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O-mannosyltransferase MaPmt2 contributes to stress tolerance, cell wall integrity and virulence in Metarhizium acridum. J Invertebr Pathol 2021; 184:107649. [PMID: 34343571 DOI: 10.1016/j.jip.2021.107649] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2021] [Revised: 07/24/2021] [Accepted: 07/25/2021] [Indexed: 11/22/2022]
Abstract
As a conserved post-translational modification, O-mannosyltransferase families play important roles in many cellular processes. Three subfamilies (MaPmt1, MaPmt2 and MaPmt4) are grouped in Metarhizium acridum according to sequence homology. The functions of MaPmt1 and MaPmt4 have been characterized in M. acridum previously. In this study, the functions of another member belonging to the Pmt2 subfamily, MaPmt2, were identified through RNAi strategy. The three MaPmt2 knockdown mutants showed dramatically decreased expression of MaPmt2. Phenotypic analyses showed that the mutants exhibited decreased tolerances to wet-heat, UV-B irradiation and cell wall perturbing chemicals. Further studies revealed that the mutants presented thinner cell walls observed by transmission electron microscope combined with changed cell wall components. Besides, knockdown of MaPmt2 decelerated conidial germination and decreased conidial yield. Compared with the wild-type strain, the MaPmt2 knockdown mutants caused impaired virulence only by topical inoculation. Results illustrated that the decreased virulence by inoculation could result from the delayed conidial germination on locust wings, reduced appressorium formation, as well as reduced turgor pressure in MaPmt2 knockdown mutants.
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Zhou H, Xu Y, Ebel F, Jin C. Galactofuranose (Galf)-containing sugar chain contributes to the hyphal growth, conidiation and virulence of F. oxysporum f.sp. cucumerinum. PLoS One 2021; 16:e0250064. [PMID: 34329342 PMCID: PMC8323920 DOI: 10.1371/journal.pone.0250064] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 03/31/2021] [Indexed: 01/14/2023] Open
Abstract
The ascomycete fungus Fusarium oxysporum f.sp. cucumerinum causes vascular wilt diseases in cucumber. However, few genes related to morphogenesis and pathogenicity of this fungal pathogen have been functionally characterized. BLASTp searches of the Aspergillus fumigatus UgmA and galatofuranosyltransferases (Galf-transferases) sequences in the F. oxysporum genome identified two genes encoding putative UDP-galactopyranose mutase (UGM), ugmA and ugmB, and six genes encoding putative Galf-transferase homologs. In this study, the single and double mutants of the ugmA, ugmB and gfsB were obtained. The roles of UGMs and GfsB were investigated by analyzing the phenotypes of the mutants. Our results showed that deletion of the ugmA gene led to a reduced production of galactofuranose-containing sugar chains, reduced growth and impaired conidiation of F. oxysporum f.sp. cucumerinum. Most importantly, the ugmA deletion mutant lost the pathogenicity in cucumber plantlets. Although deletion of the ugmB gene did not cause any visible phenotype, deletion of both ugmA and ugmB genes caused more severe phenotypes as compared with the ΔugmA, suggesting that UgmA and UgmB are redundant and they can both contribute to synthesis of UDP-Galf. Furthermore, the ΔgfsB exhibited an attenuated virulence although no other phenotype was observed. Our results demonstrate that the galactofuranose (Galf) synthesis contributes to the cell wall integrity, germination, hyphal growth, conidiation and virulence in Fusarium oxysporum f.sp. cucumerinum and an ideal target for the development of new anti-Fusarium agents.
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Affiliation(s)
- Hui Zhou
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Yueqiang Xu
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Frank Ebel
- Institute for Infectious Diseases and Zoonoses, LMU, Munich, Germany
| | - Cheng Jin
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
- National Engineering Research Center for Non-food Bio-refinery, Guangxi Academy of Sciences, Nanning, China
- * E-mail:
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Zhao G, Xu Y, Ouyang H, Luo Y, Sun S, Wang Z, Yang J, Jin C. Protein O-mannosylation affects protein secretion, cell wall integrity and morphogenesis in Trichoderma reesei. Fungal Genet Biol 2020; 144:103440. [PMID: 32758529 DOI: 10.1016/j.fgb.2020.103440] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 07/23/2020] [Accepted: 07/29/2020] [Indexed: 10/23/2022]
Abstract
Protein O-mannosyltransferases (PMTs) initiate O-mannosylation of proteins in the ER. Trichoderma reesei strains displayed a single representative of each PMT subfamily, Trpmt1, Trpmt2 and Trpmt4. In this work, two knockout strains ΔTrpmt1and ΔTrpmt4were obtained. Both mutants showed retarded growth, defective cell walls, reduced conidiation and decreased protein secretion. Additionally, the ΔTrpmt1strain displayed a thermosensitive growth phenotype, while the ΔTrpmt4 strain showed abnormal polarity. Meanwhile, OETrpmt2 strain, in which the Trpmt2 was over-expressed, exhibited increased conidiation, enhanced protein secretion and abnormal polarity. Using a lectin enrichment method and MS/MS analysis, 173 O-glycoproteins, 295 O-glycopeptides and 649 O-mannosylation sites were identified as the targets of PMTs in T. reesei. These identified O-mannoproteins are involved in various physiological processes such as protein folding, sorting, transport, quality control and secretion, as well as cell wall integrity and polarity. By comparing proteins identified in the mutants and its parent strain, the potential specific protein substrates of PMTs were identified. Based on our results, TrPMT1 is specifically involved inO-mannosylation of intracellular soluble proteins and secreted proteins, specially glycosidases. TrPMT2 is involved inO-mannosylation of secreted proteins and GPI-anchor proteins, and TrPMT4 mainly modifies multiple transmembrane proteins. The TrPMT1-TrPMT4 complex is responsible for O-mannosylation of proteins involved in cell wall integrity. Overexpression of TrPMT2 enhances protein secretion, which might be a new strategy to improve expression efficiency in T. reesei.
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Affiliation(s)
- Guangya Zhao
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing, China
| | - Yueqiang Xu
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing, China
| | - Haomiao Ouyang
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Yuanming Luo
- Public Technology Service Center, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Shutao Sun
- Public Technology Service Center, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Zhongfu Wang
- College of Food Science and Technology, Northwest University, Xi'an 710069, China
| | - Jinghua Yang
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Cheng Jin
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing, China; National Engineering Research Center for Non-food Bio-refinery, Guangxi Academy of Sciences, Nanning 530007, Guangxi, China.
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Xu Y, Zhou H, Zhao G, Yang J, Luo Y, Sun S, Wang Z, Li S, Jin C. Genetical and O-glycoproteomic analyses reveal the roles of three protein O-mannosyltransferases in phytopathogen Fusarium oxysporum f.sp. cucumerinum. Fungal Genet Biol 2020; 134:103285. [DOI: 10.1016/j.fgb.2019.103285] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 09/08/2019] [Accepted: 10/17/2019] [Indexed: 02/05/2023]
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Identification and Characterization of Key Charged Residues in the Cofilin Protein Involved in Azole Susceptibility, Apoptosis, and Virulence of Aspergillus fumigatus. Antimicrob Agents Chemother 2018; 62:AAC.01659-17. [PMID: 29483117 DOI: 10.1128/aac.01659-17] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Accepted: 02/10/2018] [Indexed: 12/28/2022] Open
Abstract
Through some specific amino acid residues, cofilin, a ubiquitous actin depolymerization factor, can significantly affect mitochondrial function related to drug resistance and apoptosis in Saccharomyces cerevisiae; however, this modulation in a major fungal pathogen, Aspergillus fumigatus, was still unclear. Hereby, it was found, first, that mutations on several charged residues in cofilin to alanine, D19A-R21A, E48A, and K36A, increased the formation of reactive oxygen species and induced apoptosis along with typical hallmarks, including mitochondrial membrane potential depolarization, cytochrome c release, upregulation of metacaspases, and DNA cleavage, in A. fumigatus Two of these mutations (D19A-R21A and K36A) increased acetyl coenzyme A and ATP concentrations by triggering fatty acid β-oxidation. The upregulated acetyl coenzyme A affected the ergosterol biosynthetic pathway, leading to overexpression of cyp51A and -B, while excess ATP fueled ATP-binding cassette transporters. Besides, both of these mutations reduced the susceptibility of A. fumigatus to azole drugs and enhanced the virulence of A. fumigatus in a Galleria mellonella infection model. Taken together, novel and key charged residues in cofilin were identified to be essential modules regulating the mitochondrial function involved in azole susceptibility, apoptosis, and virulence of A. fumigatus.
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Le THT, Oki A, Goto M, Shimizu K. Protein O-mannosyltransferases are required for sterigmatocystin production and developmental processes in Aspergillus nidulans. Curr Genet 2018; 64:1043-1056. [DOI: 10.1007/s00294-018-0816-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Revised: 02/19/2018] [Accepted: 02/20/2018] [Indexed: 12/19/2022]
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Sheridan KJ, Lechner BE, Keeffe GO, Keller MA, Werner ER, Lindner H, Jones GW, Haas H, Doyle S. Ergothioneine Biosynthesis and Functionality in the Opportunistic Fungal Pathogen, Aspergillus fumigatus. Sci Rep 2016; 6:35306. [PMID: 27748436 PMCID: PMC5066259 DOI: 10.1038/srep35306] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Accepted: 08/03/2016] [Indexed: 12/11/2022] Open
Abstract
Ergothioneine (EGT; 2-mercaptohistidine trimethylbetaine) is a trimethylated and sulphurised histidine derivative which exhibits antioxidant properties. Here we report that deletion of Aspergillus fumigatus egtA (AFUA_2G15650), which encodes a trimodular enzyme, abrogated EGT biosynthesis in this opportunistic pathogen. EGT biosynthetic deficiency in A. fumigatus significantly reduced resistance to elevated H2O2 and menadione, respectively, impaired gliotoxin production and resulted in attenuated conidiation. Quantitative proteomic analysis revealed substantial proteomic remodelling in ΔegtA compared to wild-type under both basal and ROS conditions, whereby the abundance of 290 proteins was altered. Specifically, the reciprocal differential abundance of cystathionine γ-synthase and β-lyase, respectively, influenced cystathionine availability to effect EGT biosynthesis. A combined deficiency in EGT biosynthesis and the oxidative stress response regulator Yap1, which led to extreme oxidative stress susceptibility, decreased resistance to heavy metals and production of the extracellular siderophore triacetylfusarinine C and increased accumulation of the intracellular siderophore ferricrocin. EGT dissipated H2O2 in vitro, and elevated intracellular GSH levels accompanied abrogation of EGT biosynthesis. EGT deficiency only decreased resistance to high H2O2 levels which suggests functionality as an auxiliary antioxidant, required for growth at elevated oxidative stress conditions. Combined, these data reveal new interactions between cellular redox homeostasis, secondary metabolism and metal ion homeostasis.
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Affiliation(s)
- Kevin J Sheridan
- Department of Biology, Maynooth University, Maynooth, Co. Kildare, Ireland
| | | | - Grainne O' Keeffe
- Department of Biology, Maynooth University, Maynooth, Co. Kildare, Ireland
| | - Markus A Keller
- Division of Biological Chemistry, Biocenter, Medical University Innsbruck, Innrain 80/82, Austria
| | - Ernst R Werner
- Division of Biological Chemistry, Biocenter, Medical University Innsbruck, Innrain 80/82, Austria
| | - Herbert Lindner
- Division of Clinical Biochemistry, Biocenter, Medical University Innsbruck, Innrain 80/82, Austria
| | - Gary W Jones
- Department of Biology, Maynooth University, Maynooth, Co. Kildare, Ireland
| | - Hubertus Haas
- Division of Molecular Biology, Biocenter, Medical University Innsbruck, Innrain 80/82, Austria
| | - Sean Doyle
- Department of Biology, Maynooth University, Maynooth, Co. Kildare, Ireland
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He Z, Luo L, Keyhani NO, Yu X, Ying S, Zhang Y. The C-terminal MIR-containing region in the Pmt1 O-mannosyltransferase restrains sporulation and is dispensable for virulence in Beauveria bassiana. Appl Microbiol Biotechnol 2016; 101:1143-1161. [DOI: 10.1007/s00253-016-7894-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Revised: 09/13/2016] [Accepted: 09/25/2016] [Indexed: 12/15/2022]
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9
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Guo M, Tan L, Nie X, Zhu X, Pan Y, Gao Z. The Pmt2p-Mediated Protein O-Mannosylation Is Required for Morphogenesis, Adhesive Properties, Cell Wall Integrity and Full Virulence of Magnaporthe oryzae. Front Microbiol 2016; 7:630. [PMID: 27199956 PMCID: PMC4852298 DOI: 10.3389/fmicb.2016.00630] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 04/18/2016] [Indexed: 12/28/2022] Open
Abstract
Protein O-mannosylation is a type of O-glycosylation that is characterized by the addition of mannose residues to target proteins, and is initially catalyzed by evolutionarily conserved protein O-mannosyltransferases (PMTs). In this study, three members of PMT were identified in Magnaporthe oryzae, and the pathogenic roles of MoPmt2, a member of PMT2 subfamily, were analyzed. We found that MoPmt2 is a homolog of Saccharomyces cerevisiae Pmt2 and could complement yeast Pmt2 function in resistance to CFW. Quantitative RT-PCR revealed that MoPmt2 is highly expressed during conidiation, and targeted disruption of MoPmt2 resulted in defects in conidiation and conidia morphology. The MoPmt2 mutants also showed a distinct reduction in fungal growth, which was associated with severe alterations in hyphal polarity. In addition, we found that the MoPmt2 mutants severely reduced virulence on both rice plants and barley leaves. The subsequent examination revealed that the fungal adhesion, conidial germination, CWI and invasive hyphae growth in host cells are responsible for defects on appressorium mediated penetration, and thus attenuated the pathogenicity of MoPmt2 mutants. Taken together, our results suggest that protein O-mannosyltransferase MoPmt2 plays essential roles in fungal growth and development, and is required for the full pathogenicity of M. oryzae.
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Affiliation(s)
- Min Guo
- Department of Plant Pathology, College of Plant Protection, Anhui Agricultural University Hefei, China
| | - Leyong Tan
- Department of Plant Pathology, College of Plant Protection, Anhui Agricultural University Hefei, China
| | - Xiang Nie
- Department of Plant Pathology, College of Plant Protection, Anhui Agricultural University Hefei, China
| | - Xiaolei Zhu
- Department of Plant Pathology, College of Plant Protection, Anhui Agricultural University Hefei, China
| | - Yuemin Pan
- Department of Plant Pathology, College of Plant Protection, Anhui Agricultural University Hefei, China
| | - Zhimou Gao
- Department of Plant Pathology, College of Plant Protection, Anhui Agricultural University Hefei, China
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Harries E, Gandía M, Carmona L, Marcos JF. The Penicillium digitatum protein O-mannosyltransferase Pmt2 is required for cell wall integrity, conidiogenesis, virulence and sensitivity to the antifungal peptide PAF26. MOLECULAR PLANT PATHOLOGY 2015; 16:748-761. [PMID: 25640475 PMCID: PMC6638402 DOI: 10.1111/mpp.12232] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The activity of protein O-mannosyltransferases (Pmts) affects the morphogenesis and virulence of fungal pathogens. Recently, PMT genes have been shown to determine the sensitivity of Saccharomyces cerevisiae to the antifungal peptide PAF26. This study reports the identification and characterization of the three Pdpmt genes in the citrus post-harvest pathogen Penicillium digitatum. The Pdpmt genes are expressed during fungal growth and fruit infection, with the highest induction for Pdpmt2. Pdpmt2 complemented the growth defect of the S. cerevisiae Δpmt2 strain. The Pdpmt2 gene mutation in P. digitatum caused pleiotropic effects, including a reduction in fungal growth and virulence, whereas its constitutive expression had no phenotypic effect. The Pdpmt2 null mutants also showed a distinctive colourless phenotype with a strong reduction in the number of conidia, which was associated with severe alterations in the development of conidiophores. Additional effects of the Pdpmt2 mutation were hyphal morphological alterations, increased sensitivity to cell wall-interfering compounds and a blockage of invasive growth. In contrast, the Pdpmt2 mutation increased tolerance to oxidative stress and to the antifungal activity of PAF26. These data confirm the role of protein O-glycosylation in the PAF26-mediated antifungal mechanism present in distantly related fungal species. Important to future crop protection strategies, this study demonstrates that a mutation rendering fungi more resistant to an antifungal peptide results in severe deleterious effects on fungal growth and virulence.
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Affiliation(s)
- Eleonora Harries
- Departamento de Ciencia de los Alimentos, Instituto de Agroquímica y Tecnología de Alimentos (IATA), CSIC, Avda, Agustín Escardino-7, Paterna, 46980, Valencia, Spain
| | - Mónica Gandía
- Departamento de Ciencia de los Alimentos, Instituto de Agroquímica y Tecnología de Alimentos (IATA), CSIC, Avda, Agustín Escardino-7, Paterna, 46980, Valencia, Spain
| | - Lourdes Carmona
- Departamento de Ciencia de los Alimentos, Instituto de Agroquímica y Tecnología de Alimentos (IATA), CSIC, Avda, Agustín Escardino-7, Paterna, 46980, Valencia, Spain
| | - Jose F Marcos
- Departamento de Ciencia de los Alimentos, Instituto de Agroquímica y Tecnología de Alimentos (IATA), CSIC, Avda, Agustín Escardino-7, Paterna, 46980, Valencia, Spain
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González M, Brito N, Frías M, González C. Botrytis cinerea protein O-mannosyltransferases play critical roles in morphogenesis, growth, and virulence. PLoS One 2013; 8:e65924. [PMID: 23762450 PMCID: PMC3675079 DOI: 10.1371/journal.pone.0065924] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Accepted: 04/30/2013] [Indexed: 12/22/2022] Open
Abstract
Protein O-glycosylation is crucial in determining the structure and function of numerous secreted and membrane-bound proteins. In fungi, this process begins with the addition of a mannose residue by protein O-mannosyltransferases (PMTs) in the lumen side of the ER membrane. We have generated mutants of the three Botrytis cinerea pmt genes to study their role in the virulence of this wide-range plant pathogen. B. cinerea PMTs, especially PMT2, are critical for the stability of the cell wall and are necessary for sporulation and for the generation of the extracellular matrix. PMTs are also individually required for full virulence in a variety of hosts, with a special role in the penetration of intact plant leaves. The most significant case is that of grapevine leaves, whose penetration requires the three functional PMTs. Furthermore, PMT2 also contributes significantly to fungal adherence on grapevine and tobacco leaves. Analysis of extracellular and membrane proteins showed significant changes in the pattern of protein secretion and glycosylation by the pmt mutants, and allowed the identification of new protein substrates putatively glycosylated by specific PMTs. Since plants do no possess these enzymes, PMTs constitute a promising target in the development of novel control strategies against B. cinerea.
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Affiliation(s)
- Mario González
- Departamento de Bioquímica y Biología Molecular, Universidad de La Laguna, La Laguna (Tenerife), Spain
| | - Nélida Brito
- Departamento de Bioquímica y Biología Molecular, Universidad de La Laguna, La Laguna (Tenerife), Spain
| | - Marcos Frías
- Departamento de Bioquímica y Biología Molecular, Universidad de La Laguna, La Laguna (Tenerife), Spain
| | - Celedonio González
- Departamento de Bioquímica y Biología Molecular, Universidad de La Laguna, La Laguna (Tenerife), Spain
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Govindappa N, Hanumanthappa M, Venkatarangaiah K, Kanojia K, Venkatesan K, Chatterjee A, Kusumanchi M, Dave N, Hazra P, Tiwari S, Sastry K. PMT1 gene plays a major role in O-mannosylation of insulin precursor in Pichia pastoris. Protein Expr Purif 2013; 88:164-71. [DOI: 10.1016/j.pep.2012.12.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Revised: 11/20/2012] [Accepted: 12/20/2012] [Indexed: 11/29/2022]
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Alam MK, El-Ganiny AM, Afroz S, Sanders DAR, Liu J, Kaminskyj SGW. Aspergillus nidulans galactofuranose biosynthesis affects antifungal drug sensitivity. Fungal Genet Biol 2012; 49:1033-43. [PMID: 23078837 DOI: 10.1016/j.fgb.2012.08.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Revised: 07/17/2012] [Accepted: 08/14/2012] [Indexed: 12/30/2022]
Abstract
The cell wall is essential for fungal survival in natural environments. Many fungal wall carbohydrates are absent from humans, so they are a promising source of antifungal drug targets. Galactofuranose (Galf) is a sugar that decorates certain carbohydrates and lipids. It comprises about 5% of the Aspergillus fumigatus cell wall, and may play a role in systemic aspergillosis. We are studying Aspergillus wall formation in the tractable model system, A. nidulans. Previously we showed single-gene deletions of three sequential A. nidulans Galf biosynthesis proteins each caused similar hyphal morphogenesis defects and 500-fold reduced colony growth and sporulation. Here, we generated ugeA, ugmA and ugtA strains controlled by the alcA(p) or niiA(p) regulatable promoters. For repression and expression, alcA(p)-regulated strains were grown on complete medium with glucose or threonine, whereas niiA(p)-regulated strains were grown on minimal medium with ammonium or nitrate. Expression was assessed by qPCR and colony phenotype. The alcA(p) and niiA(p) strains produced similar effects: colonies resembling wild type for gene expression, and resembling deletion strains for gene repression. Galf immunolocalization using the L10 monoclonal antibody showed that ugmA deletion and repression phenotypes correlated with loss of hyphal wall Galf. None of the gene manipulations affected itraconazole sensitivity, as expected. Deletion of any of ugmA, ugeA, ugtA, their repression by alcA(p) or niiA(p), OR, ugmA overexpression by alcA(p), increased sensitivity to Caspofungin. Strains with alcA(p)-mediated overexpression of ugeA and ugtA had lower caspofungin sensitivity. Galf appears to play an important role in A. nidulans growth and vigor.
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Affiliation(s)
- Md Kausar Alam
- Department of Biology, University of Saskatchewan, 112 Science Place, Saskatoon, SK, Canada S7N 5E2
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Protein Glycosylation in Aspergillus fumigatus Is Essential for Cell Wall Synthesis and Serves as a Promising Model of Multicellular Eukaryotic Development. Int J Microbiol 2011; 2012:654251. [PMID: 21977037 PMCID: PMC3184424 DOI: 10.1155/2012/654251] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Accepted: 07/19/2011] [Indexed: 02/05/2023] Open
Abstract
Glycosylation is a conserved posttranslational modification that is found in all eukaryotes, which helps generate proteins with multiple functions. Our knowledge of glycosylation mainly comes from the investigation of the yeast Saccharomyces cerevisiae and mammalian cells. However, during the last decade, glycosylation in the human pathogenic mold Aspergillus fumigatus has drawn significant attention. It has been revealed that glycosylation in A. fumigatus is crucial for its growth, cell wall synthesis, and development and that the process is more complicated than that found in the budding yeast S. cerevisiae. The present paper implies that the investigation of glycosylation in A. fumigatus is not only vital for elucidating the mechanism of fungal cell wall synthesis, which will benefit the design of new antifungal therapies, but also helps to understand the role of protein glycosylation in the development of multicellular eukaryotes. This paper describes the advances in functional analysis of protein glycosylation in A. fumigatus.
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Shapiro RS, Robbins N, Cowen LE. Regulatory circuitry governing fungal development, drug resistance, and disease. Microbiol Mol Biol Rev 2011; 75:213-67. [PMID: 21646428 PMCID: PMC3122626 DOI: 10.1128/mmbr.00045-10] [Citation(s) in RCA: 384] [Impact Index Per Article: 29.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Pathogenic fungi have become a leading cause of human mortality due to the increasing frequency of fungal infections in immunocompromised populations and the limited armamentarium of clinically useful antifungal drugs. Candida albicans, Cryptococcus neoformans, and Aspergillus fumigatus are the leading causes of opportunistic fungal infections. In these diverse pathogenic fungi, complex signal transduction cascades are critical for sensing environmental changes and mediating appropriate cellular responses. For C. albicans, several environmental cues regulate a morphogenetic switch from yeast to filamentous growth, a reversible transition important for virulence. Many of the signaling cascades regulating morphogenesis are also required for cells to adapt and survive the cellular stresses imposed by antifungal drugs. Many of these signaling networks are conserved in C. neoformans and A. fumigatus, which undergo distinct morphogenetic programs during specific phases of their life cycles. Furthermore, the key mechanisms of fungal drug resistance, including alterations of the drug target, overexpression of drug efflux transporters, and alteration of cellular stress responses, are conserved between these species. This review focuses on the circuitry regulating fungal morphogenesis and drug resistance and the impact of these pathways on virulence. Although the three human-pathogenic fungi highlighted in this review are those most frequently encountered in the clinic, they represent a minute fraction of fungal diversity. Exploration of the conservation and divergence of core signal transduction pathways across C. albicans, C. neoformans, and A. fumigatus provides a foundation for the study of a broader diversity of pathogenic fungi and a platform for the development of new therapeutic strategies for fungal disease.
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Affiliation(s)
| | | | - Leah E. Cowen
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
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What makes Aspergillus fumigatus a successful pathogen? Genes and molecules involved in invasive aspergillosis. Rev Iberoam Micol 2010; 27:155-82. [PMID: 20974273 DOI: 10.1016/j.riam.2010.10.003] [Citation(s) in RCA: 273] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2010] [Revised: 10/06/2010] [Accepted: 10/07/2010] [Indexed: 11/21/2022] Open
Abstract
Aspergillus fumigatus is an opportunistic pathogen that causes 90% of invasive aspergillosis (IA) due to Aspergillus genus, with a 50-95% mortality rate. It has been postulated that certain virulence factors are characteristic of A. fumigatus, but the "non-classical" virulence factors seem to be highly variable. Overall, published studies have demonstrated that the virulence of this fungus is multifactorial, associated with its structure, its capacity for growth and adaptation to stress conditions, its mechanisms for evading the immune system and its ability to cause damage to the host. In this review we intend to give a general overview of the genes and molecules involved in the development of IA. The thermotolerance section focuses on five genes related with the capacity of the fungus to grow at temperatures above 30°C (thtA, cgrA, afpmt1, kre2/afmnt1, and hsp1/asp f 12). The following sections discuss molecules and genes related to interaction with the host and with the immune responses. These sections include β-glucan, α-glucan, chitin, galactomannan, galactomannoproteins (afmp1/asp f 17 and afmp2), hydrophobins (rodA/hyp1 and rodB), DHN-melanin, their respective synthases (fks1, rho1-4, ags1-3, chsA-G, och1-4, mnn9, van1, anp1, glfA, pksP/alb1, arp1, arp2, abr1, abr2, and ayg1), and modifying enzymes (gel1-7, bgt1, eng1, ecm33, afpigA, afpmt1-2, afpmt4, kre2/afmnt1, afmnt2-3, afcwh41 and pmi); several enzymes related to oxidative stress protection such as catalases (catA, cat1/catB, cat2/katG, catC, and catE), superoxide dismutases (sod1, sod2, sod3/asp f 6, and sod4), fatty acid oxygenases (ppoA-C), glutathione tranferases (gstA-E), and others (afyap1, skn7, and pes1); and efflux transporters (mdr1-4, atrF, abcA-E, and msfA-E). In addition, this review considers toxins and related genes, such as a diffusible toxic substance from conidia, gliotoxin (gliP and gliZ), mitogillin (res/mitF/asp f 1), hemolysin (aspHS), festuclavine and fumigaclavine A-C, fumitremorgin A-C, verruculogen, fumagillin, helvolic acid, aflatoxin B1 and G1, and laeA. Two sections cover genes and molecules related with nutrient uptake, signaling and metabolic regulations involved in virulence, including enzymes, such as serine proteases (alp/asp f 13, alp2, and asp f 18), metalloproteases (mep/asp f 5, mepB, and mep20), aspartic proteases (pep/asp f 10, pep2, and ctsD), dipeptidylpeptidases (dppIV and dppV), and phospholipases (plb1-3 and phospholipase C); siderophores and iron acquisition (sidA-G, sreA, ftrA, fetC, mirB-C, and amcA); zinc acquisition (zrfA-H, zafA, and pacC); amino acid biosynthesis, nitrogen uptake, and cross-pathways control (areA, rhbA, mcsA, lysF, cpcA/gcn4p, and cpcC/gcn2p); general biosynthetic pathway (pyrG, hcsA, and pabaA), trehalose biosynthesis (tpsA and tpsB), and other regulation pathways such as those of the MAP kinases (sakA/hogA, mpkA-C, ste7, pbs2, mkk2, steC/ste11, bck1, ssk2, and sho1), G-proteins (gpaA, sfaD, and cpgA), cAMP-PKA signaling (acyA, gpaB, pkaC1, and pkaR), His kinases (fos1 and tcsB), Ca(2+) signaling (calA/cnaA, crzA, gprC and gprD), and Ras family (rasA, rasB, and rhbA), and others (ace2, medA, and srbA). Finally, we also comment on the effect of A. fumigatus allergens (Asp f 1-Asp f 34) on IA. The data gathered generate a complex puzzle, the pieces representing virulence factors or the different activities of the fungus, and these need to be arranged to obtain a comprehensive vision of the virulence of A. fumigatus. The most recent gene expression studies using DNA-microarrays may be help us to understand this complex virulence, and to detect targets to develop rapid diagnostic methods and new antifungal agents.
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Mouyna I, Kniemeyer O, Jank T, Loussert C, Mellado E, Aimanianda V, Beauvais A, Wartenberg D, Sarfati J, Bayry J, Prévost MC, Brakhage AA, Strahl S, Huerre M, Latgé JP. Members of protein O-mannosyltransferase family in Aspergillus fumigatus differentially affect growth, morphogenesis and viability. Mol Microbiol 2010; 76:1205-21. [PMID: 20398215 DOI: 10.1111/j.1365-2958.2010.07164.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
O-mannosylation is an essential protein modification in eukaryotes. It is initiated at the endoplasmic reticulum by O-mannosyltransferases (PMT) that are evolutionary conserved from yeast to humans. The PMT family is phylogenetically classified into PMT1, PMT2 and PMT4 subfamilies, which differ in protein substrate specificity and number of genes per subfamily. In this study, we characterized for the first time the whole PMT family of a pathogenic filamentous fungus, Aspergillus fumigatus. Genome analysis showed that only one member of each subfamily is present in A. fumigatus, PMT1, PMT2 and PMT4. Despite the fact that all PMTs are transmembrane proteins with conserved peptide motifs, the phenotype of each PMT deletion mutant was very different in A. fumigatus. If disruption of PMT1 did not reveal any phenotype, deletion of PMT2 was lethal. Disruption of PMT4 resulted in abnormal mycelial growth and highly reduced conidiation associated to significant proteomic changes. The double pmt1pmt4 mutant was lethal. The single pmt4 mutant exhibited an exquisite sensitivity to echinocandins that is associated to major changes in the expression of signal transduction cascade genes. These results indicate that the PMT family members play a major role in growth, morphogenesis and viability of A. fumigatus.
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Affiliation(s)
- Isabelle Mouyna
- Unité des Aspergillus, Institut Pasteur, 25 rue du Docteur Roux 75724 Paris Cedex 15, France.
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