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Zhang Z, Yao J, Jiang Z, Huang X, Wang S, Xu F. Golgi-localized APYRASE 1 is critical for Arabidopsis growth by affecting cell wall integrity under boron deficiency. PHYSIOLOGIA PLANTARUM 2024; 176:e14320. [PMID: 38686642 DOI: 10.1111/ppl.14320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Revised: 04/10/2024] [Accepted: 04/11/2024] [Indexed: 05/02/2024]
Abstract
Many nucleoside triphosphate-diphosphohydrolases (NTPDases/APYRASEs, APYs) play a key role in modulating extracellular nucleotide levels. However, the Golgi-localized APYs, which help control glycosylation, have rarely been studied. Here, we identified AtAPY1, a gene encoding an NTPDase in the Golgi apparatus, which is required for cell wall integrity and plant growth under boron (B) limited availability. Loss of function in AtAPY1 hindered cell elongation and division in root tips while increasing the number of cortical cell layers, leading to swelling of the root tip and abundant root hairs under low B stress. Further, expression pattern analysis revealed that B deficiency significantly induced AtAPY1, especially in the root meristem and stele. Fluorescent-labeled AtAPY1-GFP localized to the Golgi stack. Biochemical analysis showed that AtAPY1 exhibited a preference of UDP and GDP hydrolysis activities. Consequently, the loss of function in AtAPY1 might disturb the homoeostasis of NMP-driven NDP-sugar transport, which was closely related to the synthesis of cell wall polysaccharides. Further, cell wall-composition analysis showed that pectin content increased and borate-dimerized RG-II decreased in apy1 mutants, along with a decrease in cellulose content. Eventually, altered polysaccharide characteristics presumably cause growth defects in apy1 mutants under B deficiency. Altogether, these data strongly support a novel role for AtAPY1 in mediating responses to low B availability by regulating cell wall integrity.
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Affiliation(s)
- Ziwei Zhang
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
- Microelement Research Center, College of Resources & Environment, Huazhong Agricultural University, Wuhan, China
| | - Jinliang Yao
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
- Microelement Research Center, College of Resources & Environment, Huazhong Agricultural University, Wuhan, China
| | - Zhexuan Jiang
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
- Microelement Research Center, College of Resources & Environment, Huazhong Agricultural University, Wuhan, China
| | - XinXuan Huang
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
- Microelement Research Center, College of Resources & Environment, Huazhong Agricultural University, Wuhan, China
| | - Sheliang Wang
- Microelement Research Center, College of Resources & Environment, Huazhong Agricultural University, Wuhan, China
| | - Fangsen Xu
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
- Microelement Research Center, College of Resources & Environment, Huazhong Agricultural University, Wuhan, China
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Delivery of Nucleotide Sugars to the Mammalian Golgi: A Very Well (un)Explained Story. Int J Mol Sci 2022; 23:ijms23158648. [PMID: 35955785 PMCID: PMC9368800 DOI: 10.3390/ijms23158648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 07/31/2022] [Accepted: 08/02/2022] [Indexed: 11/25/2022] Open
Abstract
Nucleotide sugars (NSs) serve as substrates for glycosylation reactions. The majority of these compounds are synthesized in the cytoplasm, whereas glycosylation occurs in the endoplasmic reticulum (ER) and Golgi lumens, where catalytic domains of glycosyltransferases (GTs) are located. Therefore, translocation of NS across the organelle membranes is a prerequisite. This process is thought to be mediated by a group of multi-transmembrane proteins from the SLC35 family, i.e., nucleotide sugar transporters (NSTs). Despite many years of research, some uncertainties/inconsistencies related with the mechanisms of NS transport and the substrate specificities of NSTs remain. Here we present a comprehensive review of the NS import into the mammalian Golgi, which consists of three major parts. In the first part, we provide a historical view of the experimental approaches used to study NS transport and evaluate the most important achievements. The second part summarizes various aspects of knowledge concerning NSTs, ranging from subcellular localization up to the pathologies related with their defective function. In the third part, we present the outcomes of our research performed using mammalian cell-based models and discuss its relevance in relation to the general context.
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A GDPase/UDPase bifunctional enzyme from Candida albicans: purification and biochemical characterization. Antonie Van Leeuwenhoek 2022; 115:505-519. [PMID: 35175437 DOI: 10.1007/s10482-022-01714-y] [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: 12/06/2021] [Accepted: 01/30/2022] [Indexed: 10/19/2022]
Abstract
The most frequently isolated human fungal pathogen is Candida albicans which is responsible for about 50% of all Candida infections. In healthy individuals, this organism resides as a part of the normal microbiota in equilibrium with the host. However, under certain conditions, particularly in immunocompromised patients, this opportunistic pathogen adheres to host cells causing serious systemic infections. Thus, much effort has been dedicated to the study of its physiology with emphasis on factors associated to pathogenicity. A representative analysis deals with the mechanisms of glycoprotein assembly as many cell surface antigens and other macromolecules that modulate the immune system fall within this chemical category. In this regard, studies of the terminal protein glycosylation stage which occurs in Golgi vesicles has led to the identification of nucleotidases that convert glycosyltransferase-generated dinucleotides into the corresponding mononucleotides, thus playing a double function: their activity prevent inhibition of further glycosyl transfer by the accumulation of dinucleotides and the resulting mononucleotides are exchanged by specific membrane transporters for equimolecular amounts of sugar donors from the cytosol. Here, using a simple protocol for protein separation we isolated a bifunctional nucleotidase from C. albicans active on GDP and UDP that was characterized in terms of its molecular mass, response to bivalent ions and other factors, substrate specificity and affinity. Results are discussed in terms of the similarities and differences of this nucleotidase with similar counterparts from other organisms thus contributing to the knowledge of a bifunctional diphosphatase not described before in C. albicans.
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Clark G, Brown KA, Tripathy MK, Roux SJ. Recent Advances Clarifying the Structure and Function of Plant Apyrases (Nucleoside Triphosphate Diphosphohydrolases). Int J Mol Sci 2021; 22:ijms22063283. [PMID: 33807069 PMCID: PMC8004787 DOI: 10.3390/ijms22063283] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 03/18/2021] [Accepted: 03/20/2021] [Indexed: 01/22/2023] Open
Abstract
Studies implicating an important role for apyrase (NTPDase) enzymes in plant growth and development began appearing in the literature more than three decades ago. After early studies primarily in potato, Arabidopsis and legumes, especially important discoveries that advanced an understanding of the biochemistry, structure and function of these enzymes have been published in the last half-dozen years, revealing that they carry out key functions in diverse other plants. These recent discoveries about plant apyrases include, among others, novel findings on its crystal structures, its biochemistry, its roles in plant stress responses and its induction of major changes in gene expression when its expression is suppressed or enhanced. This review will describe and discuss these recent advances and the major questions about plant apyrases that remain unanswered.
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Affiliation(s)
- Greg Clark
- Department of Molecular Biosciences, University of Texas, Austin, TX 78712, USA; (G.C.); (K.A.B.)
| | - Katherine A. Brown
- Department of Molecular Biosciences, University of Texas, Austin, TX 78712, USA; (G.C.); (K.A.B.)
- Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge CB3 0HE, UK
| | | | - Stanley J. Roux
- Department of Molecular Biosciences, University of Texas, Austin, TX 78712, USA; (G.C.); (K.A.B.)
- Correspondence: ; Tel.: +1-512-471-4238
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Tanaka H, Yanai C, Miura NN, Ishibashi KI, Yamanaka D, Ohnishi H, Ohno N, Adachi Y. Coronary Vasculitis Induced in Mice by Cell Wall Mannoprotein Fractions of Clinically Isolated Candida Species. Med Mycol J 2020; 61:33-48. [PMID: 32863327 DOI: 10.3314/mmj.20-00008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Kawasaki disease (KD) is an inflammatory disease that was identified by Professor Tomisaku Kawasaki in 1961. Candida albicans-derived substances (CADS) such as the hot water extract of C. albicans and Candida water-soluble fractions (CAWS) induce coronary vasculitis similar to KD in mice. An increasing proportion of deep-seated candidiasis cases are caused by non-albicans Candida and are often resistant to antifungal drugs. We herein investigated whether the mannoprotein fractions (MN fractions) of clinically isolated Candida species induce vasculitis in mice. We prepared MN fractions from 26 strains of Candida species by conventional hot water extraction and compared vasculitis in DBA/2 mice. The results obtained revealed that the induction of vasculitis and resulting heart failure were significantly dependent on the species; namely, death rates on day 200 were as follows: Candida krusei (100%), Candida albicans (84%), Candida dubliniensis (47%), Candida parapsilosis (44%), Candida glabrata (32%), Candida guilliermondii (20%), and Candida tropicalis (20%). Even for C. albicans, some strains did not induce vasculitis. The present results suggest that MN-induced vasculitis is strongly dependent on the species and strains of Candida, and also that the MN fractions of some non-albicans Candida induce similar toxicity to those of C. albicans.
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Affiliation(s)
- Hiroaki Tanaka
- Laboratory for Immunopharmacology of Microbial Products, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences.,Department of Pharmacy, Kyorin University Hospital
| | - Chiho Yanai
- Laboratory for Immunopharmacology of Microbial Products, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences
| | - Noriko N Miura
- Center for Pharmaceutical Education, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences
| | - Ken-Ichi Ishibashi
- Laboratory for Immunopharmacology of Microbial Products, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences
| | - Daisuke Yamanaka
- Laboratory for Immunopharmacology of Microbial Products, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences
| | - Hiroaki Ohnishi
- Department of Laboratory Medicine, Kyorin University School of Medicine
| | - Naohito Ohno
- Laboratory for Immunopharmacology of Microbial Products, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences
| | - Yoshiyuki Adachi
- Laboratory for Immunopharmacology of Microbial Products, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences
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Genome-wide functional analysis of phosphatases in the pathogenic fungus Cryptococcus neoformans. Nat Commun 2020; 11:4212. [PMID: 32839469 PMCID: PMC7445287 DOI: 10.1038/s41467-020-18028-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 07/30/2020] [Indexed: 12/13/2022] Open
Abstract
Phosphatases, together with kinases and transcription factors, are key components in cellular signalling networks. Here, we present a systematic functional analysis of the phosphatases in Cryptococcus neoformans, a fungal pathogen that causes life-threatening fungal meningoencephalitis. We analyse 230 signature-tagged mutant strains for 114 putative phosphatases under 30 distinct in vitro growth conditions, revealing at least one function for 60 of these proteins. Large-scale virulence and infectivity assays using insect and mouse models indicate roles in pathogenicity for 31 phosphatases involved in various processes such as thermotolerance, melanin and capsule production, stress responses, O-mannosylation, or retromer function. Notably, phosphatases Xpp1, Ssu72, Siw14, and Sit4 promote blood-brain barrier adhesion and crossing by C. neoformans. Together with our previous systematic studies of transcription factors and kinases, our results provide comprehensive insight into the pathobiological signalling circuitry of C. neoformans. Phosphatases are key components in cellular signalling networks. Here, the authors present a systematic functional analysis of phosphatases of the fungal pathogen Cryptococcus neoformans, revealing roles in virulence, stress responses, O-mannosylation, retromer function and other processes.
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Differences in fungal immune recognition by monocytes and macrophages: N-mannan can be a shield or activator of immune recognition. ACTA ACUST UNITED AC 2020; 6:100042. [PMID: 33364531 PMCID: PMC7750734 DOI: 10.1016/j.tcsw.2020.100042] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 07/08/2020] [Accepted: 07/08/2020] [Indexed: 02/08/2023]
Abstract
Cytokine response to N-mannan mutants was dependent on the immune cell type used. N-mannan mutants stimulated less cytokines from monocytes but more from macrophages. N-mannan can therefore act as both an immune agonist or an immune shield.
We designed experiments to assess whether fungal cell wall mannans function as an immune shield or an immune agonist. Fungal cell wall β-(1,3)-glucan normally plays a major and dominant role in immune activation. The outer mannan layer has been variously described as an immune shield, because it has the potential to mask the underlying β-(1,3)-glucan, or an immune activator, as it also has the potential to engage with a wide range of mannose detecting PRRs. To resolve this conundrum we examined species-specific differences in host immune recognition in the och1Δ N-mannosylation-deficient mutant background in four species of yeast-like fungi. Irrespective of the fungal species, the cytokine response (TNFα and IL-6) induced by the och1Δ mutants in human monocytes was reduced compared to that of the wild type. In contrast, TNFα production induced by och1Δ was increased, relative to wild type, due to increased β-glucan exposure, when mouse or human macrophages were used. These observations suggest that N-mannan is not a major PAMP for macrophages and that in these cells mannan does shield the fungus from recognition of the inner cell wall β-glucan. However, N-mannan is a significant inducer of cytokine for monocytes. Therefore the metaphor of the fungal “mannan shield” can only be applied to some, but not all, myeloid cells used in immune profiling experiments of fungal species.
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Muthamil S, Prasath KG, Priya A, Precilla P, Pandian SK. Global proteomic analysis deciphers the mechanism of action of plant derived oleic acid against Candida albicans virulence and biofilm formation. Sci Rep 2020; 10:5113. [PMID: 32198447 PMCID: PMC7083969 DOI: 10.1038/s41598-020-61918-y] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Accepted: 03/02/2020] [Indexed: 01/04/2023] Open
Abstract
Candida albicans is a commensal fungus in humans, mostly found on the mucosal surfaces of the mouth, gut, vagina and skin. Incidence of ever increasing invasive candidiasis in immunocompromised patients, alarming occurrence of antifungal resistance and insufficient diagnostic methods demand more focused research into C. albicans pathogenicity. Consequently, in the present study, oleic acid from Murraya koenigii was shown to have the efficacy to inhibit biofilm formation and virulence of Candida spp. Results of in vitro virulence assays and gene expression analysis, impelled to study the protein targets which are involved in the molecular pathways of C. albicans pathogenicity. Proteomic studies of differentially expressed proteins reveals that oleic acid induces oxidative stress responses and mainly targets the proteins involved in glucose metabolism, ergosterol biosynthesis, lipase production, iron homeostasis and amino acid biosynthesis. The current study emphasizes anti-virulent potential of oleic acid which can be used as a therapeutic agent to treat Candida infections.
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Affiliation(s)
- Subramanian Muthamil
- Department of Biotechnology Science Campus Alagappa University Karaikudi, 630 003, Tamil Nadu, India
| | - Krishnan Ganesh Prasath
- Department of Biotechnology Science Campus Alagappa University Karaikudi, 630 003, Tamil Nadu, India
| | - Arumugam Priya
- Department of Biotechnology Science Campus Alagappa University Karaikudi, 630 003, Tamil Nadu, India
| | - Pitchai Precilla
- Department of Biotechnology Science Campus Alagappa University Karaikudi, 630 003, Tamil Nadu, India
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The Role of Secretory Pathways in Candida albicans Pathogenesis. J Fungi (Basel) 2020; 6:jof6010026. [PMID: 32102426 PMCID: PMC7151058 DOI: 10.3390/jof6010026] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Revised: 02/19/2020] [Accepted: 02/20/2020] [Indexed: 12/17/2022] Open
Abstract
Candida albicans is a fungus that is a commensal organism and a member of the normal human microbiota. It has the ability to transition into an opportunistic invasive pathogen. Attributes that support pathogenesis include secretion of virulence-associated proteins, hyphal formation, and biofilm formation. These processes are supported by secretion, as defined in the broad context of membrane trafficking. In this review, we examine the role of secretory pathways in Candida virulence, with a focus on the model opportunistic fungal pathogen, Candida albicans.
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10
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Kumar Tripathy M, Weeraratne G, Clark G, Roux SJ. Apyrase inhibitors enhance the ability of diverse fungicides to inhibit the growth of different plant-pathogenic fungi. MOLECULAR PLANT PATHOLOGY 2017; 18:1012-1023. [PMID: 27392542 PMCID: PMC6638264 DOI: 10.1111/mpp.12458] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Revised: 06/24/2016] [Accepted: 07/06/2016] [Indexed: 06/06/2023]
Abstract
A previous study has demonstrated that the treatment of Arabidopsis plants with chemical inhibitors of apyrase enzymes increases their sensitivity to herbicides. In this study, we found that the addition of the same or related apyrase inhibitors could potentiate the ability of different fungicides to inhibit the growth of five different pathogenic fungi in plate growth assays. The growth of all five fungi was partially inhibited by three commonly used fungicides: copper octanoate, myclobutanil and propiconazole. However, when these fungicides were individually tested in combination with any one of four different apyrase inhibitors (AI.1, AI.10, AI.13 or AI.15), their potency to inhibit the growth of five fungal pathogens was increased significantly relative to their application alone. The apyrase inhibitors were most effective in potentiating the ability of copper octanoate to inhibit fungal growth, and least effective in combination with propiconazole. Among the five pathogens assayed, that most sensitive to the fungicide-potentiating effects of the inhibitors was Sclerotinia sclerotiorum. Overall, among the 60 treatment combinations tested (five pathogens, four apyrase inhibitors, three fungicides), the addition of apyrase inhibitors increased significantly the sensitivity of fungi to the fungicide treatments in 53 of the combinations. Consistent with their predicted mode of action, inhibitors AI.1, AI.10 and AI.13 each increased the level of propiconazole retained in one of the fungi, suggesting that they could partially block the ability of efflux transporters to remove propiconazole from these fungi.
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Affiliation(s)
- Manas Kumar Tripathy
- Department of Molecular BiosciencesUniversity of Texas at AustinAustinTX78712USA
| | - Gayani Weeraratne
- Department of Molecular BiosciencesUniversity of Texas at AustinAustinTX78712USA
| | - Greg Clark
- Department of Molecular BiosciencesUniversity of Texas at AustinAustinTX78712USA
| | - Stanley J. Roux
- Department of Molecular BiosciencesUniversity of Texas at AustinAustinTX78712USA
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Dutton LC, Jenkinson HF, Lamont RJ, Nobbs AH. Role of Candida albicans secreted aspartyl protease Sap9 in interkingdom biofilm formation. Pathog Dis 2016; 74:ftw005. [PMID: 26772652 DOI: 10.1093/femspd/ftw005] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/12/2016] [Indexed: 12/23/2022] Open
Abstract
The fungus Candida albicans colonizes oral cavity surfaces and is carried by up to 60% of human populations. Biofilm development by C. albicans may be modulated by oral streptococci, such as Streptococcus gordonii, S. oralis or S. mutans, so as to augment pathogenicity. In this study we sought to determine if the cell wall-associated secreted aspartyl proteinase Sap9 was necessary for hyphal adhesin functions associated with biofilm community development. A sap9Δ mutant of C. albicans SC5314 formed biofilms that were flatter, and contained fewer blastospores and more hyphal filaments than the parent strain. This phenotypic difference was accentuated under flow (shear) conditions and in the presence of S. gordonii. Dual-species biofilms of C. albicans sap9Δ with S. oralis, S. sanguinis, S. parasanguinis, S. mutans and Enterococcus faecalis all contained more matted hyphae and more bacteria bound to substratum compared to C. albicans wild type. sap9Δ mutant hyphae showed significantly increased cell surface hydrophobicity, ∼25% increased levels of binding C. albicans cell wall protein Als3, and reduced interaction with Eap1, implicating Sap9 in fungal cell-cell recognition. These observations suggest that Sap9 is associated with protein-receptor interactions between fungal cells, and with interkingdom communication in the formation of polymicrobial biofilm communities.
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Affiliation(s)
- Lindsay C Dutton
- School of Oral and Dental Sciences, University of Bristol, Bristol BS1 2LY, UK
| | - Howard F Jenkinson
- School of Oral and Dental Sciences, University of Bristol, Bristol BS1 2LY, UK
| | - Richard J Lamont
- Department of Oral Immunology and Infectious Diseases, University of Louisville, Louisville, KY 40202, USA
| | - Angela H Nobbs
- School of Oral and Dental Sciences, University of Bristol, Bristol BS1 2LY, UK
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Juchimiuk M, Kruszewska J, Palamarczyk G. Dolichol phosphate mannose synthase from the pathogenic yeast Candida albicans is a multimeric enzyme. Biochim Biophys Acta Gen Subj 2015; 1850:2265-75. [DOI: 10.1016/j.bbagen.2015.08.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2015] [Accepted: 08/12/2015] [Indexed: 11/29/2022]
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Genome-Wide Transcription Study of Cryptococcus neoformans H99 Clinical Strain versus Environmental Strains. PLoS One 2015; 10:e0137457. [PMID: 26360021 PMCID: PMC4567374 DOI: 10.1371/journal.pone.0137457] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Accepted: 08/17/2015] [Indexed: 02/07/2023] Open
Abstract
The infection of Cryptococcus neoformans is acquired through the inhalation of desiccated yeast cells and basidiospores originated from the environment, particularly from bird’s droppings and decaying wood. Three environmental strains of C. neoformans originated from bird droppings (H4, S48B and S68B) and C. neoformans reference clinical strain (H99) were used for intranasal infection in C57BL/6 mice. We showed that the H99 strain demonstrated higher virulence compared to H4, S48B and S68B strains. To examine if gene expression contributed to the different degree of virulence among these strains, a genome-wide microarray study was performed to inspect the transcriptomic profiles of all four strains. Our results revealed that out of 7,419 genes (22,257 probes) examined, 65 genes were significantly up-or down-regulated in H99 versus H4, S48B and S68B strains. The up-regulated genes in H99 strain include Hydroxymethylglutaryl-CoA synthase (MVA1), Mitochondrial matrix factor 1 (MMF1), Bud-site-selection protein 8 (BUD8), High affinity glucose transporter 3 (SNF3) and Rho GTPase-activating protein 2 (RGA2). Pathway annotation using DAVID bioinformatics resource showed that metal ion binding and sugar transmembrane transporter activity pathways were highly expressed in the H99 strain. We suggest that the genes and pathways identified may possibly play crucial roles in the fungal pathogenesis.
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Biochemical characterization of Arabidopsis APYRASE family reveals their roles in regulating endomembrane NDP/NMP homoeostasis. Biochem J 2015; 472:43-54. [PMID: 26338998 DOI: 10.1042/bj20150235] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 09/03/2015] [Indexed: 12/27/2022]
Abstract
Plant apyrases are nucleoside triphosphate (NTP) diphosphohydrolases (NTPDases) and have been implicated in an array of functions within the plant including the regulation of extracellular ATP. Arabidopsis encodes a family of seven membrane bound apyrases (AtAPY1-7) that comprise three distinct clades, all of which contain the five conserved apyrase domains. With the exception of AtAPY1 and AtAPY2, the biochemical and the sub-cellular characterization of the other members are currently unavailable. In this research, we have shown all seven Arabidopsis apyrases localize to internal membranes comprising the cis-Golgi, endoplasmic reticulum (ER) and endosome, indicating an endo-apyrase classification for the entire family. In addition, all members, with the exception of AtAPY7, can function as endo-apyrases by complementing a yeast double mutant (Δynd1Δgda1) which lacks apyrase activity. Interestingly, complementation of the mutant yeast using well characterized human apyrases could only be accomplished by using a functional ER endo-apyrase (NTPDase6), but not the ecto-apyrase (NTPDase1). Furthermore, the substrate specificity analysis for the Arabidopsis apyrases AtAPY1-6 indicated that each member has a distinct set of preferred substrates covering various NDPs (nucleoside diphosphates) and NTPs. Combining the biochemical analysis and sub-cellular localization of the Arabidopsis apyrases family, the data suggest their possible roles in regulating endomembrane NDP/NMP (nucleoside monophosphate) homoeostasis.
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Massalski C, Bloch J, Zebisch M, Steinebrunner I. The biochemical properties of the Arabidopsis ecto-nucleoside triphosphate diphosphohydrolase AtAPY1 contradict a direct role in purinergic signaling. PLoS One 2015; 10:e0115832. [PMID: 25822168 PMCID: PMC4379058 DOI: 10.1371/journal.pone.0115832] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Accepted: 12/02/2014] [Indexed: 11/18/2022] Open
Abstract
The Arabidopsis E-NTPDase (ecto-nucleoside triphosphate diphosphohydrolase) AtAPY1 was previously shown to be involved in growth and development, pollen germination and stress responses. It was proposed to perform these functions through regulation of extracellular ATP signals. However, a GFP-tagged version was localized exclusively in the Golgi and did not hydrolyze ATP. In this study, AtAPY1 without the bulky GFP-tag was biochemically characterized with regard to its suggested role in purinergic signaling. Both the full-length protein and a soluble form without the transmembrane domain near the N-terminus were produced in HEK293 cells. Of the twelve nucleotide substrates tested, only three--GDP, IDP and UDP--were hydrolyzed, confirming that ATP was not a substrate of AtAPY1. In addition, the effects of pH, divalent metal ions, known E-NTPDase inhibitors and calmodulin on AtAPY1 activity were analyzed. AtAPY1-GFP extracted from transgenic Arabidopsis seedlings was included in the analyses. All three AtAPY1 versions exhibited very similar biochemical properties. Activity was detectable in a broad pH range, and Ca(2+), Mg(2+) and Mn(2+) were the three most efficient cofactors. Of the inhibitors tested, vanadate was the most potent one. Surprisingly, sulfonamide-based inhibitors shown to inhibit other E-NTPDases and presumed to inhibit AtAPY1 as well were not effective. Calmodulin stimulated the activity of the GFP-tagless membranous and soluble AtAPY1 forms about five-fold, but did not alter their substrate specificities. The apparent Km values obtained with AtAPY1-GFP indicate that AtAPY1 is primarily a GDPase. A putative three-dimensional structural model of the ecto-domain is presented, explaining the potent inhibitory potential of vanadate and predicting the binding mode of GDP. The found substrate specificity classifies AtAPY1 as a nucleoside diphosphatase typical of N-terminally anchored Golgi E-NTPDases and negates a direct function in purinergic signaling.
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Affiliation(s)
- Carolin Massalski
- Department of Biology, Technische Universität Dresden, Dresden, Germany
| | - Jeannine Bloch
- Department of Biology, Technische Universität Dresden, Dresden, Germany
| | - Matthias Zebisch
- Division of Structural Biology, University of Oxford, Oxford, United Kingdom
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Delgado-Carmona JD, Ramírez-Quijas MD, Vega-González A, López-Romero E, Cuéllar-Cruz M. Changes in GDPase/UDPase enzymatic activity in response to oxidative stress in four Candida species. Folia Microbiol (Praha) 2015; 60:343-50. [PMID: 25762354 DOI: 10.1007/s12223-015-0382-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 02/27/2015] [Indexed: 10/23/2022]
Abstract
The terminal processing of proteins and lipids occurs in the Golgi apparatus and involves the transport of sugar nucleotides into the Golgi lumen by specific carriers and the accumulation of nucleoside diphosphates (NDPs) as a result of oligosaccharide-protein glycosyltransferase activity. NDPs are converted into the corresponding nucleoside monophosphates (NMPs) by nucleoside diphosphatases (NDPases), thus relieving inhibition of sugar transferases. In addition, NMPs are then exchanged for equimolecular amounts of cytosolic sugar nucleotides by antiport transport systems. NDPases, commonly GDPase and UDPase, thus play a critical role in glycoprotein maturation and may influence fungal pathogenesis, morphogenesis, and cell wall properties. Interest of this laboratory has recently focused on the effect of reactive oxygen species (ROS) on enzymes involved in detoxification of these oxidants and on the metabolism of biomolecules such as lipids, nucleic acids, and proteins in human pathogenic Candida species. We therefore consider it important to extend these studies to determine how GDPase and UDPase are affected after exposure of cells to oxidants such as menadione, a superoxide (O2 (•-))-generator, and H2O2. Results indicate that activity of both enzymes decrease in response to these agents suggesting that ROS may also affect other critical cell functions such as protein glycosylation.
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Affiliation(s)
- Jenny Daniela Delgado-Carmona
- Departamento de Biología, División de Ciencias Naturales y Exactas, Campus Guanajuato, Universidad de Guanajuato, Noria Alta S/N, 36050, Guanajuato, Guanajuato, Mexico
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17
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Abstract
Candida albicans is a fungus that colonizes oral cavity surfaces, the gut, and the genital tract. Streptococcus gordonii is a ubiquitous oral bacterium that has been shown to form biofilm communities with C. albicans. Formation of dual-species S. gordonii-C. albicans biofilm communities involves interaction of the S. gordonii SspB protein with the Als3 protein on the hyphal filament surface of C. albicans. Mannoproteins comprise a major component of the C. albicans cell wall, and in this study we sought to determine if mannosylation in cell wall biogenesis of C. albicans was necessary for hyphal adhesin functions associated with interkingdom biofilm development. A C. albicans mnt1Δ mnt2Δ mutant, with deleted α-1,2-mannosyltransferase genes and thus defective in O-mannosylation, was abrogated in biofilm formation under various growth conditions and produced hyphal filaments that were not recognized by S. gordonii. Cell wall proteomes of hypha-forming mnt1Δ mnt2Δ mutant cells showed growth medium-dependent alterations, compared to findings for the wild type, in a range of protein components, including Als1, Als3, Rbt1, Scw1, and Sap9. Hyphal filaments formed by mnt1Δ mnt2Δ mutant cells, unlike wild-type hyphae, did not interact with C. albicans Als3 or Hwp1 partner cell wall proteins or with S. gordonii SspB partner adhesin, suggesting defective functionality of adhesins on the mnt1Δ mnt2Δ mutant. These observations imply that early stage O-mannosylation is critical for activation of hyphal adhesin functions required for biofilm formation, recognition by bacteria such as S. gordonii, and microbial community development. IMPORTANCE In the human mouth, microorganisms form communities known as biofilms that adhere to the surfaces present. Candida albicans is a fungus that is often found within these biofilms. We have focused on the mechanisms by which C. albicans becomes incorporated into communities containing bacteria, such as Streptococcus. We find that impairment of early stage addition of mannose sugars to C. albicans hyphal filament proteins deleteriously affects their subsequent performance in mediating formation of polymicrobial biofilms. Our analyses provide new understanding of the way that microbial communities develop, and of potential means to control C. albicans infections.
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López-Fernández L, Ruiz-Roldán C, Pareja-Jaime Y, Prieto A, Khraiwesh H, Roncero MIG. The Fusarium oxysporum gnt2, encoding a putative N-acetylglucosamine transferase, is involved in cell wall architecture and virulence. PLoS One 2013; 8:e84690. [PMID: 24416097 PMCID: PMC3886883 DOI: 10.1371/journal.pone.0084690] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Accepted: 11/26/2013] [Indexed: 01/12/2023] Open
Abstract
With the aim to decipher the molecular dialogue and cross talk between Fusarium oxysporum f.sp. lycopersci and its host during infection and to understand the molecular bases that govern fungal pathogenicity, we analysed genes presumably encoding N-acetylglucosaminyl transferases, involved in glycosylation of glycoproteins, glycolipids, proteoglycans or small molecule acceptors in other microorganisms. In silico analysis revealed the existence of seven putative N-glycosyl transferase encoding genes (named gnt) in F. oxysporum f.sp. lycopersici genome. gnt2 deletion mutants showed a dramatic reduction in virulence on both plant and animal hosts. Δgnt2 mutants had αalterations in cell wall properties related to terminal αor β-linked N-acetyl glucosamine. Mutant conidia and germlings also showed differences in structure and physicochemical surface properties. Conidial and hyphal aggregation differed between the mutant and wild type strains, in a pH independent manner. Transmission electron micrographs of germlings showed strong cell-to-cell adherence and the presence of an extracellular chemical matrix. Δgnt2 cell walls presented a significant reduction in N-linked oligosaccharides, suggesting the involvement of Gnt2 in N-glycosylation of cell wall proteins. Gnt2 was localized in Golgi-like sub-cellular compartments as determined by fluorescence microscopy of GFP::Gnt2 fusion protein after treatment with the antibiotic brefeldin A or by staining with fluorescent sphingolipid BODIPY-TR ceramide. Furthermore, density gradient ultracentrifugation allowed co-localization of GFP::Gnt2 fusion protein and Vps10p in subcellular fractions enriched in Golgi specific enzymatic activities. Our results suggest that N-acetylglucosaminyl transferases are key components for cell wall structure and influence interactions of F. oxysporum with both plant and animal hosts during pathogenicity.
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Affiliation(s)
- Loida López-Fernández
- Departamento de Genética, Universidad de Córdoba, Córdoba, Spain
- Campus de Excelencia Agroalimentario (ceiA3), Córdoba, Spain
| | - Carmen Ruiz-Roldán
- Departamento de Genética, Universidad de Córdoba, Córdoba, Spain
- Campus de Excelencia Agroalimentario (ceiA3), Córdoba, Spain
| | - Yolanda Pareja-Jaime
- Departamento de Genética, Universidad de Córdoba, Córdoba, Spain
- Campus de Excelencia Agroalimentario (ceiA3), Córdoba, Spain
| | - Alicia Prieto
- Centro de Investigaciones Biológicas-CSIC, Madrid, Spain
| | - Husam Khraiwesh
- Departamento de Biología Celular, Fisiología e Inmunología, Universidad de Córdoba, Córdoba, Spain
| | - M. Isabel G. Roncero
- Departamento de Genética, Universidad de Córdoba, Córdoba, Spain
- Campus de Excelencia Agroalimentario (ceiA3), Córdoba, Spain
- * E-mail:
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19
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Subcellular potassium and sodium distribution in Saccharomyces cerevisiae wild-type and vacuolar mutants. Biochem J 2013; 454:525-32. [DOI: 10.1042/bj20130143] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Living cells accumulate potassium (K+) to fulfil multiple functions. It is well documented that the model yeast Saccharomyces cerevisiae grows at very different concentrations of external alkali cations and keeps high and low intracellular concentrations of K+ and sodium (Na+) respectively. However less attention has been paid to the study of the intracellular distribution of these cations. The most widely used experimental approach, plasma membrane permeabilization, produces incomplete results, since it usually considers only cytoplasm and vacuoles as compartments where the cations are present in significant amounts. By isolating and analysing the main yeast organelles, we have determined the subcellular location of K+ and Na+ in S. cerevisiae. We show that while vacuoles accumulate most of the intracellular K+ and Na+, the cytosol contains relatively low amounts, which is especially relevant in the case of Na+. However K+ concentrations in the cytosol are kept rather constant during the K+-starvation process and we conclude that, for that purpose, vacuolar K+ has to be rapidly mobilized. We also show that this intracellular distribution is altered in four different mutants with impaired vacuolar physiology. Finally, we show that both in wild-type and vacuolar mutants, nuclei contain and keep a relatively constant and important percentage of total intracellular K+ and Na+, which most probably is involved in the neutralization of negative charges.
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Isolation of Sporothrix schenckii GDA1 and functional characterization of the encoded guanosine diphosphatase activity. Arch Microbiol 2013; 195:499-506. [PMID: 23715619 DOI: 10.1007/s00203-013-0901-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Revised: 03/01/2013] [Accepted: 05/17/2013] [Indexed: 12/23/2022]
Abstract
Sporothrix schenckii is a fungal pathogen of humans and the etiological agent of sporotrichosis. In fungi, proper protein glycosylation is usually required for normal composition of cell wall and virulence. Upon addition of precursor oligosaccharides to nascent proteins in the endoplasmic reticulum, glycans are further modified by Golgi-glycosyl transferases. In order to add sugar residues to precursor glycans, nucleotide diphosphate sugars are imported from the cytosol to the Golgi lumen, the sugar is transferred to glycans, and the resulting nucleoside diphosphate is dephosphorylated by the nucleoside diphosphatase Gda1 before returning to cytosol. Here, we isolated the open reading frame SsGDA1 from a S. schenckii genomic DNA library. In order to confirm the function of SsGda1, we performed complementation assays in a Saccharomyces cerevisiae gda1∆ null mutant. Our results indicated that SsGDA1 restored the nucleotide diphosphatase activity to wild-type levels and therefore is a functional ortholog of S. cerevisiae GDA1.
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Govindappa N, Hanumanthappa M, Venkatarangaiah K, Kanojia K, Venkatesan K, Chatterjee A, Kusumanchi M, Dave N, Hazra P, Tiwari S, Sastry K. PMT1 gene plays a major role in O-mannosylation of insulin precursor in Pichia pastoris. Protein Expr Purif 2013; 88:164-71. [DOI: 10.1016/j.pep.2012.12.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Revised: 11/20/2012] [Accepted: 12/20/2012] [Indexed: 11/29/2022]
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22
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Parsons HT, Christiansen K, Knierim B, Carroll A, Ito J, Batth TS, Smith-Moritz AM, Morrison S, McInerney P, Hadi MZ, Auer M, Mukhopadhyay A, Petzold CJ, Scheller HV, Loqué D, Heazlewood JL. Isolation and proteomic characterization of the Arabidopsis Golgi defines functional and novel components involved in plant cell wall biosynthesis. PLANT PHYSIOLOGY 2012; 159:12-26. [PMID: 22430844 PMCID: PMC3375956 DOI: 10.1104/pp.111.193151] [Citation(s) in RCA: 139] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2012] [Accepted: 03/04/2012] [Indexed: 05/17/2023]
Abstract
The plant Golgi plays a pivotal role in the biosynthesis of cell wall matrix polysaccharides, protein glycosylation, and vesicle trafficking. Golgi-localized proteins have become prospective targets for reengineering cell wall biosynthetic pathways for the efficient production of biofuels from plant cell walls. However, proteomic characterization of the Golgi has so far been limited, owing to the technical challenges inherent in Golgi purification. In this study, a combination of density centrifugation and surface charge separation techniques have allowed the reproducible isolation of Golgi membranes from Arabidopsis (Arabidopsis thaliana) at sufficiently high purity levels for in-depth proteomic analysis. Quantitative proteomic analysis, immunoblotting, enzyme activity assays, and electron microscopy all confirm high purity levels. A composition analysis indicated that approximately 19% of proteins were likely derived from contaminating compartments and ribosomes. The localization of 13 newly assigned proteins to the Golgi using transient fluorescent markers further validated the proteome. A collection of 371 proteins consistently identified in all replicates has been proposed to represent the Golgi proteome, marking an appreciable advancement in numbers of Golgi-localized proteins. A significant proportion of proteins likely involved in matrix polysaccharide biosynthesis were identified. The potential within this proteome for advances in understanding Golgi processes has been demonstrated by the identification and functional characterization of the first plant Golgi-resident nucleoside diphosphatase, using a yeast complementation assay. Overall, these data show key proteins involved in primary cell wall synthesis and include a mixture of well-characterized and unknown proteins whose biological roles and importance as targets for future research can now be realized.
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23
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Liu L, Hirschberg CB. Developmental diseases caused by impaired nucleotide sugar transporters. Glycoconj J 2012; 30:5-10. [PMID: 22527830 DOI: 10.1007/s10719-012-9375-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Accepted: 03/28/2012] [Indexed: 01/24/2023]
Abstract
Nucleotide sugar transporters play critical roles in glycosylation of proteins, lipids and proteoglycans, which are essential for organogenesis, development, mammalian cellular immunity and pathogenicity of human pathogenic agents. Functional deficiencies of these transporters result in global defects of glycoconjugates, which in turn lead to a diversity of biochemical, physiological and pathological phenotypes. In this short review, we will highlight human and bovine diseases caused by mutations of these transporters.
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Affiliation(s)
- Li Liu
- Department of Molecular and Cell Biology, Boston University Goldman School of Dental Medicine, Evans-E438, 72 East Concord Street, Boston, MA 02118, USA
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24
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The role of the NTPDase enzyme family in parasites: what do we know, and where to from here? Parasitology 2012; 139:963-80. [DOI: 10.1017/s003118201200025x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
SUMMARYNucleoside triphosphate diphosphohydrolases (NTPDases, GDA1_CD39 protein superfamily) play a diverse range of roles in a number of eukaryotic organisms. In humans NTPDases function in regulating the inflammatory and immune responses, control of vascular haemostasis and purine salvage. In yeast NTPDases are thought to function primarily in the Golgi, crucially involved in nucleotide sugar transport into the Golgi apparatus and subsequent protein glycosylation. Although rare in bacteria, in Legionella pneumophila secreted NTPDases function as virulence factors. In the last 2 decades it has become clear that a large number of parasites encode putative NTPDases, and the functions of a number of these have been investigated. In this review, the available evidence for NTPDases in parasites and the role of these NTPDases is summarized and discussed. Furthermore, the processes by which NTPDases could function in pathogenesis, purine salvage, thromboregulation, inflammation and glycoconjugate formation are considered, and the data supporting such putative roles reviewed. Potential future research directions to further clarify the role and importance of NTPDases in parasites are proposed. An attempt is also made to clarify the nomenclature used in the parasite field for the GDA1_CD39 protein superfamily, and a uniform system suggested.
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Ernst JF, Pla J. Signaling the glycoshield: maintenance of the Candida albicans cell wall. Int J Med Microbiol 2011; 301:378-83. [PMID: 21555242 DOI: 10.1016/j.ijmm.2011.04.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
In fungi, the cell wall is a scaffold, an armor and an environmental gate. Sugar polymers including protein-O- or N-linked glycosyl chains or polysaccharides such as glucan or chitin are essential components to maintain cell wall functions. We describe mechanisms in the human fungal pathogen Candida albicans, by which the integrity of glycostructures are sensed and regulated. The results stress the importance of membrane sensors and MAP kinase pathways in the maintenance of cell wall structure and function.
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Affiliation(s)
- Joachim F Ernst
- Institut für Mikrobiologie, Molekulare Mykologie, Heinrich-Heine-Universität Düsseldorf, Universitätsstr. 1/26.12, 40225 Düsseldorf, Germany.
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26
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Cantero PD, Ernst JF. Damage to the glycoshield activates PMT-directed O-mannosylation via the Msb2-Cek1 pathway in Candida albicans. Mol Microbiol 2011; 80:715-25. [PMID: 21375589 DOI: 10.1111/j.1365-2958.2011.07604.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Protein-O-mannosyltransferases (Pmt) transfer mannosyl residues to secretory proteins. Five isoforms of Pmt proteins in the human fungal pathogen Candida albicans have distinct functions in growth, morphogenesis and antifungal resistance. We found that PMT genes encoding the major isoforms Pmt1, Pmt2, Pmt4 are regulated differently in response to impaired glycostructures. While the PMT1 transcript level increased in cell wall mutants and under inhibition of N-glycosylation by tunicamycin, PMT2 and PMT4 transcripts were upregulated only by inhibition of Pmt1 activity. Reporter fusions revealed specific promoter sequences to be required for PMT1 repression in undamaged cells, which was de-repressed by tunicamycin. Constitutive PMT1 de-repression was observed in mutants lacking the Cek1 MAP kinase and its upstream sensor Msb2. In contrast, in msb2 and cek1 mutants, upregulation of PMT2/PMT4 by Pmt1 inhibition did not occur and basal expression of both transcripts were decreased. We identified Ace2 as a novel transcription factor, which upregulates PMT basal expression and induction in response to glycostructure damage. Mutants lacking Msb2, Cek1 and Ace2 were supersensitive to glycosylation and cell wall inhibitors. We propose that a Msb2, Cek1 and Ace2 signalling pathway addresses PMT genes as downstream targets and that different modes of regulation have evolved for PMT1 and PMT2/PMT4 genes.
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Affiliation(s)
- Pilar D Cantero
- Institut für Mikrobiologie, Molekulare Mykologie, Heinrich-Heine-Universität Düsseldorf, Universitätsstr. 1/26.12, 40225 Düsseldorf, Germany
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Mora-Montes HM, Ponce-Noyola P, Villagómez-Castro JC, Gow NA, Flores-Carreón A, López-Romero E. Protein glycosylation in Candida. Future Microbiol 2010; 4:1167-83. [PMID: 19895219 DOI: 10.2217/fmb.09.88] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Candidiasis is a significant cause of invasive human mycosis with associated mortality rates that are equivalent to, or worse than, those cited for most cases of bacterial septicemia. As a result, considerable efforts are being made to understand how the fungus invades host cells and to identify new targets for fungal chemotherapy. This has led to an increasing interest in Candida glycobiology, with an emphasis on the identification of enzymes essential for glycoprotein and adhesion metabolism, and the role of N- and O-linked glycans in host recognition and virulence. Here, we refer to studies dealing with the identification and characterization of enzymes such as dolichol phosphate mannose synthase, dolichol phosphate glucose synthase and processing glycosidases and synthesis, structure and recognition of mannans and discuss recent findings in the context of Candida albicans pathogenesis.
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28
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Li D, Williams D, Lowman D, Monteiro MA, Tan X, Kruppa M, Fonzi W, Roman E, Pla J, Calderone R. The Candida albicans histidine kinase Chk1p: signaling and cell wall mannan. Fungal Genet Biol 2009; 46:731-41. [PMID: 19563901 DOI: 10.1016/j.fgb.2009.06.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2009] [Revised: 06/22/2009] [Accepted: 06/23/2009] [Indexed: 12/18/2022]
Abstract
Several published functions associated with the CHK1 histidine kinase of Candida albicans resemble those of the MAPK Cek1p and its cognate receptor Sho1p (SSU81). To explore this further, we have compared mutants lacking the proteins mentioned above and have constructed a double sho1/chk1Delta null mutant to determine relationships among these proteins. We observed that the sensitivity to Congo red (CR), calcofluor white (CW), as well as clumping of cells, was slightly increased in the double mutant compared to the single chk1Delta or sho1Delta mutants. However, Cek1p phosphorylation via Sho1p, which occurs during log phase growth in the presence or absence of CR in Wt cells, does not require Chk1p. These data suggest that Chk1p and Sho1p are components of parallel but independent signal pathways. In addition, bulk mannan of strains was analyzed by GLC/MS and GPC MALLS and NMR. Compared to Wt and a CHK1 gene-reconstituted strain (CHK23) that contained high, intermediate and low Mw mannan species, we found that the mannan of strains CHK21 (chk1Delta null), the cek1Delta null, and the double mutant consisted only of low Mw mannan. The sho1Delta null mutant only demonstrated a reduced intermediate type of mannan. Alcian blue binding was lower in cek1Delta, chk1Delta, and the double sho1/chk1Delta null mutant lacking high and intermediate Mw mannan than in the sho1Delta null which had a partial loss of intermediate Mw mannan only. We conclude that the Chk1p HK is part of a functionally similar but parallel pathway to the Sho1p-Cek1p pathway that confers resistance to the cell wall inhibitors CR and CW. However, a functional relationship in mannan biosynthesis of Chk1p and Cek1p exists that only partially requires Sho1p.
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Affiliation(s)
- Dongmei Li
- Department of Microbiology and Immunology, Georgetown University Medical Center, Washington, DC 20057, USA
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29
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Abstract
Protein O-mannosylation is an essential modification in fungi and animals. Different from most other types of O-glycosylation, protein O-mannosylation is initiated in the endoplasmic reticulum by the transfer of mannose from dolichol monophosphate-activated mannose to serine and threonine residues of secretory proteins. In recent years, it has emerged that even bacteria are capable of O-mannosylation and that the biosynthetic pathway of O-mannosyl glycans is conserved between pro- and eukaryotes. In this review, we summarize the observations that have opened up the field and highlight characteristics of O-mannosylation in the different domains/kingdoms of life.
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Affiliation(s)
- Mark Lommel
- Department V Cell Chemistry, Heidelberg Institute for Plant Sciences, University of Heidelberg, Heidelberg, Germany
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30
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Hoyer LL, Green CB, Oh SH, Zhao X. Discovering the secrets of the Candida albicans agglutinin-like sequence (ALS) gene family--a sticky pursuit. Med Mycol 2008; 46:1-15. [PMID: 17852717 PMCID: PMC2742883 DOI: 10.1080/13693780701435317] [Citation(s) in RCA: 245] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The agglutinin-like sequence (ALS) family of Candida albicans includes eight genes that encode large cell-surface glycoproteins. The high degree of sequence relatedness between the ALS genes and the tremendous allelic variability often present in the same C. albicans strain complicated definition and characterization of the gene family. The main hypothesis driving ALS family research is that the genes encode adhesins, primarily involved in host-pathogen interactions. Although adhesive function has been demonstrated for several Als proteins, the challenge of studying putative adhesins in a highly adhesive organism like C. albicans has led to varying ideas about how best to pursue such investigations, and results that are sometimes contradictory. Recent analysis of alsdelta/alsdelta strains suggested roles for Als proteins outside of adhesion to host surfaces, and a broader scope of Als protein function than commonly believed. The availability and use of experimental methodologies to study C. albicans at the genomic level, and the ALS family en masse, have advanced knowledge of these genes and emphasized their importance in C. albicans biology and pathogenesis.
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Affiliation(s)
- Lois L Hoyer
- Department of Pathobiology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA.
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31
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Zhao X, Oh SH, Hoyer LL. Unequal contribution of ALS9 alleles to adhesion between Candida albicans and human vascular endothelial cells. MICROBIOLOGY-SGM 2007; 153:2342-2350. [PMID: 17600078 PMCID: PMC2753836 DOI: 10.1099/mic.0.2006/005017-0] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The Candida albicans ALS (agglutinin-like sequence) family includes eight genes (ALS1 to ALS7, and ALS9) that share a common general organization, consisting of a relatively conserved 5' domain, a central domain of tandemly repeated sequence units, and a 3' domain of relatively variable length and sequence. To test the hypothesis that the cell-surface glycoproteins encoded by the ALS genes mediate contact between the fungal cell and host surfaces, a set of C. albicans mutant strains was systematically constructed, each lacking one of the ALS sequences. Phenotypes of the mutant strains were evaluated, primarily using adhesion assays. ALS9 is unique within the ALS family due to extensive allelic sequence variation within the 5' domain that may result in functional differences between proteins encoded by ALS9-1 and ALS9-2. Deletion of ALS9 significantly reduces C. albicans adhesion to human vascular endothelial cell monolayers. The mutation was complemented by reintegration of a wild-type copy of ALS9-2, but not ALS9-1, suggesting allelic functional differences. Complementation of the mutation with a gene fusion between the 5' domain of ALS9-2 and the tandem repeats and 3' domain of ALS9-1 also restored wild-type adhesion levels. Analysis of the als9Delta/als9Delta mutant phenotype in other assays demonstrated no significant difference from a control strain for adhesion to buccal epithelial cells or laminin-coated plastic plates. The als9Delta/als9Delta mutant did not show significant differences from the control for adhesion to or destruction of cells in the reconstituted human epithelium (RHE) disease model, or for cell-wall defects, germ-tube formation or biofilm formation in a catheter model. Analysis of ALS9 allelic frequency in a collection of geographically diverse clinical isolates showed a distinct preference for ALS9-2 allelic sequences, within both the 5' and the 3' domain of the ALS9 coding region. These data suggest greater selective pressure to maintain the ALS9-2 allele in C. albicans isolates and imply its greater relative importance in host-pathogen interactions.
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Affiliation(s)
- Xiaomin Zhao
- Department of Pathobiology, University of Illinois, Urbana, IL 61802, USA
| | - Soon-Hwan Oh
- Department of Pathobiology, University of Illinois, Urbana, IL 61802, USA
| | - Lois L Hoyer
- Department of Pathobiology, University of Illinois, Urbana, IL 61802, USA
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Endoplasmic reticulum alpha-glycosidases of Candida albicans are required for N glycosylation, cell wall integrity, and normal host-fungus interaction. EUKARYOTIC CELL 2007; 6:2184-93. [PMID: 17933909 PMCID: PMC2168260 DOI: 10.1128/ec.00350-07] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The cell surface of Candida albicans is enriched in highly glycosylated mannoproteins that are involved in the interaction with the host tissues. N glycosylation is a posttranslational modification that is initiated in the endoplasmic reticulum (ER), where the Glc(3)Man(9)GlcNAc(2) N-glycan is processed by alpha-glucosidases I and II and alpha1,2-mannosidase to generate Man(8)GlcNAc(2). This N-oligosaccharide is then elaborated in the Golgi to form N-glycans with highly branched outer chains rich in mannose. In Saccharomyces cerevisiae, CWH41, ROT2, and MNS1 encode for alpha-glucosidase I, alpha-glucosidase II catalytic subunit, and alpha1,2-mannosidase, respectively. We disrupted the C. albicans CWH41, ROT2, and MNS1 homologs to determine the importance of N-oligosaccharide processing on the N-glycan outer-chain elongation and the host-fungus interaction. Yeast cells of Cacwh41Delta, Carot2Delta, and Camns1Delta null mutants tended to aggregate, displayed reduced growth rates, had a lower content of cell wall phosphomannan and other changes in cell wall composition, underglycosylated beta-N-acetylhexosaminidase, and had a constitutively activated PKC-Mkc1 cell wall integrity pathway. They were also attenuated in virulence in a murine model of systemic infection and stimulated an altered pro- and anti-inflammatory cytokine profile from human monocytes. Therefore, N-oligosaccharide processing by ER glycosidases is required for cell wall integrity and for host-fungus interactions.
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Goto M. Protein O-glycosylation in fungi: diverse structures and multiple functions. Biosci Biotechnol Biochem 2007; 71:1415-27. [PMID: 17587671 DOI: 10.1271/bbb.70080] [Citation(s) in RCA: 135] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Protein glycosylation is essential for eukaryotic cells from yeasts to humans. When compared to N-glycosylation, O-glycosylation is variable in sugar components and the mode of linkages connecting the sugars. In fungi, secretory proteins are commonly mannosylated by protein O-mannosyltransferase (PMT) in the endoplasmic reticulum, and subsequently glycosylated by several glycosyltransferases in the Golgi apparatus to form glycoproteins with diverse O-glycan structures. Protein O-glycosylation has roles in modulating the function of secretory proteins by enhancing the stability and solubility of the proteins, by affording protection from protease degradation, and by acting as a sorting determinant in yeasts. In filamentous fungi, protein O-glycosylation contributes to proper maintenance of fungal morphology, hyphal development, and differentiation. This review describes recent studies of the structure and function of protein O-glycosylation in industrially and medically important fungi.
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Affiliation(s)
- Masatoshi Goto
- Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, Japan.
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Uccelletti D, Anticoli S, Palleschi C. The apyrase KlYnd1p of Kluyveromyces lactis affects glycosylation, secretion, and cell wall properties. FEMS Yeast Res 2007; 7:731-9. [PMID: 17425676 DOI: 10.1111/j.1567-1364.2007.00229.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The Kluyveromyces lactis ORF r_klactIV3,463 on chromosome IV, hereafter named KlYND1, encodes an endoapyrase that has nucleoside phosphatase activity with a lumenal orientation. The enzyme showed equally high activity towards GDP/UDP and ADP, and also showed activity, although to a lesser extent, towards GTP. No activity was detected with the other triphosphates and all monophosphates. The overexpression of KlYND1 in Klgda1Delta cells of K. lactis, devoid of the encoded GDPase/UDPase activity, suppressed the loss of O-glycosylation and cell wall-related defects described in such mutants, and suggests a partial overlap of function between the two genes, and therefore some redundancy. The overexpression of KlYND1 in wild-type cells enhanced the secretion of the recombinant human serum albumin and glucoamylase employed as reporters.
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Affiliation(s)
- Daniela Uccelletti
- Department of Developmental and Cell Biology, University of Rome La Sapienza, Rome, Italy
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35
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Caffaro CE, Hirschberg CB. Nucleotide sugar transporters of the Golgi apparatus: from basic science to diseases. Acc Chem Res 2006; 39:805-12. [PMID: 17115720 DOI: 10.1021/ar0400239] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Approximately 80% of secreted and membrane proteins (40% of all proteins) of eukaryotes become covalently linked to sugars in the lumen of the Golgi apparatus, a cellular organelle that is part of the secretory system of all eukaryotes. The sugar donors are mostly nucleoside diphosphate sugars (nucleotide sugars) and must be translocated from the cytosol, their site of synthesis, across the Golgi apparatus membrane and into the lumen by specific transporters. These are hydrophobic, homodimeric proteins that span the membrane multiple times. Mutants of these proteins have developmental phenotypes including diseases in humans and cattle.
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Affiliation(s)
- Carolina E Caffaro
- Department of Molecular and Cell Biology, Boston University Goldman School of Dental Medicine, Boston, Massachusetts 02118, USA
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36
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González-Novo A, Labrador L, Jiménez A, Sánchez-Pérez M, Jiménez J. Role of the septin Cdc10 in the virulence of Candida albicans. Microbiol Immunol 2006; 50:499-511. [PMID: 16858141 DOI: 10.1111/j.1348-0421.2006.tb03820.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The relationship between the morphology and virulence of Candida albicans has aroused interest in the study of the proteins involved in its morphogenesis. We present virulence data for one important element in fungal morphogenesis-septins. We disrupted CaCDC10 and studied the virulence in a mouse infection model and the different steps followed by the fungus during the infection: adherence to epithelial cells, organ colonisation, macrophage phagocytosis, and host survival. We found the altered subcellular localisation of Int1--a C. albicans adhesin- in the septin null mutants. The Int1 mislocalisation and the defects in the cell wall of defective CaCdc10 strains permit us to propose a model for explaining the biological meaning of the absence of virulence presented by these septin mutants.
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Affiliation(s)
- Alberto González-Novo
- Dpto. de Microbiología y Genética, Instituto de Microbiología Bioquímica, Universidad de Salamanca/CSIC, Salamanca, Spain
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37
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Rauceo JM, De Armond R, Otoo H, Kahn PC, Klotz SA, Gaur NK, Lipke PN. Threonine-rich repeats increase fibronectin binding in the Candida albicans adhesin Als5p. EUKARYOTIC CELL 2006; 5:1664-73. [PMID: 16936142 PMCID: PMC1595330 DOI: 10.1128/ec.00120-06] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Commensal and pathogenic states of Candida albicans depend on cell surface-expressed adhesins, including those of the Als family. Mature Als proteins consist of a 300-residue N-terminal region predicted to have an immunoglobulin (Ig)-like fold, a 104-residue conserved Thr-rich region (T), a central domain of a variable number of tandem repeats (TR) of a 36-residue Thr-rich sequence, and a heavily glycosylated C-terminal Ser/Thr-rich stalk region, also of variable length (N. K. Gaur and S. A. Klotz, Infect. Immun. 65: 5289-5294, 1997). Domain deletions in ALS5 were expressed in Saccharomyces cerevisiae to excrete soluble protein and for surface display. Far UV circular dichroism indicated that soluble Ig-T showed a single negative peak at 212 nm, consistent with previous data indicating that this region has high beta-sheet content with very little alpha-helix. A truncation of Als5p with six tandem repeats (Ig-T-TR(6)) gave spectra with additional negative ellipticity at 200 nm and, at 227 to 240 nm, spectra characteristic of a structure with a similar fraction of beta-sheet but with additional structural elements as well. Soluble Als5p Ig-T and Ig-T-TR(6) fragments bound to fibronectin in vitro, but the inclusion of the TR region substantially increased affinity. Cellular adhesion assays with S. cerevisiae showed that the Ig-T domain mediated adherence to fibronectin and that TR repeats greatly increased cell-to-cell aggregation. Thus, the TR region of Als5p modulated the structure of the Ig-T region, augmented cell adhesion activity through increased binding to mammalian ligands, and simultaneously promoted fungal cell-cell interactions.
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Affiliation(s)
- Jason M Rauceo
- Dept. of Biology, Brooklyn College, 2900 Bedford Ave., Brooklyn, NY 11210, USA
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Rida PC, Nishikawa A, Won GY, Dean N. Yeast-to-hyphal transition triggers formin-dependent Golgi localization to the growing tip in Candida albicans. Mol Biol Cell 2006; 17:4364-78. [PMID: 16855023 PMCID: PMC1635370 DOI: 10.1091/mbc.e06-02-0143] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Rapid and long-distance secretion of membrane components is critical for hyphal formation in filamentous fungi, but the mechanisms responsible for polarized trafficking are not well understood. Here, we demonstrate that in Candida albicans, the majority of the Golgi complex is redistributed to the distal region during hyphal formation. Randomly distributed Golgi puncta in yeast cells cluster toward the growing tip during hyphal formation, remain associated with the distal portion of the filament during its extension, and are almost absent from the cell body. This restricted Golgi localization pattern is distinct from other organelles, including the endoplasmic reticulum, vacuole and mitochondria, which remain distributed throughout the cell body and hypha. Hyphal-induced positioning of the Golgi and the maintenance of its structural integrity requires actin cytoskeleton, but not microtubules. Absence of the formin Bni1 causes a hyphal-specific dispersal of the Golgi into a haze of finely dispersed vesicles with a sedimentation density no different from that of normal Golgi. These results demonstrate the existence of a hyphal-specific, Bni1-dependent cue for Golgi integrity and positioning at the distal portion of the hyphal tip, and suggest that filamentous fungi have evolved a novel strategy for polarized secretion, involving a redistribution of the Golgi to the growing tip.
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Affiliation(s)
- Padmashree C.G. Rida
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215
| | - Akiko Nishikawa
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215
| | - Gena Y. Won
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215
| | - Neta Dean
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215
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Raman SB, Nguyen MH, Zhang Z, Cheng S, Jia HY, Weisner N, Iczkowski K, Clancy CJ. Candida albicans SET1 encodes a histone 3 lysine 4 methyltransferase that contributes to the pathogenesis of invasive candidiasis. Mol Microbiol 2006; 60:697-709. [PMID: 16629671 DOI: 10.1111/j.1365-2958.2006.05121.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Candida albicans causes diverse mucosal and systemic diseases. Although this versatility likely depends upon carefully co-ordinated gene expression, epigenetic regulation in C. albicans remains poorly characterized. Screening a genomic expression library, we identified C. albicans Set1p as an immunogenic protein with homology to a lysine histone methyltransferase of Saccharomyces cerevisiae. In this study, we demonstrated that total immunoglobulin, IgG and IgM titers against a unique Set1p N-terminal fragment were significantly higher among patients with disseminated candidiasis (DC) or oropharyngeal candidiasis than controls. Disruption of SET1 resulted in complete loss of methylation of histone 3 at lysine residue 4, hyperfilamentous growth under embedded conditions, less negative cell surface charges and diminished adherence to epithelial cells, effects that were reversed upon gene re-insertion at a disrupted locus. During murine DC, the null mutant was associated with prolonged survival and lower tissue burdens. Taken together, our findings suggest that SET1 regulates multiple processes important to the pathogenesis of candidiasis. The Set1p N-terminal fragment does not exhibit significant homology to eukaryotic or microbial proteins, and might represent a novel therapeutic, preventive or diagnostic target.
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Affiliation(s)
- Suresh Babu Raman
- Department of Medicine, University of Florida College of Medicine, Gainesville, FL 32610, USA
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40
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Bai C, Xu XL, Chan FY, Lee RTH, Wang Y. MNN5 encodes an iron-regulated alpha-1,2-mannosyltransferase important for protein glycosylation, cell wall integrity, morphogenesis, and virulence in Candida albicans. EUKARYOTIC CELL 2006; 5:238-47. [PMID: 16467465 PMCID: PMC1405895 DOI: 10.1128/ec.5.2.238-247.2006] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The cell walls of microbial pathogens mediate physical interactions with host cells and hence play a key role in infection. Mannosyltransferases have been shown to determine the cell wall properties and virulence of the pathogenic fungus Candida albicans. We previously identified a C. albicans alpha-1,2-mannosyltransferase, Mnn5, for its novel ability to enhance iron usage in Saccharomyces cerevisiae. Here we have studied the enzymatic properties of purified Mnn5 and characterized its function in its natural host. Mnn5 catalyzes the transfer of mannose to both alpha-1,2- and alpha-1,6-mannobiose, and this activity requires Mn2+ as a cofactor and is regulated by the Fe2+ concentration. An mnn5Delta mutant showed a lowered ability to extend O-linked, and possibly also N-linked, mannans, hypersensitivity to cell wall-damaging agents, and a reduction of cell wall mannosylphosphate content, phenotypes typical of many fungal mannosyltransferase mutants. The mnn5Delta mutant also exhibited some unique defects, such as impaired hyphal growth on solid media and attenuated virulence in mice. An unanticipated phenotype was the mnn5Delta mutant's resistance to killing by the iron-chelating protein lactoferrin, rendering it the first protein found that mediates lactoferrin killing of C. albicans. In summary, MNN5 deletion impairs a wide range of cellular events, most likely due to its broad substrate specificity. Of particular interest was the observed role of iron in regulating the enzymatic activity, suggesting an underlying relationship between Mnn5 activity and cellular iron homeostasis.
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Affiliation(s)
- Chen Bai
- Institute of Molecular and Cell Biology, 61 Biopolis Drive, Singapore 138673, Singapore
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41
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Collopy-Junior I, Kneipp LF, da Silva FC, Rodrigues ML, Alviano CS, Meyer-Fernandes JR. Characterization of an ecto-ATPase activity in Fonsecaea pedrosoi. Arch Microbiol 2006; 185:355-62. [PMID: 16528535 DOI: 10.1007/s00203-006-0100-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2005] [Revised: 02/16/2006] [Accepted: 02/20/2006] [Indexed: 10/24/2022]
Abstract
In this work, we characterized an ecto-ATPase activity in intact mycelial forms of Fonsecaea pedrosoi, the primary causative agent of chromoblastomycosis. In the presence of 1 mM EDTA, fungal cells hydrolyzed adenosine-5'-triphosphate (ATP) at a rate of 84.6 +/- 11.3 nmol Pi h(-1) mg(-1) mycelial dry weight. The ecto-ATPase activity was increased at about five times (498.3 +/- 27.6 nmol Pi h(-1) mg(-1)) in the presence of 5 mM MgCl2, with values of Vmax and apparent Km for Mg-ATP(2-) corresponding to 541.9 +/- 48.6 nmol Pi h(-1) mg(-1) cellular dry weight and 1.9 +/- 0.2 mM, respectively. The Mg2+-stimulated ecto-ATPase activity was insensitive to inhibitors of intracellular ATPases such as vanadate (P-ATPases), bafilomycin A1(V-ATPases), and oligomycin (F-ATPases). Inhibitors of acid phosphatases (molybdate, vanadate, and fluoride) or alkaline phosphatases (levamizole) had no effect on the ecto-ATPase activity. The surface of the Mg2+ -stimulated ATPase in F. pedrosoi was confirmed by assays in which 4,4'-diisothiocyanostylbene-2,2'-disulfonic acid (DIDS), a membrane impermeant inhibitor, and suramin, an inhibitor of ecto-ATPase and antagonist of P2 purinoreceptors. Based on the differential expression of ecto-ATPases in the different morphological stages of F. pedrosoi, the putative role of this enzyme in fungal biology is discussed.
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Affiliation(s)
- Italo Collopy-Junior
- Instituto de Bioquímica Médica, Universidade Federal do Rio de Janeiro, CCS, Bloco H, Cidade Universitária, Ilha do Fundão, 21541-590, Rio de Janeiro, Brazil
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Bates S, Hughes HB, Munro CA, Thomas WPH, MacCallum DM, Bertram G, Atrih A, Ferguson MAJ, Brown AJP, Odds FC, Gow NAR. Outer chain N-glycans are required for cell wall integrity and virulence of Candida albicans. J Biol Chem 2005; 281:90-8. [PMID: 16263704 DOI: 10.1074/jbc.m510360200] [Citation(s) in RCA: 186] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The outer layer of the Candida albicans cell wall is enriched in highly glycosylated mannoproteins that are the immediate point of contact with the host and strongly influence the host-fungal interaction. N-Glycans are the major form of mannoprotein modification and consist of a core structure, common to all eukaryotes, that is further elaborated in the Golgi to form the highly branched outer chain that is characteristic of fungi. In yeasts, outer chain branching is initiated by the action of the alpha1,6-mannosyltransferase Och1p; therefore, we disrupted the C. albicans OCH1 homolog to determine the importance of outer chain N-glycans on the host-fungal interaction. Loss of CaOCH1 resulted in a temperature-sensitive growth defect and cellular aggregation. Outer chain elongation of N-glycans was absent in the null mutant, demonstrated by the lack of the alpha1,6-linked polymannose backbone and the underglycosylation of N-acetylglucosaminidase. A null mutant lacking OCH1 was hypersensitive to a range of cell wall perturbing agents and had a constitutively activated cell wall integrity pathway. These mutants had near normal growth rates in vitro but were attenuated in virulence in a murine model of systemic infection. However, tissue burdens for the Caoch1delta null mutant were similar to control strains with normal N-glycosylation, suggesting the host-fungal interaction was altered such that high burdens were tolerated. This demonstrates the importance of N-glycan outer chain epitopes to the host-fungal interaction and virulence.
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Affiliation(s)
- Steven Bates
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, United Kingdom
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43
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Bates S, MacCallum DM, Bertram G, Munro CA, Hughes HB, Buurman ET, Brown AJP, Odds FC, Gow NAR. Candida albicans Pmr1p, a secretory pathway P-type Ca2+/Mn2+-ATPase, is required for glycosylation and virulence. J Biol Chem 2005; 280:23408-15. [PMID: 15843378 DOI: 10.1074/jbc.m502162200] [Citation(s) in RCA: 142] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The cell surface of Candida albicans is the immediate point of contact with the host. The outer layer of the cell wall is enriched in highly glycosylated mannoproteins that are implicated in many aspects of the host-fungus interaction. Glycosylation of cell wall proteins is initiated in the endoplasmic reticulum and then elaborated in the Golgi as the protein passes through the secretory pathway. Golgi-bound mannosyltransferases require Mn(2+) as an essential cofactor. In Saccharomyces cerevisiae, the P-type ATPase Pmr1p transports Ca(2+) and Mn(2+) ions into the Golgi. To determine the effect of a gross defect in glycosylation on host-fungus interactions of C. albicans, we disrupted the PMR1 homolog, CaPMR1. This mutation would simultaneously inhibit many Golgi-located, Mn(2+)-dependent mannosyltransferases. The Capmr1Delta null mutant was viable in vitro and had no growth defect even on media containing low Ca(2+)/Mn(2+) ion concentrations. However, cells grown in these media progressively lost viability upon entering stationary phase. Phosphomannan was almost completely absent, and O-mannan was severely truncated in the null mutant. A defect in N-linked outer chain glycosylation was also apparent, demonstrated by the underglycosylation of surface acid phosphatase. Consistent with the glycosylation defect, the null mutant had a weakened cell wall, exemplified by hypersensitivity to Calcofluor white, Congo red, and hygromycin B and constitutive activation of the cell integrity pathway. In a murine model of systemic infection, the null mutant was severely attenuated in virulence. These results demonstrate the importance of glycosylation for cell wall structure and virulence of C. albicans.
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Affiliation(s)
- Steven Bates
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Scotland, UK
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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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Zhao X, Oh SH, Cheng G, Green CB, Nuessen JA, Yeater K, Leng RP, Brown AJP, Hoyer LL. ALS3 and ALS8 represent a single locus that encodes a Candida albicans adhesin; functional comparisons between Als3p and Als1p. MICROBIOLOGY-SGM 2004; 150:2415-2428. [PMID: 15256583 DOI: 10.1099/mic.0.26943-0] [Citation(s) in RCA: 190] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The ALS (agglutinin-like sequence) gene family of Candida albicans encodes eight cell-surface glycoproteins, some of which are involved in adherence to host surfaces. A mutational analysis of each ALS gene is currently being performed to deduce the functions of the encoded proteins and to better understand the role of these proteins in C. albicans biology and pathogenesis. This paper describes construction of an als3/als3 mutant and comparison of its phenotype to an als1/als1 strain. Efforts to disrupt ALS3 indicated that the gene could be deleted in two transformation steps, suggesting that the gene is encoded by a single locus and that the ALS3-like locus, ALS8, does not exist. Strains lacking ALS3 or ALS1 did not exhibit a defect in germ tube formation when grown in RPMI 1640 medium, but the als1/als1 mutant formed significantly fewer germ tubes in Lee medium. Analysis of ALS3 and ALS1 promoter activity using green fluorescent protein (GFP) reporter strains and flow cytometry showed that when cells are placed into medium that promotes germ tube formation, ALS1 is transcribed prior to ALS3. Comparison of the mutant strains in adhesion assays showed that the als3/als3 strain was defective in adhesion to both human umbilical vein endothelial cells (HUVEC) and buccal epithelial cells (BEC), but not to fibronectin-coated plastic plates. In contrast, the als1/als1 strain showed decreased adherence to HUVEC, but adherence to BEC and fibronectin were the same as wild-type controls. Inoculation of the buccal reconstituted human epithelium (RHE) model of oral candidiasis with the mutant strains showed nearly a total lack of adhesion and epithelial destruction by the als3/als3 mutant while the als1/als1 strain showed only a slightly reduced degree of epithelial destruction compared to the wild-type control. Adhesion data presented here suggest that, in the assays performed, loss of Als3p affects C. albicans adhesion more than loss of Als1p. Collectively, these results demonstrate functional similarities and differences between Als1p and Als3p, and suggest the potential for more complex interrelationships between the ALS genes and their encoded proteins.
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Affiliation(s)
- Xiaomin Zhao
- Department of Veterinary Pathobiology, University of Illinois at Urbana-Champaign, Urbana, IL 61802, USA
| | - Soon-Hwan Oh
- Department of Veterinary Pathobiology, University of Illinois at Urbana-Champaign, Urbana, IL 61802, USA
| | - Georgina Cheng
- Department of Veterinary Pathobiology, University of Illinois at Urbana-Champaign, Urbana, IL 61802, USA
| | - Clayton B Green
- Department of Veterinary Pathobiology, University of Illinois at Urbana-Champaign, Urbana, IL 61802, USA
| | - Jennifer A Nuessen
- Department of Veterinary Pathobiology, University of Illinois at Urbana-Champaign, Urbana, IL 61802, USA
| | - Kathleen Yeater
- Department of Veterinary Pathobiology, University of Illinois at Urbana-Champaign, Urbana, IL 61802, USA
| | - Roger P Leng
- Department of Molecular and Cell Biology, University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen, UK
| | - Alistair J P Brown
- Department of Molecular and Cell Biology, University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen, UK
| | - Lois L Hoyer
- Department of Veterinary Pathobiology, University of Illinois at Urbana-Champaign, Urbana, IL 61802, USA
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Uccelletti D, O'Callaghan C, Berninsone P, Zemtseva I, Abeijon C, Hirschberg CB. ire-1-dependent Transcriptional Up-regulation of a Lumenal Uridine Diphosphatase from Caenorhabditis elegans. J Biol Chem 2004; 279:27390-8. [PMID: 15102851 DOI: 10.1074/jbc.m402624200] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Lumenal ecto-nucleoside tri- and di-phosphohydrolases (ENTPDases) of the secretory pathway of eukaryotes hydrolyze nucleoside diphosphates resulting from glycosyltransferase-mediated reactions, yielding nucleoside monophosphates. The latter are weaker inhibitors of glycosyltransferases than the former and are also antiporters for the transport of nucleotide sugars from the cytosol to the endoplasmic reticulum (ER) and Golgi apparatus (GA) lumen. Here we describe the presence of two cation-dependent nucleotide phosphohydrolase activities in membranes of Caenorhabditis elegans: one, UDA-1, is a UDP/GDPase encoded by the gene uda-1, whereas the other is an apyrase encoded by the gene ntp-1. UDA-1 shares significant amino acid sequence similarity to yeast GA Gda1p and mammalian UDP/GDPases and has a lumenal active site in vesicles displaying an intermediate density between those of the ER and GA when expressed in S. cerevisiae. NTP-1 expressed in COS-7 cells appeared to localize to the GA. The transcript of uda-1 but not those of two other C. elegans ENTPDase mRNAs (ntp-1 and mig-23) was induced up to 3.5-fold by high temperature, tunicamycin, and ethanol. The same effectors triggered the unfolded protein response as shown by the induction of expression of green fluorescent protein under the control of the BiP chaperone promoter and the UDP-glucose:glycoprotein glucosyltransferase. Up-regulation of uda-1 did not occur in ire-1-deficient mutants, demonstrating the role of this ER stress sensor in this event. We hypothesize that up-regulation of uda-1 favors hydrolysis of the glucosyltransferase inhibitory product UDP to UMP, and that the latter product then exits the lumen of the ER or pre-GA compartment in a coupled exchange with the entry of UDP-glucose, thereby further relieving ER stress by favoring protein re-glycosylation.
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Affiliation(s)
- Daniela Uccelletti
- Department of Molecular and Cell Biology, Boston University Goldman School of Dental Medicine, Boston, Massachusetts 02118, USA
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Masuoka J. Surface glycans of Candida albicans and other pathogenic fungi: physiological roles, clinical uses, and experimental challenges. Clin Microbiol Rev 2004; 17:281-310. [PMID: 15084502 PMCID: PMC387410 DOI: 10.1128/cmr.17.2.281-310.2004] [Citation(s) in RCA: 122] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Although fungi have always been with us as commensals and pathogens, fungal infections have been increasing in frequency over the past few decades. There is a growing body of literature describing the involvement of carbohydrate groups in various aspects of fungal disease. Carbohydrates comprising the cell wall or capsule, or as a component of glycoproteins, are the fungal cell surface entities most likely to be exposed to the surrounding environment. Thus, the fungus-host interaction is likely to involve carbohydrates before DNA, RNA, or even protein. The interaction between fungal and host cells is also complex, and early studies using whole cells or crude cell fractions often produced seemingly conflicting results. What was needed, and what has been developing, is the ability to identify specific glycan structures and determine how they interact with immune system components. Carbohydrate analysis is complicated by the complexity of glycan structures and by the challenges of separating and detecting carbohydrates experimentally. Advances in carbohydrate chemistry have enabled us to move from the foundation of composition analysis to more rapid characterization of specific structures. This, in turn, will lead to a greater understanding of how fungi coexist with their hosts as commensals or exist in conflict as pathogens.
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Affiliation(s)
- James Masuoka
- Department of Pathology, University of Virginia, Charlottesville, Virginia 22908-0904, USA.
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Sánchez R, Franco A, Gacto M, Notario V, Cansado J. Characterization ofgdp1+as encoding a GDPase in the fission yeastSchizosaccharomyces pombe. FEMS Microbiol Lett 2003; 228:33-8. [PMID: 14612233 DOI: 10.1016/s0378-1097(03)00698-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We have isolated the gdp1+ gene from Schizosaccharomyces pombe coding for a membrane protein with guanosine diphosphatase (GDPase) activity, which is highly homologous to Golgi GDPases isolated from other yeast species. The gdp1+ product, Gdp1p, displays both GDPase and uridine diphosphatase (UDPase) activities in vitro, with a strong dependence for calcium and manganese cations. The observation of a defect in N-glycosylation of invertase in S. pombe Deltagdp1 cells together with the ability of gdp1+ to functionally complement the defective O-mannosylation of chitinase in Saccharomyces cerevisiae cells disrupted in the GDA1 gene (gdp1+ homolog), suggests a main role for Gdp1p in protein glycosylation in fission yeast.
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Affiliation(s)
- Raquel Sánchez
- Department of Genetics and Microbiology, Faculty of Biology, Universidad de Murcia, 30071 Murcia, Spain
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Current awareness on yeast. Yeast 2003; 20:455-62. [PMID: 12728936 DOI: 10.1002/yea.943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Martinez-Duncker I, Mollicone R, Codogno P, Oriol R. The nucleotide-sugar transporter family: a phylogenetic approach. Biochimie 2003; 85:245-60. [PMID: 12770764 DOI: 10.1016/s0300-9084(03)00046-4] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Nucleotide sugar transporters (NST) establish the functional link of membrane transport between the nucleotide sugars synthesized in the cytoplasm and nucleus, and the glycosylation processes that take place in the endoplasmic reticulum (ER) and Golgi apparatus. The aim of the present work was to perform a phylogenetic analysis of 87 bank annotated protein sequences comprising all the NST so far characterized and their homologues retrieved by BLAST searches, as well as the closely related triose-phosphate translocator (TPT) plant family. NST were classified in three comprehensive families by linking them to the available experimental data. This enabled us to point out both the possible ER subcellular targeting of these transporters mediated by the dy-lysine motif and the substrate recognition mechanisms specific to each family as well as an important acceptor site motif, establishing the role of evolution in the functional properties of each NST family.
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Affiliation(s)
- Ivan Martinez-Duncker
- Inserm U504 Glycobiologie et signalisation cellulaire, Université de Paris Sud XI, 16, avenue Paul-Vaillant-Couturier, 94807 Villejuif, France.
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