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Cai M, Wu X, Liang X, Hu H, Liu Y, Yong T, Li X, Xiao C, Gao X, Chen S, Xie Y, Wu Q. Comparative proteomic analysis of two divergent strains provides insights into thermotolerance mechanisms of Ganoderma lingzhi. Fungal Genet Biol 2023; 167:103796. [PMID: 37146899 DOI: 10.1016/j.fgb.2023.103796] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 02/18/2023] [Accepted: 04/03/2023] [Indexed: 05/07/2023]
Abstract
Heat stress (HS) is a major abiotic factor influencing fungal growth and metabolism. However, the genetic basis of thermotolerance in Ganoderma lingzhi (G. lingzhi) remains largely unknown. In this study, we investigated the thermotolerance capacities of 21 G. lingzhi strains and screened the thermo-tolerant (S566) and heat-sensitive (Z381) strains. The mycelia of S566 and Z381 were collected and subjected to a tandem mass tag (TMT)-based proteome assay. We identified 1493 differentially expressed proteins (DEPs), with 376 and 395 DEPs specific to the heat-tolerant and heat-susceptible genotypes, respectively. In the heat-tolerant genotype, upregulated proteins were linked to stimulus regulation and response. Proteins related to oxidative phosphorylation, glycosylphosphatidylinositol-anchor biosynthesis, and cell wall macromolecule metabolism were downregulated in susceptible genotypes. After HS, the mycelial growth of the heat-sensitive Z381 strain was inhibited, and mitochondrial cristae and cell wall integrity of this strain were severely impaired, suggesting that HS may inhibit mycelial growth of Z381 by damaging the cell wall and mitochondrial structure. Furthermore, thermotolerance-related regulatory pathways were explored by analyzing the protein-protein interaction network of DEPs considered to participate in the controlling the thermotolerance capacity. This study provides insights into G. lingzhi thermotolerance mechanisms and a basis for breeding a thermotolerant germplasm bank for G. lingzhi and other fungi.
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Affiliation(s)
- Manjun Cai
- Key Laboratory of Agricultural Microbiomics and Precision Application, Ministry of Agriculture and Rural Affairs, Guangdong Provincial Key Laboratory of Microbial Safety and Health, State Key Laboratory of Applied Microbiology Southern China, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou 510070, China
| | - Xiaoxian Wu
- Key Laboratory of Agricultural Microbiomics and Precision Application, Ministry of Agriculture and Rural Affairs, Guangdong Provincial Key Laboratory of Microbial Safety and Health, State Key Laboratory of Applied Microbiology Southern China, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou 510070, China
| | - Xiaowei Liang
- Key Laboratory of Agricultural Microbiomics and Precision Application, Ministry of Agriculture and Rural Affairs, Guangdong Provincial Key Laboratory of Microbial Safety and Health, State Key Laboratory of Applied Microbiology Southern China, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou 510070, China
| | - Huiping Hu
- Key Laboratory of Agricultural Microbiomics and Precision Application, Ministry of Agriculture and Rural Affairs, Guangdong Provincial Key Laboratory of Microbial Safety and Health, State Key Laboratory of Applied Microbiology Southern China, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou 510070, China
| | - Yuanchao Liu
- Key Laboratory of Agricultural Microbiomics and Precision Application, Ministry of Agriculture and Rural Affairs, Guangdong Provincial Key Laboratory of Microbial Safety and Health, State Key Laboratory of Applied Microbiology Southern China, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou 510070, China
| | - Tianqiao Yong
- Key Laboratory of Agricultural Microbiomics and Precision Application, Ministry of Agriculture and Rural Affairs, Guangdong Provincial Key Laboratory of Microbial Safety and Health, State Key Laboratory of Applied Microbiology Southern China, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou 510070, China
| | - Xiangmin Li
- Key Laboratory of Agricultural Microbiomics and Precision Application, Ministry of Agriculture and Rural Affairs, Guangdong Provincial Key Laboratory of Microbial Safety and Health, State Key Laboratory of Applied Microbiology Southern China, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou 510070, China
| | - Chun Xiao
- Key Laboratory of Agricultural Microbiomics and Precision Application, Ministry of Agriculture and Rural Affairs, Guangdong Provincial Key Laboratory of Microbial Safety and Health, State Key Laboratory of Applied Microbiology Southern China, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou 510070, China
| | - Xiong Gao
- Key Laboratory of Agricultural Microbiomics and Precision Application, Ministry of Agriculture and Rural Affairs, Guangdong Provincial Key Laboratory of Microbial Safety and Health, State Key Laboratory of Applied Microbiology Southern China, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou 510070, China
| | - Shaodan Chen
- Key Laboratory of Agricultural Microbiomics and Precision Application, Ministry of Agriculture and Rural Affairs, Guangdong Provincial Key Laboratory of Microbial Safety and Health, State Key Laboratory of Applied Microbiology Southern China, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou 510070, China
| | - Yizhen Xie
- Key Laboratory of Agricultural Microbiomics and Precision Application, Ministry of Agriculture and Rural Affairs, Guangdong Provincial Key Laboratory of Microbial Safety and Health, State Key Laboratory of Applied Microbiology Southern China, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou 510070, China; Guangdong Yuewei Edible Fungi Technology Co. Ltd., Guangzhou 510663, China.
| | - Qingping Wu
- Key Laboratory of Agricultural Microbiomics and Precision Application, Ministry of Agriculture and Rural Affairs, Guangdong Provincial Key Laboratory of Microbial Safety and Health, State Key Laboratory of Applied Microbiology Southern China, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou 510070, China.
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2
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Hira D, Onoue T, Oka T. Structural basis for the core-mannan biosynthesis of cell wall fungal-type galactomannan in Aspergillus fumigatus. J Biol Chem 2020; 295:15407-15417. [PMID: 32873705 DOI: 10.1074/jbc.ra120.013742] [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: 04/13/2020] [Revised: 08/17/2020] [Indexed: 11/06/2022] Open
Abstract
Fungal cell walls and their biosynthetic enzymes are potential targets for novel antifungal agents. Recently, two mannosyltransferases, namely core-mannan synthases A (CmsA/Ktr4) and B (CmsB/Ktr7), were found to play roles in the core-mannan biosynthesis of fungal-type galactomannan. CmsA/Ktr4 is an α-(1→2)-mannosyltransferase responsible for α-(1→2)-mannan biosynthesis in fungal-type galactomannan, which covers the cell surface of Aspergillus fumigatus Strains with disrupted cmsA/ktr4 have been shown to exhibit strongly suppressed hyphal elongation and conidiation alongside reduced virulence in a mouse model of invasive aspergillosis, indicating that CmsA/Ktr4 is a potential novel antifungal candidate. In this study we present the 3D structures of the soluble catalytic domain of CmsA/Ktr4, as determined by X-ray crystallography at a resolution of 1.95 Å, as well as the enzyme and Mn2+/GDP complex to 1.90 Å resolution. The CmsA/Ktr4 protein not only contains a highly conserved binding pocket for the donor substrate, GDP-mannose, but also has a unique broad cleft structure formed by its N- and C-terminal regions and is expected to recognize the acceptor substrate, a mannan chain. Based on these crystal structures, we also present a 3D structural model of the enzyme-substrate complex generated using docking and molecular dynamics simulations with α-Man-(1→6)-α-Man-(1→2)-α-Man-OMe as the model structure for the acceptor substrate. This predicted enzyme-substrate complex structure is also supported by findings from single amino acid substitution CmsA/Ktr4 mutants expressed in ΔcmsA/ktr4 A. fumigatus cells. Taken together, these results provide basic information for developing specific α-mannan biosynthesis inhibitors for use as pharmaceuticals and/or pesticides.
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Affiliation(s)
- Daisuke Hira
- Department of Applied Life Science, Faculty of Biotechnology and Life Science, Sojo University, Kumamoto, Kumamoto, Japan.
| | - Takuya Onoue
- Department of Applied Microbial Technology, Faculty of Biotechnology and Life Science, Sojo University, Kumamoto, Kumamoto, Japan
| | - Takuji Oka
- Department of Applied Microbial Technology, Faculty of Biotechnology and Life Science, Sojo University, Kumamoto, Kumamoto, Japan.
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Wang P, Ye Z, Banfield DK. A novel mechanism for the retention of Golgi membrane proteins mediated by the Bre5p/Ubp3p deubiquitinase complex. Mol Biol Cell 2020; 31:2139-2155. [PMID: 32673164 PMCID: PMC7530903 DOI: 10.1091/mbc.e20-03-0168] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The mechanisms employed in the retention of Golgi resident membrane proteins are diverse and include features such as the composition and length of the protein’s transmembrane domain and motifs that mediate direct or indirect associations with COPI-coatomer. However, in sum the current compendium of mechanisms cannot account for the localization of all Golgi membrane proteins, and this is particularly the case for proteins such as the glycosyltransferases. Here we describe a novel mechanism that mediates the steady-state retention of a subset of glycosyltransferases in the Golgi of budding yeast cells. This mechanism is mediated by a deubiquitinase complex composed of Bre5p and Ubp3p. We show that in the absence of this deubiquitinase certain glycosyltransferases are mislocalized to the vacuole, where they are degraded. We also show that Bre5p/Ubp3p clients bind to COPI-coatomer via a series of positively charged amino acids in their cytoplasmically exposed N-termini. Furthermore, we identify two proteins (Ktr3p and Mnn4p) that show a requirement for both Bre5p/Ubp3p as well as the COPI-coatomer–affiliated sorting receptor Vps74p. We also establish that some proteins show a nutrient-dependent role for Vps74p in their Golgi retention. This study expands the repertoire of mechanisms mediating the retention of Golgi membrane proteins.
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Affiliation(s)
- Peng Wang
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Ziyun Ye
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - David K Banfield
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
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Kats I, Khmelinskii A, Kschonsak M, Huber F, Knieß RA, Bartosik A, Knop M. Mapping Degradation Signals and Pathways in a Eukaryotic N-terminome. Mol Cell 2019; 70:488-501.e5. [PMID: 29727619 DOI: 10.1016/j.molcel.2018.03.033] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Revised: 01/26/2018] [Accepted: 03/27/2018] [Indexed: 01/01/2023]
Abstract
Most eukaryotic proteins are N-terminally acetylated. This modification can be recognized as a signal for selective protein degradation (degron) by the N-end rule pathways. However, the prevalence and specificity of such degrons in the proteome are unclear. Here, by systematically examining how protein turnover is affected by N-terminal sequences, we perform a comprehensive survey of degrons in the yeast N-terminome. We find that approximately 26% of nascent protein N termini encode cryptic degrons. These degrons exhibit high hydrophobicity and are frequently recognized by the E3 ubiquitin ligase Doa10, suggesting a role in protein quality control. In contrast, N-terminal acetylation rarely functions as a degron. Surprisingly, we identify two pathways where N-terminal acetylation has the opposite function and blocks protein degradation through the E3 ubiquitin ligase Ubr1. Our analysis highlights the complexity of N-terminal degrons and argues that hydrophobicity, not N-terminal acetylation, is the predominant feature of N-terminal degrons in nascent proteins.
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Affiliation(s)
- Ilia Kats
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
| | - Anton Khmelinskii
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
| | - Marc Kschonsak
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
| | - Florian Huber
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
| | - Robert A Knieß
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
| | - Anna Bartosik
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
| | - Michael Knop
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany; Deutsches Krebsforschungszentrum (DKFZ), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany.
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5
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Identification of Two Mannosyltransferases Contributing to Biosynthesis of the Fungal-type Galactomannan α-Core-Mannan Structure in Aspergillus fumigatus. Sci Rep 2018; 8:16918. [PMID: 30446686 PMCID: PMC6240093 DOI: 10.1038/s41598-018-35059-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Accepted: 10/28/2018] [Indexed: 01/31/2023] Open
Abstract
Fungal-type galactomannan (FTGM) is a polysaccharide composed of α-(1 → 2)-/α-(1 → 6)-mannosyl and β-(1 → 5)-/β-(1 → 6)-galactofuranosyl residues located at the outer cell wall of the human pathogenic fungus Aspergillus fumigatus. FTGM contains a linear α-mannan structure called core-mannan composed of 9 or 10 α-(1 → 2)-mannotetraose units jointed by α-(1 → 6)-linkages. However, the enzymes involved in core-mannan biosynthesis remain unknown. We speculated that two putative α-1,2-mannosyltransferase genes in A. fumigatus, Afu5g02740/AFUB_051270 (here termed core-mannan synthase A [CmsA]) and Afu5g12160/AFUB_059750 (CmsB) are involved in FTGM core-mannan biosynthesis. We constructed recombinant proteins for CmsA and detected robust mannosyltransferase activity using the chemically synthesized substrate p-nitrophenyl α-d-mannopyranoside as an acceptor. Analyses of CmsA enzymatic product revealed that CmsA possesses the capacity to transfer a mannopyranoside to the C-2 position of α-mannose. CmsA could also transfer a mannose residue to α-(1 → 2)-mannobiose and α-(1 → 6)-mannobiose and showed a 31-fold higher specific activity toward α-(1 → 6)-mannobiose than toward α-(1 → 2)-mannobiose. Proton nuclear magnetic resonance (1H-NMR) spectroscopy and gel filtration chromatography of isolated FTGM revealed that core-mannan structures were drastically altered and shortened in disruptant A. fumigatus strains ∆cmsA, ∆cmsB, and ∆cmsA∆cmsB. Disruption of cmsA or cmsB resulted in severely repressed hyphal extension, abnormal branching hyphae, formation of a balloon structure in hyphae, and decreased conidia formation. The normal wild type core-mannan structure and developmental phenotype were restored by the complementation of cmsA and cmsB in the corresponding disruptant strains. These findings indicate that both CmsA, an α-1,2-mannosyltransferase, and CmsB, a putative mannosyltransferase, are involved in FTGM biosynthesis.
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López-Ramírez LA, Hernández NV, Lozoya-Pérez NE, Lopes-Bezerra LM, Mora-Montes HM. Functional characterization of the Sporothrix schenckii Ktr4 and Ktr5, mannosyltransferases involved in the N-linked glycosylation pathway. Res Microbiol 2018; 169:188-197. [PMID: 29476824 DOI: 10.1016/j.resmic.2018.02.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Revised: 02/05/2018] [Accepted: 02/06/2018] [Indexed: 01/22/2023]
Abstract
Sporothrix schenckii is one of the causative agents of the deep-seated mycosis sporotrichosis, a fungal infection with worldwide distribution. Fungus-specific molecules and biosynthetic pathways are potential targets for the development of new antifungal drugs. The MNT1/KRE2 gene family is a group of genes that encode fungus-specific Golgi-resident mannosyltransferases that participate in the synthesis of O-linked and N-linked glycans. While this family is composed of five and nine members in Candida albicans and Saccharomyces cerevisiae, respectively, the S. schenckii genome contains only three putative members. MNT1 has been previously characterized as an enzyme that participates in the synthesis of both N-linked and O-linked glycans. Here, we aimed to establish the functional role of the two remaining family members, KTR4 and KTR5, in the protein glycosylation pathways by using heterologous complementation in C. albicans mutants lacking genes of the MNT1/KRE2 family. The two S. schenckii genes restored defects in the elaboration of N-linked glycans, but no complementation of mutants that synthesize truncated O-linked glycans was observed. Therefore, our results suggest that MNT1 is the sole member with a role in O-linked glycan elaboration, whereas the three family members have redundant activity in the S. schenckii N-linked glycan synthesis.
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Affiliation(s)
- Luz A López-Ramírez
- Departamento de Biología, División de Ciencias Naturales y Exactas, Campus Guanajuato, Universidad de Guanajuato, Noria Alta s/n, col. Noria Alta, C.P. 36050, Guanajuato Gto., Mexico
| | - Nahúm V Hernández
- Departamento de Biología, División de Ciencias Naturales y Exactas, Campus Guanajuato, Universidad de Guanajuato, Noria Alta s/n, col. Noria Alta, C.P. 36050, Guanajuato Gto., Mexico
| | - Nancy E Lozoya-Pérez
- Departamento de Biología, División de Ciencias Naturales y Exactas, Campus Guanajuato, Universidad de Guanajuato, Noria Alta s/n, col. Noria Alta, C.P. 36050, Guanajuato Gto., Mexico
| | - Leila M Lopes-Bezerra
- Laboratory of Cellular Mycology and Proteomics, Universidade do Estado do Rio de Janeiro, Brazil; Faculdade de Farmácia, Universidade de São Paulo, Brazil
| | - Héctor M Mora-Montes
- Departamento de Biología, División de Ciencias Naturales y Exactas, Campus Guanajuato, Universidad de Guanajuato, Noria Alta s/n, col. Noria Alta, C.P. 36050, Guanajuato Gto., Mexico.
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Hernández NV, López-Ramírez LA, Díaz-Jiménez DF, Mellado-Mojica E, Martínez-Duncker I, López MG, Mora-Montes HM. Saccharomyces cerevisiae KTR4 , KTR5 and KTR7 encode mannosyltransferases differentially involved in the N - and O -linked glycosylation pathways. Res Microbiol 2017; 168:740-750. [DOI: 10.1016/j.resmic.2017.07.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 07/21/2017] [Accepted: 07/22/2017] [Indexed: 12/23/2022]
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Bowman SM, Piwowar A, Ciocca M, Free SJ. Mannosyltransferase is required for cell wall biosynthesis, morphology and control of asexual development inNeurospora crassa. Mycologia 2017. [DOI: 10.1080/15572536.2006.11832778] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
| | | | | | - Stephen J. Free
- Department of Biological Sciences, University at Buffalo, Buffalo, New York 14260
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Yamauchi Y, Izawa S. Prioritized Expression of BTN2 of Saccharomyces cerevisiae under Pronounced Translation Repression Induced by Severe Ethanol Stress. Front Microbiol 2016; 7:1319. [PMID: 27602028 PMCID: PMC4993754 DOI: 10.3389/fmicb.2016.01319] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Accepted: 08/10/2016] [Indexed: 11/24/2022] Open
Abstract
Severe ethanol stress (>9% ethanol, v/v) as well as glucose deprivation rapidly induces a pronounced repression of overall protein synthesis in budding yeast Saccharomyces cerevisiae. Therefore, transcriptional activation in yeast cells under severe ethanol stress does not always indicate the production of expected protein levels. Messenger RNAs of genes containing heat shock elements can be intensively translated under glucose deprivation, suggesting that some mRNAs are preferentially translated even under severe ethanol stress. In the present study, we tried to identify the mRNA that can be preferentially translated under severe ethanol stress. BTN2 encodes a v-SNARE binding protein, and its null mutant shows hypersensitivity to ethanol. We found that BTN2 mRNA was efficiently translated under severe ethanol stress but not under mild ethanol stress. Moreover, the increased Btn2 protein levels caused by severe ethanol stress were smoothly decreased with the elimination of ethanol stress. These findings suggested that severe ethanol stress extensively induced BTN2 expression. Further, the BTN2 promoter induced protein synthesis of non-native genes such as CUR1, GIC2, and YUR1 in the presence of high ethanol concentrations, indicating that this promoter overcame severe ethanol stress-induced translation repression. Thus, our findings provide an important clue about yeast response to severe ethanol stress and suggest that the BTN2 promoter can be used to improve the efficiency of ethanol production and stress tolerance of yeast cells by modifying gene expression in the presence of high ethanol concentration.
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Affiliation(s)
- Yukina Yamauchi
- Laboratory of Microbial Technology, Department of Applied Biology, Graduate School of Science and Technology, Kyoto Institute of Technology Kyoto, Japan
| | - Shingo Izawa
- Laboratory of Microbial Technology, Department of Applied Biology, Graduate School of Science and Technology, Kyoto Institute of Technology Kyoto, Japan
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Neubert P, Halim A, Zauser M, Essig A, Joshi HJ, Zatorska E, Larsen ISB, Loibl M, Castells-Ballester J, Aebi M, Clausen H, Strahl S. Mapping the O-Mannose Glycoproteome in Saccharomyces cerevisiae. Mol Cell Proteomics 2016; 15:1323-37. [PMID: 26764011 PMCID: PMC4824858 DOI: 10.1074/mcp.m115.057505] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Indexed: 11/17/2022] Open
Abstract
O-Mannosylation is a vital protein modification conserved from fungi to humans. Yeast is a perfect model to study this post-translational modification, because in contrast to mammals O-mannosylation is the only type of O-glycosylation. In an essential step toward the full understanding of protein O-mannosylation we mapped the O-mannose glycoproteome in baker's yeast. Taking advantage of an O-glycan elongation deficient yeast strain to simplify sample complexity, we identified over 500 O-glycoproteins from all subcellular compartments for which over 2300 O-mannosylation sites were mapped by electron-transfer dissociation (ETD)-based MS/MS. In this study, we focus on the 293 O-glycoproteins (over 1900 glycosylation sites identified by ETD-MS/MS) that enter the secretory pathway and are targets of ER-localized protein O-mannosyltransferases. We find that O-mannosylation is not only a prominent modification of cell wall and plasma membrane proteins, but also of a large number of proteins from the secretory pathway with crucial functions in protein glycosylation, folding, quality control, and trafficking. The analysis of glycosylation sites revealed that O-mannosylation is favored in unstructured regions and β-strands. Furthermore, O-mannosylation is impeded in the proximity of N-glycosylation sites suggesting the interplay of these types of post-translational modifications. The detailed knowledge of the target proteins and their O-mannosylation sites opens for discovery of new roles of this essential modification in eukaryotes, and for a first glance on the evolution of different types of O-glycosylation from yeast to mammals.
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Affiliation(s)
- Patrick Neubert
- From the ‡Centre for Organismal Studies (COS), Department of Cell Chemistry, Heidelberg University, Im Neuenheimer Feld 360, D-69120 Heidelberg, Germany
| | - Adnan Halim
- §Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
| | - Martin Zauser
- From the ‡Centre for Organismal Studies (COS), Department of Cell Chemistry, Heidelberg University, Im Neuenheimer Feld 360, D-69120 Heidelberg, Germany
| | - Andreas Essig
- ¶Institute of Microbiology, Department of Biology, Swiss Federal Institute of Technology, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Hiren J Joshi
- §Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
| | - Ewa Zatorska
- From the ‡Centre for Organismal Studies (COS), Department of Cell Chemistry, Heidelberg University, Im Neuenheimer Feld 360, D-69120 Heidelberg, Germany
| | - Ida Signe Bohse Larsen
- §Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
| | - Martin Loibl
- From the ‡Centre for Organismal Studies (COS), Department of Cell Chemistry, Heidelberg University, Im Neuenheimer Feld 360, D-69120 Heidelberg, Germany
| | - Joan Castells-Ballester
- From the ‡Centre for Organismal Studies (COS), Department of Cell Chemistry, Heidelberg University, Im Neuenheimer Feld 360, D-69120 Heidelberg, Germany
| | - Markus Aebi
- ¶Institute of Microbiology, Department of Biology, Swiss Federal Institute of Technology, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Henrik Clausen
- §Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
| | - Sabine Strahl
- From the ‡Centre for Organismal Studies (COS), Department of Cell Chemistry, Heidelberg University, Im Neuenheimer Feld 360, D-69120 Heidelberg, Germany;
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Possner DDD, Claesson M, Guy JE. Structure of the Glycosyltransferase Ktr4p from Saccharomyces cerevisiae. PLoS One 2015; 10:e0136239. [PMID: 26296208 PMCID: PMC4546622 DOI: 10.1371/journal.pone.0136239] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 07/30/2015] [Indexed: 11/18/2022] Open
Abstract
In the yeast Saccharomyces cerevisiae, members of the Kre2/Mnt1 protein family have been shown to be α-1,2-mannosyltransferases or α-1,2-mannosylphosphate transferases, utilising an Mn2+-coordinated GDP-mannose as the sugar donor and a variety of mannose derivatives as acceptors. Enzymes in this family are localised to the Golgi apparatus, and have been shown to be involved in both N- and O-linked glycosylation of newly-synthesised proteins, including cell wall glycoproteins. Our knowledge of the nine proteins in this family is however very incomplete at present. Only one family member, Kre2p/Mnt1p, has been studied by structural methods, and three (Ktr4p, Ktr5p, Ktr7p) are completely uncharacterised and remain classified only as putative glycosyltransferases. Here we use in vitro enzyme activity assays to provide experimental confirmation of the predicted glycosyltransferase activity of Ktr4p. Using GDP-mannose as the donor, we observe activity towards the acceptor methyl-α-mannoside, but little or no activity towards mannose or α-1,2-mannobiose. We also present the structure of the lumenal catalytic domain of S. cerevisiae Ktr4p, determined by X-ray crystallography to a resolution of 2.2 Å, and the complex of the enzyme with GDP to 1.9 Å resolution.
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Affiliation(s)
- Dominik D. D. Possner
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Tomtebodavägen 6, S 171-77, Stockholm, Sweden
| | - Magnus Claesson
- Department of Biochemistry and Biophysics, Stockholm University, Svante Arrhenius väg 16C, S 106-91, Stockholm, Sweden
| | - Jodie E. Guy
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Tomtebodavägen 6, S 171-77, Stockholm, Sweden
- * E-mail:
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12
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Lee DJ, Bahn YS, Kim HJ, Chung SY, Kang HA. Unraveling the novel structure and biosynthetic pathway of O-linked glycans in the Golgi apparatus of the human pathogenic yeast Cryptococcus neoformans. J Biol Chem 2014; 290:1861-73. [PMID: 25477510 DOI: 10.1074/jbc.m114.607705] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Cryptococcus neoformans is an encapsulated basidiomycete causing cryptococcosis in immunocompromised humans. The cell surface mannoproteins of C. neoformans were reported to stimulate the host T-cell response and to be involved in fungal pathogenicity; however, their O-glycan structure is uncharacterized. In this study, we performed a detailed structural analysis of the O-glycans attached to cryptococcal mannoproteins using HPLC combined with exoglycosidase treatment and showed that the major C. neoformans O-glycans were short manno-oligosaccharides that were connected mostly by α1,2-linkages but connected by an α1,6-linkage at the third mannose residue. Comparison of the O-glycan profiles from wild-type and uxs1Δ mutant strains strongly supports the presence of minor O-glycans carrying a xylose residue. Further analyses of C. neoformans mutant strains identified three mannosyltransferase genes involved in O-glycan extensions in the Golgi. C. neoformans KTR3, the only homolog of the Saccharomyces cerevisiae KRE2/MNT1 family genes, was shown to encode an α1,2-mannosyltransferase responsible for the addition of the second mannose residue via an α1,2-linkage to the major O-glycans. C. neoformans HOC1 and HOC3, homologs of the Saccharomyces cerevisiae OCH1 family genes, were shown to encode α1,6-mannosyltransferases that can transfer the third mannose residue, via an α1,6-linkage, to minor O-glycans containing xylose and to major O-glycans without xylose, respectively. Moreover, the C. neoformans ktr3Δ mutant strain, which displayed increased sensitivity to SDS, high salt, and high temperature, showed attenuated virulence in a mouse model of cryptococcosis, suggesting that the extended structure of O-glycans is required for cell integrity and full pathogenicity of C. neoformans.
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Affiliation(s)
- Dong-Jik Lee
- From the Department of Life Science, Center for Fungal Pathogenesis, and
| | - Yong-Sun Bahn
- the Department of Biotechnology, Center for Fungal Pathogenesis, Yonsei University, Seoul 120-749, Korea
| | - Hong-Jin Kim
- the College of Pharmacy, Chung-Ang University, Seoul 156-756, Korea and
| | - Seung-Yeon Chung
- From the Department of Life Science, Center for Fungal Pathogenesis, and
| | - Hyun Ah Kang
- From the Department of Life Science, Center for Fungal Pathogenesis, and
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13
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Nakjang S, Williams TA, Heinz E, Watson AK, Foster PG, Sendra KM, Heaps SE, Hirt RP, Martin Embley T. Reduction and expansion in microsporidian genome evolution: new insights from comparative genomics. Genome Biol Evol 2014; 5:2285-303. [PMID: 24259309 PMCID: PMC3879972 DOI: 10.1093/gbe/evt184] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Microsporidia are an abundant group of obligate intracellular parasites of other eukaryotes, including immunocompromised humans, but the molecular basis of their intracellular lifestyle and pathobiology are poorly understood. New genomes from a taxonomically broad range of microsporidians, complemented by published expression data, provide an opportunity for comparative analyses to identify conserved and lineage-specific patterns of microsporidian genome evolution that have underpinned this success. In this study, we infer that a dramatic bottleneck in the last common microsporidian ancestor (LCMA) left a small conserved core of genes that was subsequently embellished by gene family expansion driven by gene acquisition in different lineages. Novel expressed protein families represent a substantial fraction of sequenced microsporidian genomes and are significantly enriched for signals consistent with secretion or membrane location. Further evidence of selection is inferred from the gain and reciprocal loss of functional domains between paralogous genes, for example, affecting transport proteins. Gene expansions among transporter families preferentially affect those that are located on the plasma membrane of model organisms, consistent with recruitment to plug conserved gaps in microsporidian biosynthesis and metabolism. Core microsporidian genes shared with other eukaryotes are enriched in orthologs that, in yeast, are highly expressed, highly connected, and often essential, consistent with strong negative selection against further reduction of the conserved gene set since the LCMA. Our study reveals that microsporidian genome evolution is a highly dynamic process that has balanced constraint, reductive evolution, and genome expansion during adaptation to an extraordinarily successful obligate intracellular lifestyle.
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Affiliation(s)
- Sirintra Nakjang
- Institute for Cell and Molecular Biosciences, The Medical School, Newcastle University, United Kingdom
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14
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Wang JJ, Qiu L, Cai Q, Ying SH, Feng MG. Three α-1,2-mannosyltransferases contribute differentially to conidiation, cell wall integrity, multistress tolerance and virulence of Beauveria bassiana. Fungal Genet Biol 2014; 70:1-10. [PMID: 24981201 DOI: 10.1016/j.fgb.2014.06.010] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Revised: 06/02/2014] [Accepted: 06/22/2014] [Indexed: 11/25/2022]
Abstract
Members of α-1,2-mannosyltransferase (Ktr) family are required for protein O-mannosylation for the elongation of Ser/Thr mannose residues in yeasts but functionally unknown in most filamentous fungi. Here we characterized the functions of the Ktr orthologues Ktr1, Ktr4 and Kre2/Mnt1 in Beauveria bassiana, a filamentous enotmopathogen, and found that they were positive, but differential, mediators of many biological traits. Inactivation of Ktr4 and Kre2 resulted in 92% reduction of conidial yield on a standard medium and growth defects on substrates with altered carbon or nitrogen sources and availability, accompanied with reduced conidial size and complexity. This contrasts to the dispensability of Ktr1 for fungal growth and conidiation. More cell wall damage occurred in Δktr4 and Δkre2 than in Δktr1, including altered contents of the cell wall components mannoproteins, α-glucans and chitin, more carbohydrate epitopes changed on conidial surfaces, much lower conidial hydrophobicity, and thinner cell walls. Consequently, Δktr4 and Δkre2 became more sensitive to oxidation and cell wall perturbation than Δktr1 during colony growth or conidial germination despite less difference in their sensitivities to two osmotic agents. Conidial thermotolerance, UV-B resistance and virulence were all lowered greatly in Δktr4 and Δkre2 but only the thermotolerance decreased in Δktr1. All the phenotypical changes were well restored to wild-type levels by the complementation of each target gene. Our results indicate that Ktr4 and Kre2 contribute more to the biocontrol potential of B. bassiana than Ktr1 although all of them are significant contributors.
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Affiliation(s)
- Juan-Juan Wang
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, People's Republic of China
| | - Lei Qiu
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, People's Republic of China
| | - Qing Cai
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, People's Republic of China
| | - Sheng-Hua Ying
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, People's Republic of China
| | - Ming-Guang Feng
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, People's Republic of China.
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15
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Schwarzmüller T, Ma B, Hiller E, Istel F, Tscherner M, Brunke S, Ames L, Firon A, Green B, Cabral V, Marcet-Houben M, Jacobsen ID, Quintin J, Seider K, Frohner I, Glaser W, Jungwirth H, Bachellier-Bassi S, Chauvel M, Zeidler U, Ferrandon D, Gabaldón T, Hube B, d'Enfert C, Rupp S, Cormack B, Haynes K, Kuchler K. Systematic phenotyping of a large-scale Candida glabrata deletion collection reveals novel antifungal tolerance genes. PLoS Pathog 2014; 10:e1004211. [PMID: 24945925 PMCID: PMC4063973 DOI: 10.1371/journal.ppat.1004211] [Citation(s) in RCA: 135] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Accepted: 05/13/2014] [Indexed: 11/28/2022] Open
Abstract
The opportunistic fungal pathogen Candida glabrata is a frequent cause of candidiasis, causing infections ranging from superficial to life-threatening disseminated disease. The inherent tolerance of C. glabrata to azole drugs makes this pathogen a serious clinical threat. To identify novel genes implicated in antifungal drug tolerance, we have constructed a large-scale C. glabrata deletion library consisting of 619 unique, individually bar-coded mutant strains, each lacking one specific gene, all together representing almost 12% of the genome. Functional analysis of this library in a series of phenotypic and fitness assays identified numerous genes required for growth of C. glabrata under normal or specific stress conditions, as well as a number of novel genes involved in tolerance to clinically important antifungal drugs such as azoles and echinocandins. We identified 38 deletion strains displaying strongly increased susceptibility to caspofungin, 28 of which encoding proteins that have not previously been linked to echinocandin tolerance. Our results demonstrate the potential of the C. glabrata mutant collection as a valuable resource in functional genomics studies of this important fungal pathogen of humans, and to facilitate the identification of putative novel antifungal drug target and virulence genes. Clinical infections by the yeast-like pathogen Candida glabrata have been ever-increasing over the past years. Importantly, C. glabrata is one of the most prevalent causes of drug-refractory fungal infections in humans. We have generated a novel large-scale collection encompassing 619 bar-coded C. glabrata mutants, each lacking a single gene. Extensive profiling of phenotypes reveals a number of novel genes implicated in tolerance to antifungal drugs that interfere with proper cell wall function, as well as genes affecting fitness of C. glabrata both during normal growth and under environmental stress. This fungal deletion collection will be a valuable resource for the community to study mechanisms of virulence and antifungal drug tolerance in C. glabrata, which is particularly relevant in view of the increasing prevalence of infections caused by this important human fungal pathogen.
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Affiliation(s)
- Tobias Schwarzmüller
- Medical University Vienna, Max F. Perutz Laboratories, Department of Medical Biochemistry, Vienna, Austria
| | - Biao Ma
- Department of Microbiology, Imperial College London, London, United Kingdom
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Ekkehard Hiller
- Molekulare Biotechnologie MBT Fraunhofer Institut für Grenzflächen- und Bioverfahrenstechnik IGB Fraunhofer, Stuttgart, Germany
| | - Fabian Istel
- Medical University Vienna, Max F. Perutz Laboratories, Department of Medical Biochemistry, Vienna, Austria
| | - Michael Tscherner
- Medical University Vienna, Max F. Perutz Laboratories, Department of Medical Biochemistry, Vienna, Austria
| | - Sascha Brunke
- Department Microbial Pathogenicity Mechanisms, Hans-Knoell-Institute, Jena, Germany
- Friedrich Schiller University, Jena, Germany
- Center for Sepsis Control and Care, CSCC, Jena University Hospital, Jena, Germany
| | - Lauren Ames
- Department of Microbiology, Imperial College London, London, United Kingdom
- Biosciences, College of Life & Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | - Arnaud Firon
- Institut Pasteur, Unité Biologie et Pathogénicité Fongiques, Département Génomes et Génétique, Paris, France
- INRA, USC2019, Paris, France
| | - Brian Green
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Vitor Cabral
- Institut Pasteur, Unité Biologie et Pathogénicité Fongiques, Département Génomes et Génétique, Paris, France
- INRA, USC2019, Paris, France
- Université Paris Diderot, Sorbonne Paris Cité, Cellule Pasteur, Paris, France
| | - Marina Marcet-Houben
- Bioinformatics and Genomics Programme, Centre for Genomic Regulation (CRG), Barcelona, Spain
| | - Ilse D. Jacobsen
- Department Microbial Pathogenicity Mechanisms, Hans-Knoell-Institute, Jena, Germany
- Friedrich Schiller University, Jena, Germany
- Center for Sepsis Control and Care, CSCC, Jena University Hospital, Jena, Germany
| | - Jessica Quintin
- UPR 9022 du CNRS, Université de Strasbourg, Equipe Fondation Recherche Médicale, Institut de Biologie Moléculaire et Cellulaire, Strasbourg, France
| | - Katja Seider
- Department Microbial Pathogenicity Mechanisms, Hans-Knoell-Institute, Jena, Germany
| | - Ingrid Frohner
- Medical University Vienna, Max F. Perutz Laboratories, Department of Medical Biochemistry, Vienna, Austria
| | - Walter Glaser
- Medical University Vienna, Max F. Perutz Laboratories, Department of Medical Biochemistry, Vienna, Austria
| | - Helmut Jungwirth
- Institut für Molekulare Biowissenschaften, Universität Graz, Graz, Austria
| | - Sophie Bachellier-Bassi
- Institut Pasteur, Unité Biologie et Pathogénicité Fongiques, Département Génomes et Génétique, Paris, France
| | - Murielle Chauvel
- Institut Pasteur, Unité Biologie et Pathogénicité Fongiques, Département Génomes et Génétique, Paris, France
| | - Ute Zeidler
- Institut Pasteur, Unité Biologie et Pathogénicité Fongiques, Département Génomes et Génétique, Paris, France
| | - Dominique Ferrandon
- UPR 9022 du CNRS, Université de Strasbourg, Equipe Fondation Recherche Médicale, Institut de Biologie Moléculaire et Cellulaire, Strasbourg, France
| | - Toni Gabaldón
- Bioinformatics and Genomics Programme, Centre for Genomic Regulation (CRG), Barcelona, Spain
- Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - Bernhard Hube
- Department Microbial Pathogenicity Mechanisms, Hans-Knoell-Institute, Jena, Germany
- Friedrich Schiller University, Jena, Germany
- Center for Sepsis Control and Care, CSCC, Jena University Hospital, Jena, Germany
| | - Christophe d'Enfert
- Institut Pasteur, Unité Biologie et Pathogénicité Fongiques, Département Génomes et Génétique, Paris, France
- INRA, USC2019, Paris, France
- * E-mail: (CE); (SR); (BC); (KH); (KK)
| | - Steffen Rupp
- Molekulare Biotechnologie MBT Fraunhofer Institut für Grenzflächen- und Bioverfahrenstechnik IGB Fraunhofer, Stuttgart, Germany
- * E-mail: (CE); (SR); (BC); (KH); (KK)
| | - Brendan Cormack
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- * E-mail: (CE); (SR); (BC); (KH); (KK)
| | - Ken Haynes
- Department of Microbiology, Imperial College London, London, United Kingdom
- Biosciences, College of Life & Environmental Sciences, University of Exeter, Exeter, United Kingdom
- * E-mail: (CE); (SR); (BC); (KH); (KK)
| | - Karl Kuchler
- Medical University Vienna, Max F. Perutz Laboratories, Department of Medical Biochemistry, Vienna, Austria
- * E-mail: (CE); (SR); (BC); (KH); (KK)
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16
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Noda Y, Hara T, Ishii M, Yoda K. Distinct adaptor proteins assist exit of Kre2-family proteins from the yeast ER. Biol Open 2014; 3:209-24. [PMID: 24585773 PMCID: PMC4001239 DOI: 10.1242/bio.20146312] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Svp26 protein of S. cerevisiae is an ER- and Golgi-localized integral membrane protein with 4 potential membrane-spanning domains. It functions as an adaptor protein that facilitates the ER exit of Ktr3, a mannosyltransferase required for biosynthesis of O-linked oligosaccharides, and the ER exit of Mnn2 and Mnn5, mannosyltransferases, which participate in the biosynthesis of N-linked oligosaccharides. Ktr3 belongs to the Kre2 family, which consists of 9 members of type-II membrane proteins sharing sequence similarities. In this report, we examined all Kre2 family members and found that the Golgi localizations of two others, Kre2 and Ktr1, were dependent on Svp26 by immunofluorescence microscopy and cell fractionations in sucrose density gradients. We show that Svp26 functions in facilitating the ER exit of Kre2 and Ktr1 by an in vitro COPII budding assay. Golgi localization of Ktr4 was not dependent on Svp26. Screening null mutants of the genes encoding abundant COPII membrane proteins for those showing mislocalization of Ktr4 in the ER revealed that Erv41 and Erv46 are required for the correct Golgi localization of Ktr4. We provide biochemical evidence that the Erv41-Erv46 complex functions as an adaptor protein for ER exit of Ktr4. This is the first demonstration of the molecular function of this evolutionally conserved protein complex. The domain switching experiments show that the lumenal domain of Ktr4 is responsible for recognition by the Erv41-Erv46 complex. Thus, ER exit of Kre2-family proteins is dependent on distinct adaptor proteins and our results provide new insights into the traffic of Kre2-family mannosyltransferases.
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Affiliation(s)
- Yoichi Noda
- Department of Biotechnology, University of Tokyo, Yayoi, Bunkyo-Ku, Tokyo 113-8657, Japan
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17
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West L, Lowman DW, Mora-Montes HM, Grubb S, Murdoch C, Thornhill MH, Gow NAR, Williams D, Haynes K. Differential virulence of Candida glabrata glycosylation mutants. J Biol Chem 2013; 288:22006-18. [PMID: 23720756 PMCID: PMC3724654 DOI: 10.1074/jbc.m113.478743] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The fungus Candida glabrata is an important and increasingly common pathogen of humans, particularly in immunocompromised hosts. Despite this, little is known about the attributes that allow this organism to cause disease or its interaction with the host immune system. However, in common with other fungi, the cell wall of C. glabrata is the initial point of contact between the host and pathogen, and as such, it is likely to play an important role in mediating interactions and hence virulence. Here, we show both through genetic complementation and polysaccharide structural analyses that C. glabrata ANP1, MNN2, and MNN11 encode functional orthologues of the respective Saccharomyces cerevisiae mannosyltransferases. Furthermore, we show that deletion of the C. glabrata Anp1, Mnn2, and Mnn11 mannosyltransferases directly affects the structure of the fungal N-linked mannan, in line with their predicted functions, and this has implications for cell wall integrity and consequently virulence. C. glabrata anp1 and mnn2 mutants showed increased virulence, compared with wild-type (and mnn11) cells. This is in contrast to Candida albicans where inactivation of genes involved in mannan biosynthesis has usually been linked to an attenuation of virulence. In the long term, a better understanding of the attributes that allow C. glabrata to cause disease will provide insights that can be adopted for the development of novel therapeutic and diagnostic approaches.
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Affiliation(s)
- Lara West
- Department of Microbiology, Imperial College London, London, SW7 2AZ, United Kingdom
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18
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Orlean P. Architecture and biosynthesis of the Saccharomyces cerevisiae cell wall. Genetics 2012; 192:775-818. [PMID: 23135325 PMCID: PMC3522159 DOI: 10.1534/genetics.112.144485] [Citation(s) in RCA: 303] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2012] [Accepted: 08/06/2012] [Indexed: 01/02/2023] Open
Abstract
The wall gives a Saccharomyces cerevisiae cell its osmotic integrity; defines cell shape during budding growth, mating, sporulation, and pseudohypha formation; and presents adhesive glycoproteins to other yeast cells. The wall consists of β1,3- and β1,6-glucans, a small amount of chitin, and many different proteins that may bear N- and O-linked glycans and a glycolipid anchor. These components become cross-linked in various ways to form higher-order complexes. Wall composition and degree of cross-linking vary during growth and development and change in response to cell wall stress. This article reviews wall biogenesis in vegetative cells, covering the structure of wall components and how they are cross-linked; the biosynthesis of N- and O-linked glycans, glycosylphosphatidylinositol membrane anchors, β1,3- and β1,6-linked glucans, and chitin; the reactions that cross-link wall components; and the possible functions of enzymatic and nonenzymatic cell wall proteins.
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Affiliation(s)
- Peter Orlean
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
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19
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Hernández-Cervantes A, Mora-Montes HM, Álvarez-Vargas A, Jiménez DFD, Robledo-Ortiz CI, Flores-Carreón A. Isolation of Sporothrix schenckii MNT1 and the biochemical and functional characterization of the encoded α1,2-mannosyltransferase activity. Microbiology (Reading) 2012; 158:2419-2427. [DOI: 10.1099/mic.0.060392-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Affiliation(s)
- Arturo Hernández-Cervantes
- Departamento de Biología, División de Ciencias Naturales y Exactas, Campus Guanajuato, Universidad de Guanajuato, Noria Alta s/n, Col. Noria Alta, C.P. 36050, Guanajuato, Gto., Mexico
| | - Héctor M. Mora-Montes
- Departamento de Biología, División de Ciencias Naturales y Exactas, Campus Guanajuato, Universidad de Guanajuato, Noria Alta s/n, Col. Noria Alta, C.P. 36050, Guanajuato, Gto., Mexico
| | - Aurelio Álvarez-Vargas
- Departamento de Biología, División de Ciencias Naturales y Exactas, Campus Guanajuato, Universidad de Guanajuato, Noria Alta s/n, Col. Noria Alta, C.P. 36050, Guanajuato, Gto., Mexico
| | - Diana F. Díaz Jiménez
- Departamento de Biología, División de Ciencias Naturales y Exactas, Campus Guanajuato, Universidad de Guanajuato, Noria Alta s/n, Col. Noria Alta, C.P. 36050, Guanajuato, Gto., Mexico
| | - Claudia I. Robledo-Ortiz
- Departamento de Biología, División de Ciencias Naturales y Exactas, Campus Guanajuato, Universidad de Guanajuato, Noria Alta s/n, Col. Noria Alta, C.P. 36050, Guanajuato, Gto., Mexico
| | - Arturo Flores-Carreón
- Departamento de Biología, División de Ciencias Naturales y Exactas, Campus Guanajuato, Universidad de Guanajuato, Noria Alta s/n, Col. Noria Alta, C.P. 36050, Guanajuato, Gto., Mexico
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20
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Mora-Montes HM, Bates S, Netea MG, Castillo L, Brand A, Buurman ET, Díaz-Jiménez DF, Jan Kullberg B, Brown AJP, Odds FC, Gow NAR. A multifunctional mannosyltransferase family in Candida albicans determines cell wall mannan structure and host-fungus interactions. J Biol Chem 2010; 285:12087-95. [PMID: 20164191 PMCID: PMC2852947 DOI: 10.1074/jbc.m109.081513] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The cell wall proteins of fungi are modified by N- and O-linked mannosylation and phosphomannosylation, resulting in changes to the physical and immunological properties of the cell. Glycosylation of cell wall proteins involves the activities of families of endoplasmic reticulum and Golgi-located glycosyl transferases whose activities are difficult to infer through bioinformatics. The Candida albicans MNT1/KRE2 mannosyl transferase family is represented by five members. We showed previously that Mnt1 and Mnt2 are involved in O-linked mannosylation and are required for virulence. Here, the role of C. albicans MNT3, MNT4, and MNT5 was determined by generating single and multiple MnTDelta null mutants and by functional complementation experiments in Saccharomyces cerevisiae. CaMnt3, CaMnt4, and CaMnt5 did not participate in O-linked mannosylation, but CaMnt3 and CaMnt5 had redundant activities in phosphomannosylation and were responsible for attachment of approximately half of the phosphomannan attached to N-linked mannans. CaMnt4 and CaMnt5 participated in N-mannan branching. Deletion of CaMNT3, CaMNT4, and CaMNT5 affected the growth rate and virulence of C. albicans, affected the recognition of the yeast by human monocytes and cytokine stimulation, and led to increased cell wall chitin content and exposure of beta-glucan at the cell wall surface. Therefore, the MNT1/KRE2 gene family participates in three types of protein mannosylation in C. albicans, and these modifications play vital roles in fungal cell wall structure and cell surface recognition by the innate immune system.
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Affiliation(s)
- Héctor M Mora-Montes
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, Scotland, UK
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21
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Tu L, Banfield DK. Localization of Golgi-resident glycosyltransferases. Cell Mol Life Sci 2010; 67:29-41. [PMID: 19727557 PMCID: PMC11115592 DOI: 10.1007/s00018-009-0126-z] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2009] [Revised: 07/30/2009] [Accepted: 08/04/2009] [Indexed: 10/20/2022]
Abstract
For many glycosyltransferases, the information that instructs Golgi localization is located within a relatively short sequence of amino acids in the N-termini of these proteins comprising: the cytoplasmic tail, the transmembrane spanning region, and the stem region (CTS). Also, one enzyme may be more reliant on a particular region in the CTS for its localization than another. The predominance of these integral membrane proteins in the Golgi has seen these enzymes become central players in the development of membrane trafficking models of transport within this organelle. It is now understood that the means by which the characteristic distributions of glycosyltransferases arise within the subcompartments of the Golgi is inextricably linked to the mechanisms that cells employ to direct the flow of proteins and lipids within this organelle.
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Affiliation(s)
- Linna Tu
- Department of Biology, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, People’s Republic of China
| | - David Karl Banfield
- Department of Biology, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, People’s Republic of China
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22
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White MA, Clark KM, Grayhack EJ, Dumont ME. Characteristics affecting expression and solubilization of yeast membrane proteins. J Mol Biol 2007; 365:621-36. [PMID: 17078969 PMCID: PMC1839945 DOI: 10.1016/j.jmb.2006.10.004] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2006] [Revised: 09/27/2006] [Accepted: 10/03/2006] [Indexed: 11/26/2022]
Abstract
Biochemical and structural analysis of membrane proteins often critically depends on the ability to overexpress and solubilize them. To identify properties of eukaryotic membrane proteins that may be predictive of successful overexpression, we analyzed expression levels of the genomic complement of over 1000 predicted membrane proteins in a recently completed Saccharomyces cerevisiae protein expression library. We detected statistically significant positive and negative correlations between high membrane protein expression and protein properties such as size, overall hydrophobicity, number of transmembrane helices, and amino acid composition of transmembrane segments. Although expression levels of membrane and soluble proteins exhibited similar negative correlations with overall hydrophobicity, high-level membrane protein expression was positively correlated with the hydrophobicity of predicted transmembrane segments. To further characterize yeast membrane proteins as potential targets for structure determination, we tested the solubility of 122 of the highest expressed yeast membrane proteins in six commonly used detergents. Almost all the proteins tested could be solubilized using a small number of detergents. Solubility in some detergents depended on protein size, number of transmembrane segments, and hydrophobicity of predicted transmembrane segments. These results suggest that bioinformatic approaches may be capable of identifying membrane proteins that are most amenable to overexpression and detergent solubilization for structural and biochemical analyses. Bioinformatic approaches could also be used in the redesign of proteins that are not intrinsically well-adapted to such studies.
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Affiliation(s)
- Michael A. White
- Department of Biochemistry & Biophysics, University of Rochester Medical Center, Rochester, NY 14642
| | - Kathleen M. Clark
- Department of Pediatrics, University of Rochester Medical Center, Rochester, NY 14642
| | - Elizabeth J. Grayhack
- Department of Biochemistry & Biophysics, University of Rochester Medical Center, Rochester, NY 14642
- Department of Pediatrics, University of Rochester Medical Center, Rochester, NY 14642
| | - Mark E. Dumont
- Department of Biochemistry & Biophysics, University of Rochester Medical Center, Rochester, NY 14642
- Department of Pediatrics, University of Rochester Medical Center, Rochester, NY 14642
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23
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Abstract
The fungal cell wall is a dynamic structure that protects the cell from changes in osmotic pressure and other environmental stresses, while allowing the fungal cell to interact with its environment. The structure and biosynthesis of a fungal cell wall is unique to the fungi, and is therefore an excellent target for the development of anti-fungal drugs. The structure of the fungal cell wall and the drugs that target its biosynthesis are reviewed. Based on studies in a number of fungi, the cell wall has been shown to be primarily composed of chitin, glucans, mannans and glycoproteins. The biosynthesis of the various components of the fungal cell wall and the importance of the components in the formation of a functional cell wall, as revealed through mutational analyses, are discussed. There is strong evidence that the chitin, glucans and glycoproteins are covalently cross-linked together and that the cross-linking is a dynamic process that occurs extracellularly.
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Affiliation(s)
- Shaun M Bowman
- Department of Biological Sciences, The University at Buffalo, Buffalo, New York 14260, USA
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24
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Abstract
An extracellular matrix composed of a layered meshwork of beta-glucans, chitin, and mannoproteins encapsulates cells of the yeast Saccharomyces cerevisiae. This organelle determines cellular morphology and plays a critical role in maintaining cell integrity during cell growth and division, under stress conditions, upon cell fusion in mating, and in the durable ascospore cell wall. Here we assess recent progress in understanding the molecular biology and biochemistry of cell wall synthesis and its remodeling in S. cerevisiae. We then review the regulatory dynamics of cell wall assembly, an area where functional genomics offers new insights into the integration of cell wall growth and morphogenesis with a polarized secretory system that is under cell cycle and cell type program controls.
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Affiliation(s)
- Guillaume Lesage
- Department of Biology, McGill University, Montreal, PQ H3A 1B1, Canada
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25
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Gilbert MJ, Thornton CR, Wakley GE, Talbot NJ. A P-type ATPase required for rice blast disease and induction of host resistance. Nature 2006; 440:535-9. [PMID: 16554820 DOI: 10.1038/nature04567] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2005] [Accepted: 12/22/2005] [Indexed: 11/09/2022]
Abstract
To cause diseases in plants, pathogenic microorganisms have evolved mechanisms to deliver proteins directly into plant cells, where they suppress plant defences and facilitate tissue invasion. How plant pathogenic fungi, which cause many of the world's most serious plant diseases, deliver proteins during plant infection is currently unknown. Here we report the characterization of a P-type ATPase-encoding gene, MgAPT2, in the economically important rice blast pathogen Magnaporthe grisea, which is required for exocytosis during plant infection. Targeted gene replacement showed that MgAPT2 is required for both foliar and root infection by the fungus, and for the rapid induction of host defence responses in an incompatible reaction. DeltaMgapt2 mutants are impaired in the secretion of a range of extracellular enzymes and accumulate abnormal Golgi-like cisternae. However, the loss of MgAPT2 does not significantly affect hyphal growth or sporulation, indicating that the establishment of rice blast disease involves the use of MgApt2-dependent exocytotic processes that operate during plant infection.
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Affiliation(s)
- Martin J Gilbert
- School of Biosciences, University of Exeter, Washington Singer Laboratories, Perry Road, Exeter EX4 4QG, UK
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26
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Corbacho I, Olivero I, Hernández LM. A genome-wide screen for Saccharomyces cerevisiae nonessential genes involved in mannosyl phosphate transfer to mannoprotein-linked oligosaccharides. Fungal Genet Biol 2005; 42:773-90. [PMID: 15993632 DOI: 10.1016/j.fgb.2005.05.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2005] [Revised: 05/10/2005] [Accepted: 05/10/2005] [Indexed: 11/21/2022]
Abstract
A collection of haploid Saccharomyces cerevisiae deletion strains--both MAT a and alpha--was screened for mutants that exhibit low dye binding (ldb) phenotype. This phenotype has previously been associated with reduced incorporation of mannosyl phosphate groups into the mannoprotein-linked oligosaccharides. We identified 199 nonessential genes whose deletion resulted in a detectable ldb phenotype. They fell into diverse functional categories, including those involved in protein glycosylation, vacuolar function, intracellular transport, cytoskeleton organization, transcription, signal transduction, among others. The study extends the number of known genes that affect mannosyl phosphorylation of mannoprotein-linked oligosaccharides, and establishes a link with other relevant pathways in the cell, especially vacuolar function. We have assigned an LDB name to four uncharacterized ORFs identified in this study: YCL005W, LDB16; YDL146W, LDB17; YLL049W, LDB18; and YOR322C, LDB19.
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Affiliation(s)
- Isaac Corbacho
- Department of Microbiology, University of Extremadura, Avda Elvas s/n, 06071 Badajoz, Spain
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27
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Novotná D, Flegelová H, Janderová B. Different action of killer toxins K1 and K2 on the plasma membrane and the cell wall of Saccharomyces cerevisiae. FEMS Yeast Res 2004; 4:803-13. [PMID: 15450187 DOI: 10.1016/j.femsyr.2004.04.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2004] [Revised: 04/07/2004] [Accepted: 04/30/2004] [Indexed: 11/29/2022] Open
Abstract
Study of Saccharomyces cerevisiae killer toxin-sensitive strains with the deltakre2 phenotype (resistant to toxin K1, sensitive to toxin K2) showed that the phenotype is complemented by the KRE2 gene not only in intact cells but also in spheroplasts, and resistance to K1 thus resides very probably in the plasma membrane. deltakre1 deletant displays a faulty interaction with both K1 and K2 toxin. Hence, Kre1p probably serves as plasma membrane receptor for both toxins. Deletants in seven other genes (GDA1, SAC1, LUV1, KRE23, SAC2, KRE21, ERG4) exhibit different degrees of the deltakre2-like resistance pattern, but the phenotype in deltagda1 and deltasac1 is not connected with a defect in K1 toxin interaction with the plasma membrane, similarly as in deltakre6 and deltakre11 strains with a higher resistance to K2 toxin. Differences between the K1 and K2 killer toxin thus occur on the level of both the plasma membrane and the cell wall.
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Affiliation(s)
- Drahomíra Novotná
- Department of Genetics and Microbiology, Faculty of Science, Charles University, Vinicná 5, 128 44, Prague 2, Czech Republic.
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28
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Munro CA, Bates S, Buurman ET, Hughes HB, MacCallum DM, Bertram G, Atrih A, Ferguson MAJ, Bain JM, Brand A, Hamilton S, Westwater C, Thomson LM, Brown AJP, Odds FC, Gow NAR. Mnt1p and Mnt2p of Candida albicans are partially redundant alpha-1,2-mannosyltransferases that participate in O-linked mannosylation and are required for adhesion and virulence. J Biol Chem 2004; 280:1051-60. [PMID: 15519997 PMCID: PMC3749086 DOI: 10.1074/jbc.m411413200] [Citation(s) in RCA: 142] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The MNT1 gene of the human fungal pathogen Candida albicans is involved in O-glycosylation of cell wall and secreted proteins and is important for adherence of C. albicans to host surfaces and for virulence. Here we describe the molecular analysis of CaMNT2, a second member of the MNT1-like gene family in C. albicans. Mnt2p also functions in O-glycosylation. Mnt1p and Mnt2p encode partially redundant alpha-1,2-mannosyltransferases that catalyze the addition of the second and third mannose residues in an O-linked mannose pentamer. Deletion of both copies of MNT1 and MNT2 resulted in reduction in the level of in vitro mannosyltransferase activity and truncation of O-mannan. Both the mnt2Delta and mnt1Delta single mutants were significantly reduced in adherence to human buccal epithelial cells and Matrigel-coated surfaces, indicating a role for O-glycosylated cell wall proteins or O-mannan itself in adhesion to host surfaces. The double mnt1Deltamnt2Delta mutant formed aggregates of cells that appeared to be the result of abnormal cell separation. The double mutant was attenuated in virulence, underlining the importance of O-glycosylation in pathogenesis of C. albicans infections.
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Affiliation(s)
- Carol A. Munro
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD United Kingdom
| | - Steven Bates
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD United Kingdom
| | - Ed T. Buurman
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD United Kingdom
| | - H. Bleddyn Hughes
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD United Kingdom
| | - Donna M. MacCallum
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD United Kingdom
| | - Gwyneth Bertram
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD United Kingdom
| | - Abdel Atrih
- School of Life Sciences, Wellcome Trust Building, University of Dundee, Dundee DD1 4NH, United Kingdom
| | - Michael A. J. Ferguson
- School of Life Sciences, Wellcome Trust Building, University of Dundee, Dundee DD1 4NH, United Kingdom
| | - Judith M. Bain
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD United Kingdom
| | - Alexandra Brand
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD United Kingdom
| | - Suzanne Hamilton
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD United Kingdom
| | - Caroline Westwater
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD United Kingdom
| | - Lynn M. Thomson
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD United Kingdom
| | - Alistair J. P. Brown
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD United Kingdom
| | - Frank C. Odds
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD United Kingdom
| | - Neil A. R. Gow
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD United Kingdom
- To whom correspondence should be addressed. Tel.: 44-1224-555879; Fax.: 44-1224-555844;
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29
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Bulik DA, Olczak M, Lucero HA, Osmond BC, Robbins PW, Specht CA. Chitin synthesis in Saccharomyces cerevisiae in response to supplementation of growth medium with glucosamine and cell wall stress. EUKARYOTIC CELL 2004; 2:886-900. [PMID: 14555471 PMCID: PMC219353 DOI: 10.1128/ec.2.5.886-900.2003] [Citation(s) in RCA: 124] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In Saccharomyces cerevisiae most chitin is synthesized by Chs3p, which deposits chitin in the lateral cell wall and in the bud-neck region during cell division. We have recently found that addition of glucosamine (GlcN) to the growth medium leads to a three- to fourfold increase in cell wall chitin levels. We compared this result to the increases in cellular chitin levels associated with cell wall stress and with treatment of yeast with mating pheromone. Since all three phenomena lead to increases in precursors of chitin, we hypothesized that chitin synthesis is at least in part directly regulated by the size of this pool. This hypothesis was strengthened by our finding that addition of GlcN to the growth medium causes a rapid increase in chitin synthesis without any pronounced change in the expression of more than 6,000 genes monitored with Affymetrix gene expression chips. In other studies we found that the specific activity of Chs3p is higher in the total membrane fractions from cells grown in GlcN and from mutants with weakened cell walls. Sucrose gradient analysis shows that Chs3p is present in an inactive form in what may be Golgi compartments but as an active enzyme in other intracellular membrane-bound vesicles, as well as in the plasma membrane. We conclude that Chs3p-dependent chitin synthesis in S. cerevisiae is regulated both by the levels of intermediates of the UDP-GlcNAc biosynthetic pathway and by an increase in the activity of the enzyme in the plasma membrane.
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Affiliation(s)
- Dorota A Bulik
- Department of Molecular and Cell Biology, School of Dental Medicine, Boston University, Boston, Massachusetts 02118, USA
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30
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Lagorce A, Hauser NC, Labourdette D, Rodriguez C, Martin-Yken H, Arroyo J, Hoheisel JD, François J. Genome-wide analysis of the response to cell wall mutations in the yeast Saccharomyces cerevisiae. J Biol Chem 2003; 278:20345-57. [PMID: 12644457 DOI: 10.1074/jbc.m211604200] [Citation(s) in RCA: 198] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Perturbations of the yeast cell wall trigger a repair mechanism that reconfigures its molecular structure to preserve cell integrity. To investigate this mechanism, we compared the global gene expression in five mutant strains, each bearing a mutation (i.e. fks1, kre6, mnn9, gas1, and knr4 mutants) that affects in a different manner the cell wall construction. Altogether, 300 responsive genes were kept based on high stringency criteria during data processing. Functional classification of these differentially expressed genes showed a substantial subset of induced genes involved in cell wall construction and an enrichment of metabolic, energy generation, and cell defense categories, whereas families of genes belonging to transcription, protein synthesis, and cellular growth were underrepresented. Clustering methods isolated a single group of approximately 80 up-regulated genes that could be considered as the stereotypical transcriptional response of the cell wall compensatory mechanism. The in silico analysis of the DNA upstream region of these co-regulated genes revealed pairwise combinations of DNA-binding sites for transcriptional factors implicated in stress and heat shock responses (Msn2/4p and Hsf1p) with Rlm1p and Swi4p, two PKC1-regulated transcription factors involved in the activation genes related to cell wall biogenesis and G1/S transition. Moreover, this computational analysis also uncovered the 6-bp 5'-AGCCTC-3' CDRE (calcineurin-dependent response element) motif in 40% of the co-regulated genes. This motif was recently shown to be the DNA binding site for Crz1p, the major effector of calcineurin-regulated gene expression in yeast. Taken altogether, the data presented here lead to the conclusion that the cell wall compensatory mechanism, as triggered by cell wall mutations, integrates three major regulatory systems: namely the PKC1-SLT2 mitogen-activated protein kinase-signaling module, the "global stress" response mediated by Msn2/4p, and the Ca2+/calcineurin-dependent pathway. The relative importance of these regulatory systems in the cell wall compensatory mechanism is discussed.
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Affiliation(s)
- Arnaud Lagorce
- Centre de Bioingenierie Gilbert Durand, UMR-CNRS 5504 and INRA 792, France
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31
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Travers KJ, Patil CK, Weissman JS. Functional genomic approaches to understanding molecular chaperones and stress responses. ADVANCES IN PROTEIN CHEMISTRY 2002; 59:345-90. [PMID: 11868277 DOI: 10.1016/s0065-3233(01)59011-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- K J Travers
- Howard Hughes Medical Institute, Department of Cellular and Molecular Pharmacology, Department of Biochemistry and Biophysics, University of California-San Francisco, San Francisco, California, USA
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32
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Harkins HA, Pagé N, Schenkman LR, De Virgilio C, Shaw S, Bussey H, Pringle JR. Bud8p and Bud9p, proteins that may mark the sites for bipolar budding in yeast. Mol Biol Cell 2001; 12:2497-518. [PMID: 11514631 PMCID: PMC58609 DOI: 10.1091/mbc.12.8.2497] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2000] [Revised: 04/10/2001] [Accepted: 04/25/2001] [Indexed: 11/11/2022] Open
Abstract
The bipolar budding pattern of a/alpha Saccharomyces cerevisiae cells appears to depend on persistent spatial markers in the cell cortex at the two poles of the cell. Previous analysis of mutants with specific defects in bipolar budding identified BUD8 and BUD9 as potentially encoding components of the markers at the poles distal and proximal to the birth scar, respectively. Further genetic analysis reported here supports this hypothesis. Mutants deleted for BUD8 or BUD9 grow normally but bud exclusively from the proximal and distal poles, respectively, and the double-mutant phenotype suggests that the bipolar budding pathway has been totally disabled. Moreover, overexpression of these genes can cause either an increased bias for budding at the distal (BUD8) or proximal (BUD9) pole or a randomization of bud position, depending on the level of expression. The structures and localizations of Bud8p and Bud9p are also consistent with their postulated roles as cortical markers. Both proteins appear to be integral membrane proteins of the plasma membrane, and they have very similar overall structures, with long N-terminal domains that are both N- and O-glycosylated followed by a pair of putative transmembrane domains surrounding a short hydrophilic domain that is presumably cytoplasmic. The putative transmembrane and cytoplasmic domains of the two proteins are very similar in sequence. When Bud8p and Bud9p were localized by immunofluorescence and tagging with GFP, each protein was found predominantly in the expected location, with Bud8p at presumptive bud sites, bud tips, and the distal poles of daughter cells and Bud9p at the necks of large-budded cells and the proximal poles of daughter cells. Bud8p localized approximately normally in several mutants in which daughter cells are competent to form their first buds at the distal pole, but it was not detected in a bni1 mutant, in which such distal-pole budding is lost. Surprisingly, Bud8p localization to the presumptive bud site and bud tip also depends on actin but is independent of the septins.
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Affiliation(s)
- H A Harkins
- Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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33
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Cipollo JF, Trimble RB, Chi JH, Yan Q, Dean N. The yeast ALG11 gene specifies addition of the terminal alpha 1,2-Man to the Man5GlcNAc2-PP-dolichol N-glycosylation intermediate formed on the cytosolic side of the endoplasmic reticulum. J Biol Chem 2001; 276:21828-40. [PMID: 11278778 DOI: 10.1074/jbc.m010896200] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The initial steps in N-linked glycosylation involve the synthesis of a lipid-linked core oligosaccharide followed by the transfer of the core glycan to nascent polypeptides in the endoplasmic reticulum (ER). Here, we describe alg11, a new yeast glycosylation mutant that is defective in the last step of the synthesis of the Man(5)GlcNAc(2)-PP-dolichol core oligosaccharide on the cytosolic face of the ER. A deletion of the ALG11 gene leads to poor growth and temperature-sensitive lethality. In an alg11 lesion, both Man(3)GlcNAc(2)-PP-dolichol and Man(4)GlcNAc(2)-PP-dolichol are translocated into the ER lumen as substrates for the Man-P-dolichol-dependent sugar transferases in this compartment. This leads to a unique family of oligosaccharide structures lacking one or both of the lower arm alpha1,2-linked Man residues. The former are elongated to mannan, whereas the latter are poor substrates for outerchain initiation by Ochlp (Nakayama, K.-I., Nakanishi-Shindo, Y., Tanaka, A., Haga-Toda, Y., and Jigami, Y. (1997) FEBS Lett. 412, 547-550) and accumulate largely as truncated biosynthetic end products. The ALG11 gene is predicted to encode a 63.1-kDa membrane protein that by indirect immunofluorescence resides in the ER. The Alg11 protein is highly conserved, with homologs in fission yeast, worms, flies, and plants. In addition to these Alg11-related proteins, Alg11p is also similar to Alg2p, a protein that regulates the addition of the third mannose to the core oligosaccharide. All of these Alg11-related proteins share a 23-amino acid sequence that is found in over 60 proteins from bacteria to man whose function is in sugar metabolism, implicating this sequence as a potential sugar nucleotide binding motif.
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Affiliation(s)
- J F Cipollo
- Department of Biomedical Sciences, State University of New York at Albany, Albany, New York 12201, USA
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34
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35
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Tomlin GC, Hamilton GE, Gardner DCJ, Walmsley RM, Stateva LI, Oliver SG. Suppression of sorbitol dependence in a strain bearing a mutation in the SRB1/PSA1/VIG9 gene encoding GDP-mannose pyrophosphorylase by PDE2 overexpression suggests a role for the Ras/cAMP signal-transduction pathway in the control of yeast cell-wall biogenesis. MICROBIOLOGY (READING, ENGLAND) 2000; 146 ( Pt 9):2133-2146. [PMID: 10974101 DOI: 10.1099/00221287-146-9-2133] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Complementation studies and allele replacement in Saccharomyces cerevisiae revealed that PSA1/VIG9, an essential gene that encodes GDP-mannose pyrophosphorylase, is the wild-type SRB1 gene. Cloning and sequencing of the srb1-1 allele showed that it determines a single amino acid change from glycine to aspartic acid at residue 276 (srb1(D276)). Genetic evidence is presented showing that at least one further mutation is required for the sorbitol dependence of srb1(D276). A previously reported complementing gene, which this study has now identified as PDE2, is a multi-copy suppressor of sorbitol dependence and is not, as was previously suggested, the SRB1 gene. srb and pde2 mutants share a number of phenotypes, including lysis upon hypotonic shock and enhanced transformability. These data are consistent with the idea that the Ras/cAMP pathway might modulate cell-wall construction.
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Affiliation(s)
- Gregory C Tomlin
- School of Biological Sciences, 2.205 Stopford Building, University of Manchester, Oxford Road, Manchester M13 9PT, UK1
| | - Grant E Hamilton
- Department of Biomolecular Sciences, UMIST, PO Box 88, Manchester M60 1QD, UK2
| | - David C J Gardner
- Department of Biomolecular Sciences, UMIST, PO Box 88, Manchester M60 1QD, UK2
| | - Richard M Walmsley
- Department of Biomolecular Sciences, UMIST, PO Box 88, Manchester M60 1QD, UK2
| | - Lubomira I Stateva
- Department of Biomolecular Sciences, UMIST, PO Box 88, Manchester M60 1QD, UK2
| | - Stephen G Oliver
- School of Biological Sciences, 2.205 Stopford Building, University of Manchester, Oxford Road, Manchester M13 9PT, UK1
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36
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Thomson LM, Bates S, Yamazaki S, Arisawa M, Aoki Y, Gow NA. Functional characterization of the Candida albicans MNT1 mannosyltransferase expressed heterologously in Pichia pastoris. J Biol Chem 2000; 275:18933-8. [PMID: 10766761 DOI: 10.1074/jbc.m909699199] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The alpha1,2-mannosyltransferase gene MNT1 of the human fungal pathogen Candida albicans has been shown to be important for its adherence to various human surfaces and for virulence (Buurman, E. T. , Westwater, C., Hube, B., Brown, A. P. J., Odds, F. C., and Gow, N. A. R. (1998) Proc. Natl. Acad. Sci. U. S. A. 95, 7670-7675). The CaMnt1p is a type II membrane protein, which is part of a family of proteins that are important for both O- and N-linked mannosylation in fungi and which represent a distinct subclass of glycosyltransferase enzymes. Here we use heterologous expression of CaMNT1 in the methylotrophic yeast Pichia pastoris to characterize the properties of the CaMnt1p enzyme as an example of this family of enzymes and to identify key amino acid residues required for coordination of the metal co-factor and for the retaining nucleophilic mechanism of the transferase reaction. We show that the enzyme can use both Mn(2+) and Zn(2+) as metal ion co-factors and that the reaction catalyzed is specific for alpha-methyl mannoside and alpha1,2-mannobiose acceptors. The N-terminal cytoplasmic tail, transmembrane domains, and stem regions were shown to be dispensable for activity, whereas truncations to the C-terminal catalytic domain destroyed activity without markedly affecting transcription of the truncated gene.
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Affiliation(s)
- L M Thomson
- Department of Molecular and Cell Biology, Institute of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, United Kingdom
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37
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Montijn RC, Vink E, Müller WH, Verkleij AJ, Van Den Ende H, Henrissat B, Klis FM. Localization of synthesis of beta1,6-glucan in Saccharomyces cerevisiae. J Bacteriol 1999; 181:7414-20. [PMID: 10601196 PMCID: PMC94196 DOI: 10.1128/jb.181.24.7414-7420.1999] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Beta1,6-Glucan is a key component of the yeast cell wall, interconnecting cell wall proteins, beta1,3-glucan, and chitin. It has been postulated that the synthesis of beta1,6-glucan begins in the endoplasmic reticulum with the formation of protein-bound primer structures and that these primer structures are extended in the Golgi complex by two putative glucosyltransferases that are functionally redundant, Kre6 and Skn1. This is followed by maturation steps at the cell surface and by coupling to other cell wall macromolecules. We have reinvestigated the role of Kre6 and Skn1 in the biogenesis of beta1,6-glucan. Using hydrophobic cluster analysis, we found that Kre6 and Skn1 show significant similarities to family 16 glycoside hydrolases but not to nucleotide diphospho-sugar glycosyltransferases, indicating that they are glucosyl hydrolases or transglucosylases instead of genuine glucosyltransferases. Next, using immunogold labeling, we tried to visualize intracellular beta1,6-glucan in cryofixed sec1-1 cells which had accumulated secretory vesicles at the restrictive temperature. No intracellular labeling was observed, but the cell surface was heavily labeled. Consistent with this, we could detect substantial amounts of beta1,6-glucan in isolated plasma membrane-derived microsomes but not in post-Golgi secretory vesicles. Taken together, our data indicate that the synthesis of beta1, 6-glucan takes place largely at the cell surface. An alternative function for Kre6 and Skn1 is discussed.
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Affiliation(s)
- R C Montijn
- Swammerdam Institute of Life Science, University of Amsterdam, BioCentrum Amsterdam, Amsterdam 1098 SM, The Netherlands
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38
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Abstract
The Golgi complex is the site where the terminal carbohydrate modification of proteins and lipids occurs. These carbohydrates play a variety of biological roles, ranging from the stabilization of glycoprotein structure to the provision of ligands for cell-cell interactions to the regulation of cell surface properties. Progress in our understanding of the biosynthesis and regulation of glycoconjugates has been accelerating at a rapid pace. Recent advances in the field of yeast glycobiology have been particularly impressive. This review focuses on glycosylation of proteins in the Golgi of the yeast Saccharomyces cerevisiae, with emphasis on the candidate mannosyltransferases that participate in the synthesis of N-linked oligosaccharides. Current views on how these enzymes may be regulated and how glycosylation relates on other cellular processes are also discussed.
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Affiliation(s)
- N Dean
- Department of Biochemistry and Cell Biology, Institute for Cell and Developmental Biology, State University of New York, Stony Brook, NY 11794-5215, USA.
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39
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Lussier M, Sdicu AM, Bussey H. The KTR and MNN1 mannosyltransferase families of Saccharomyces cerevisiae. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1426:323-34. [PMID: 9878809 DOI: 10.1016/s0304-4165(98)00133-0] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Glycosylation constitutes one of the most important of all the post-translational modifications and may have numerous effects on the function, structure, physical properties and targeting of particular proteins. Eukaryotic glycan structures are progressively elaborated in the secretory pathway. Following the addition of a core N-linked carbohydrate in the endoplasmic reticulum, glycoproteins move to the Golgi complex where the elongation of O-linked sugar chains and processing of complex N-linked oligosaccharide structures take place. In order to better define how such post-translational modifications occur, we have been studying the yeast KTR and MNN1 mannosyltransferase gene families. The KTR family contains nine members: KRE2, YUR1, KTR1, KTR2, KTR3, KTR4, KTR5, KTR6 and KTR7. The MNN1 family contains six members: MNN1, TTP1, YGL257c, YNR059w, YIL014w and YJL86w. In this review, we address protein structure, sequence similarities and enzymatic activity in the context of each gene family. In addition, a description of the known function of many family members in O- and N-linked glycosylation is included. Finally, the genetic interactions and functional redundancies within a gene family are also discussed.
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Affiliation(s)
- M Lussier
- Department of Biology, McGill University, 1205 Dr. Penfield Avenue, Montreal, Que. H3A 1B1, Canada
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40
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Buurman ET, Westwater C, Hube B, Brown AJ, Odds FC, Gow NA. Molecular analysis of CaMnt1p, a mannosyl transferase important for adhesion and virulence of Candida albicans. Proc Natl Acad Sci U S A 1998; 95:7670-5. [PMID: 9636208 PMCID: PMC22718 DOI: 10.1073/pnas.95.13.7670] [Citation(s) in RCA: 114] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/1998] [Accepted: 04/06/1998] [Indexed: 02/07/2023] Open
Abstract
There is an immediate need for identification of new antifungal targets in opportunistic pathogenic fungi like Candida albicans. In the past, efforts have focused on synthesis of chitin and glucan, which confer mechanical strength and rigidity upon the cell wall. This paper describes the molecular analysis of CaMNT1, a gene involved in synthesis of mannoproteins, the third major class of macromolecule found in the cell wall. CaMNT1 encodes an alpha-1, 2-mannosyl transferase, which adds the second mannose residue in a tri-mannose oligosaccharide structure which represents O-linked mannan in C. albicans. The deduced amino acid sequence suggests that CaMnt1p is a type II membrane protein residing in a medial Golgi compartment. The absence of CaMnt1p reduced the ability of C. albicans cells to adhere to each other, to human buccal epithelial cells, and to rat vaginal epithelial cells. Both heterozygous and homozygous Camnt1 null mutants of C. albicans showed strong attenuation of virulence in guinea pig and mouse models of systemic candidosis, which, in guinea pigs, could be attributed to a decreased ability to reach and/or adhere internal organs. Therefore, correct CaMnt1p-mediated O-linked mannosylation of proteins is critical for adhesion and virulence of C. albicans.
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Affiliation(s)
- E T Buurman
- Department of Molecular and Cell Biology, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, United Kingdom
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41
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Kukuruzinska MA, Lennon K. Protein N-glycosylation: molecular genetics and functional significance. CRITICAL REVIEWS IN ORAL BIOLOGY AND MEDICINE : AN OFFICIAL PUBLICATION OF THE AMERICAN ASSOCIATION OF ORAL BIOLOGISTS 1998; 9:415-48. [PMID: 9825220 DOI: 10.1177/10454411980090040301] [Citation(s) in RCA: 119] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Protein N-glycosylation is a metabolic process that has been highly conserved in evolution. In all eukaryotes, N-glycosylation is obligatory for viability. It functions by modifying appropriate asparagine residues of proteins with oligosaccharide structures, thus influencing their properties and bioactivities. N-glycoprotein biosynthesis involves a multitude of enzymes, glycosyltransferases, and glycosidases, encoded by distinct genes. The majority of these enzymes are transmembrane proteins that function in the endoplasmic reticulum and Golgi apparatus in an ordered and well-orchestrated manner. The complexity of N-glycosylation is augmented by the fact that different asparagine residues within the same polypeptide may be modified with different oligosaccharide structures, and various proteins are distinguished from one another by the characteristics of their carbohydrate moieties. Furthermore, biological consequences of derivatization of proteins with N-glycans range from subtle to significant. In the past, all these features of N-glycosylation have posed a formidable challenge to an elucidation of the physiological role for this modification. Recent advances in molecular genetics, combined with the availability of diverse in vivo experimental systems ranging from yeast to transgenic mice, have expedited the identification, isolation, and characterization of N-glycosylation genes. As a result, rather unexpected information regarding relationships between N-glycosylation and other cellular functions--including secretion, cytoskeletal organization, proliferation, and apoptosis--has emerged. Concurrently, increased understanding of molecular details of N-glycosylation has facilitated the alignment between N-glycosylation deficiencies and human diseases, and has highlighted the possibility of using N-glycan expression on cells as potential determinants of disease and its progression. Recent studies suggest correlations between N-glycosylation capacities of cells and drug sensitivities, as well as susceptibility to infection. Therefore, knowledge of the regulatory features of N-glycosylation may prove useful in the design of novel therapeutics. While facing the demanding task of defining properties, functions, and regulation of the numerous, as yet uncharacterized, N-glycosylation genes, glycobiologists of the 21st century offer exciting possibilities for new approaches to disease diagnosis, prevention, and cure.
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Affiliation(s)
- M A Kukuruzinska
- Department of Molecular and Cell Biology, School of Dental Medicine, Boston University Medical Center, Massachusetts 02118, USA
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42
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Abstract
A summary of previously defined phenotypes in the yeast Saccharomyces cerevisiae is presented. The purpose of this review is to provide a compendium of phenotypes that can be readily screened to identify pleiotropic phenotypes associated with primary or suppressor mutations. Many of these phenotypes provide a convenient alternative to the primary phenotype for following a gene, or as a marker for cloning a gene by genetic complementation. In many cases a particular phenotype or set of phenotypes can suggest a function for the product of the mutated gene.
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Affiliation(s)
- M Hampsey
- Department of Biochemistry, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, Piscataway 08854, USA
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Wang XH, Nakayama K, Shimma Y, Tanaka A, Jigami Y. MNN6, a member of the KRE2/MNT1 family, is the gene for mannosylphosphate transfer in Saccharomyces cerevisiae. J Biol Chem 1997; 272:18117-24. [PMID: 9218445 DOI: 10.1074/jbc.272.29.18117] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
In yeast Saccharomyces cerevisiae the N-linked sugar chain is modified at different positions by the addition of mannosylphosphate. The mnn6 mutant is deficient in the mannosylphosphate transferase activity toward mannotetraose (Karson, E. M., and Ballou, C. E. (1978) J. Biol. Chem. 253, 6484-6492). We have cloned the MNN6 gene by complementation. It has encoded a 446-amino acid polypeptide with the characteristics of type II membrane protein. The deduced Mnn6p showed a significant similarity to Kre2p/Mnt1p, a Golgi alpha-1, 2-mannosyltransferase involved in O-glycosylation. The null mutant of MNN6 showed a normal cell growth, less binding to Alcian blue, hypersensitivity to Calcoflour White and hygromycin B, and diminished mannosylphosphate transferase activity toward the endoplasmic reticulum core oligosaccharide acceptors (Man8GlcNAc2-PA and Man5GlcNAc2-PA) in vitro, suggesting the involvement of the MNN6 gene in the endoplasmic reticulum core oligosaccharide phosphorylation. However, no differences were observed in N-linked mannoprotein oligosaccharides between Deltaoch1 Deltamnn1 cells and Deltaoch1Deltamnn1Deltamnn6 cells, indicating the existence of redundant genes required for the core oligosaccharide phosphorylation. Based on a dramatic decrease in polymannose outer chain phosphorylation by MNN6 gene disruption and a determination of the mannosylphosphorylation site in the acceptor, it is postulated that the MNN6 gene may be a structural gene encoding a mannosylphosphate transferase, which recognizes any oligosaccharides with at least one alpha-1,2-linked mannobiose unit.
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Affiliation(s)
- X H Wang
- National Institute of Bioscience and Human Technology, Tsukuba, Ibaraki 305, Japan
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44
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Suzuki A, Shibata N, Suzuki M, Saitoh F, Oyamada H, Kobayashi H, Suzuki S, Okawa Y. Characterization of beta-1,2-mannosyltransferase in Candida guilliermondii and its utilization in the synthesis of novel oligosaccharides. J Biol Chem 1997; 272:16822-8. [PMID: 9201988 DOI: 10.1074/jbc.272.27.16822] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
A particulate insoluble enzyme fraction containing mannosyltransferases from Candida guilliermondii IFO 10279 strain cells was obtained as the residue after extracting a 105,000 x g pellet of cell homogenate with 1% Triton X-100. Incubation of this fraction with a mannopentaose, Manalpha1-->3(Manalpha1-->6)Manalpha1-->2Manalpha1+ ++-->2Man, in the presence of GDP-mannose and Mn2+ ion at pH 6.0 gave a third type of beta-1,2 linkage-containing mannohexaose, Manbeta1-->2Manalpha1-->3(Manalpha1-->6)Manalpha1++ +-->2Manalpha1-->2Man , the structure of which was identified by means of a sequential NMR assignment. The results of a substrate specificity study indicated that the beta-1,2-mannosyltransferase requires a mannobiosyl unit, Manalpha1--> 3Manalpha1-->, at the nonreducing terminal site. We synthesized novel oligosaccharides using substrates possessing a nonreducing terminal alpha-1,3-linked mannose unit prepared from various yeast mannans. Further incubation of the enzymatically synthesized oligosaccharide with the enzyme fraction gave the following structure, Manbeta1-->2Manbeta1-->2Manalpha1-->3(Manalpha1- ->6)Manalpha1--> 2Manalpha1-->2Man, which has been found to correspond to antigenic factor 9. Incubation of Candida albicans serotype B mannan with the enzyme fraction gave significantly transformed mannan, which contains the third type of beta-1,2-linked mannose units.
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Affiliation(s)
- A Suzuki
- Second Department of Hygienic Chemistry, Tohoku College of Pharmacy, 4-4-1 Komatsushima, Aoba-ku, Sendai, Miyagi 981, Japan
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45
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Lussier M, Sdicu AM, Bussereau F, Jacquet M, Bussey H. The Ktr1p, Ktr3p, and Kre2p/Mnt1p mannosyltransferases participate in the elaboration of yeast O- and N-linked carbohydrate chains. J Biol Chem 1997; 272:15527-31. [PMID: 9182588 DOI: 10.1074/jbc.272.24.15527] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
We have determined a role for Ktr1p and Ktr3p as mannosyltransferases in the synthesis of the carbohydrate chains attached to Saccharomyces cerevisiae O- and N-modified proteins. KTR1 and KTR3 encode related proteins that are highly similar to the Kre2p/Mnt1p Golgi alpha1,2-mannosyltransferase (Lussier, M., Camirand, A., Sdicu, A.-M., and Bussey, H. (1993) Yeast 9, 1057-1063; Mallet, L., Bussereau, F., and Jacquet, M. (1994) Yeast 10, 819-831). Examination of the electrophoretic mobility of a specifically O-linked protein from mutants and an analysis of their total O-linked mannosyl chains demonstrates that Ktr1p, Ktr3p, and Kre2p/Mnt1p have overlapping roles and collectively add most of the second and the third alpha1,2-linked mannose residues on O-linked oligosaccharides. Determination of the mobility of the specifically N-linked glycoprotein invertase in different null strains indicates that Ktr1p, Ktr3p, and Kre2p are also jointly involved in N-linked glycosylation, possibly in establishing some of the outer chain alpha1,2-linkages.
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Affiliation(s)
- M Lussier
- Department of Biology, McGill University, Montréal, Québec, Canada, H3A 1B1
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46
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Lussier M, Sdicu AM, Winnett E, Vo DH, Sheraton J, Düsterhöft A, Storms RK, Bussey H. Completion of the Saccharomyces cerevisiae genome sequence allows identification of KTR5, KTR6 and KTR7 and definition of the nine-membered KRE2/MNT1 mannosyltransferase gene family in this organism. Yeast 1997; 13:267-74. [PMID: 9090056 DOI: 10.1002/(sici)1097-0061(19970315)13:3<267::aid-yea72>3.0.co;2-k] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The KRE2/MNT1 mannosyltransferase gene family of Saccharomyces cerevisiae currently consists of the KRE2, YUR1, KTR1, KTR2, KTR3 and KTR4 genes. All six encode putative type II membrane proteins with a short cytoplasmic N-terminus, a membrane-spanning region and a highly conserved catalytic lumenal domain. Here we report the identification of the three remaining members of this family in the yeast genome. KTR5 corresponds to an open reading frame (ORF) of the left arm of chromosome XIV, and KTR6 and KTR7 to ORFs on the left arms of chromosomes XVI and IX respectively. The KTR5, KTR6 and KTR7 gene products are highly similar to the Kre2p/Mnt1p family members. Initial functional characterization revealed that some mutant yeast strains containing null copies of these genes displayed cell wall phenotypes. None was K1 killer toxin resistant but ktr6 and ktr7 null mutants were found to be hypersensitive and resistant, respectively, to the drug Calcofluor White.
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Affiliation(s)
- M Lussier
- Department of Biology, McGill University, Montréal, Québec, Canada
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47
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Romero PA, Lussier M, Sdicu AM, Bussey H, Herscovics A. Ktr1p is an alpha-1,2-mannosyltransferase of Saccharomyces cerevisiae. Comparison of the enzymic properties of soluble recombinant Ktr1p and Kre2p/Mnt1p produced in Pichia pastoris. Biochem J 1997; 321 ( Pt 2):289-95. [PMID: 9020857 PMCID: PMC1218067 DOI: 10.1042/bj3210289] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The yeast genome contains a KRE2/MNT1 family of nine related genes with amino acid similarity to the alpha 1,2-mannosyltransferase Kre2p/Mnt1p, the only member of this family whose enzymic properties have been studied. In this study, the enzymic properties of Ktr1p, another member of this family, were studied and compared to those of Kre2p/Mnt1p. Recombinant soluble forms of Kre2p/Mnt1p and Ktr1p lacking their N-terminal regions were expressed as secreted proteins from the methylotrophic yeast Pichia pastoris. After induction with methanol, the medium contained approx, 40 and 400 mg/l of soluble recombinant Kre2p/Mnt1p and Ktr1p respectively. Both recombinant proteins were shown to exhibit alpha 1,2-mannosyltransferase activity. The enzymes have an absolute requirement for Mn2+ and a similar K(m) for mannose (280-350 mM), methyl-alpha-mannoside (60-90 mM) and GDP-mannose (50-90 microM), but the Vmax was approx. 10 times higher for Kre2p/Mnt1p than for Ktr1p. The enzymes have similar substrate specificities and utilize mannose, methyl-alpha-mannoside, alpha-1,2-mannobiose and methyl-alpha-1,2-mannobiose, as well as Man15-30GlcNAc, derived from mnn2 mutant glycoproteins, as substrates. The enzymes do not utilize alpha-1,6-mannobiose, alpha-1,6-mannotriose, alpha-1,6-mannotetraose, mammalian Man9GlcNAc or yeast Man9-10GlcNAc. These results indicate that Kre2p/ Mnt1p and Ktr1p are capable of participating in both N-glycan and O-glycan biosynthesis.
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Affiliation(s)
- P A Romero
- McGill Cancer Centre, McGill University, Montréal, Québec, Canada
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