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Gong X, Zhou Y, Qin Q, Wang B, Wang L, Jin C, Fang W. Nitrate assimilation compensates for cell wall biosynthesis in the absence of Aspergillus fumigatus phosphoglucose isomerase. Appl Environ Microbiol 2024; 90:e0113824. [PMID: 39158312 PMCID: PMC11412302 DOI: 10.1128/aem.01138-24] [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: 06/11/2024] [Accepted: 07/20/2024] [Indexed: 08/20/2024] Open
Abstract
Phosphoglucose isomerase (PGI) links glycolysis, the pentose phosphate pathway (PPP), and the synthesis of cell wall precursors in fungi by facilitating the reversible conversion between glucose-6-phosphate (Glc6p) and fructose-6-phosphate (Fru6P). In a previous study, we established the essential role of PGI in cell wall biosynthesis in the opportunistic human fungal pathogen Aspergillus fumigatus, highlighting its potential as a therapeutic target. In this study, we conducted transcriptomic analysis and discovered that the Δpgi mutant exhibited enhanced glycolysis, reduced PPP, and an upregulation of cell wall precursor biosynthesis pathways. Phenotypic analysis revealed defective protein N-glycosylation in the mutant, notably the absence of glycosylated virulence factors DPP V and catalase 1. Interestingly, the cell wall defects in the mutant were not accompanied by activation of the MpkA-dependent cell wall integrity (CWI) signaling pathway. Instead, nitrate assimilation was activated in the Δpgi mutant, stimulating glutamine synthesis and providing amino donors for chitin precursor biosynthesis. Blocking the nitrate assimilation pathway severely impaired the growth of the Δpgi mutant, highlighting the crucial role of nitrate assimilation in rescuing cell wall defects. This study unveils the connection between nitrogen assimilation and cell wall compensation in A. fumigatus.IMPORTANCEAspergillus fumigatus is a common and serious human fungal pathogen that causes a variety of diseases. Given the limited availability of antifungal drugs and increasing drug resistance, it is imperative to understand the fungus' survival mechanisms for effective control of fungal infections. Our previous study highlighted the essential role of A. fumigatus PGI in maintaining cell wall integrity, phosphate sugar homeostasis, and virulence. The present study further illuminates the involvement of PGI in protein N-glycosylation. Furthermore, this research reveals that the nitrogen assimilation pathway, rather than the canonical MpkA-dependent CWI pathway, compensates for cell wall deficiencies in the mutant. These findings offer valuable insights into a novel adaptation mechanism of A. fumigatus to address cell wall defects, which could hold promise for the treatment of infections.
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Affiliation(s)
- Xiufang Gong
- Institute of
Biological Sciences and Technology, Guangxi Academy of
Sciences, Nanning,
Guangxi, China
- State Key Laboratory
of Mycology, Institute of Microbiology, Chinese Academy of
Sciences, Beijing,
China
| | - Yao Zhou
- Institute of
Biological Sciences and Technology, Guangxi Academy of
Sciences, Nanning,
Guangxi, China
| | - Qijian Qin
- Institute of
Biological Sciences and Technology, Guangxi Academy of
Sciences, Nanning,
Guangxi, China
| | - Bin Wang
- Institute of
Biological Sciences and Technology, Guangxi Academy of
Sciences, Nanning,
Guangxi, China
| | - Linqi Wang
- State Key Laboratory
of Mycology, Institute of Microbiology, Chinese Academy of
Sciences, Beijing,
China
| | - Cheng Jin
- Institute of
Biological Sciences and Technology, Guangxi Academy of
Sciences, Nanning,
Guangxi, China
- State Key Laboratory
of Mycology, Institute of Microbiology, Chinese Academy of
Sciences, Beijing,
China
| | - Wenxia Fang
- Institute of
Biological Sciences and Technology, Guangxi Academy of
Sciences, Nanning,
Guangxi, China
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2
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Redrado-Hernández S, Macías-León J, Castro-López J, Belén Sanz A, Dolader E, Arias M, González-Ramírez AM, Sánchez-Navarro D, Petryk Y, Farkaš V, Vincke C, Muyldermans S, García-Barbazán I, Del Agua C, Zaragoza O, Arroyo J, Pardo J, Gálvez EM, Hurtado-Guerrero R. Broad Protection against Invasive Fungal Disease from a Nanobody Targeting the Active Site of Fungal β-1,3-Glucanosyltransferases. Angew Chem Int Ed Engl 2024; 63:e202405823. [PMID: 38856634 DOI: 10.1002/anie.202405823] [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: 04/01/2024] [Revised: 05/20/2024] [Accepted: 06/10/2024] [Indexed: 06/11/2024]
Abstract
Invasive fungal disease accounts for about 3.8 million deaths annually, an unacceptable rate that urgently prompts the discovery of new knowledge-driven treatments. We report the use of camelid single-domain nanobodies (Nbs) against fungal β-1,3-glucanosyltransferases (Gel) involved in β-1,3-glucan transglycosylation. Crystal structures of two Nbs with Gel4 from Aspergillus fumigatus revealed binding to a dissimilar CBM43 domain and a highly conserved catalytic domain across fungal species, respectively. Anti-Gel4 active site Nb3 showed significant antifungal efficacy in vitro and in vivo prophylactically and therapeutically against different A. fumigatus and Cryptococcus neoformans isolates, reducing the fungal burden and disease severity, thus significantly improving immunocompromised animal survival. Notably, C. deneoformans (serotype D) strains were more susceptible to Nb3 and genetic Gel deletion than C. neoformans (serotype A) strains, indicating a key role for β-1,3-glucan remodelling in C. deneoformans survival. These findings add new insight about the role of β-1,3-glucan in fungal biology and demonstrate the potential of nanobodies in targeting fungal enzymes to combat invasive fungal diseases.
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Grants
- PID2022-136362NB-I00 Ministerio de Asuntos Económicos y Transformación Digital, Gobierno de España
- BIO2016-79289-P Ministerio de Economía y Competitividad, Gobierno de España
- PID2019-105223GB-I00 Ministerio de Ciencia, Innovación y Universidades y Agencia Estatal de Investigación, Gobierno de España
- PID2022-136888NB-I00 Ministerio de Ciencia e Innovación y Agencia Estatal de Investigación, Gobierno de España
- PID2020-114546RB Ministerio de Ciencia e Innovación y Agencia Estatal de Investigación, Gobierno de España
- PID2020-113963RB-I00 Ministerio de Ciencia e Innovación y Agencia Estatal de Investigación, Gobierno de España
- S2017/BMD3691-InGEMICS-CM Comunidad de Madrid
- B29_17R, E34_R17, LMP58_18 and LMP139_21 Gobierno de Aragon
- Nanofungi Precipita (crowdfunding)
- BIOSTRUCTX_5186 FP7 (2007-2013), BioStruct-X
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Affiliation(s)
- Sergio Redrado-Hernández
- Instituto de Carboquímica ICB-CSIC, 50018, Zaragoza, Spain
- Center for Biomedical Research in Network in Infectious Diseases (CIBERINFEC), Health Institute Carlos III, 28029, Madrid, Spain
| | - Javier Macías-León
- Institute of Biocomputation and Physics of Complex Systems (BIFI), University of Zaragoza, Mariano Esquillor s/n, Campus Rio Ebro, Edificio I+D, 50018, Zaragoza, Spain
| | - Jorge Castro-López
- Institute of Biocomputation and Physics of Complex Systems (BIFI), University of Zaragoza, Mariano Esquillor s/n, Campus Rio Ebro, Edificio I+D, 50018, Zaragoza, Spain
| | - Ana Belén Sanz
- Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad Complutense de Madrid, 28040, Madrid, Spain
| | - Elena Dolader
- Department of Microbiology, Pediatry, Radiology and Public Health, University of Zaragoza, 50009, Zaragoza, Spain
- Aragón Health Research Institute (IIS Aragón), Biomedical Research Centre of Aragón (CIBA), 50009, Zaragoza, Spain
| | - Maykel Arias
- Center for Biomedical Research in Network in Infectious Diseases (CIBERINFEC), Health Institute Carlos III, 28029, Madrid, Spain
- Department of Microbiology, Pediatry, Radiology and Public Health, University of Zaragoza, 50009, Zaragoza, Spain
- Aragón Health Research Institute (IIS Aragón), Biomedical Research Centre of Aragón (CIBA), 50009, Zaragoza, Spain
| | - Andrés Manuel González-Ramírez
- Institute of Biocomputation and Physics of Complex Systems (BIFI), University of Zaragoza, Mariano Esquillor s/n, Campus Rio Ebro, Edificio I+D, 50018, Zaragoza, Spain
| | - David Sánchez-Navarro
- Institute of Biocomputation and Physics of Complex Systems (BIFI), University of Zaragoza, Mariano Esquillor s/n, Campus Rio Ebro, Edificio I+D, 50018, Zaragoza, Spain
| | - Yuliya Petryk
- Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad Complutense de Madrid, 28040, Madrid, Spain
| | - Vladimír Farkaš
- Department of Glycobiology, Institute of Chemistry, Center for Glycomics, Slovak Academy of Sciences, 84538, Bratislava, Slovakia
| | - Cécile Vincke
- Laboratory of Cellular and Molecular Immunology, Vrije Universiteit Brussel, 1050, Brussels, Belgium
| | - Serge Muyldermans
- Laboratory of Cellular and Molecular Immunology, Vrije Universiteit Brussel, 1050, Brussels, Belgium
| | - Irene García-Barbazán
- Mycology Reference Laboratory. National Centre for Microbiology., Health Institute Carlos III, 28220, Majadahonda, Madrid, Spain
| | - Celia Del Agua
- Aragón Health Research Institute (IIS Aragón), Biomedical Research Centre of Aragón (CIBA), 50009, Zaragoza, Spain
- Department of Pathology, Hospital Clínico Universitario Lozano Blesa, IIS-Aragón, 50009, Zaragoza, Spain
| | - Oscar Zaragoza
- Center for Biomedical Research in Network in Infectious Diseases (CIBERINFEC), Health Institute Carlos III, 28029, Madrid, Spain
- Mycology Reference Laboratory. National Centre for Microbiology., Health Institute Carlos III, 28220, Majadahonda, Madrid, Spain
| | - Javier Arroyo
- Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad Complutense de Madrid, 28040, Madrid, Spain
| | - Julián Pardo
- Center for Biomedical Research in Network in Infectious Diseases (CIBERINFEC), Health Institute Carlos III, 28029, Madrid, Spain
- Department of Microbiology, Pediatry, Radiology and Public Health, University of Zaragoza, 50009, Zaragoza, Spain
- Aragón Health Research Institute (IIS Aragón), Biomedical Research Centre of Aragón (CIBA), 50009, Zaragoza, Spain
| | - Eva M Gálvez
- Instituto de Carboquímica ICB-CSIC, 50018, Zaragoza, Spain
- Center for Biomedical Research in Network in Infectious Diseases (CIBERINFEC), Health Institute Carlos III, 28029, Madrid, Spain
| | - Ramon Hurtado-Guerrero
- Institute of Biocomputation and Physics of Complex Systems (BIFI), University of Zaragoza, Mariano Esquillor s/n, Campus Rio Ebro, Edificio I+D, 50018, Zaragoza, Spain
- Fundación ARAID, 50018, Zaragoza, Spain
- Copenhagen Center for Glycomics, Department of Cellular and Molecular Medicine, University of Copenhagen, DK-2200, Copenhagen, Denmark
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3
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Chen Y, Gao F, Chen X, Tao S, Chen P, Lin W. The basic leucine zipper transcription factor MeaB is critical for biofilm formation, cell wall integrity, and virulence in Aspergillus fumigatus. mSphere 2024; 9:e0061923. [PMID: 38284755 PMCID: PMC10900910 DOI: 10.1128/msphere.00619-23] [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: 10/17/2023] [Accepted: 12/18/2023] [Indexed: 01/30/2024] Open
Abstract
The regulation of fungal cell wall biosynthesis is crucial for cell wall integrity maintenance and directly impacts fungal pathogen virulence. Although numerous genes are involved in fungal cell wall polysaccharide biosynthesis through multiple pathways, the underlying regulatory mechanism is still not fully understood. In this study, we identified and functionally characterized a direct downstream target of SomA, the basic-region leucine zipper transcription factor MeaB, playing a certain role in Aspergillus fumigatus cell wall integrity. Loss of meaB reduces hyphal growth, causes severe defects in galactosaminogalactan-mediated biofilm formation, and attenuates virulence in a Galleria mellonella infection model. Furthermore, the meaB null mutant strain exhibited hypersensitivity to cell wall-perturbing agents and significantly alters the cell wall structure. Transcriptional profile analysis revealed that MeaB positively regulates the expression of the galactosaminogalactan biosynthesis and β-1,3-glucanosyltransferase genes uge3, agd3, and sph3 and gel1, gel5, and gel7, respectively, as well as genes involved in amino sugar and nucleotide sugar metabolism. Further study demonstrated that MeaB could respond to cell wall stress and contribute to the proper expression of mitogen-activated protein kinase genes mpkA and mpkC in the presence of different concentrations of congo red. In conclusion, A. fumigatus MeaB plays a critical role in cell wall integrity by governing the expression of genes encoding cell wall-related proteins, thus impacting the virulence of this fungus.IMPORTANCEAspergillus fumigatus is a common opportunistic mold that causes life-threatening infections in immunosuppressed patients. The fungal cell wall is a complex and dynamic organelle essential for the development of pathogenic fungi. Genes involved in cell wall polysaccharide biosynthesis and remodeling are crucial for fungal pathogen virulence. However, the potential regulatory mechanism for cell wall integrity remains to be fully defined in A. fumigatus. In the present study, we identify basic-region leucine zipper transcription factor MeaB as an important regulator of cell wall galactosaminogalactan biosynthesis and β-1,3-glucan remodeling that consequently impacts stress response and virulence of fungal pathogens. Thus, we illuminate a mechanism of transcriptional control fungal cell wall polysaccharide biosynthesis and stress response. As these cell wall components are promising therapeutic targets for fungal infections, understanding the regulatory mechanism of such polysaccharides will provide new therapeutic opportunities.
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Affiliation(s)
- Yuan Chen
- Nanjing University of Chinese Medicine, Nanjing Drum Tower Hospital, Nanjing, China
| | - Fei Gao
- Nanjing University of Chinese Medicine, Nanjing Drum Tower Hospital, Nanjing, China
| | - Xiaojin Chen
- Nanjing University of Chinese Medicine, Nanjing Drum Tower Hospital, Nanjing, China
| | - Siyuan Tao
- Nanjing University of Chinese Medicine, Nanjing Drum Tower Hospital, Nanjing, China
| | - Peiying Chen
- Nanjing University of Chinese Medicine, Nanjing Drum Tower Hospital, Nanjing, China
| | - Wei Lin
- Nanjing University of Chinese Medicine, Nanjing Drum Tower Hospital, Nanjing, China
- Jiangsu Collaborative Innovation Center of Chinese Medicinal Resources Industrialization, Nanjing, China
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
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4
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Schruefer S, Pschibul A, Wong SSW, Sae-Ong T, Wolf T, Schäuble S, Panagiotou G, Brakhage AA, Aimanianda V, Kniemeyer O, Ebel F. Distinct transcriptional responses to fludioxonil in Aspergillus fumigatus and its ΔtcsC and Δskn7 mutants reveal a crucial role for Skn7 in the cell wall reorganizations triggered by this antifungal. BMC Genomics 2023; 24:684. [PMID: 37964194 PMCID: PMC10647056 DOI: 10.1186/s12864-023-09777-5] [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: 03/10/2023] [Accepted: 10/31/2023] [Indexed: 11/16/2023] Open
Abstract
BACKGROUND Aspergillus fumigatus is a major fungal pathogen that causes severe problems due to its increasing resistance to many therapeutic agents. Fludioxonil is a compound that triggers a lethal activation of the fungal-specific High Osmolarity Glycerol pathway. Its pronounced antifungal activity against A. fumigatus and other pathogenic molds renders this agent an attractive lead substance for the development of new therapeutics. The group III hydride histidine kinase TcsC and its downstream target Skn7 are key elements of the multistep phosphorelay that represents the initial section of the High Osmolarity Glycerol pathway. Loss of tcsC results in resistance to fludioxonil, whereas a Δskn7 mutant is partially, but not completely resistant. RESULTS In this study, we compared the fludioxonil-induced transcriptional responses in the ΔtcsC and Δskn7 mutant and their parental A. fumigatus strain. The number of differentially expressed genes correlates well with the susceptibility level of the individual strains. The wild type and, to a lesser extend also the Δskn7 mutant, showed a multi-faceted stress response involving genes linked to ribosomal and peroxisomal function, iron homeostasis and oxidative stress. A marked difference between the sensitive wild type and the largely resistant Δskn7 mutant was evident for many cell wall-related genes and in particular those involved in the biosynthesis of chitin. Biochemical data corroborate this differential gene expression that does not occur in response to hyperosmotic stress. CONCLUSIONS Our data reveal that fludioxonil induces a strong and TcsC-dependent stress that affects many aspects of the cellular machinery. The data also demonstrate a link between Skn7 and the cell wall reorganizations that foster the characteristic ballooning and the subsequent lysis of fludioxonil-treated cells.
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Affiliation(s)
- Sebastian Schruefer
- Institute for Infectious Diseases and Zoonoses, Ludwig-Maximilians-University, Munich, Germany
| | - Annica Pschibul
- Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knöll Institute, Jena, Germany
| | - Sarah Sze Wah Wong
- UMR2000, Molecular Mycology Unit, Mycology Department, Institut Pasteur, Université Paris Cité, CNRS, Paris, France
| | - Tongta Sae-Ong
- Microbiome Dynamics, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knöll Institute, Jena, Germany
| | - Thomas Wolf
- Microbiome Dynamics, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knöll Institute, Jena, Germany
| | - Sascha Schäuble
- Microbiome Dynamics, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knöll Institute, Jena, Germany
| | - Gianni Panagiotou
- Microbiome Dynamics, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knöll Institute, Jena, Germany
- Institute of Microbiology, Friedrich Schiller University, Jena, Germany
| | - Axel A Brakhage
- Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knöll Institute, Jena, Germany
- Institute of Microbiology, Friedrich Schiller University, Jena, Germany
| | - Vishukumar Aimanianda
- UMR2000, Molecular Mycology Unit, Mycology Department, Institut Pasteur, Université Paris Cité, CNRS, Paris, France
- Institut Pasteur, Université Paris Cité, Immunobiology of Aspergillus, Mycology Department, Paris, France
| | - Olaf Kniemeyer
- Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knöll Institute, Jena, Germany
| | - Frank Ebel
- Institute for Infectious Diseases and Zoonoses, Ludwig-Maximilians-University, Munich, Germany.
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5
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Liu H, Lu X, Li M, Lun Z, Yan X, Yin C, Yuan G, Wang X, Liu N, Liu D, Wu M, Luo Z, Zhang Y, Bhadauria V, Yang J, Talbot NJ, Peng YL. Plant immunity suppression by an exo-β-1,3-glucanase and an elongation factor 1α of the rice blast fungus. Nat Commun 2023; 14:5491. [PMID: 37679340 PMCID: PMC10484928 DOI: 10.1038/s41467-023-41175-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Accepted: 08/23/2023] [Indexed: 09/09/2023] Open
Abstract
Fungal cell walls undergo continual remodeling that generates β-1,3-glucan fragments as products of endo-glycosyl hydrolases (GHs), which can be recognized as pathogen-associated molecular patterns (PAMPs) and trigger plant immune responses. How fungal pathogens suppress those responses is often poorly understood. Here, we study mechanisms underlying the suppression of β-1,3-glucan-triggered plant immunity by the blast fungus Magnaporthe oryzae. We show that an exo-β-1,3-glucanase of the GH17 family, named Ebg1, is important for fungal cell wall integrity and virulence of M. oryzae. Ebg1 can hydrolyze β-1,3-glucan and laminarin into glucose, thus suppressing β-1,3-glucan-triggered plant immunity. However, in addition, Ebg1 seems to act as a PAMP, independent of its hydrolase activity. This Ebg1-induced immunity appears to be dampened by the secretion of an elongation factor 1 alpha protein (EF1α), which interacts and co-localizes with Ebg1 in the apoplast. Future work is needed to understand the mechanisms behind Ebg1-induced immunity and its suppression by EF1α.
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Affiliation(s)
- Hang Liu
- Ministry of Agriculture and Rural Affairs Key Laboratory for Crop Pest Monitoring and Green Control, China Agricultural University, Beijing, 100193, China
| | - Xunli Lu
- Ministry of Agriculture and Rural Affairs Key Laboratory for Crop Pest Monitoring and Green Control, China Agricultural University, Beijing, 100193, China
| | - Mengfei Li
- Ministry of Agriculture and Rural Affairs Key Laboratory for Crop Pest Monitoring and Green Control, China Agricultural University, Beijing, 100193, China
| | - Zhiqin Lun
- Ministry of Agriculture and Rural Affairs Key Laboratory for Crop Pest Monitoring and Green Control, China Agricultural University, Beijing, 100193, China
| | - Xia Yan
- The Sainsbury Laboratory, University of East Anglia, Norwich Research Park, Norwich, NR4 7UH, UK
| | - Changfa Yin
- Ministry of Agriculture and Rural Affairs Key Laboratory for Crop Pest Monitoring and Green Control, China Agricultural University, Beijing, 100193, China
| | - Guixin Yuan
- Ministry of Agriculture and Rural Affairs Key Laboratory for Crop Pest Monitoring and Green Control, China Agricultural University, Beijing, 100193, China
| | - Xingbin Wang
- Ministry of Agriculture and Rural Affairs Key Laboratory for Crop Pest Monitoring and Green Control, China Agricultural University, Beijing, 100193, China
| | - Ning Liu
- Ministry of Agriculture and Rural Affairs Key Laboratory for Crop Pest Monitoring and Green Control, China Agricultural University, Beijing, 100193, China
| | - Di Liu
- Ministry of Agriculture and Rural Affairs Key Laboratory for Crop Pest Monitoring and Green Control, China Agricultural University, Beijing, 100193, China
| | - Mian Wu
- Ministry of Agriculture and Rural Affairs Key Laboratory for Crop Pest Monitoring and Green Control, China Agricultural University, Beijing, 100193, China
| | - Ziluolong Luo
- Ministry of Agriculture and Rural Affairs Key Laboratory for Crop Pest Monitoring and Green Control, China Agricultural University, Beijing, 100193, China
| | - Yan Zhang
- Ministry of Agriculture and Rural Affairs Key Laboratory for Crop Pest Monitoring and Green Control, China Agricultural University, Beijing, 100193, China
| | - Vijai Bhadauria
- Ministry of Agriculture and Rural Affairs Key Laboratory for Crop Pest Monitoring and Green Control, China Agricultural University, Beijing, 100193, China
| | - Jun Yang
- Ministry of Agriculture and Rural Affairs Key Laboratory for Crop Pest Monitoring and Green Control, China Agricultural University, Beijing, 100193, China
| | - Nicholas J Talbot
- The Sainsbury Laboratory, University of East Anglia, Norwich Research Park, Norwich, NR4 7UH, UK
| | - You-Liang Peng
- Ministry of Agriculture and Rural Affairs Key Laboratory for Crop Pest Monitoring and Green Control, China Agricultural University, Beijing, 100193, China.
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Samalova M, Flamant P, Beau R, Bromley M, Moya-Nilges M, Fontaine T, Latgé JP, Mouyna I. The New GPI-Anchored Protein, SwgA, Is Involved in Nitrogen Metabolism in the Pathogenic Filamentous Fungus Aspergillus fumigatus. J Fungi (Basel) 2023; 9:256. [PMID: 36836370 PMCID: PMC9960506 DOI: 10.3390/jof9020256] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 02/09/2023] [Accepted: 02/10/2023] [Indexed: 02/17/2023] Open
Abstract
GPI-anchored proteins display very diverse biological (biochemical and immunological) functions. An in silico analysis has revealed that the genome of Aspergillus fumigatus contains 86 genes coding for putative GPI-anchored proteins (GPI-APs). Past research has demonstrated the involvement of GPI-APs in cell wall remodeling, virulence, and adhesion. We analyzed a new GPI-anchored protein called SwgA. We showed that this protein is mainly present in the Clavati of Aspergillus and is absent from yeasts and other molds. The protein, localized in the membrane of A. fumigatus, is involved in germination, growth, and morphogenesis, and is associated with nitrogen metabolism and thermosensitivity. swgA is controlled by the nitrogen regulator AreA. This current study indicates that GPI-APs have more general functions in fungal metabolism than cell wall biosynthesis.
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Affiliation(s)
- Marketa Samalova
- Unité des Aspergillus, Département de Mycologie Institut Pasteur, 25-28 rue du Docteur Roux, CEDEX 15, 75724 Paris, France
| | - Patricia Flamant
- Unité des Aspergillus, Département de Mycologie Institut Pasteur, 25-28 rue du Docteur Roux, CEDEX 15, 75724 Paris, France
| | - Rémi Beau
- Unité des Aspergillus, Département de Mycologie Institut Pasteur, 25-28 rue du Docteur Roux, CEDEX 15, 75724 Paris, France
| | - Mike Bromley
- Manchester Fungal Infection Group, Division of Infection, Immunity and Respiratory Medicine, Faculty of Biology, Medicine and Health, University of Manchester, CTF Building, Grafton Street, Manchester M13 9NT, UK
| | - Maryse Moya-Nilges
- Unité Technologie et Service Bioimagerie Ultrastructurale (UTechS UBI), Institut Pasteur, 28 rue du Docteur Roux, 75015 Paris, France
| | - Thierry Fontaine
- Unité des Aspergillus, Département de Mycologie Institut Pasteur, 25-28 rue du Docteur Roux, CEDEX 15, 75724 Paris, France
| | - Jean-Paul Latgé
- Unité des Aspergillus, Département de Mycologie Institut Pasteur, 25-28 rue du Docteur Roux, CEDEX 15, 75724 Paris, France
| | - Isabelle Mouyna
- Unité des Aspergillus, Département de Mycologie Institut Pasteur, 25-28 rue du Docteur Roux, CEDEX 15, 75724 Paris, France
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7
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Exposure of Aspergillus fumigatus to Klebsiella pneumoniae Culture Filtrate Inhibits Growth and Stimulates Gliotoxin Production. J Fungi (Basel) 2023; 9:jof9020222. [PMID: 36836336 PMCID: PMC9961802 DOI: 10.3390/jof9020222] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 02/01/2023] [Accepted: 02/03/2023] [Indexed: 02/10/2023] Open
Abstract
Aspergillus fumigatus is an opportunistic fungal pathogen capable of inducing chronic and acute infection in susceptible patients. A. fumigatus interacts with numerous bacteria that compose the microbiota of the lung, including Pseudomonas aeruginosa and Klebsiella pneumoniae, both of which are common isolates from cystic fibrosis sputum. Exposure of A. fumigatus to K. pneumoniae culture filtrate reduced fungal growth and increased gliotoxin production. Qualitative proteomic analysis of the K. pneumoniae culture filtrate identified proteins associated with metal sequestering, enzymatic degradation and redox activity, which may impact fungal growth and development. Quantitative proteomic analysis of A. fumigatus following exposure to K. pneumoniae culture filtrate (25% v/v) for 24 h revealed a reduced abundance of 1,3-beta-glucanosyltransferase (-3.97 fold), methyl sterol monooxygenase erg25B (-2.9 fold) and calcium/calmodulin-dependent protein kinase (-4.2 fold) involved in fungal development, and increased abundance of glutathione S-transferase GliG (+6.17 fold), non-ribosomal peptide synthase GliP (+3.67 fold), O-methyltransferase GliM (+3.5 fold), gamma-glutamyl acyltransferase GliK (+2.89 fold) and thioredoxin reductase GliT (+2.33 fold) involved in gliotoxin production. These results reveal that exposure of A. fumigatus to K. pneumoniae in vivo could exacerbate infection and negatively impact patient prognosis.
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8
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Liu Z, Valsecchi I, Le Meur RA, Simenel C, Guijarro JI, Comte C, Muszkieta L, Mouyna I, Henrissat B, Aimanianda V, Latgé JP, Fontaine T. Conidium Specific Polysaccharides in Aspergillus fumigatus. J Fungi (Basel) 2023; 9:jof9020155. [PMID: 36836270 PMCID: PMC9964227 DOI: 10.3390/jof9020155] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 01/09/2023] [Accepted: 01/19/2023] [Indexed: 01/27/2023] Open
Abstract
Earlier studies have shown that the outer layers of the conidial and mycelial cell walls of Aspergillus fumigatus are different. In this work, we analyzed the polysaccharidome of the resting conidial cell wall and observed major differences within the mycelium cell wall. Mainly, the conidia cell wall was characterized by (i) a smaller amount of α-(1,3)-glucan and chitin; (ii) a larger amount of β-(1,3)-glucan, which was divided into alkali-insoluble and water-soluble fractions, and (iii) the existence of a specific mannan with side chains containing galactopyranose, glucose, and N-acetylglucosamine residues. An analysis of A. fumigatus cell wall gene mutants suggested that members of the fungal GH-72 transglycosylase family play a crucial role in the conidia cell wall β-(1,3)-glucan organization and that α-(1,6)-mannosyltransferases of GT-32 and GT-62 families are essential to the polymerization of the conidium-associated cell wall mannan. This specific mannan and the well-known galactomannan follow two independent biosynthetic pathways.
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Affiliation(s)
- Zhonghua Liu
- Institut Pasteur, Unité des Aspergillus, 75015 Paris, France
| | - Isabel Valsecchi
- Institut Pasteur, Unité des Aspergillus, 75015 Paris, France
- DYNAMYC 7380, Faculté de Santé, Université Paris-Est Créteil (UPEC), 94010 Créteil, France
| | - Rémy A. Le Meur
- Institut Pasteur, Université Paris Cité, Centre National de la Recherche Scientifique (CNRS) UMR3528, Biological NMR and HDX-MS Technological Platform, 75015 Paris, France
| | - Catherine Simenel
- Institut Pasteur, Université Paris Cité, Centre National de la Recherche Scientifique (CNRS) UMR3528, Biological NMR and HDX-MS Technological Platform, 75015 Paris, France
| | - J. Iñaki Guijarro
- Institut Pasteur, Université Paris Cité, Centre National de la Recherche Scientifique (CNRS) UMR3528, Biological NMR and HDX-MS Technological Platform, 75015 Paris, France
| | - Catherine Comte
- Institut Pasteur, Unité des Aspergillus, 75015 Paris, France
| | | | - Isabelle Mouyna
- Institut Pasteur, Unité des Aspergillus, 75015 Paris, France
- Institut Pasteur, Université Paris Cité, Unité de Biologie des ARN des Pathogènes Fongiques, 75015 Paris, France
| | - Bernard Henrissat
- Architecture et Fonction des Macromolécules Biologiques, CNRS, Aix-Marseille Université Marseille, 163 Avenue de Luminy, CEDEX 09, 13288 Marseille, France
| | - Vishukumar Aimanianda
- Institut Pasteur, Université Paris Cité, CNRS UMR2000, Unité de Mycologie Moléculaire, 75015 Paris, France
| | - Jean-Paul Latgé
- Institut Pasteur, Unité des Aspergillus, 75015 Paris, France
| | - Thierry Fontaine
- Institut Pasteur, Unité des Aspergillus, 75015 Paris, France
- Institut Pasteur, Université Paris Cité, INRAE, USC2019, Unité Biologie et Pathogénicité Fongiques, 75015 Paris, France
- Correspondence:
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9
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Understanding Aspergillus fumigatus galactosaminogalactan biosynthesis: A few questions remain. Cell Surf 2023; 9:100095. [PMID: 36691652 PMCID: PMC9860509 DOI: 10.1016/j.tcsw.2023.100095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 01/05/2023] [Accepted: 01/06/2023] [Indexed: 01/08/2023] Open
Abstract
Half a century after their discovery, polymers of N-acetylgalactosamine produced by the Aspergilli have garnered new interest as mediators of fungal virulence. Recent work has focused on the Aspergillus fumigatus secreted and cell wall-associated heteropolymer, galactosaminogalactan (GAG). This polymer, composed of galactose (Gal) and partially deacetylated N-acetylgalactosamine (GalNAc), plays a role in a variety of pathogenic processes including biofilm formation, immune modulation and evasion, and resistance to antifungals. Given its many potential contributions to fungal pathogenesis, GAG is a promising therapeutic target for novel antifungal strategies. As such, several studies have sought to elucidate the biosynthetic pathways required for GAG production and secretion. Herein we review the progress made in the understanding of the molecular mechanisms underlying GAG synthesis and identify several gaps in our understanding of this process.
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10
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Kim KH, Kang S, Seo H, Yun CW. AfSec1 is a signal peptidase and removes signal peptides of 1,3-β-glucanosyltransferases in Aspergillus fumigatus. Med Mycol 2022; 61:6993075. [PMID: 36657388 DOI: 10.1093/mmy/myad005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 01/11/2023] [Accepted: 01/18/2023] [Indexed: 01/20/2023] Open
Abstract
To identify the infection mechanism of Aspergillus fumigatus, which is an opportunistic fungal pathogen, we analyzed the expression profile of the whole genome of A. fumigatus during the infection of murine macrophages. A previously reported RNA-seq data analysis showed that many genes involved in cell wall synthesis were upregulated during the infection process. Interestingly, AfSec1 (3g12840), which encodes a putative signal peptidase, was upregulated dramatically, and its putative target protein Gel1, which encodes a 1,3-β-glucanosyltransferase, was also upregulated. Instead of the AfSec1 deletion strain, the AfSec1-ΔP strain was constructed, in which the promoter region of AfSec1 was deleted, and AfSec1 expression was not detected in the AfSec1-ΔP strain. The expression of AfSec1 was recovered by the introduction of the promoter region (the AfSec1-ΔP/P strain). The nonprocessed form of Gel1 was identified in the AfSec1-ΔP strain, which lacked the promoter, but mature forms of Gel1 were found in the wild-type and in AfSec1-ΔP/P, which was the promoter complementation strain. In the plate assay, the AfSec1-ΔP strain showed higher sensitivity against caspofungin than the wild-type. However, compared with the wild-type, the deletion strain showed no difference in the sensitivity to other antifungal drugs, such as amphotericin B and voriconazole, which inhibit different targets compared with caspofungin. The AfSec1-ΔP strain exhibited ∼20% lower levels of β-glucan in the cell wall than the wild-type. Finally, the virulence decreased when the promoter region of AfSec1 was deleted, as observed in the murine infection test and conidia-killing assay using human macrophages and neutrophils. These results suggest that AfSec1 exerts signal peptidase activity on its target Gel1 and has an important role in fungal pathogenesis.
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Affiliation(s)
- Ki-Hwan Kim
- School of Life Sciences and Biotechnology, Korea University Anam-dong, Sungbuk-gu, Seoul, Republic of Korea
| | - Suzie Kang
- School of Life Sciences and Biotechnology, Korea University Anam-dong, Sungbuk-gu, Seoul, Republic of Korea
| | - Hyewon Seo
- School of Life Sciences and Biotechnology, Korea University Anam-dong, Sungbuk-gu, Seoul, Republic of Korea
| | - Cheol-Won Yun
- School of Life Sciences and Biotechnology, Korea University Anam-dong, Sungbuk-gu, Seoul, Republic of Korea.,NeuroEsgel Co., Anam-dong, Sungbuk-gu, Seoul, 02841, Korea
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11
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Verburg K, van Neer J, Duca M, de Cock H. Novel Treatment Approach for Aspergilloses by Targeting Germination. J Fungi (Basel) 2022; 8:758. [PMID: 35893126 PMCID: PMC9331470 DOI: 10.3390/jof8080758] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 07/03/2022] [Accepted: 07/19/2022] [Indexed: 12/24/2022] Open
Abstract
Germination of conidia is an essential process within the Aspergillus life cycle and plays a major role during the infection of hosts. Conidia are able to avoid detection by the majority of leukocytes when dormant. Germination can cause severe health problems, specifically in immunocompromised people. Aspergillosis is most often caused by Aspergillus fumigatus (A. fumigatus) and affects neutropenic patients, as well as people with cystic fibrosis (CF). These patients are often unable to effectively detect and clear the conidia or hyphae and can develop chronic non-invasive and/or invasive infections or allergic inflammatory responses. Current treatments with (tri)azoles can be very effective to combat a variety of fungal infections. However, resistance against current azoles has emerged and has been increasing since 1998. As a consequence, patients infected with resistant A. fumigatus have a reported mortality rate of 88% to 100%. Especially with the growing number of patients that harbor azole-resistant Aspergilli, novel antifungals could provide an alternative. Aspergilloses differ in defining characteristics, but germination of conidia is one of the few common denominators. By specifically targeting conidial germination with novel antifungals, early intervention might be possible. In this review, we propose several morphotypes to disrupt conidial germination, as well as potential targets. Hopefully, new antifungals against such targets could contribute to disturbing the ability of Aspergilli to germinate and grow, resulting in a decreased fungal burden on patients.
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Affiliation(s)
- Kim Verburg
- Molecular Microbiology, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands; (K.V.); (J.v.N.)
| | - Jacq van Neer
- Molecular Microbiology, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands; (K.V.); (J.v.N.)
| | - Margherita Duca
- Department of Chemical Biology & Drug Discovery, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, 3584 CG Utrecht, The Netherlands;
| | - Hans de Cock
- Molecular Microbiology, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands; (K.V.); (J.v.N.)
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12
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Chen Y, Wu X, Chen C, Huang Q, Li C, Zhang X, Tan X, Zhang D, Liu Y. Proteomics Analysis Reveals the Molecular Mechanism of MoPer1 Regulating the Development and Pathogenicity of Magnaporthe oryzae. Front Cell Infect Microbiol 2022; 12:926771. [PMID: 35811686 PMCID: PMC9269092 DOI: 10.3389/fcimb.2022.926771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2022] [Accepted: 05/19/2022] [Indexed: 11/13/2022] Open
Abstract
Glycosylphosphatidylinositol (GPI) anchoring the protein GPI modification post-transcriptionally is commonly seen. In our previous study, MoPer1, a GPI anchoring essential factor, has a critical effect on Magnaporthe oryzae growth, pathogenicity, and conidiogenesis, but its molecular mechanism is not clear. Here, we extracted the glycoproteins from the ΔMoper1 mutant and wild-type Guy11 to analyze their differential levels by quantitative proteomic analysis of TMT markers. After background subtraction, a total of 431 proteins, with significant changes in expression, were successfully identified, and these differential proteins were involved in biological regulation, as well as cellular process and metabolic process, binding, catalytic activity, and other aspects. Moreover, we found that MoPer1 regulates the expression of 14 proteins involved in growth, development, and pathogenicity of M. oryzae. The above findings shed light on MoPer1’s underlying mechanism in regulating growth, development, and pathogenicity of M. oryzae.
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Affiliation(s)
- Yue Chen
- State Key Laboratory of Hybrid Rice and Institute of Plant Protection, Hunan Academy of Agricultural Sciences, Changsha, China
- Long Ping Branch, Graduate School of Hunan University, Changsha, China
| | - Xiyang Wu
- State Key Laboratory of Hybrid Rice and Institute of Plant Protection, Hunan Academy of Agricultural Sciences, Changsha, China
- Long Ping Branch, Graduate School of Hunan University, Changsha, China
| | - Chunyan Chen
- College of Plant Protection, Hunan Agricultural University, Changsha, China
| | - Qiang Huang
- College of Plant Protection, Hunan Agricultural University, Changsha, China
| | - Chenggang Li
- State Key Laboratory of Hybrid Rice and Institute of Plant Protection, Hunan Academy of Agricultural Sciences, Changsha, China
| | - Xin Zhang
- State Key Laboratory of Hybrid Rice and Institute of Plant Protection, Hunan Academy of Agricultural Sciences, Changsha, China
| | - Xinqiu Tan
- State Key Laboratory of Hybrid Rice and Institute of Plant Protection, Hunan Academy of Agricultural Sciences, Changsha, China
- Long Ping Branch, Graduate School of Hunan University, Changsha, China
| | - Deyong Zhang
- State Key Laboratory of Hybrid Rice and Institute of Plant Protection, Hunan Academy of Agricultural Sciences, Changsha, China
- Long Ping Branch, Graduate School of Hunan University, Changsha, China
- *Correspondence: Yong Liu, ; Deyong Zhang,
| | - Yong Liu
- State Key Laboratory of Hybrid Rice and Institute of Plant Protection, Hunan Academy of Agricultural Sciences, Changsha, China
- Long Ping Branch, Graduate School of Hunan University, Changsha, China
- *Correspondence: Yong Liu, ; Deyong Zhang,
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13
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Liu J, Ge L, Mei H, Zheng H, Peng J, Liang G, Liu W. Comparative Genomics and Molecular Analysis of Epidermophyton floccosum. Mycopathologia 2021; 186:487-497. [PMID: 34164772 DOI: 10.1007/s11046-021-00567-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Accepted: 05/26/2021] [Indexed: 12/01/2022]
Abstract
Epidermophyton floccosum is one of the most common agents of human superficial fungal infections, compared with genus Trichophyton and Microsporum, it possesses uniqueness in ecology traits and rarely causing hair infections. E. floccosum is so far the only representative species of genera Epidermophyton, and it is known as anthropophilic dermatophytes. To further reveal the genome sequences and clues of virulence factors, thus in this study, we sequenced the genome of E. floccosum (CGMCC (F) E1d), and performed comparative genomic analysis with other dermatophytes. It is revealed that E. floccosum owns the largest genome size and similar GC content compared with other dermatophytes. A total of 7565 genes are predicted. By comparing with the closest species N. gypseum, our study reveals that number and structure of adhesion factors, secreted proteases and LysM domain might contribute to the pathogenic and ecological traits of E. floccosum. Mating genes is also detected in genome data. Furthermore, we performed AFLP analysis trying to discuss intraspecific differences of E. floccosum, but no significant relationship is found between genotype and geographical distribution. Upon above, our study provides a deeper understanding and strong foundation for future researches about E. floccosum.
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Affiliation(s)
- Jia Liu
- Department of Medical Mycology, Institute of Dermatology, Chinese Academy of Medical Sciences and Peking Union Medical College, Nanjing, 210042, Jiangsu, China
| | - Liyu Ge
- Department of Medical Mycology, Institute of Dermatology, Chinese Academy of Medical Sciences and Peking Union Medical College, Nanjing, 210042, Jiangsu, China.,Department of Dermatology, Affiliated Hangzhou Third Hospital, Anhui Medical University, Hangzhou, China
| | - Huan Mei
- Department of Medical Mycology, Institute of Dermatology, Chinese Academy of Medical Sciences and Peking Union Medical College, Nanjing, 210042, Jiangsu, China.,Jiangsu Key Laboratory of Molecular Biology for Skin Diseases and STIs, Nanjing, 210042, Jiangsu, China
| | - Hailin Zheng
- Department of Medical Mycology, Institute of Dermatology, Chinese Academy of Medical Sciences and Peking Union Medical College, Nanjing, 210042, Jiangsu, China.,Jiangsu Key Laboratory of Molecular Biology for Skin Diseases and STIs, Nanjing, 210042, Jiangsu, China
| | - Jingwen Peng
- Department of Medical Mycology, Institute of Dermatology, Chinese Academy of Medical Sciences and Peking Union Medical College, Nanjing, 210042, Jiangsu, China.,Jiangsu Key Laboratory of Molecular Biology for Skin Diseases and STIs, Nanjing, 210042, Jiangsu, China
| | - Guanzhao Liang
- Department of Medical Mycology, Institute of Dermatology, Chinese Academy of Medical Sciences and Peking Union Medical College, Nanjing, 210042, Jiangsu, China.,Jiangsu Key Laboratory of Molecular Biology for Skin Diseases and STIs, Nanjing, 210042, Jiangsu, China
| | - Weida Liu
- Department of Medical Mycology, Institute of Dermatology, Chinese Academy of Medical Sciences and Peking Union Medical College, Nanjing, 210042, Jiangsu, China. .,Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, 211166, Jiangsu, China. .,Jiangsu Key Laboratory of Molecular Biology for Skin Diseases and STIs, Nanjing, 210042, Jiangsu, China.
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14
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Rangel Pedersen N, Tovborg M, Soleimani Farjam A, Della Pia EA. Multicomponent carbohydrase system from Trichoderma reesei: A toolbox to address complexity of cell walls of plant substrates in animal feed. PLoS One 2021; 16:e0251556. [PMID: 34086701 PMCID: PMC8177525 DOI: 10.1371/journal.pone.0251556] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 04/27/2021] [Indexed: 11/19/2022] Open
Abstract
A diverse range of monocot and dicot grains and their by-products are commonly used in the animal feed industry. They all come with complex and variable cell wall structures which in turn contribute significant fiber to the complete feed. The cell wall is a highly interconnected matrix of various polysaccharides, proteins and lignin and, as such, requires a collaborative effort of different enzymes for its degradation. In this regard, we investigated the potential of a commercial multicomponent carbohydrase product from a wild type fermentation of Trichoderma reesei (T. reesei) (RONOZYME® MultiGrain) in degrading cell wall components of wheat, barley, rye, de-oiled rice bran, sunflower, rapeseed and cassava. A total of thirty-one different enzyme proteins were identified in the T. Reesei carbohydrase product using liquid chromatography with tandem mass spectrometry LC-MS/MS including glycosyl hydrolases and carbohydrate esterases. As measured by in vitro incubations and non-starch polysaccharide component analysis, and visualization by immunocytochemistry and confocal microscopy imaging of immuno-labeled samples with confocal microscopy, the carbohydrase product effectively solubilized cellulolytic and hemicellulolytic polysaccharides present in the cell walls of all the feed ingredients evaluated. The T. reesei fermentation also decreased viscosity of arabinoxylan, xyloglucan, galactomannan and β-glucan substrates. Combination of several debranching enzymes including arabinofuranosidase, xylosidase, α-galactosidase, acetyl xylan esterase, and 4-O-methyl-glucuronoyl methylesterase with both GH10 and GH11 xylanases in the carbohydrase product resulted in effective hydrolyzation of heavily branched glucuronoarabinoxylans. The different β-glucanases (both endo-β-1,3(4)-glucanase and endo-β-1,3-glucanase), cellulases and a β-glucosidase in the T. reesei fermentation effectively reduced polymerization of both β-glucans and cellulose polysaccharides of viscous cereals grains (wheat, barley, rye and oat). Interestingly, the secretome of T. reesei contained significant amounts of an exceptional direct chain-cutting enzyme from the GH74 family (Cel74A, xyloglucan-specific β-1,4-endoglucanase), that strictly cleaves the xyloglucan backbone at the substituted regions. Here, we demonstrated that the balance of enzymes present in the T. reesei secretome is capable of degrading various cell wall components in both monocot and dicot plant raw material used as animal feed.
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15
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Functional Genomic and Biochemical Analysis Reveals Pleiotropic Effect of Congo Red on Aspergillus fumigatus. mBio 2021; 12:mBio.00863-21. [PMID: 34006660 PMCID: PMC8262895 DOI: 10.1128/mbio.00863-21] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Inhibition of fungal growth by Congo red (CR) has been putatively associated with specific binding to β-1,3-glucans, which blocks cell wall polysaccharide synthesis. In this study, we searched for transcription factors (TFs) that regulate the response to CR and interrogated their regulon. During the investigation of the susceptibility to CR of the TF mutant library, several CR-resistant and -hypersensitive mutants were discovered and further studied. Abnormal distorted swollen conidia called Quasimodo cells were seen in the presence of CR. Quasimodo cells in the resistant mutants were larger than the ones in the sensitive and parental strains; consequently, the conidia of the resistant mutants absorbed more CR than the germinating conidia of the sensitive or parental strains. Accordingly, this higher absorption rate by Quasimodo cells resulted in the removal of CR from the culture medium, allowing a subset of conidia to germinate and grow. In contrast, all resting conidia of the sensitive mutants and the parental strain were killed. This result indicated that the heterogeneity of the conidial population is essential to promote the survival of Aspergillus fumigatus in the presence of CR. Moreover, amorphous surface cell wall polysaccharides such as galactosaminogalactan control the influx of CR inside the cells and, accordingly, resistance to the drug. Finally, long-term incubation with CR led to the discovery of a new CR-induced growth effect, called drug-induced growth stimulation (DIGS), since the growth of one of them could be stimulated after recovery from CR stress.
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16
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GPI Anchored Proteins in Aspergillus fumigatus and Cell Wall Morphogenesis. Curr Top Microbiol Immunol 2020; 425:167-186. [PMID: 32418035 DOI: 10.1007/82_2020_207] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Glycosylphosphatidylinositol (GPI) anchored proteins are a class of proteins attached to the extracellular leaflet of the plasma membrane via a post-translational modification, the glycolipid anchor. GPI anchored proteins are expressed in all eukaryotes, from fungi to plants and animals. They display very diverse functions ranging from enzymatic activity, signaling, cell adhesion, cell wall metabolism, and immune response. In this review, we investigated for the first time an exhaustive list of all the GPI anchored proteins present in the Aspergillus fumigatus genome. An A. fumigatus mutant library of all the genes that encode in silico identified GPI anchored proteins has been constructed and the phenotypic analysis of all these mutants has been characterized including their growth, conidial viability or morphology, adhesion and the ability to form biofilms. We showed the presence of different fungal categories of GPI anchored proteins in the A. fumigatus genome associated to their role in cell wall remodeling, adhesion, and biofilm formation.
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17
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Abstract
Fungal cells use extracellular vesicles (EVs) to export biologically active molecules to the extracellular space. In this study, we used protoplasts of Aspergillus fumigatus, a major fungal pathogen, as a model to evaluate the role of EV production in cell wall biogenesis. Our results demonstrated that wall-less A. fumigatus exports plasma membrane-derived EVs containing a complex combination of proteins and glycans. Our report is the first to characterize fungal EVs in the absence of a cell wall. Our results suggest that protoplasts represent a promising model for functional studies of fungal vesicles. Extracellular vesicles (EVs) are membranous compartments produced by yeast and mycelial forms of several fungal species. One of the difficulties in perceiving the role of EVs during the fungal life, and particularly in cell wall biogenesis, is caused by the presence of a thick cell wall. One alternative to have better access to these vesicles is to use protoplasts. This approach has been investigated here with Aspergillus fumigatus, one of the most common opportunistic fungal pathogens worldwide. Analysis of regenerating protoplasts by scanning electron microscopy and fluorescence microscopy indicated the occurrence of outer membrane projections in association with surface components and the release of particles with properties resembling those of fungal EVs. EVs in culture supernatants were characterized by transmission electron microscopy and nanoparticle tracking analysis. Proteomic and glycome analysis of EVs revealed the presence of a complex array of enzymes related to lipid/sugar metabolism, pathogenic processes, and cell wall biosynthesis. Our data indicate that (i) EV production is a common feature of different morphological stages of this major fungal pathogen and (ii) protoplastic EVs are promising tools for undertaking studies of vesicle functions in fungal cells. IMPORTANCE Fungal cells use extracellular vesicles (EVs) to export biologically active molecules to the extracellular space. In this study, we used protoplasts of Aspergillus fumigatus, a major fungal pathogen, as a model to evaluate the role of EV production in cell wall biogenesis. Our results demonstrated that wall-less A. fumigatus exports plasma membrane-derived EVs containing a complex combination of proteins and glycans. Our report is the first to characterize fungal EVs in the absence of a cell wall. Our results suggest that protoplasts represent a promising model for functional studies of fungal vesicles.
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18
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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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19
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Pham TA, Kyriacou BA, Schwerdt JG, Shirley NJ, Xing X, Bulone V, Little A. Composition and biosynthetic machinery of the Blumeria graminis f. sp. hordei conidia cell wall. ACTA ACUST UNITED AC 2020; 5:100029. [PMID: 32743145 PMCID: PMC7388969 DOI: 10.1016/j.tcsw.2019.100029] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 08/08/2019] [Accepted: 08/08/2019] [Indexed: 01/01/2023]
Abstract
Infection of barley with the powdery mildew causal agent, Blumeria graminis f. sp. hordei (Bgh), can lead to devastating damage to barley crops. The recent emergence of fungicide resistance imposes a need to develop new antifungal strategies. The enzymes involved in cell wall biosynthesis are ideal targets for the development of fungicides. However, in order to narrow down any target proteins involved in cell wall formation, a greater understanding of the cell wall structure and composition is required. Here, we present a detailed carbohydrate analysis of the Bgh conidial cell wall, a full annotation of Carbohydrate Active enZymes (CAZy) in the Bgh genome, and a comprehensive expression profile of the genes involved in cell wall metabolism. Glycosidic linkage analysis has revealed that the cell wall polysaccharide fraction of Bgh conidia predominantly consists of glucosyl residues (63.1%) and has a greater proportion of galactopyranosyl residues compared to other species (8.5%). Trace amounts of xylosyl residues were also detected, which is unusual in ascomycetes. Transcripts of the genes involved in cell wall metabolism show high expression of chitin deacetylases, which assist fungi in evading the host defence system by deacetylating chitin to chitosan. The data presented suggest that the cell wall components of the conidia and the corresponding obligate biotrophic CAZy gene profile play a key role in the infection process.
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Affiliation(s)
- Trang A.T. Pham
- ARC Centre of Excellence in Plant Cell Walls, School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Glen Osmond, SA 5064, Australia
| | - Bianca A. Kyriacou
- ARC Centre of Excellence in Plant Cell Walls, School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Glen Osmond, SA 5064, Australia
| | - Julian G. Schwerdt
- ARC Centre of Excellence in Plant Cell Walls, School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Glen Osmond, SA 5064, Australia
| | - Neil J. Shirley
- ARC Centre of Excellence in Plant Cell Walls, School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Glen Osmond, SA 5064, Australia
| | - Xiaohui Xing
- Adelaide Glycomics, School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Glen Osmond, SA 5064, Australia
| | - Vincent Bulone
- ARC Centre of Excellence in Plant Cell Walls, School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Glen Osmond, SA 5064, Australia
- Adelaide Glycomics, School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Glen Osmond, SA 5064, Australia
| | - Alan Little
- ARC Centre of Excellence in Plant Cell Walls, School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Glen Osmond, SA 5064, Australia
- Corresponding author.
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Pérez-Llano Y, Rodríguez-Pupo EC, Druzhinina IS, Chenthamara K, Cai F, Gunde-Cimerman N, Zalar P, Gostinčar C, Kostanjšek R, Folch-Mallol JL, Batista-García RA, Sánchez-Carbente MDR. Stress Reshapes the Physiological Response of Halophile Fungi to Salinity. Cells 2020; 9:E525. [PMID: 32106416 PMCID: PMC7140475 DOI: 10.3390/cells9030525] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 02/12/2020] [Accepted: 02/19/2020] [Indexed: 11/16/2022] Open
Abstract
(1) Background: Mechanisms of cellular and molecular adaptation of fungi to salinity have been commonly drawn from halotolerant strains and few studies in basidiomycete fungi. These studies have been conducted in settings where cells are subjected to stress, either hypo- or hyperosmotic, which can be a confounding factor in describing physiological mechanisms related to salinity. (2) Methods: We have studied transcriptomic changes in Aspergillussydowii, a halophilic species, when growing in three different salinity conditions (No NaCl, 0.5 M, and 2.0 M NaCl). (3) Results: In this fungus, major physiological modifications occur under high salinity (2.0 M NaCl) and not when cultured under optimal conditions (0.5 M NaCl), suggesting that most of the mechanisms described for halophilic growth are a consequence of saline stress response and not an adaptation to saline conditions. Cell wall modifications occur exclusively at extreme salinity, with an increase in cell wall thickness and lamellar structure, which seem to involve a decrease in chitin content and an augmented content of alfa and beta-glucans. Additionally, three hydrophobin genes were differentially expressed under hypo- or hyperosmotic stress but not when the fungus grows optimally. Regarding compatible solutes, glycerol is the main compound accumulated in salt stress conditions, whereas trehalose is accumulated in the absence of salt. (4) Conclusions: Physiological responses to salinity vary greatly between optimal and high salt concentrations and are not a simple graded effect as the salt concentration increases. Our results highlight the influence of stress in reshaping the response of extremophiles to environmental challenges.
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Affiliation(s)
- Yordanis Pérez-Llano
- Center of Research on Cell Dynamics, Autonomous University of the State of Morelos, Morelos 62210, Mexico; (Y.P.-L.); (E.C.R.-P.)
| | - Eya Caridad Rodríguez-Pupo
- Center of Research on Cell Dynamics, Autonomous University of the State of Morelos, Morelos 62210, Mexico; (Y.P.-L.); (E.C.R.-P.)
| | - Irina S. Druzhinina
- Institute of Chemical, Environmental and Bioscience Engineering (ICEBE), TU Wien, 1060 Vienna, Austria; (I.S.D.); (K.C.); (F.C.)
- Fungal Genomics Group, Nanjing Agricultural University, Nanjing 210095, China
| | - Komal Chenthamara
- Institute of Chemical, Environmental and Bioscience Engineering (ICEBE), TU Wien, 1060 Vienna, Austria; (I.S.D.); (K.C.); (F.C.)
| | - Feng Cai
- Institute of Chemical, Environmental and Bioscience Engineering (ICEBE), TU Wien, 1060 Vienna, Austria; (I.S.D.); (K.C.); (F.C.)
- Fungal Genomics Group, Nanjing Agricultural University, Nanjing 210095, China
| | - Nina Gunde-Cimerman
- Department of Biology, Biotechnical Faculty, University of Ljubljana, SI-1000 Ljubljana, Slovenia; (N.G.-C.); (P.Z.); (C.G.); (R.K.)
| | - Polona Zalar
- Department of Biology, Biotechnical Faculty, University of Ljubljana, SI-1000 Ljubljana, Slovenia; (N.G.-C.); (P.Z.); (C.G.); (R.K.)
| | - Cene Gostinčar
- Department of Biology, Biotechnical Faculty, University of Ljubljana, SI-1000 Ljubljana, Slovenia; (N.G.-C.); (P.Z.); (C.G.); (R.K.)
| | - Rok Kostanjšek
- Department of Biology, Biotechnical Faculty, University of Ljubljana, SI-1000 Ljubljana, Slovenia; (N.G.-C.); (P.Z.); (C.G.); (R.K.)
| | - Jorge Luis Folch-Mallol
- Laboratory of Molecular Biology of Fungi, Center for Research on Biotechnology, Autonomous University of the State of Morelos, Morelos 62210, Mexico;
| | - Ramón Alberto Batista-García
- Center of Research on Cell Dynamics, Autonomous University of the State of Morelos, Morelos 62210, Mexico; (Y.P.-L.); (E.C.R.-P.)
| | - María del Rayo Sánchez-Carbente
- Laboratory of Molecular Biology of Fungi, Center for Research on Biotechnology, Autonomous University of the State of Morelos, Morelos 62210, Mexico;
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Chhetri A, Loksztejn A, Nguyen H, Pianalto KM, Kim MJ, Hong J, Alspaugh JA, Yokoyama K. Length Specificity and Polymerization Mechanism of (1,3)-β-d-Glucan Synthase in Fungal Cell Wall Biosynthesis. Biochemistry 2020; 59:682-693. [PMID: 31899625 DOI: 10.1021/acs.biochem.9b00896] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
(1,3)-β-d-Glucan synthase (GS) catalyzes formation of the linear (1,3)-β-d-glucan in the fungal cell wall and is a target of clinically approved antifungal antibiotics. The catalytic subunit of GS, FKS protein, does not exhibit significant sequence homology to other glycosyltransferases, and thus, significant ambiguity about its catalytic mechanism remains. One of the major technical barriers in studying GS is the absence of activity assay methods that allow characterization of the lengths and amounts of (1,3)-β-d-glucan due to its poor solubility in water and organic solvents. Here, we report a successful development of a novel GS activity assay based on size-exclusion chromatography coupled with pulsed amperometric detection and radiation counting (SEC-PAD-RC), which allows for the simultaneous characterization of the amount and length of the polymer product. The assay revealed that the purified yeast GS produces glucan with a length of 6550 ± 760 mer, consistent with the reported degree of polymerization of (1,3)-β-d-glucan isolated from intact cells. Pre-steady state kinetic analysis revealed a highly efficient but rate-determining chain elongation rate of 51.5 ± 9.8 s-1, which represents the first observation of chain elongation by a nucleotide-sugar-dependent polysaccharide synthase. Coupling the SEC-PAD-RC method with substrate analogue mechanistic probes provided the first unambiguous evidence that GS catalyzes non-reducing end polymerization. On the basis of these observations, we propose a detailed model for the catalytic mechanism of GS. The approaches described here can be used to determine the mechanism of catalysis of other polysaccharide synthases.
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Affiliation(s)
- Abhishek Chhetri
- Department of Biochemistry , Duke University School of Medicine , Durham , North Carolina 27710 , United States
| | - Anna Loksztejn
- Department of Biochemistry , Duke University School of Medicine , Durham , North Carolina 27710 , United States
| | - Hai Nguyen
- Department of Biochemistry , Duke University School of Medicine , Durham , North Carolina 27710 , United States
| | - Kaila M Pianalto
- Department of Medicine , Duke University School of Medicine , Durham , North Carolina 27710 , United States
| | - Mi Jung Kim
- Department of Chemistry , Duke University , Durham , North Carolina 27708-0354 , United States
| | - Jiyong Hong
- Department of Chemistry , Duke University , Durham , North Carolina 27708-0354 , United States
| | - J Andrew Alspaugh
- Department of Medicine , Duke University School of Medicine , Durham , North Carolina 27710 , United States
| | - Kenichi Yokoyama
- Department of Biochemistry , Duke University School of Medicine , Durham , North Carolina 27710 , United States.,Department of Chemistry , Duke University , Durham , North Carolina 27708-0354 , United States
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Garcia-Rubio R, de Oliveira HC, Rivera J, Trevijano-Contador N. The Fungal Cell Wall: Candida, Cryptococcus, and Aspergillus Species. Front Microbiol 2020; 10:2993. [PMID: 31993032 PMCID: PMC6962315 DOI: 10.3389/fmicb.2019.02993] [Citation(s) in RCA: 368] [Impact Index Per Article: 92.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 12/10/2019] [Indexed: 01/23/2023] Open
Abstract
The fungal cell wall is located outside the plasma membrane and is the cell compartment that mediates all the relationships of the cell with the environment. It protects the contents of the cell, gives rigidity and defines the cellular structure. The cell wall is a skeleton with high plasticity that protects the cell from different stresses, among which osmotic changes stand out. The cell wall allows interaction with the external environment since some of its proteins are adhesins and receptors. Since, some components have a high immunogenic capacity, certain wall components can drive the host's immune response to promote fungus growth and dissemination. The cell wall is a characteristic structure of fungi and is composed mainly of glucans, chitin and glycoproteins. As the components of the fungal cell wall are not present in humans, this structure is an excellent target for antifungal therapy. In this article, we review recent data on the composition and synthesis, influence of the components of the cell wall in fungi-host interaction and the role as a target for the next generation of antifungal drugs in yeasts (Candida and Cryptococcus) and filamentous fungi (Aspergillus).
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Affiliation(s)
- Rocio Garcia-Rubio
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, NJ, United States
| | | | - Johanna Rivera
- Division of Infectious Diseases, Department of Medicine, Albert Einstein College of Medicine, New York, NY, United States
| | - Nuria Trevijano-Contador
- Division of Infectious Diseases, Department of Medicine, Albert Einstein College of Medicine, New York, NY, United States
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Blatzer M, Beauvais A, Henrissat B, Latgé JP. Revisiting Old Questions and New Approaches to Investigate the Fungal Cell Wall Construction. Curr Top Microbiol Immunol 2020; 425:331-369. [PMID: 32418033 DOI: 10.1007/82_2020_209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The beginning of our understanding of the cell wall construction came from the work of talented biochemists in the 70-80's. Then came the era of sequencing. Paradoxically, the accumulation of fungal genomes complicated rather than solved the mystery of cell wall construction, by revealing the involvement of a much higher number of proteins than originally thought. The situation has become even more complicated since it is now recognized that the cell wall is an organelle whose composition continuously evolves with the changes in the environment or with the age of the fungal cell. The use of new and sophisticated technologies to observe cell wall construction at an almost atomic scale should improve our knowledge of the cell wall construction. This essay will present some of the major and still unresolved questions to understand the fungal cell wall biosynthesis and some of these exciting futurist approaches.
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Affiliation(s)
- Michael Blatzer
- Experimental Neuropathology Unit, Institut Pasteur, 25 rue du Docteur Roux, 75015, Paris, France
| | - Anne Beauvais
- Mycology Department, Institut Pasteur, 25 rue du Docteur Roux, 75015, Paris, France
| | - Bernard Henrissat
- Architecture et Fonction des Macromolécules Biologiques, UMR 7257-CNRS & Aix-Marseille Université, 13288, Marseille cedex 9, France.,Department of Biological Sciences, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Jean-Paul Latgé
- Institute of Molecular Biology and Biotechnology of the Foundation for Research and Technology Hellas (IMBB-FORTH), Heraklion, Greece.
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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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Abstract
Aspergillus fumigatus is a saprotrophic fungus; its primary habitat is the soil. In its ecological niche, the fungus has learned how to adapt and proliferate in hostile environments. This capacity has helped the fungus to resist and survive against human host defenses and, further, to be responsible for one of the most devastating lung infections in terms of morbidity and mortality. In this review, we will provide (i) a description of the biological cycle of A. fumigatus; (ii) a historical perspective of the spectrum of aspergillus disease and the current epidemiological status of these infections; (iii) an analysis of the modes of immune response against Aspergillus in immunocompetent and immunocompromised patients; (iv) an understanding of the pathways responsible for fungal virulence and their host molecular targets, with a specific focus on the cell wall; (v) the current status of the diagnosis of different clinical syndromes; and (vi) an overview of the available antifungal armamentarium and the therapeutic strategies in the clinical context. In addition, the emergence of new concepts, such as nutritional immunity and the integration and rewiring of multiple fungal metabolic activities occurring during lung invasion, has helped us to redefine the opportunistic pathogenesis of A. fumigatus.
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Affiliation(s)
- Jean-Paul Latgé
- School of Medicine, University of Crete, Heraklion, Crete, Greece
| | - Georgios Chamilos
- School of Medicine, University of Crete, Heraklion, Crete, Greece
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology, Heraklion, Crete, Greece
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26
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Abstract
Aspergilli produce conidia for reproduction or to survive hostile conditions, and they are highly effective in the distribution of conidia through the environment. In immunocompromised individuals, inhaled conidia can germinate inside the respiratory tract, which may result in invasive pulmonary aspergillosis. The management of invasive aspergillosis has become more complex, with new risk groups being identified and the emergence of antifungal resistance. Patient survival is threatened by these developments, stressing the need for alternative therapeutic strategies. As germination is crucial for infection, prevention of this process might be a feasible approach. A broader understanding of conidial germination is important to identify novel antigermination targets. In this review, we describe conidial resistance against various stresses, transition from dormant conidia to hyphal growth, the underlying molecular mechanisms involved in germination of the most common Aspergillus species, and promising antigermination targets. Germination of Aspergillus is characterized by three morphotypes: dormancy, isotropic growth, and polarized growth. Intra- and extracellular proteins play an important role in the protection against unfavorable environmental conditions. Isotropically expanding conidia remodel the cell wall, and biosynthetic machineries are needed for cellular growth. These biosynthetic machineries are also important during polarized growth, together with tip formation and the cell cycle machinery. Genes involved in isotropic and polarized growth could be effective antigermination targets. Transcriptomic and proteomic studies on specific Aspergillus morphotypes will improve our understanding of the germination process and allow discovery of novel antigermination targets and biomarkers for early diagnosis and therapy.
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Waldron R, McGowan J, Gordon N, Mitchell EB, Fitzpatrick DA, Doyle S. Characterisation of three novel β-1,3 glucanases from the medically important house dust mite Dermatophagoides pteronyssinus (airmid). INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2019; 115:103242. [PMID: 31520716 DOI: 10.1016/j.ibmb.2019.103242] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Revised: 09/09/2019] [Accepted: 09/09/2019] [Indexed: 06/10/2023]
Abstract
The European house dust mite, Dermatophagoides pteronyssinus is a major source of airborne allergens worldwide and is found in half of European homes. Interactions between microbes and house dust mites (HDM) are considered important factors that allow them to persist in the home. Laboratory studies indicate the European HDM, D. pteronyssinus is a mycophagous mite, capable of utilising a variety of fungi for nutrients, however specific mycolytic digestive enzymes are unknown. Our previous work identified a number of putative glycosyl hydrolases present in the predicted proteome of D. pteronyssinus airmid and validated the expression of 42 of these. Of note, three GH16 proteins with predicted β-1,3 glucanase activity were found to be consistently present in the mite body and excretome. Here, we performed an extensive bioinformatic, proteomic and biochemical study to characterize three-novel β-1,3 glucanases from this medically important house dust mite. The genes encoding novel β-1,3 glucanases designated Glu1, Glu2 and Glu3 were identified in D. pteronyssinus airmid, each exhibited more than 59% amino acid identity to one another. These enzymes are encoded by Glu genes present in a tri-gene cluster and protein homologs are found in other acari. The patchy phyletic distribution of Glu proteins means their evolutionary history remains elusive, however horizontal gene transfer cannot be completely excluded. Recombinant Glu1 and Glu2 exhibit hydrolytic activity toward laminarin, pachyman and barley glucan. Excreted β-1,3 glucanase activity was increased in response to D. pteronyssinus airmid feeding on baker's yeast. Active β-1,3 glucanases are expressed and excreted in the faeces of D. pteronyssinus airmid indicating they are digestive enzymes capable of breaking down β-1,3 glucans of fungi present in house dust.
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Affiliation(s)
- Rose Waldron
- Department of Biology, Maynooth University, Maynooth, Co. Kildare, Ireland; Airmid Healthgroup Ltd., Trinity Enterprise Campus, Dublin, Ireland
| | - Jamie McGowan
- Department of Biology, Maynooth University, Maynooth, Co. Kildare, Ireland; Human Health Research Institute, Maynooth University, Maynooth, Co. Kildare, Ireland
| | - Natasha Gordon
- Airmid Healthgroup Ltd., Trinity Enterprise Campus, Dublin, Ireland
| | - E Bruce Mitchell
- Airmid Healthgroup Ltd., Trinity Enterprise Campus, Dublin, Ireland
| | - David A Fitzpatrick
- Department of Biology, Maynooth University, Maynooth, Co. Kildare, Ireland; Human Health Research Institute, Maynooth University, Maynooth, Co. Kildare, Ireland
| | - Sean Doyle
- Department of Biology, Maynooth University, Maynooth, Co. Kildare, Ireland.
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Patel PK, Free SJ. The Genetics and Biochemistry of Cell Wall Structure and Synthesis in Neurospora crassa, a Model Filamentous Fungus. Front Microbiol 2019; 10:2294. [PMID: 31649638 PMCID: PMC6796803 DOI: 10.3389/fmicb.2019.02294] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Accepted: 09/20/2019] [Indexed: 01/25/2023] Open
Abstract
This review discusses the wealth of information available for the N. crassa cell wall. The basic organization and structure of the cell wall is presented and how the wall changes during the N. crassa life cycle is discussed. Over forty cell wall glycoproteins have been identified by proteomic analyses. Genetic and biochemical studies have identified many of the key enzymes needed for cell wall biogenesis, and the roles these enzymes play in cell wall biogenesis are discussed. The review includes a discussion of how the major cell wall components (chitin, β-1,3-glucan, mixed β-1,3-/ β-1,4- glucans, glycoproteins, and melanin) are synthesized and incorporated into the cell wall. We present a four-step model for how cell wall glycoproteins are covalently incorporated into the cell wall. In N. crassa, the covalent incorporation of cell wall glycoproteins into the wall occurs through a glycosidic linkage between lichenin (a mixed β-1,3-/β-1,4- glucan) and a "processed" galactomannan that has been attached to the glycoprotein N-linked oligosaccharides. The first step is the addition of the galactomannan to the N-linked oligosaccharide. Mutants affected in galactomannan formation are unable to incorporate glycoproteins into their cell walls. The second step is carried out by the enzymes from the GH76 family of α-1,6-mannanases, which cleave the galactomannan to generate a processed galactomannan. The model suggests that the third and fourth steps are carried out by members of the GH72 family of glucanosyltransferases. In the third step the glucanosyltransferases cleave lichenin and generate enzyme/substrate intermediates in which the lichenin is covalently attached to the active site of the glucanosyltransferases. In the final step, the glucanosyltransferases attach the lichenin onto the processed galactomannans, which creates new glycosidic bonds and effectively incorporates the glycoproteins into the cross-linked cell wall glucan/chitin matrix.
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Affiliation(s)
| | - Stephen J. Free
- Department of Biological Sciences, SUNY University at Buffalo, Buffalo, NY, United States
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Souza JAM, Baltazar LDM, Carregal VM, Gouveia-Eufrasio L, de Oliveira AG, Dias WG, Campos Rocha M, Rocha de Miranda K, Malavazi I, Santos DDA, Frézard FJG, de Souza DDG, Teixeira MM, Soriani FM. Characterization of Aspergillus fumigatus Extracellular Vesicles and Their Effects on Macrophages and Neutrophils Functions. Front Microbiol 2019; 10:2008. [PMID: 31551957 PMCID: PMC6738167 DOI: 10.3389/fmicb.2019.02008] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 08/16/2019] [Indexed: 12/26/2022] Open
Abstract
Extracellular vesicles (EVs) has been considered an alternative process for intercellular communication. EVs release by filamentous fungi and the role of vesicular secretion during fungus-host cells interaction remain unknown. Here, we identified the secretion of EVs from the pathogenic filamentous fungus, Aspergillus fumigatus. Analysis of the structure of EVs demonstrated that A. fumigatus produces round shaped bilayer structures ranging from 100 to 200 nm size, containing ergosterol and a myriad of proteins involved in REDOX, cell wall remodeling and metabolic functions of the fungus. We demonstrated that macrophages can phagocytose A. fumigatus EVs. Phagocytic cells, stimulated with EVs, increased fungal clearance after A. fumigatus conidia challenge. EVs were also able to induce the production of TNF-α and CCL2 by macrophages and a synergistic effect was observed in the production of these mediators when the cells were challenged with the conidia. In bone marrow-derived neutrophils (BMDN) treated with EVs, there was enhancement of the production of TNF-α and IL-1β in response to conidia. Together, our results demonstrate, for the first time, that A. fumigatus produces EVs containing a diverse set of proteins involved in fungal physiology and virulence. Moreover, EVs are biologically active and stimulate production of inflammatory mediators and fungal clearance.
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Affiliation(s)
- Jéssica Amanda Marques Souza
- Centro de Pesquisa e Desenvolvimento de Fármacos, Departamento de Genética, Ecologia e Evolução, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Ludmila de Matos Baltazar
- Laboratório de Interação Microrganismo-Hospedeiro, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Virgínia Mendes Carregal
- Laboratório de Biofísica e Sistemas Nanoestruturados, Departamento de Fisiologia e Biofísica, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Ludmila Gouveia-Eufrasio
- Laboratório de Micologia, Departamento de Microbiologia, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - André Gustavo de Oliveira
- Lab Circuitos Fisiológicos, Departamento de Fisiologia e Biofísica, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Wendell Girard Dias
- Plataforma de Microscopia Eletrônica Rudolf Barth, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | - Marina Campos Rocha
- Centro de Ciências Biológicas e da Saúde, Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, Brazil
| | - Kildare Rocha de Miranda
- Laboratório de Ultraestrutura Celular Hertha Meyer, Programa de Biologia Celular e Parasitologia, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Iran Malavazi
- Centro de Ciências Biológicas e da Saúde, Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, Brazil
| | - Daniel de Assis Santos
- Laboratório de Micologia, Departamento de Microbiologia, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Frédéric Jean Georges Frézard
- Laboratório de Biofísica e Sistemas Nanoestruturados, Departamento de Fisiologia e Biofísica, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Daniele da Glória de Souza
- Laboratório de Interação Microrganismo-Hospedeiro, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Mauro Martins Teixeira
- Centro de Pesquisa e Desenvolvimento de Fármacos, Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Frederico Marianetti Soriani
- Centro de Pesquisa e Desenvolvimento de Fármacos, Departamento de Genética, Ecologia e Evolução, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
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Muszkieta L, Fontaine T, Beau R, Mouyna I, Vogt MS, Trow J, Cormack BP, Essen LO, Jouvion G, Latgé JP. The Glycosylphosphatidylinositol-Anchored DFG Family Is Essential for the Insertion of Galactomannan into the β-(1,3)-Glucan-Chitin Core of the Cell Wall of Aspergillus fumigatus. mSphere 2019; 4:e00397-19. [PMID: 31366710 PMCID: PMC6669337 DOI: 10.1128/msphere.00397-19] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Accepted: 06/25/2019] [Indexed: 11/20/2022] Open
Abstract
The fungal cell wall is a complex and dynamic entity essential for the development of fungi. It is composed mainly of polysaccharides that are synthetized by protein complexes. At the cell wall level, enzyme activities are involved in postsynthesis polysaccharide modifications such as cleavage, elongation, branching, and cross-linking. Glycosylphosphatidylinositol (GPI)-anchored proteins have been shown to participate in cell wall biosynthesis and specifically in polysaccharide remodeling. Among these proteins, the DFG family plays an essential role in controlling polar growth in yeast. In the filamentous fungus and opportunistic human pathogen Aspergillus fumigatus, the DFG gene family contains seven orthologous DFG genes among which only six are expressed under in vitro growth conditions. Deletions of single DFG genes revealed that DFG3 plays the most important morphogenetic role in this gene family. A sextuple-deletion mutant resulting from the deletion of all in vitro expressed DFG genes did not contain galactomannan in the cell wall and has severe growth defects. This study has shown that DFG members are absolutely necessary for the insertion of galactomannan into the cell wall of A. fumigatus and that the proper cell wall localization of the galactomannan is essential for correct fungal morphogenesis in A. fumigatusIMPORTANCE The fungal cell wall is a complex and dynamic entity essential for the development of fungi. It is composed mainly of polysaccharides that are synthetized by protein complexes. Enzymes involved in postsynthesis polysaccharide modifications, such as cleavage, elongation, branching, and cross-linking, are essential for fungal life. Here, we investigated in Aspergillus fumigatus the role of the members of the Dfg family, one of the 4 GPI-anchored protein families common to yeast and molds involved in cell wall remodeling. Molecular and biochemical approaches showed that DFG members are required for filamentous growth, conidiation, and cell wall organization and are essential for the life of this fungal pathogen.
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Affiliation(s)
| | | | - Rémi Beau
- Unité des Aspergillus, Institut Pasteur, Paris, France
| | | | | | - Jonathan Trow
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Brendan P Cormack
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Lars-Oliver Essen
- Faculty of Chemistry, Philipps-Universität Marburg, Marburg, Germany
| | - Gregory Jouvion
- Histopathologie humaine et modèles animaux, Institut Pasteur, Paris, France
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Fang W, Sanz AB, Bartual SG, Wang B, Ferenbach AT, Farkaš V, Hurtado-Guerrero R, Arroyo J, van Aalten DMF. Mechanisms of redundancy and specificity of the Aspergillus fumigatus Crh transglycosylases. Nat Commun 2019; 10:1669. [PMID: 30971696 PMCID: PMC6458159 DOI: 10.1038/s41467-019-09674-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 03/20/2019] [Indexed: 11/13/2022] Open
Abstract
Fungal cell wall synthesis is achieved by a balance of glycosyltransferase, hydrolase and transglycosylase activities. Transglycosylases strengthen the cell wall by forming a rigid network of crosslinks through mechanisms that remain to be explored. Here we study the function of the Aspergillus fumigatus family of five Crh transglycosylases. Although crh genes are dispensable for cell viability, simultaneous deletion of all genes renders cells sensitive to cell wall interfering compounds. In vitro biochemical assays and localisation studies demonstrate that this family of enzymes functions redundantly as transglycosylases for both chitin-glucan and chitin-chitin cell wall crosslinks. To understand the molecular basis of this acceptor promiscuity, we solved the crystal structure of A. fumigatus Crh5 (AfCrh5) in complex with a chitooligosaccharide at the resolution of 2.8 Å, revealing an extensive elongated binding cleft for the donor (−4 to −1) substrate and a short acceptor (+1 to +2) binding site. Together with mutagenesis, the structure suggests a “hydrolysis product assisted” molecular mechanism favouring transglycosylation over hydrolysis. Transglycosylases strengthen the fungal cell wall by forming a rigid network of crosslinks. Here, Fang et al. show that the five Crh transglycosylases of Aspergillus fumigatus are dispensable for cell wall integrity in vitro, and solve the crystal structure of Crh5 in complex with chitooligosaccharides.
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Affiliation(s)
- Wenxia Fang
- School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK.,National Engineering Research Center for Non-Food Biorefinery, State Key Laboratory of Non-Food Biomass and Enzyme Technology, Guangxi Academy of Sciences, 530007, Nanning, China
| | - Ana Belén Sanz
- Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad Complutense de Madrid, IRYCIS, 28040, Madrid, Spain
| | | | - Bin Wang
- National Engineering Research Center for Non-Food Biorefinery, State Key Laboratory of Non-Food Biomass and Enzyme Technology, Guangxi Academy of Sciences, 530007, Nanning, China
| | | | - Vladimír Farkaš
- Department of Glycobiology, Institute of Chemistry, Center for Glycomics, Slovak Academy of Sciences, 84538, Bratislava, Slovakia
| | - Ramon Hurtado-Guerrero
- Institute of Biocomputation and Physics of Complex Systems (BIFI), University of Zaragoza, BIFI-IQFR (CSIC), 50018, Zaragoza, Spain.,Fundación ARAID, Av. de Ranillas, 50018, Zaragoza, Spain
| | - Javier Arroyo
- Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad Complutense de Madrid, IRYCIS, 28040, Madrid, Spain.
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Two KTR Mannosyltransferases Are Responsible for the Biosynthesis of Cell Wall Mannans and Control Polarized Growth in Aspergillus fumigatus. mBio 2019; 10:mBio.02647-18. [PMID: 30755510 PMCID: PMC6372797 DOI: 10.1128/mbio.02647-18] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The fungal cell wall is a complex and dynamic entity essential for the development of fungi. It allows fungal pathogens to survive environmental challenge posed by nutrient stress and host defenses, and it also is central to polarized growth. The cell wall is mainly composed of polysaccharides organized in a three-dimensional network. Aspergillus fumigatus produces a cell wall galactomannan whose biosynthetic pathway and biological functions remain poorly defined. Here, we described two new mannosyltransferases essential to the synthesis of the cell wall galactomannan. Their absence leads to a growth defect with misregulation of polarization and altered conidiation, with conidia which are bigger and more permeable than the conidia of the parental strain. This study showed that in spite of its low concentration in the cell wall, this polysaccharide is absolutely required for cell wall stability, for apical growth, and for the full virulence of A. fumigatus. Fungal cell wall mannans are complex carbohydrate polysaccharides with different structures in yeasts and molds. In contrast to yeasts, their biosynthetic pathway has been poorly investigated in filamentous fungi. In Aspergillus fumigatus, the major mannan structure is a galactomannan that is cross-linked to the β-1,3-glucan-chitin cell wall core. This polymer is composed of a linear mannan with a repeating unit composed of four α1,6-linked and α1,2-linked mannoses with side chains of galactofuran. Despite its use as a biomarker to diagnose invasive aspergillosis, its biosynthesis and biological function were unknown. Here, we have investigated the function of three members of the Ktr (also named Kre2/Mnt1) family (Ktr1, Ktr4, and Ktr7) in A. fumigatus and show that two of them are required for the biosynthesis of galactomannan. In particular, we describe a newly discovered form of α-1,2-mannosyltransferase activity encoded by the KTR4 gene. Biochemical analyses showed that deletion of the KTR4 gene or the KTR7 gene leads to the absence of cell wall galactomannan. In comparison to parental strains, the Δktr4 and Δktr7 mutants showed a severe growth phenotype with defects in polarized growth and in conidiation, marked alteration of the conidial viability, and reduced virulence in a mouse model of invasive aspergillosis. In yeast, the KTR proteins are involved in protein 0- and N-glycosylation. This study provided another confirmation that orthologous genes can code for proteins that have very different biological functions in yeasts and filamentous fungi. Moreover, in A. fumigatus, cell wall mannans are as important structurally as β-glucans and chitin.
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Fernando U, Chatur S, Joshi M, Thomas Bonner C, Fan T, Hubbard K, Chabot D, Rowland O, Wang L, Subramaniam R, Rampitsch C. Redox signalling from NADPH oxidase targets metabolic enzymes and developmental proteins in Fusarium graminearum. MOLECULAR PLANT PATHOLOGY 2019; 20:92-106. [PMID: 30113774 PMCID: PMC6430467 DOI: 10.1111/mpp.12742] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
NADPH oxidase (NOX) is one of the sources of reactive oxygen species (ROS) that modulates the activity of proteins through modifications of their cysteine residues. In a previous study, we demonstrated the importance of NOX in both the development and pathogenicity of the phytopathogen Fusarium graminearum. In this article, comparative proteomics between the wild-type and a Nox mutant of F. graminearum was used to identify active cysteine residues on candidate redox-sensing proteins. A two-dimensional gel approach based on labelling with monobromobimane (mBBR) identified 19 candidate proteins, and was complemented with a gel-free shotgun approach based on a biotin switch method, which yielded 99 candidates. The results indicated that, in addition to temporal regulation, a large number of primary metabolic enzymes are potentially targeted by NoxAB-generated ROS. Targeted disruption of these metabolic genes showed that, although some are dispensable, others are essential. In addition to metabolic enzymes, developmental proteins, such as the Woronin body major protein (FGSG_08737) and a glycosylphosphatidylinositol (GPI)-anchored protein (FGSG_10089), were also identified. Deletion of either of these genes reduced the virulence of F. graminearum. Furthermore, changing the redox-modified cysteine (Cys325 ) residue in FGSG_10089 to either serine or phenylalanine resulted in a similar phenotype to the FGSG_10089 knockout strain, which displayed reduced virulence and altered cell wall morphology; this underscores the importance of Cys325 to the function of the protein. Our results indicate that NOX-generated ROS act as intracellular signals in F. graminearum and modulate the activity of proteins affecting development and virulence in planta.
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Affiliation(s)
- Ursla Fernando
- Agriculture and Agrifood Canada, Morden Research & Development CentreMordenR6M 1Y5MBCanada
| | - Salima Chatur
- Agriculture and Agrifood Canada, Ottawa Research & Development CentreOttawaK1A 0C6ONCanada
| | - Manisha Joshi
- Agriculture and Agrifood Canada, Morden Research & Development CentreMordenR6M 1Y5MBCanada
- Agriculture and Agrifood Canada, Ottawa Research & Development CentreOttawaK1A 0C6ONCanada
| | - Christopher Thomas Bonner
- Agriculture and Agrifood Canada, Ottawa Research & Development CentreOttawaK1A 0C6ONCanada
- Department of BiologyCarleton UniversityOttawaK1S 5B6ONCanada
| | - Tao Fan
- Agriculture and Agrifood Canada, Morden Research & Development CentreMordenR6M 1Y5MBCanada
| | - Keith Hubbard
- Agriculture and Agrifood Canada, Ottawa Research & Development CentreOttawaK1A 0C6ONCanada
| | - Denise Chabot
- Agriculture and Agrifood Canada, Ottawa Research & Development CentreOttawaK1A 0C6ONCanada
| | - Owen Rowland
- Department of BiologyCarleton UniversityOttawaK1S 5B6ONCanada
| | - Li Wang
- Agriculture and Agrifood Canada, Ottawa Research & Development CentreOttawaK1A 0C6ONCanada
| | - Rajagopal Subramaniam
- Agriculture and Agrifood Canada, Ottawa Research & Development CentreOttawaK1A 0C6ONCanada
| | - Christof Rampitsch
- Agriculture and Agrifood Canada, Morden Research & Development CentreMordenR6M 1Y5MBCanada
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Kar B, Patel P, Ao J, Free SJ. Neurospora crassa family GH72 glucanosyltransferases function to crosslink cell wall glycoprotein N-linked galactomannan to cell wall lichenin. Fungal Genet Biol 2018; 123:60-69. [PMID: 30503329 DOI: 10.1016/j.fgb.2018.11.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Revised: 10/05/2018] [Accepted: 11/28/2018] [Indexed: 11/24/2022]
Abstract
The formation of a glucan/chitin/glycoprotein cell wall matrix is vital for fungal survival, growth, and morphogenesis. The cell wall proteins are important cell wall components and function in adhesion, signal transduction, and as cell wall structural elements. In this report we demonstrate that Neurospora crassa GH72 glucan transferases function to crosslink cell wall glycoproteins into the cell wall. With an in vitro assay, we show that the glucan transferases are able to attach lichenin, a cell wall glucan with a repeating β-1,4-glucose-β-1,4-glucose-β-1,3-glucose structure, to cell wall glycoproteins. We propose that the pathway for attachment of lichenin to the glycoprotein has four steps. First, N-linked oligosaccharides present on the glycoproteins are modified by the addition of a galactomannan. As part of our report we have characterized the structure of the galactomannan, which consists of an α-1,6-mannose backbone with galactofuranose side chains. In the second step, the galactomannan is processed by members of the GH76 α-1,6-mannanases. In the third step, the glucan transferases cleave the lichenin and create substrate-enzyme intermediates. In the final step, the transferases transfer the lichenin to the processed galactomannan. We demonstrate that the N. crassa glucan transferases have demonstrate specificity for the processed galactomannan and for lichenin. The energy from the cleaved glycosidic bond in lichenin is retained in the substrate-enzyme intermediate and used to create a new glycosidic bond between the lichenin and the processed galactomannan. The pathway effectively crosslinks glycoproteins into the fungal cell wall.
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Affiliation(s)
- Bibekananda Kar
- Department of Biological Sciences, SUNY University at Buffalo, Buffalo, NY 14260, USA
| | - Pavan Patel
- Department of Biological Sciences, SUNY University at Buffalo, Buffalo, NY 14260, USA
| | - Jie Ao
- Department of Biological Sciences, SUNY University at Buffalo, Buffalo, NY 14260, USA
| | - Stephen J Free
- Department of Biological Sciences, SUNY University at Buffalo, Buffalo, NY 14260, USA.
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Luo Z, Zhang T, Liu P, Bai Y, Chen Q, Zhang Y, Keyhani NO. The Beauveria bassiana Gas3 β-Glucanosyltransferase Contributes to Fungal Adaptation to Extreme Alkaline Conditions. Appl Environ Microbiol 2018; 84:e01086-18. [PMID: 29802184 PMCID: PMC6052264 DOI: 10.1128/aem.01086-18] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 05/17/2018] [Indexed: 12/20/2022] Open
Abstract
Fungal β-1,3-glucanosyltransferases are cell wall-remodeling enzymes implicated in stress response, cell wall integrity, and virulence, with most fungal genomes containing multiple members. The insect-pathogenic fungus Beauveria bassiana displays robust growth over a wide pH range (pH 4 to 10). A random insertion mutant library screening for increased sensitivity to alkaline (pH 10) growth conditions resulted in the identification and mapping of a mutant to a β-1,3-glucanosyltransferase gene (Bbgas3). Bbgas3 expression was pH dependent and regulated by the PacC transcription factor, which activates genes in response to neutral/alkaline growth conditions. Targeted gene knockout of Bbgas3 resulted in reduced growth under alkaline conditions, with only minor effects of increased sensitivity to cell wall stress (Congo red and calcofluor white) and no significant effects on fungal sensitivity to oxidative or osmotic stress. The cell walls of ΔBbgas3 aerial conidia were thinner than those of the wild-type and complemented strains in response to alkaline conditions, and β-1,3-glucan antibody and lectin staining revealed alterations in cell surface carbohydrate epitopes. The ΔBbgas3 mutant displayed alterations in cell wall chitin and carbohydrate content in response to alkaline pH. Insect bioassays revealed impaired virulence for the ΔBbgas3 mutant depending upon the pH of the media on which the conidia were grown and harvested. Unexpectedly, a decreased median lethal time to kill (LT50, i.e., increased virulence) was seen for the mutant using intrahemocoel injection assays using conidia grown at acidic pH (5.6). These data show that BbGas3 acts as a pH-responsive cell wall-remodeling enzyme involved in resistance to extreme pH (>9).IMPORTANCE Little is known about adaptations required for growth at high (>9) pH. Here, we show that a specific fungal membrane-remodeling β-1,3-glucanosyltransferase gene (Bbgas3) regulated by the pH-responsive PacC transcription factor forms a critical aspect of the ability of the insect-pathogenic fungus Beauveria bassiana to grow at extreme pH. The loss of Bbgas3 resulted in a unique decreased ability to grow at high pH, with little to no effects seen with respect to other stress conditions, i.e., cell wall integrity and osmotic and oxidative stress. However, pH-dependent alternations in cell wall properties and virulence were noted for the ΔBbgas3 mutant. These data provide a mechanistic insight into the importance of the specific cell wall structure required to stabilize the cell at high pH and link it to the PacC/Pal/Rim pH-sensing and regulatory system.
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Affiliation(s)
- Zhibing Luo
- Academy of Agricultural Sciences, Southwest University, Chongqing, People's Republic of China
- Biotechnology Research Center, Southwest University, Chongqing, People's Republic of China
| | - Tongbing Zhang
- Academy of Agricultural Sciences, Southwest University, Chongqing, People's Republic of China
- Biotechnology Research Center, Southwest University, Chongqing, People's Republic of China
| | - Pengfei Liu
- Academy of Agricultural Sciences, Southwest University, Chongqing, People's Republic of China
- Biotechnology Research Center, Southwest University, Chongqing, People's Republic of China
| | - Yuting Bai
- Academy of Agricultural Sciences, Southwest University, Chongqing, People's Republic of China
- Biotechnology Research Center, Southwest University, Chongqing, People's Republic of China
| | - Qiyan Chen
- Academy of Agricultural Sciences, Southwest University, Chongqing, People's Republic of China
- Biotechnology Research Center, Southwest University, Chongqing, People's Republic of China
| | - Yongjun Zhang
- Academy of Agricultural Sciences, Southwest University, Chongqing, People's Republic of China
- Biotechnology Research Center, Southwest University, Chongqing, People's Republic of China
| | - Nemat O Keyhani
- Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida, USA
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Escobar N, Valdes ID, Keizer EM, Ordonez SR, Ohm RA, Wösten HAB, de Cock H. Expression profile analysis reveals that Aspergillus fumigatus but not Aspergillus niger makes type II epithelial lung cells less immunological alert. BMC Genomics 2018; 19:534. [PMID: 30005605 PMCID: PMC6044037 DOI: 10.1186/s12864-018-4895-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Accepted: 06/25/2018] [Indexed: 12/17/2022] Open
Abstract
Background Aspergillus fumigatus is the main causative agent of aspergillosis. Infections rarely occur in immunocompetent individuals, indicating efficient clearance of conidia by pulmonary defense mechanisms. Other aspergilli like Aspergillus niger also cause infections but to a much lesser extent. Our previous studies showed that A. fumigatus and A. niger have different behavior in the presence of type II alveolar A549 epithelial cells. A. fumigatus conidia are more efficiently internalized by these cells and germination is delayed when compared to A. niger. In addition, hyphae that have escaped the epithelial cells grow parallel to the epithelium, while A. niger grows away from this cell layer. Results Here it is shown that global gene expression of A. fumigatus and A. niger is markedly different upon contact with A549 cells. A total of 545 and 473 genes of A. fumigatus and A. niger, respectively, were differentially expressed when compared to growth in the absence of A549 cells. Notably, only 53 genes (approximately 10%) were shared in these gene sets. The different response was also illustrated by the fact that only 4 out of 75 GO terms were shared that were enriched in the differentially expressed gene sets. The orthologues of A. fumigatus genes involved in hypoxia regulation and heat shock were also up-regulated in A. niger, whereas thioredoxin reductase and allergen genes were found up-regulated in A. fumigatus but down-regulated in A. niger. Infection with A. fumigatus resulted in only 62 up and 47 down-regulated genes in A549. These numbers were 17 and 34 in the case of A. niger. GO terms related with immune response were down-regulated upon exposure to A. fumigatus but not in the case of A. niger. This indicates that A. fumigatus reprograms A549 to be less immunologically alert. Conclusions Our dual transcriptomic analysis supports earlier observations of a marked difference in life style between A. fumigatus and A. niger when grown in the presence of type II epithelial cells. The results indicate important differences in gene expression, amongst others down regulation of immune response genes in lung epithelial cells by A. fumigatus but not by A niger. Electronic supplementary material The online version of this article (10.1186/s12864-018-4895-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Natalia Escobar
- Microbiology & Institute of Biomembranes, Department of Biology, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
| | - Ivan D Valdes
- Microbiology & Institute of Biomembranes, Department of Biology, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
| | - Esther M Keizer
- Microbiology & Institute of Biomembranes, Department of Biology, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
| | - Soledad R Ordonez
- Department of Infectious Diseases and Immunology, Division Molecular Host Defence, Utrecht University, Yalelaan 1, 3584CL, Utrecht, The Netherlands
| | - Robin A Ohm
- Microbiology & Institute of Biomembranes, Department of Biology, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
| | - Han A B Wösten
- Microbiology & Institute of Biomembranes, Department of Biology, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
| | - Hans de Cock
- Microbiology & Institute of Biomembranes, Department of Biology, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands.
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Baltussen TJH, Coolen JPM, Zoll J, Verweij PE, Melchers WJG. Gene co-expression analysis identifies gene clusters associated with isotropic and polarized growth in Aspergillus fumigatus conidia. Fungal Genet Biol 2018; 116:62-72. [PMID: 29705402 DOI: 10.1016/j.fgb.2018.04.013] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Revised: 04/24/2018] [Accepted: 04/25/2018] [Indexed: 12/18/2022]
Abstract
Aspergillus fumigatus is a saprophytic fungus that extensively produces conidia. These microscopic asexually reproductive structures are small enough to reach the lungs. Germination of conidia followed by hyphal growth inside human lungs is a key step in the establishment of infection in immunocompromised patients. RNA-Seq was used to analyze the transcriptome of dormant and germinating A. fumigatus conidia. Construction of a gene co-expression network revealed four gene clusters (modules) correlated with a growth phase (dormant, isotropic growth, polarized growth). Transcripts levels of genes encoding for secondary metabolites were high in dormant conidia. During isotropic growth, transcript levels of genes involved in cell wall modifications increased. Two modules encoding for growth and cell cycle/DNA processing were associated with polarized growth. In addition, the co-expression network was used to identify highly connected intermodular hub genes. These genes may have a pivotal role in the respective module and could therefore be compelling therapeutic targets. Generally, cell wall remodeling is an important process during isotropic and polarized growth, characterized by an increase of transcripts coding for hyphal growth and cell cycle/DNA processing when polarized growth is initiated.
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Affiliation(s)
- Tim J H Baltussen
- (a)Department of Medical Microbiology, Radboud University Medical Centre, Nijmegen, The Netherlands; (b)Centre of Expertise in Mycology, Radboudumc/CWZ, Nijmegen, The Netherlands.
| | - Jordy P M Coolen
- (a)Department of Medical Microbiology, Radboud University Medical Centre, Nijmegen, The Netherlands; (b)Centre of Expertise in Mycology, Radboudumc/CWZ, Nijmegen, The Netherlands
| | - Jan Zoll
- (a)Department of Medical Microbiology, Radboud University Medical Centre, Nijmegen, The Netherlands; (b)Centre of Expertise in Mycology, Radboudumc/CWZ, Nijmegen, The Netherlands
| | - Paul E Verweij
- (a)Department of Medical Microbiology, Radboud University Medical Centre, Nijmegen, The Netherlands; (b)Centre of Expertise in Mycology, Radboudumc/CWZ, Nijmegen, The Netherlands
| | - Willem J G Melchers
- (a)Department of Medical Microbiology, Radboud University Medical Centre, Nijmegen, The Netherlands; (b)Centre of Expertise in Mycology, Radboudumc/CWZ, Nijmegen, The Netherlands
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Li J, Mouyna I, Henry C, Moyrand F, Malosse C, Chamot-Rooke J, Janbon G, Latgé JP, Fontaine T. Glycosylphosphatidylinositol Anchors from Galactomannan and GPI-Anchored Protein Are Synthesized by Distinct Pathways in Aspergillus fumigatus. J Fungi (Basel) 2018; 4:E19. [PMID: 29393895 PMCID: PMC5872322 DOI: 10.3390/jof4010019] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Revised: 01/12/2018] [Accepted: 01/19/2018] [Indexed: 11/16/2022] Open
Abstract
Glycosylphosphatidylinositols (GPIs) are lipid anchors allowing the exposure of proteins at the outer layer of the plasma membrane. In fungi, a number of GPI-anchored proteins (GPI-APs) are involved in the remodeling of the cell wall polymers. GPIs follow a specific biosynthetic pathway in the endoplasmic reticulum. After the transfer of the protein onto the GPI-anchor, a lipid remodeling occurs to substitute the diacylglycerol moiety by a ceramide. In addition to GPI-APs, A. fumigatus produces a GPI-anchored polysaccharide, the galactomannan (GM), that remains unique in the fungal kingdom. To investigate the role of the GPI pathway in the biosynthesis of the GM and cell wall organization, the deletion of PER1-coding for a phospholipase required for the first step of the GPI lipid remodeling-was undertaken. Biochemical characterization of the GPI-anchor isolated from GPI-APs showed that the PER1 deficient mutant produced a lipid anchor with a diacylglycerol. The absence of a ceramide on GPI-anchors in the Δper1 mutant led to a mislocation of GPI-APs and to an alteration of the composition of the cell wall alkali-insoluble fraction. On the other hand, the GM isolated from the Δper1 mutant membranes possesses a ceramide moiety as the parental strain, showing that GPI anchor of the GM follow a distinct unknown biosynthetic pathway.
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Affiliation(s)
- Jizhou Li
- Unité des Aspergillus, 25 rue du Docteur Roux, Institut Pasteur, 25 rue du Docteur Roux, 75015 Paris, France.
| | - Isabelle Mouyna
- Unité des Aspergillus, 25 rue du Docteur Roux, Institut Pasteur, 25 rue du Docteur Roux, 75015 Paris, France.
| | - Christine Henry
- Unité des Aspergillus, 25 rue du Docteur Roux, Institut Pasteur, 25 rue du Docteur Roux, 75015 Paris, France.
| | - Frédérique Moyrand
- Unité de Biologie des ARN des Pathogènes Fongiques, Institut Pasteur, 25 rue du Docteur Roux, 75015 Paris, France.
| | - Christian Malosse
- Unité de Spectrométrie de Masse pour la Biologie, Institut Pasteur, CNRS USR 2000, 28 rue du Docteur Roux, 75015 Paris, France.
| | - Julia Chamot-Rooke
- Unité de Spectrométrie de Masse pour la Biologie, Institut Pasteur, CNRS USR 2000, 28 rue du Docteur Roux, 75015 Paris, France.
| | - Guilhem Janbon
- Unité de Biologie des ARN des Pathogènes Fongiques, Institut Pasteur, 25 rue du Docteur Roux, 75015 Paris, France.
| | - Jean-Paul Latgé
- Unité des Aspergillus, 25 rue du Docteur Roux, Institut Pasteur, 25 rue du Docteur Roux, 75015 Paris, France.
| | - Thierry Fontaine
- Unité des Aspergillus, 25 rue du Docteur Roux, Institut Pasteur, 25 rue du Docteur Roux, 75015 Paris, France.
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Members of Glycosyl-Hydrolase Family 17 of A. fumigatus Differentially Affect Morphogenesis. J Fungi (Basel) 2018; 4:jof4010018. [PMID: 29385695 PMCID: PMC5872321 DOI: 10.3390/jof4010018] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Revised: 01/24/2018] [Accepted: 01/26/2018] [Indexed: 11/16/2022] Open
Abstract
Cell wall biosynthesis and remodeling are essential for fungal growth and development. In the fungal pathogen Aspergillus fumigatus, the β(1,3)glucan is the major cell wall polysaccharide. This polymer is synthesized at the plasma membrane by a transmembrane complex, then released into the parietal space to be remodeled by enzymes, and finally incorporated into the pre-existing cell wall. In the Glycosyl-Hydrolases family 17 (GH17) of A. fumigatus, two β(1,3)glucanosyltransferases, Bgt1p and Bgt2p, have been previously characterized. Disruption of BGT1 and BGT2 did not result in a phenotype, but sequence comparison and hydrophobic cluster analysis showed that three other genes in A. fumigatus belong to the GH17 family, SCW4, SCW11, and BGT3. In constrast to Δbgt1bgt2 mutants, single and multiple deletion of SCW4, SCW11, and BGT3 showed a decrease in conidiation associated with a higher conidial mortality and an abnormal conidial shape. Moreover, mycelium was also affected with a slower growth, stronger sensitivity to cell wall disturbing agents, and altered cell wall composition. Finally, the synthetic interactions between Bgt1p, Bgt2p, and the three other members, which support a functional cooperation in cell-wall assembly, were analyzed. Our data suggest that Scw4p, Scw11p, and Bgt3p are essential for cell wall integrity and might have antagonistic and distinct functions to Bgt1p and Bgt2p.
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Valsecchi I, Dupres V, Stephen-Victor E, Guijarro JI, Gibbons J, Beau R, Bayry J, Coppee JY, Lafont F, Latgé JP, Beauvais A. Role of Hydrophobins in Aspergillus fumigatus. J Fungi (Basel) 2017; 4:jof4010002. [PMID: 29371496 PMCID: PMC5872305 DOI: 10.3390/jof4010002] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 12/20/2017] [Accepted: 12/22/2017] [Indexed: 01/21/2023] Open
Abstract
Resistance of Aspergillus fumigatus conidia to desiccation and their capacity to reach the alveoli are partly due to the presence of a hydrophobic layer composed of a protein from the hydrophobin family, called RodA, which covers the conidial surface. In A. fumigatus there are seven hydrophobins (RodA-RodG) belonging to class I and III. Most of them have never been studied. We constructed single and multiple hydrophobin-deletion mutants until the generation of a hydrophobin-free mutant. The phenotype, immunogenicity, and virulence of the mutants were studied. RODA is the most expressed hydrophobin in sporulating cultures, whereas RODB is upregulated in biofilm conditions and in vivo Only RodA, however, is responsible for rodlet formation, sporulation, conidial hydrophobicity, resistance to physical insult or anionic dyes, and immunological inertia of the conidia. None of the hydrophobin plays a role in biofilm formation or its hydrophobicity. RodA is the only needed hydrophobin in A. fumigatus, conditioning the structure, permeability, hydrophobicity, and immune-inertia of the cell wall surface in conidia. Moreover, the defect of rodlets on the conidial cell wall surface impacts on the drug sensitivity of the fungus.
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Affiliation(s)
- Isabel Valsecchi
- Aspergillus Unit, Institut Pasteur, 75015 Paris, France.
- Unité de RMN des Biomolécules, Institut Pasteur, 75015 Paris, France.
| | - Vincent Dupres
- Centre for Infection and Immunity, Institut Pasteur de Lille-CNRS UMR8204-INSERM U1019-CHRU Lille-Université Lille, 59655 Lille, France.
| | - Emmanuel Stephen-Victor
- Institut National de la Santé et de la Recherche Médicale, Unité 1138, 75006 Paris, France.
- Centre de Recherche des Cordeliers, Université Pierre et Marie Curie-Paris 6, Université Paris Descartes, 75006 Paris, France.
| | - J Iñaki Guijarro
- Unité de RMN des Biomolécules, Institut Pasteur, 75015 Paris, France.
| | - John Gibbons
- Biology Department, Clark University, Worcester, MA 01610, USA.
| | - Rémi Beau
- Aspergillus Unit, Institut Pasteur, 75015 Paris, France.
| | - Jagadeesh Bayry
- Institut National de la Santé et de la Recherche Médicale, Unité 1138, 75006 Paris, France.
- Centre de Recherche des Cordeliers, Université Pierre et Marie Curie-Paris 6, Université Paris Descartes, 75006 Paris, France.
| | - Jean-Yves Coppee
- Transcriptome et Epigénome, Institut Pasteur, 75015 Paris, France.
| | - Frank Lafont
- Centre for Infection and Immunity, Institut Pasteur de Lille-CNRS UMR8204-INSERM U1019-CHRU Lille-Université Lille, 59655 Lille, France.
| | | | - Anne Beauvais
- Aspergillus Unit, Institut Pasteur, 75015 Paris, France.
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42
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Doyle S, Jones GW, Dolan SK. Dysregulated gliotoxin biosynthesis attenuates the production of unrelated biosynthetic gene cluster-encoded metabolites in Aspergillus fumigatus. Fungal Biol 2017; 122:214-221. [PMID: 29551195 DOI: 10.1016/j.funbio.2017.12.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 11/20/2017] [Accepted: 12/10/2017] [Indexed: 11/17/2022]
Abstract
Gliotoxin is an epipolythiodioxopiperazine (ETP) class toxin, contains a disulfide bridge that mediates its toxic effects via redox cycling and is produced by the opportunistic fungal pathogen Aspergillus fumigatus. The gliotoxin bis-thiomethyltransferase, GtmA, attenuates gliotoxin biosynthesis in A. fumigatus by conversion of dithiol gliotoxin to bis-thiomethylgliotoxin (BmGT). Here we show that disruption of dithiol gliotoxin bis-thiomethylation functionality in A. fumigatus results in significant remodelling of the A. fumigatus secondary metabolome upon extended culture. RP-HPLC and LC-MS/MS analysis revealed the reduced production of a plethora of unrelated biosynthetic gene cluster-encoded metabolites, including pseurotin A, fumagillin, fumitremorgin C and tryprostatin B, occurs in A. fumigatus ΔgtmA upon extended incubation. Parallel quantitative proteomic analysis of A. fumigatus wild-type and ΔgtmA during extended culture revealed cognate abundance alteration of proteins encoded by relevant biosynthetic gene clusters, allied to multiple alterations in hypoxia-related proteins. The data presented herein reveal a previously concealed functionality of GtmA in facilitating the biosynthesis of other BGC-encoded metabolites produced by A. fumigatus.
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Affiliation(s)
- Sean Doyle
- Department of Biology, Maynooth University, Maynooth, Co. Kildare, Ireland
| | - Gary W Jones
- Department of Biology, Maynooth University, Maynooth, Co. Kildare, Ireland; Centre for Biomedical Science Research, Leeds Beckett University, Leeds LS1 3HE, UK
| | - Stephen K Dolan
- Department of Biology, Maynooth University, Maynooth, Co. Kildare, Ireland; Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, UK.
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43
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Delso I, Valero-Gonzalez J, Gomollón-Bel F, Castro-López J, Fang W, Navratilova I, van Aalten DMF, Tejero T, Merino P, Hurtado-Guerrero R. Inhibitors against Fungal Cell Wall Remodeling Enzymes. ChemMedChem 2017; 13:128-132. [PMID: 29164827 DOI: 10.1002/cmdc.201700720] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Indexed: 11/09/2022]
Abstract
Fungal β-1,3-glucan glucanosyltransferases are glucan-remodeling enzymes that play important roles in cell wall integrity, and are essential for the viability of pathogenic fungi and yeasts. As such, they are considered possible drug targets, although inhibitors of this class of enzymes have not yet been reported. Herein we report a multidisciplinary approach based on a structure-guided design using a highly conserved transglycosylase from Sacharomyces cerevisiae, that leads to carbohydrate derivatives with high affinity for Aspergillus fumigatus Gel4. We demonstrate by X-ray crystallography that the compounds bind in the active site of Gas2/Gel4 and interact with the catalytic machinery. The topological analysis of noncovalent interactions demonstrates that the combination of a triazole with positively charged aromatic moieties are important for optimal interactions with Gas2/Gel4 through unusual pyridinium cation-π and face-to-face π-π interactions. The lead compound is capable of inhibiting AfGel4 with an IC50 value of 42 μm.
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Affiliation(s)
- Ignacio Delso
- Instituto de Síntesis Química y Catálisis Homogénea (ISQCH), Universidad de Zaragoza, CSIC, 50009, Zaragoza, Aragón, Spain
| | - Jessika Valero-Gonzalez
- Institute of Biocomputation and Physics of Complex Systems (BIFI), University of Zaragoza, BIFI-IQFR (CSIC) Joint Unit, Campus Rio Ebro, Zaragoza, Aragón, Spain
| | - Fernando Gomollón-Bel
- Instituto de Síntesis Química y Catálisis Homogénea (ISQCH), Universidad de Zaragoza, CSIC, 50009, Zaragoza, Aragón, Spain
| | - Jorge Castro-López
- Institute of Biocomputation and Physics of Complex Systems (BIFI), University of Zaragoza, BIFI-IQFR (CSIC) Joint Unit, Campus Rio Ebro, Zaragoza, Aragón, Spain
| | - Wenxia Fang
- Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, Scotland, UK
| | - Iva Navratilova
- Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, Scotland, UK
| | - Daan M F van Aalten
- Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, Scotland, UK
| | - Tomás Tejero
- Instituto de Síntesis Química y Catálisis Homogénea (ISQCH), Universidad de Zaragoza, CSIC, 50009, Zaragoza, Aragón, Spain
| | - Pedro Merino
- Institute of Biocomputation and Physics of Complex Systems (BIFI), University of Zaragoza, BIFI-IQFR (CSIC) Joint Unit, Campus Rio Ebro, Zaragoza, Aragón, Spain
| | - Ramon Hurtado-Guerrero
- Institute of Biocomputation and Physics of Complex Systems (BIFI), University of Zaragoza, BIFI-IQFR (CSIC) Joint Unit, Campus Rio Ebro, Zaragoza, Aragón, Spain.,Fundación ARAID, 50018, Zaragoza, Spain
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44
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The PHR Family: The Role of Extracellular Transglycosylases in Shaping Candida albicans Cells. J Fungi (Basel) 2017; 3:jof3040059. [PMID: 29371575 PMCID: PMC5753161 DOI: 10.3390/jof3040059] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Revised: 10/19/2017] [Accepted: 10/24/2017] [Indexed: 01/25/2023] Open
Abstract
Candida albicans is an opportunistic microorganism that can become a pathogen causing mild superficial mycosis or more severe invasive infections that can be life-threatening for debilitated patients. In the etiology of invasive infections, key factors are the adaptability of C. albicans to the different niches of the human body and the transition from a yeast form to hypha. Hyphal morphology confers high adhesiveness to the host cells, as well as the ability to penetrate into organs. The cell wall plays a crucial role in the morphological changes C. albicans undergoes in response to specific environmental cues. Among the different categories of enzymes involved in the formation of the fungal cell wall, the GH72 family of transglycosylases plays an important assembly role. These enzymes cut and religate β-(1,3)-glucan, the major determinant of cell shape. In C. albicans, the PHR family encodes GH72 enzymes, some of which work in specific environmental conditions. In this review, we will summarize the work from the initial discovery of PHR genes to the study of the pH-dependent expression of PHR1 and PHR2, from the characterization of the gene products to the recent findings concerning the stress response generated by the lack of GH72 activity in C. albicans hyphae.
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45
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Latgé JP, Beauvais A, Chamilos G. The Cell Wall of the Human Fungal Pathogen Aspergillus fumigatus: Biosynthesis, Organization, Immune Response, and Virulence. Annu Rev Microbiol 2017; 71:99-116. [PMID: 28701066 DOI: 10.1146/annurev-micro-030117-020406] [Citation(s) in RCA: 139] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
More than 90% of the cell wall of the filamentous fungus Aspergillus fumigatus comprises polysaccharides. Biosynthesis of the cell wall polysaccharides is under the control of three types of enzymes: transmembrane synthases, which are anchored to the plasma membrane and use nucleotide sugars as substrates, and cell wall-associated transglycosidases and glycosyl hydrolases, which are responsible for remodeling the de novo synthesized polysaccharides and establishing the three-dimensional structure of the cell wall. For years, the cell wall was considered an inert exoskeleton of the fungal cell. The cell wall is now recognized as a living organelle, since the composition and cellular localization of the different constitutive cell wall components (especially of the outer layers) vary when the fungus senses changes in the external environment. The cell wall plays a major role during infection. The recognition of the fungal cell wall by the host is essential in the initiation of the immune response. The interactions between the different pattern-recognition receptors (PRRs) and cell wall pathogen-associated molecular patterns (PAMPs) orientate the host response toward either fungal death or growth, which would then lead to disease development. Understanding the molecular determinants of the interplay between the cell wall and host immunity is fundamental to combatting Aspergillus diseases.
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Affiliation(s)
- Jean-Paul Latgé
- Unité des Aspergillus, Institut Pasteur, 75015 Paris, France; ,
| | - Anne Beauvais
- Unité des Aspergillus, Institut Pasteur, 75015 Paris, France; ,
| | - Georgios Chamilos
- Department of Clinical Microbiology and Microbial Pathogenesis, University of Crete, Heraklion, Crete 74100, Greece.,Institute of Molecular Biology and Biotechnology, Heraklion, Crete 70013, Greece;
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46
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Abstract
β-(1,3)-Glucan, the major fungal cell wall component, ramifies through β-(1,6)-glycosidic linkages, which facilitates its binding with other cell wall components contributing to proper cell wall assembly. Using Saccharomyces cerevisiae as a model, we developed a protocol to quantify β-(1,6)-branching on β-(1,3)-glucan. Permeabilized S. cerevisiae and radiolabeled substrate UDP-(14C)glucose allowed us to determine branching kinetics. A screening aimed at identifying deletion mutants with reduced branching among them revealed only two, the bgl2Δ and gas1Δ mutants, showing 15% and 70% reductions in the branching, respectively, compared to the wild-type strain. Interestingly, a recombinant Gas1p introduced β-(1,6)-branching on the β-(1,3)-oligomers following its β-(1,3)-elongase activity. Sequential elongation and branching activity of Gas1p occurred on linear β-(1,3)-oligomers as well as Bgl2p-catalyzed products [short β-(1,3)-oligomers linked by a linear β-(1,6)-linkage]. The double S. cerevisiae gas1Δ bgl2Δ mutant showed a drastically sick phenotype. An ScGas1p ortholog, Gel4p from Aspergillus fumigatus, also showed dual β-(1,3)-glucan elongating and branching activity. Both ScGas1p and A. fumigatus Gel4p sequences are endowed with a carbohydrate binding module (CBM), CBM43, which was required for the dual β-(1,3)-glucan elongating and branching activity. Our report unravels the β-(1,3)-glucan branching mechanism, a phenomenon occurring during construction of the cell wall which is essential for fungal life. The fungal cell wall is essential for growth, morphogenesis, protection, and survival. In spite of being essential, cell wall biogenesis, especially the core β-(1,3)-glucan ramification, is poorly understood; the ramified β-(1,3)-glucan interconnects other cell wall components. Once linear β-(1,3)-glucan is synthesized by plasma membrane-bound glucan synthase, the subsequent event is its branching event in the cell wall space. Using Saccharomyces cerevisiae as a model, we identified GH72 and GH17 family glycosyltransferases, Gas1p and Bgl2p, respectively, involved in the β-(1,3)-glucan branching. The sick phenotype of the double Scgas1Δ bgl2Δ mutant suggested that β-(1,3)-glucan branching is essential. In addition to ScGas1p, GH72 family ScGas2p and Aspergillus fumigatus Gel4p, having CBM43 in their sequences, showed dual β-(1,3)-glucan elongating and branching activity. Our report identifies the fungal cell wall β-(1,3)-glucan branching mechanism. The essentiality of β-(1,3)-glucan branching suggests that enzymes involved in the glucan branching could be exploited as antifungal targets.
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47
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Ao J, Free SJ. Genetic and biochemical characterization of the GH72 family of cell wall transglycosylases in Neurospora crassa. Fungal Genet Biol 2017; 101:46-54. [PMID: 28285007 DOI: 10.1016/j.fgb.2017.03.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Revised: 02/20/2017] [Accepted: 03/07/2017] [Indexed: 11/18/2022]
Abstract
The Neurospora crassa genome encodes five GH72 family transglycosylases, and four of these enzymes (GEL-1, GEL-2, GEL-3 and GEL-5) have been found to be present in the cell wall proteome. We carried out an extensive genetic analysis on the role of these four transglycosylases in cell wall biogenesis and demonstrated that the transglycosylases are required for the formation of a normal cell wall. As suggested by the proteomic analysis, we found that multiple transglycosylases were being expressed in N. crassa cells and that different combinations of the enzymes are required in different cell types. The combination of GEL-1, GEL-2 and GEL-5 is required for the growth of vegetative hyphae, while the GEL-1, GEL-2, GEL-3 combination is needed for the production of aerial hyphae and conidia. Our data demonstrates that the enzymes are redundant with partially overlapping enzymatic activities, which provides the fungus with a robust cell wall biosynthetic system. Characterization of the transglycosylase-deficient mutants demonstrated that the incorporation of cell wall proteins was severely compromised. Interestingly, we found that the transglycosylase-deficient mutant cell walls contained more β-1,3-glucan than the wild type cell wall. Our results demonstrate that the GH72 transglycosylases are not needed for the incorporation of β-1,3-glucan into the cell wall, but they are required for the incorporation of cell wall glycoprotein into the cell wall.
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Affiliation(s)
- Jie Ao
- Department of Biological Sciences, SUNY University at Buffalo, Buffalo, NY 14260, United States
| | - Stephen J Free
- Department of Biological Sciences, SUNY University at Buffalo, Buffalo, NY 14260, United States.
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48
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Samalova M, Mélida H, Vilaplana F, Bulone V, Soanes DM, Talbot NJ, Gurr SJ. The β-1,3-glucanosyltransferases (Gels) affect the structure of the rice blast fungal cell wall during appressorium-mediated plant infection. Cell Microbiol 2016; 19. [PMID: 27568483 PMCID: PMC5396357 DOI: 10.1111/cmi.12659] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Revised: 08/23/2016] [Accepted: 08/24/2016] [Indexed: 12/02/2022]
Abstract
The fungal wall is pivotal for cell shape and function, and in interfacial protection during host infection and environmental challenge. Here, we provide the first description of the carbohydrate composition and structure of the cell wall of the rice blast fungus Magnaporthe oryzae. We focus on the family of glucan elongation proteins (Gels) and characterize five putative β‐1,3‐glucan glucanosyltransferases that each carry the Glycoside Hydrolase 72 signature. We generated targeted deletion mutants of all Gel isoforms, that is, the GH72+, which carry a putative carbohydrate‐binding module, and the GH72− Gels, without this motif. We reveal that M. oryzaeGH72+GELs are expressed in spores and during both infective and vegetative growth, but each individual Gel enzymes are dispensable for pathogenicity. Further, we demonstrated that a Δgel1Δgel3Δgel4 null mutant has a modified cell wall in which 1,3‐glucans have a higher degree of polymerization and are less branched than the wild‐type strain. The mutant showed significant differences in global patterns of gene expression, a hyper‐branching phenotype and no sporulation, and thus was unable to cause rice blast lesions (except via wounded tissues). We conclude that Gel proteins play significant roles in structural modification of the fungal cell wall during appressorium‐mediated plant infection.
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Affiliation(s)
| | - Hugo Mélida
- Division of Glycoscience, School of Biotechnology, Royal Institute of Technology (KTH), Stockholm, Sweden.,Centre for Plant Biotechnology and Genomics, Universidad Politécnica de Madrid, Madrid, Spain
| | - Francisco Vilaplana
- Division of Glycoscience, School of Biotechnology, Royal Institute of Technology (KTH), Stockholm, Sweden
| | - Vincent Bulone
- Division of Glycoscience, School of Biotechnology, Royal Institute of Technology (KTH), Stockholm, Sweden.,ARC Centre of Excellence in Plant Cell Walls and School of Agriculture, Food and Wine, University of Adelaide, Urrbrae, South Australia, Australia
| | - Darren M Soanes
- School of Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | - Nicholas J Talbot
- School of Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | - Sarah J Gurr
- Department of Plant Sciences, University of Oxford, Oxford, UK.,School of Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
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49
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Latgé JP. 30 years of battling the cell wall. Med Mycol 2016; 55:4-9. [DOI: 10.1093/mmy/myw076] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Revised: 05/27/2016] [Accepted: 07/28/2016] [Indexed: 11/13/2022] Open
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50
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Matsushika A, Negi K, Suzuki T, Goshima T, Hoshino T. Identification and Characterization of a Novel Issatchenkia orientalis GPI-Anchored Protein, IoGas1, Required for Resistance to Low pH and Salt Stress. PLoS One 2016; 11:e0161888. [PMID: 27589271 PMCID: PMC5010203 DOI: 10.1371/journal.pone.0161888] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2016] [Accepted: 08/12/2016] [Indexed: 01/01/2023] Open
Abstract
The use of yeasts tolerant to acid (low pH) and salt stress is of industrial importance for several bioproduction processes. To identify new candidate genes having potential roles in low-pH tolerance, we screened an expression genomic DNA library of a multiple-stress-tolerant yeast, Issatchenkia orientalis (Pichia kudriavzevii), for clones that allowed Saccharomyces cerevisiae cells to grow under highly acidic conditions (pH 2.0). A genomic DNA clone containing two putative open reading frames was obtained, of which the putative protein-coding gene comprising 1629 bp was retransformed into the host. This transformant grew significantly at pH 2.0, and at pH 2.5 in the presence of 7.5% Na2SO4. The predicted amino acid sequence of this new gene, named I. orientalis GAS1 (IoGAS1), was 60% identical to the S. cerevisiae Gas1 protein, a glycosylphosphatidylinositol-anchored protein essential for maintaining cell wall integrity, and 58-59% identical to Candida albicans Phr1 and Phr2, pH-responsive proteins implicated in cell wall assembly and virulence. Northern hybridization analyses indicated that, as for the C. albicans homologs, IoGAS1 expression was pH-dependent, with expression increasing with decreasing pH (from 4.0 to 2.0) of the medium. These results suggest that IoGAS1 represents a novel pH-regulated system required for the adaptation of I. orientalis to environments of diverse pH. Heterologous expression of IoGAS1 complemented the growth and morphological defects of a S. cerevisiae gas1Δ mutant, demonstrating that IoGAS1 and the corresponding S. cerevisiae gene play similar roles in cell wall biosynthesis. Site-directed mutagenesis experiments revealed that two conserved glutamate residues (E161 and E262) in the IoGas1 protein play a crucial role in yeast morphogenesis and tolerance to low pH and salt stress. Furthermore, overexpression of IoGAS1 in S. cerevisiae remarkably improved the ethanol fermentation ability at pH 2.5, and at pH 2.0 in the presence of salt (5% Na2SO4), compared to that of a reference strain. Our results strongly suggest that constitutive expression of the IoGAS1 gene in S. cerevisiae could be advantageous for several fermentation processes under these stress conditions.
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Affiliation(s)
- Akinori Matsushika
- Research Institute for Sustainable Chemistry (ISC), National Institute of Advanced Industrial Science and Technology (AIST), Hiroshima, Japan
- Graduate School of Advanced Sciences of Matter, Hiroshima University, Hiroshima, Japan
- * E-mail:
| | - Kanako Negi
- Research Institute for Sustainable Chemistry (ISC), National Institute of Advanced Industrial Science and Technology (AIST), Hiroshima, Japan
| | - Toshihiro Suzuki
- Research Institute for Sustainable Chemistry (ISC), National Institute of Advanced Industrial Science and Technology (AIST), Hiroshima, Japan
| | - Tetsuya Goshima
- National Research Institute of Brewing (NRIB), Hiroshima, Japan
| | - Tamotsu Hoshino
- Research Institute for Sustainable Chemistry (ISC), National Institute of Advanced Industrial Science and Technology (AIST), Hiroshima, Japan
- Graduate School of Advanced Sciences of Matter, Hiroshima University, Hiroshima, Japan
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