhabditis elegans infection model, Galleria mellonella larval model, and crop seeds. Our results indicate that PGI in A. flavus is a key enzyme in maintaining sugar homeostasis, stress response, and pathogenicity of A. flavus. Therefore, PGI is a potential target for controlling infection and AF contamination caused by A. flavus.
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Affiliation(s)
- Yao Zhou
- State Key Laboratory of Non-Food Biomass and Enzyme Technology, Guangxi Academy of Sciences, Nanning, China.,College of Life Science and Technology, Guangxi University, Nanning, China
| | - Chao Du
- State Key Laboratory of Non-Food Biomass and Enzyme Technology, Guangxi Academy of Sciences, Nanning, China.,College of Life Science and Technology, Guangxi University, Nanning, China
| | - Arome Solomon Odiba
- State Key Laboratory of Non-Food Biomass and Enzyme Technology, Guangxi Academy of Sciences, Nanning, China
| | - Rui He
- State Key Laboratory of Non-Food Biomass and Enzyme Technology, Guangxi Academy of Sciences, Nanning, China.,College of Life Science and Technology, Guangxi University, Nanning, China
| | | | - Bin Wang
- State Key Laboratory of Non-Food Biomass and Enzyme Technology, Guangxi Academy of Sciences, Nanning, China.,National Engineering Research Center for Non-Food Biorefinery, Guangxi Academy of Sciences, Nanning, China
| | - Cheng Jin
- State Key Laboratory of Non-Food Biomass and Enzyme Technology, Guangxi Academy of Sciences, Nanning, China.,College of Life Science and Technology, Guangxi University, Nanning, China.,State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Wenxia Fang
- State Key Laboratory of Non-Food Biomass and Enzyme Technology, Guangxi Academy of Sciences, Nanning, China.,National Engineering Research Center for Non-Food Biorefinery, Guangxi Academy of Sciences, Nanning, China
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Valorization of the green seaweed Ulva rigida for production of fungal biomass protein using a hypercellulolytic terrestrial fungus. ALGAL RES 2021. [DOI: 10.1016/j.algal.2021.102457] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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Zhou Z, Zhang J, Lu F, Duan Y, Zhou M. Glucose-6-Phosphate Isomerase FgGPI, a β 2 Tubulin-Interacting Protein, Is Indispensable for Fungal Development and Deoxynivalenol Biosynthesis in Fusarium graminearum. PHYTOPATHOLOGY 2021; 111:531-540. [PMID: 33544003 DOI: 10.1094/phyto-07-20-0279-r] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Glucose-6-phosphate isomerase (GPI) is ubiquitous in most organisms, catalyzing the reversible isomerization of glucose-6-phosphate and fructose-6-phosphate. In this study, we investigated biological and genetic functions of FgGPI in the phytopathogen Fusarium graminearum. We found that hyphal growth, conidial germination, and septa formation were significantly inhibited in FgGPI deletion mutant ∆FgGPI. FgGPI was also positively associated with glucose metabolism, ATP biosynthesis, and carbon source utilization. In addition, pyruvate production, deoxynivalenol (DON) biosynthesis, and virulence were reduced in ∆FgGPI. A coimmunoprecipitation assay demonstrated that FgGPI interacts with Fgβ2. More importantly, the coimmunoprecipitation assay showed that carbendazim-resistant substitutions in β2 tubulin could reduce the interaction intensity between FgGPI and Fgβ2, thereby increasing FgGPI expression and accelerating DON biosynthesis in carbendazim-resistant strains. Taken together, our work revealed the indispensable role of FgGPI in fungal developmental processes, DON biosynthesis, and pathogenicity in F. graminearum.
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Affiliation(s)
- Zehua Zhou
- College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
| | - Jie Zhang
- College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
| | - Fei Lu
- College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
| | - Yabing Duan
- College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
- Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing 210095, China
| | - Mingguo Zhou
- College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
- Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing 210095, China
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Mukherjee S, Chandrababunaidu MM, Panda A, Khowala S, Tripathy S. Tricking Arthrinium malaysianum into Producing Industrially Important Enzymes Under 2-Deoxy D-Glucose Treatment. Front Microbiol 2016; 7:596. [PMID: 27242677 PMCID: PMC4865484 DOI: 10.3389/fmicb.2016.00596] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Accepted: 04/11/2016] [Indexed: 01/24/2023] Open
Abstract
This study catalogs production of industrially important enzymes and changes in transcript expression caused by 2-deoxy D-glucose (2-DG) treatment in Arthrinium malaysianum cultures. Carbon Catabolite Repression (CCR) induced by 2-DG in this species is cAMP independent unlike many other organisms. Higher levels of secreted endoglucanase (EG), β-glucosidase (BGL), β-xylosidase (BXL), and filter paper activity assay (FPase) enzymes under 2-DG treatment can be exploited for commercial purposes. An integrated RNA sequencing and quantitative proteomic analysis was performed to investigate the cellular response to 2-DG in A. malaysianum. Analysis of RNASeq data under 2-DG treated and control condition reveals that 56% of the unigenes do not have any known similarity to proteins in non-redundant database. Gene Ontology IDs were assigned to 36% of the transcripts (13260) and about 5207 (14%) were mapped to Kyoto Encyclopedia of Genes and Genomes pathway (KEGG). About 1711 genes encoding 2691 transcripts were differentially expressed in treated vs. control samples. Out of the 2691 differentially expressed transcripts, only 582 have any known function. The most up regulated genes belonged to Pentose Phosphate Pathways and carbohydrate degradation class as expected. In addition, genes involved in protein folding, binding, catalytic activity, DNA repair, and secondary metabolites were up-regulated under 2-DG treatment. Whereas genes encoding glycosylation pathways, growth, nutrient reservoir activity was repressed. Gene ontology analysis of the differentially expressed genes indicates metabolic process (35%) is the pre-dominant class followed by carbohydrate degradation (11%), protein folding, and trafficking (6.2%) and transport (5.3%) classes. Unlike other organisms, conventional unfolded protein response (UPR) was not activated in either control or treated conditions. Major enzymes secreted by A. malaysianum are those degrading plant polysaccharides, the most dominant ones being β-glucosidase, as demonstrated by the 2D gel analysis. A set of 7 differentially expressed mRNAs were validated by qPCR. Transmission electron microscopy analyses demonstrated that the 2-DG treated cell walls of hyphae showed significant differences in the cell-wall thickness. Overall 2-DG treatment in A. malaysianum induced secretion of large amount of commercially viable enzymes compared to other known species.
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Affiliation(s)
- Soumya Mukherjee
- Drug Development Diagnostic and Biotechnology Division, Council of Scientific and Industrial Research-Indian Institute of Chemical BiologyKolkata, India
| | - Mathu Malar Chandrababunaidu
- Structural Biology and Bioinformatics Division, Council of Scientific and Industrial Research-Indian Institute of Chemical BiologyKolkata, India
| | - Arijit Panda
- Structural Biology and Bioinformatics Division, Council of Scientific and Industrial Research-Indian Institute of Chemical BiologyKolkata, India
| | - Suman Khowala
- Drug Development Diagnostic and Biotechnology Division, Council of Scientific and Industrial Research-Indian Institute of Chemical BiologyKolkata, India
| | - Sucheta Tripathy
- Structural Biology and Bioinformatics Division, Council of Scientific and Industrial Research-Indian Institute of Chemical BiologyKolkata, India
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8
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Xiong Y, Sun J, Glass NL. VIB1, a link between glucose signaling and carbon catabolite repression, is essential for plant cell wall degradation by Neurospora crassa. PLoS Genet 2014; 10:e1004500. [PMID: 25144221 PMCID: PMC4140635 DOI: 10.1371/journal.pgen.1004500] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2013] [Accepted: 05/27/2014] [Indexed: 11/18/2022] Open
Abstract
Filamentous fungi that thrive on plant biomass are the major producers of hydrolytic enzymes used to decompose lignocellulose for biofuel production. Although induction of cellulases is regulated at the transcriptional level, how filamentous fungi sense and signal carbon-limited conditions to coordinate cell metabolism and regulate cellulolytic enzyme production is not well characterized. By screening a transcription factor deletion set in the filamentous fungus Neurospora crassa for mutants unable to grow on cellulosic materials, we identified a role for the transcription factor, VIB1, as essential for cellulose utilization. VIB1 does not directly regulate hydrolytic enzyme gene expression or function in cellulosic inducer signaling/processing, but affects the expression level of an essential regulator of hydrolytic enzyme genes, CLR2. Transcriptional profiling of a Δvib-1 mutant suggests that it has an improper expression of genes functioning in metabolism and energy and a deregulation of carbon catabolite repression (CCR). By characterizing new genes, we demonstrate that the transcription factor, COL26, is critical for intracellular glucose sensing/metabolism and plays a role in CCR by negatively regulating cre-1 expression. Deletion of the major player in CCR, cre-1, or a deletion of col-26, did not rescue the growth of Δvib-1 on cellulose. However, the synergistic effect of the Δcre-1; Δcol-26 mutations circumvented the requirement of VIB1 for cellulase gene expression, enzyme secretion and cellulose deconstruction. Our findings support a function of VIB1 in repressing both glucose signaling and CCR under carbon-limited conditions, thus enabling a proper cellular response for plant biomass deconstruction and utilization.
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Affiliation(s)
- Yi Xiong
- Plant and Microbial Biology Department and The Energy Biosciences Institute, The University of California, Berkeley, Berkeley, California, United States of America
| | - Jianping Sun
- Plant and Microbial Biology Department and The Energy Biosciences Institute, The University of California, Berkeley, Berkeley, California, United States of America
| | - N. Louise Glass
- Plant and Microbial Biology Department and The Energy Biosciences Institute, The University of California, Berkeley, Berkeley, California, United States of America
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Hideno A, Inoue H, Fujii T, Yano S, Tsukahara K, Murakami K, Yunokawa H, Sawayama S. High-coverage gene expression profiling analysis of the cellulase-producing fungus Acremonium cellulolyticus cultured using different carbon sources. Appl Microbiol Biotechnol 2013; 97:5483-92. [DOI: 10.1007/s00253-013-4689-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Revised: 12/26/2012] [Accepted: 12/27/2012] [Indexed: 10/27/2022]
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Seiboth B, Herold S, Kubicek CP. Metabolic engineering of inducer formation for cellulase and hemicellulase gene expression in Trichoderma reesei. Subcell Biochem 2012; 64:367-90. [PMID: 23080260 DOI: 10.1007/978-94-007-5055-5_18] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The filamentous fungus T. reeseiis today a paradigm for the commercial scale production of different plant cell wall degrading enzymes mainly cellulases and hemicellulases. Its enzymes have a long history of safe use in industry and well established applications are found within the pulp, paper, food, feed or textile processing industries. However, when these enzymes are to be used for the saccharification of cellulosic plant biomass to simple sugars which can be further converted to biofuels or other biorefinery products, and thus compete with chemicals produced from fossil sources, additional efforts are needed to reduce costs and maximize yield and efficiency of the produced enzyme mixtures. One approach to this end is the use of genetic engineering to manipulate the biochemical and regulatory pathways that operate during enzyme production and control enzyme yield. This review aims at a description of the state of art in this area.
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Affiliation(s)
- Bernhard Seiboth
- Research Division Biotechnology and Microbiology, Institute of Chemical Engineering, Vienna University of Technology, Gumpendorferstraße 1a, 166-5, A-1060, Vienna, Austria
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Peterson R, Nevalainen H. Trichoderma reesei RUT-C30--thirty years of strain improvement. MICROBIOLOGY-SGM 2011; 158:58-68. [PMID: 21998163 DOI: 10.1099/mic.0.054031-0] [Citation(s) in RCA: 292] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The hypersecreting mutant Trichoderma reesei RUT-C30 (ATCC 56765) is one of the most widely used strains of filamentous fungi for the production of cellulolytic enzymes and recombinant proteins, and for academic research. The strain was obtained after three rounds of random mutagenesis of the wild-type QM6a in a screening program focused on high cellulase production and catabolite derepression. Whereas RUT-C30 achieves outstanding levels of protein secretion and high cellulolytic activity in comparison to the wild-type QM6a, recombinant protein production has been less successful. Here, we bring together and discuss the results from biochemical-, microscopic-, genomic-, transcriptomic-, glycomic- and proteomic-based research on the RUT-C30 strain published over the last 30 years.
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Affiliation(s)
- Robyn Peterson
- Biomolecular Frontiers Research Centre, Macquarie University, Australia
- Department of Chemistry and Biomolecular Sciences, Macquarie University, Australia
| | - Helena Nevalainen
- Biomolecular Frontiers Research Centre, Macquarie University, Australia
- Department of Chemistry and Biomolecular Sciences, Macquarie University, Australia
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Díaz-Sánchez V, Estrada AF, Trautmann D, Limón MC, Al-Babili S, Avalos J. Analysis of al-2 mutations in Neurospora. PLoS One 2011; 6:e21948. [PMID: 21818281 PMCID: PMC3139582 DOI: 10.1371/journal.pone.0021948] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Accepted: 06/14/2011] [Indexed: 01/06/2023] Open
Abstract
The orange pigmentation of the fungus Neurospora crassa is due to the accumulation of the xanthophyll neurosporaxanthin and precursor carotenoids. Two key reactions in the synthesis of these pigments, the formation of phytoene from geranylgeranyl pyrophosphate and the introduction of β cycles in desaturated carotenoid products, are catalyzed by two domains of a bifunctional protein, encoded by the gene al-2. We have determined the sequence of nine al-2 mutant alleles and analyzed the carotenoid content in the corresponding strains. One of the mutants is reddish and it is mutated in the cyclase domain of the protein, and the remaining eight mutants are albino and harbor different mutations on the phytoene synthase (PS) domain. Some of the mutations are expected to produce truncated polypeptides. A strain lacking most of the PS domain contained trace amounts of a carotenoid-like pigment, tentatively identified as the squalene desaturation product diapolycopene. In support, trace amounts of this compound were also found in a knock-out mutant for gene al-2, but not in that for gene al-1, coding for the carotene desaturase. The cyclase activity of the AL-2 enzyme from two albino mutants was investigated by heterologous expression in an appropriately engineered E. coli strain. One of the AL-2 enzymes, predictably with only 20% of the PS domain, showed full cyclase activity, suggesting functional independence of both domains. However, the second mutant showed no cyclase activity, indicating that some alterations in the phytoene synthase segment affect the cyclase domain. Expression experiments showed a diminished photoinduction of al-2 transcripts in the al-2 mutants compared to the wild type strain, suggesting a synergic effect between reduced expression and impaired enzymatic activities in the generation of their albino phenotypes.
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Affiliation(s)
- Violeta Díaz-Sánchez
- Department of Genetics, Faculty of Biology, University of Seville, Seville, Spain
| | - Alejandro F. Estrada
- Department of Genetics, Faculty of Biology, University of Seville, Seville, Spain
| | - Danika Trautmann
- Faculty of Biology, Albert-Ludwigs University of Freiburg, Freiburg, Germany
| | - M. Carmen Limón
- Department of Genetics, Faculty of Biology, University of Seville, Seville, Spain
| | - Salim Al-Babili
- Faculty of Biology, Albert-Ludwigs University of Freiburg, Freiburg, Germany
| | - Javier Avalos
- Department of Genetics, Faculty of Biology, University of Seville, Seville, Spain
- * E-mail:
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