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Ness TJ, Gamage DG, Ekanayaka SA, Hendrickson TL. A Soluble, Minimalistic Glycosylphosphatidylinositol Transamidase (GPI-T) Retains Transamidation Activity. Biochemistry 2022; 61:1273-1285. [PMID: 35730892 DOI: 10.1021/acs.biochem.2c00196] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Glycosylphosphatidylinositol (GPI) anchoring of proteins is a eukaryotic, post-translational modification catalyzed by GPI transamidase (GPI-T). The Saccharomyces cerevisiae GPI-T is composed of five membrane-bound subunits: Gpi8, Gaa1, Gpi16, Gpi17, and Gab1. GPI-T has been recalcitrant to in vitro structure and function studies because of its complexity and membrane-solubility. Furthermore, a reliable, quantitative, in vitro assay for this important post-translational modification has remained elusive despite its discovery more than three decades ago.Three recent reports describe the structure of GPI-T from S. cerevisiae and humans, shedding critical light on this important enzyme and offering insight into the functions of its different subunits. Here, we present the purification and characterization of a truncated soluble GPI-T heterotrimer complex (Gpi823-306, Gaa150-343, and Gpi1620-551) without transmembrane domains. Using this simplified heterotrimer, we report the first quantitative method to measure GPI-T activity in vitro and demonstrate that this soluble, minimalistic GPI-T retains transamidase activity. These results contribute to our understanding of how this enzyme is organized and functions, and provide a method to screen potential GPI-T inhibitors.
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Affiliation(s)
- Travis J Ness
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, United States
| | - Dilani G Gamage
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, United States
| | - Sandamali A Ekanayaka
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, United States
| | - Tamara L Hendrickson
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, United States
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Omura F, Takagi M, Kodama Y. Compromised chitin synthesis in lager yeast affects its Congo red resistance and release of mannoproteins from the cells. FEMS Microbiol Lett 2020; 367:5974272. [PMID: 33175116 DOI: 10.1093/femsle/fnaa181] [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] [Received: 07/06/2020] [Accepted: 11/08/2020] [Indexed: 11/14/2022] Open
Abstract
A mutant lager strain resistant to the cell wall-perturbing agent Congo red (CR) was isolated and the genetic alterations underlying CR resistance were investigated by whole genome sequencing. The parental lager strain was found to contain three distinct Saccharomyces cerevisiae (Sc)-type CHS6 (CHitin Synthase-related 6) alleles, two of which have one or two nonsense mutations in the open reading frame, leaving only one functional allele, whereas the functional allele was missing in the isolated CR-resistant strain. On the other hand, the Saccharomyces eubayanus-type CHS6 alleles shared by both the parental and mutant strains appeared to contribute poorly to chitin synthase-activating function. Therefore, the CR resistance of the mutant strain was attributable to the overall compromised activity of CHS6 gene products. The CR-resistant mutant cells exhibited less chitin production on the cell surface and smaller amounts of mannoprotein release into the medium. All these traits, in addition to the CR resistance, were complemented by the functional ScCHS6 gene. It is of great interest whether the frequent nonsense mutations found in ScCHS6 open reading frame in lager yeast strains are a consequence of the domestication process of lager yeast.
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Affiliation(s)
- Fumihiko Omura
- Suntory Global Innovation Center Ltd., 8-1-1 Seikadai, Seika-cho, Soraku-gun, Kyoto 619-0284, Japan
| | - Motoshige Takagi
- Suntory System Technology Ltd., 2-1-5 Doujima, Kita-ku, Osaka-shi, Osaka 530-8204, Japan
| | - Yukiko Kodama
- Suntory Global Innovation Center Ltd., 8-1-1 Seikadai, Seika-cho, Soraku-gun, Kyoto 619-0284, Japan
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Sah SK, Shefali S, Yadav A, Som P, Komath SS. The caspase-like Gpi8 subunit of Candida albicans GPI transamidase is a metal-dependent endopeptidase. Biochem Biophys Res Commun 2020; 525:S0006-291X(20)30268-0. [PMID: 32081427 DOI: 10.1016/j.bbrc.2020.02.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Accepted: 02/03/2020] [Indexed: 10/25/2022]
Abstract
GPI anchored proteins (GPI-APs) act at the frontiers of cells, decoding environmental cues and determining host-pathogen interactions in several lower eukaryotes. They are also essential for viability in lower eukaryotes. The GPI biosynthetic pathway begins at the ER and follows a roughly linear pathway to generate the complete precursor (CP) glycolipid. The GPI transamidase (GPIT) transfers this glycolipid to the C-terminal end of newly translated proteins after removing their GPI attachment signal sequence (SS). The GPIT subunit that cleaves SS is Gpi8, a protein with a conserved Cys/His catalytic dyad typical of cysteine proteases. A CaGPI8 heterozygous mutant accumulates CPs and has reduced cell surface GPI-APs. Using a simple cell-free assay, we demonstrate that the heterozygous CaGPI8 strain has low endopeptidase activity as well. The revertant strain is restored in all these phenotypes. CaGpi8 is also shown to be a metalloenzyme, whose protease activity is sensitive to agents that modify Cys/His residues.
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Affiliation(s)
- Sudisht Kumar Sah
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067, India
| | - Shailja Shefali
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067, India
| | - Anshuman Yadav
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067, India
| | - Punnag Som
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067, India
| | - Sneha Sudha Komath
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067, India.
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Komath SS, Singh SL, Pratyusha VA, Sah SK. Generating anchors only to lose them: The unusual story of glycosylphosphatidylinositol anchor biosynthesis and remodeling in yeast and fungi. IUBMB Life 2019; 70:355-383. [PMID: 29679465 DOI: 10.1002/iub.1734] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Revised: 02/16/2018] [Accepted: 02/22/2018] [Indexed: 02/06/2023]
Abstract
Glycosylphosphatidylinositol (GPI)-anchored proteins (GPI-APs) are present ubiquitously at the cell surface in all eukaryotes. They play a crucial role in the interaction of the cell with its external environment, allowing the cell to receive signals, respond to challenges, and mediate adhesion. In yeast and fungi, they also participate in the structural integrity of the cell wall and are often essential for survival. Roughly four decades after the discovery of the first GPI-APs, this review provides an overview of the insights gained from studies of the GPI biosynthetic pathway and the future challenges in the field. In particular, we focus on the biosynthetic pathway in Saccharomyces cerevisiae, which has for long been studied as a model organism. Where available, we also provide information about the GPI biosynthetic steps in other yeast/ fungi. Although the core structure of the GPI anchor is conserved across organisms, several variations are built into the biosynthetic pathway. The present Review specifically highlights these variations and their implications. There is growing evidence to suggest that several phenotypes are common to GPI deficiency and should be expected in GPI biosynthetic mutants. However, it appears that several phenotypes are unique to a specific step in the pathway and may even be species-specific. These could suggest the points at which the GPI biosynthetic pathway intersects with other important cellular pathways and could be points of regulation. They could be of particular significance in the study of pathogenic fungi and in identification of new and specific antifungal drugs/ drug targets. © 2018 IUBMB Life, 70(5):355-383, 2018.
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Affiliation(s)
| | - Sneh Lata Singh
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | | | - Sudisht Kumar Sah
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
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The Glycosylphosphatidylinositol Transamidase Complex Subunit PbGPI16 of Plasmodium berghei Is Important for Inducing Experimental Cerebral Malaria. Infect Immun 2018; 86:IAI.00929-17. [PMID: 29784863 DOI: 10.1128/iai.00929-17] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Accepted: 05/18/2018] [Indexed: 02/07/2023] Open
Abstract
In animal models of experimental cerebral malaria (ECM), the glycosylphosphatidylinositols (GPIs) and GPI anchors are the major factors that induce nuclear factor kappa B (NF-κB) activation and proinflammatory responses, which contribute to malaria pathogenesis. GPIs and GPI anchors are transported to the cell surface via a process called GPI transamidation, which involves the GPI transamidase (GPI-T) complex. In this study, we showed that GPI16, one of the GPI-T subunits, is highly conserved among Plasmodium species. Genetic knockout of pbgpi16 (Δpbgpi16) in the rodent malaria parasite Plasmodium berghei strain ANKA led to a significant reduction of the amounts of GPIs in the membranes of merozoites, as well as surface display of several GPI-anchored merozoite surface proteins. Compared with the wild-type parasites, Δpbgpi16 parasites in C57BL/6 mice caused much less NF-κB activation and elicited a substantially attenuated T helper type 1 response. As a result, Δpbgpi16 mutant-infected mice displayed much less severe brain pathology, and considerably fewer Δpbgpi16 mutant-infected mice died from ECM. This study corroborated the GPI toxin as a significant inducer of ECM and further suggested that vaccines against parasite GPIs may be a promising strategy to limit the severity of malaria.
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Eisenhaber B, Sinha S, Wong WC, Eisenhaber F. Function of a membrane-embedded domain evolutionarily multiplied in the GPI lipid anchor pathway proteins PIG-B, PIG-M, PIG-U, PIG-W, PIG-V, and PIG-Z. Cell Cycle 2018; 17:874-880. [PMID: 29764287 PMCID: PMC6056205 DOI: 10.1080/15384101.2018.1456294] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Distant homology relationships among proteins with many transmembrane regions (TMs) are difficult to detect as they are clouded by the TMs’ hydrophobic compositional bias and mutational divergence in connecting loops. In the case of several GPI lipid anchor biosynthesis pathway components, the hidden evolutionary signal can be revealed with dissectHMMER, a sequence similarity search tool focusing on fold-critical, high complexity sequence segments. We find that a sequence module with 10 TMs in PIG-W, described as acyl transferase, is homologous to PIG-U, a transamidase subunit without characterized molecular function, and to mannosyltransferases PIG-B, PIG-M, PIG-V and PIG-Z. We conclude that this new, membrane-embedded domain named BindGPILA functions as the unit for recognizing, binding and stabilizing the GPI lipid anchor in a modification-competent form as this appears the only functional aspect shared among all proteins. Thus, PIG-U's likely molecular function is shuttling/presenting the anchor in a productive conformation to the transamidase complex.
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Affiliation(s)
- Birgit Eisenhaber
- a Bioinformatics Institute, Agency for Science , Technology and Research (A*STAR) , 30 Biopolis Street, #07-01 Matrix, Singapore 138671 , Republic of Singapore
| | - Swati Sinha
- a Bioinformatics Institute, Agency for Science , Technology and Research (A*STAR) , 30 Biopolis Street, #07-01 Matrix, Singapore 138671 , Republic of Singapore
| | - Wing-Cheong Wong
- a Bioinformatics Institute, Agency for Science , Technology and Research (A*STAR) , 30 Biopolis Street, #07-01 Matrix, Singapore 138671 , Republic of Singapore
| | - Frank Eisenhaber
- a Bioinformatics Institute, Agency for Science , Technology and Research (A*STAR) , 30 Biopolis Street, #07-01 Matrix, Singapore 138671 , Republic of Singapore.,b School of Computer Engineering , Nanyang Technological University (NTU) , 50 Nanyang Drive, Singapore 637553 , Republic of Singapore
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7
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The soluble domains of Gpi8 and Gaa1, two subunits of glycosylphosphatidylinositol transamidase (GPI-T), assemble into a complex. Arch Biochem Biophys 2017; 633:58-67. [DOI: 10.1016/j.abb.2017.09.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Revised: 09/06/2017] [Accepted: 09/07/2017] [Indexed: 11/23/2022]
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Disulfide Bond Formation and N-Glycosylation Modulate Protein-Protein Interactions in GPI-Transamidase (GPIT). Sci Rep 2017; 8:45912. [PMID: 28374821 PMCID: PMC5379210 DOI: 10.1038/srep45912] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Accepted: 03/06/2017] [Indexed: 12/28/2022] Open
Abstract
Glycosylphosphatidylinositol (GPI) transamidase (GPIT), the enzyme that attaches GPI anchors to proteins as they enter the lumen of the endoplasmic reticulum, is a membrane-bound hetero-pentameric complex consisting of Gpi8, Gpi16, Gaa1, Gpi17 and Gab1. Here, we expressed and purified the luminal domain of Saccharomyces cerevisiae (S. cerevisiae) Gpi8 using different expression systems, and examined its interaction with insect cell expressed luminal domain of S. cerevisiae Gpi16. We found that the N-terminal caspase-like domain of Gpi8 forms a disulfide-linked dimer, which is strengthened by N-glycosylation. The non-core domain of Gpi8 following the caspase-like domain inhibits this dimerization. In contrast to the previously reported disulfide linkage between Gpi8 and Gpi16 in human and trypanosome GPIT, our data show that the luminal domains of S. cerevisiae Gpi8 and S. cerevisiae Gpi16 do not interact directly, nor do they form a disulfide bond in the intact S. cerevisiae GPIT. Our data suggest that subunit interactions within the GPIT complex from different species may vary, a feature that should be taken into account in future structural and functional studies.
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Oliveira-Garcia E, Deising HB. The Glycosylphosphatidylinositol Anchor Biosynthesis Genes GPI12, GAA1, and GPI8 Are Essential for Cell-Wall Integrity and Pathogenicity of the Maize Anthracnose Fungus Colletotrichum graminicola. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2016; 29:889-901. [PMID: 27937175 DOI: 10.1094/mpmi-09-16-0175-r] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Glycosylphosphatidylinositol (GPI) anchoring of proteins is one of the most common posttranslational modifications of proteins in eukaryotic cells and is important for associating proteins with the cell surface. In fungi, GPI-anchored proteins play essential roles in cross-linking of β-glucan cell-wall polymers and cell-wall rigidity. GPI-anchor synthesis is successively performed at the cytoplasmic and the luminal face of the ER membrane and involves approximately 25 proteins. While mutagenesis of auxiliary genes of this pathway suggested roles of GPI-anchored proteins in hyphal growth and virulence, essential genes of this pathway have not been characterized. Taking advantage of RNA interference (RNAi) we analyzed the function of the three essential genes GPI12, GAA1 and GPI8, encoding a cytoplasmic N-acetylglucosaminylphosphatidylinositol deacetylase, a metallo-peptide-synthetase and a cystein protease, the latter two representing catalytic components of the GPI transamidase complex. RNAi strains showed drastic cell-wall defects, resulting in exploding infection cells on the plant surface and severe distortion of in planta-differentiated infection hyphae, including formation of intrahyphal hyphae. Reduction of transcript abundance of the genes analyzed resulted in nonpathogenicity. We show here for the first time that the GPI synthesis genes GPI12, GAA1, and GPI8 are indispensable for vegetative development and pathogenicity of the causal agent of maize anthracnose, Colletotrichum graminicola.
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Affiliation(s)
- Ely Oliveira-Garcia
- 1 Martin-Luther-Universität Halle-Wittenberg, Naturwissenschaftliche Fakultät III, Institut für Agrar- und Ernährungswissenschaften, Phytopathologie und Pflanzenschutz, and
| | - Holger B Deising
- 1 Martin-Luther-Universität Halle-Wittenberg, Naturwissenschaftliche Fakultät III, Institut für Agrar- und Ernährungswissenschaften, Phytopathologie und Pflanzenschutz, and
- 2 Interdisziplinäres Zentrum für Nutzpflanzenforschung; Betty-Heimann-Str. 3. D-06120 Halle/Saale, Germany
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Recent progress in synthetic and biological studies of GPI anchors and GPI-anchored proteins. Curr Opin Chem Biol 2013; 17:1006-13. [PMID: 24128440 DOI: 10.1016/j.cbpa.2013.09.016] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Revised: 09/22/2013] [Accepted: 09/24/2013] [Indexed: 10/26/2022]
Abstract
Covalent attachment of glycosylphosphatidylinositols (GPIs) to the protein C-terminus is one of the most common posttranslational modifications in eukaryotic cells. In addition to anchoring surface proteins to the cell membrane, GPIs also have many other important biological functions, determined by their unique structure and property. This account has reviewed the recent progress made in disclosing GPI and GPI-anchored protein biosynthesis, in the chemical and chemoenzymatic synthesis of GPIs and GPI-anchored proteins, and in understanding the conformation, organization, and distribution of GPIs in the lipid membrane.
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Gamage DG, Hendrickson TL. GPI Transamidase and GPI anchored proteins: Oncogenes and biomarkers for cancer. Crit Rev Biochem Mol Biol 2013; 48:446-64. [DOI: 10.3109/10409238.2013.831024] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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12
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Guo Z. Synthetic Studies of Glycosylphosphatidylinositol (GPI) Anchors and GPI-Anchored Peptides, Glycopeptides, and Proteins. Curr Org Synth 2013; 10:366-383. [PMID: 24955081 DOI: 10.2174/1570179411310030003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Glycosylphosphatidylinositol (GPI) anchorage of proteins and glycoproteins onto the cell surface is ubiquitous in eukaryotes, and GPI-anchored proteins and glycoproteins play an important role in many biological processes. To study GPI anchorage and explore the functions of GPIs and GPI-anchored proteins and glycoproteins, it is essential to have access to these molecules in homogeneous and structurally defined forms. This review is focused on the progress that our laboratory has made towards the chemical and chemoenzymatic synthesis of structurally defined GPI anchors and GPI-anchored peptides, glycopeptides, and proteins. Briefly, highly convergent strategies were developed for GPI synthesis and were employed to successfully synthesize a number of GPIs, including those carrying unsaturated lipids and other useful functionalities such as the azido and alkynyl groups. The latter enabled further site-specific modification of GPIs by click chemistry. GPI-linked peptides, glycopeptides, and proteins were prepared by regioselective chemical coupling of properly protected GPIs and peptides/glycopeptides or through site-specific ligation of synthetic GPIs and peptides/glycopeptides/proteins under the influence of sortase A. The investigation of interactions between GPI anchors and pore-forming bacterial toxins by means of synthetic GPI anchors and GPI analogs is also discussed.
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Affiliation(s)
- Zhongwu Guo
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, USA
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13
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Orlean P. Architecture and biosynthesis of the Saccharomyces cerevisiae cell wall. Genetics 2012; 192:775-818. [PMID: 23135325 PMCID: PMC3522159 DOI: 10.1534/genetics.112.144485] [Citation(s) in RCA: 296] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2012] [Accepted: 08/06/2012] [Indexed: 01/02/2023] Open
Abstract
The wall gives a Saccharomyces cerevisiae cell its osmotic integrity; defines cell shape during budding growth, mating, sporulation, and pseudohypha formation; and presents adhesive glycoproteins to other yeast cells. The wall consists of β1,3- and β1,6-glucans, a small amount of chitin, and many different proteins that may bear N- and O-linked glycans and a glycolipid anchor. These components become cross-linked in various ways to form higher-order complexes. Wall composition and degree of cross-linking vary during growth and development and change in response to cell wall stress. This article reviews wall biogenesis in vegetative cells, covering the structure of wall components and how they are cross-linked; the biosynthesis of N- and O-linked glycans, glycosylphosphatidylinositol membrane anchors, β1,3- and β1,6-linked glucans, and chitin; the reactions that cross-link wall components; and the possible functions of enzymatic and nonenzymatic cell wall proteins.
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Affiliation(s)
- Peter Orlean
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
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Lee SH, Kim PJ, Jeong H. Global organization of protein complexome in the yeast Saccharomyces cerevisiae. BMC SYSTEMS BIOLOGY 2011; 5:126. [PMID: 21843333 PMCID: PMC3169507 DOI: 10.1186/1752-0509-5-126] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/14/2011] [Accepted: 08/15/2011] [Indexed: 11/10/2022]
Abstract
BACKGROUND Proteins in organisms, rather than act alone, usually form protein complexes to perform cellular functions. We analyze the topological network structure of protein complexes and their component proteins in the budding yeast in terms of the bipartite network and its projections, where the complexes and proteins are its two distinct components. Compared to conventional protein-protein interaction networks, the networks from the protein complexes show more homogeneous structures than those of the binary protein interactions, implying the formation of complexes that cause a relatively more uniform number of interaction partners. In addition, we suggest a new optimization method to determine the abundance and function of protein complexes, based on the information of their global organization. Estimating abundance and biological functions is of great importance for many researches, by providing a quantitative description of cell behaviors, instead of just a "catalogues" of the lists of protein interactions. RESULTS With our new optimization method, we present genome-wide assignments of abundance and biological functions for complexes, as well as previously unknown abundance and functions of proteins, which can provide significant information for further investigations in proteomics. It is strongly supported by a number of biologically relevant examples, such as the relationship between the cytoskeleton proteins and signal transduction and the metabolic enzyme Eno2's involvement in the cell division process. CONCLUSIONS We believe that our methods and findings are applicable not only to the specific area of proteomics, but also to much broader areas of systems biology with the concept of optimization principle.
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Affiliation(s)
- Sang Hoon Lee
- IceLab, Department of Physics, Umeå University, 901 87 Umeå, Sweden
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16
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Mercker M, Kollath-Leiß K, Allgaier S, Weiland N, Kempken F. The BEM46-like protein appears to be essential for hyphal development upon ascospore germination in Neurospora crassa and is targeted to the endoplasmic reticulum. Curr Genet 2009; 55:151-61. [DOI: 10.1007/s00294-009-0232-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2009] [Revised: 01/29/2009] [Accepted: 01/29/2009] [Indexed: 10/21/2022]
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17
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Chapter 1 Overview of GPI Biosynthesis. ACTA ACUST UNITED AC 2009. [DOI: 10.1016/s1874-6047(09)26001-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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18
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López-Mirabal HR, Winther JR, Thorsen M, Kielland-Brandt MC. Mutations in the RAM network confer resistance to the thiol oxidant 4,4'-dipyridyl disulfide. Mol Genet Genomics 2008; 279:629-42. [PMID: 18357467 DOI: 10.1007/s00438-008-0339-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2007] [Accepted: 03/04/2008] [Indexed: 11/29/2022]
Abstract
Thiol oxidants are expected to have multiple effects in living cells. Hence, mutations giving resistance to such agents are likely to reveal important targets and/or mechanisms influencing the cellular capacity to withstand thiol oxidation. A screen for mutants resistant to the thiol-specific oxidant dipyridyl disulfide (DPS) yielded tao3-516, which is impaired in the function of the RAM signaling network protein Tao3/Pag1p. We suggest that the DPS-resistance of the tao3-516 mutant might be due to deficient cell-cycle-regulated production of the chitinase Cts1p, which functions in post-mitotic cell separation and depends on Tao3p and the RAM network for regulated expression. Consistent with this, deletion of other RAM genes or CTS1 also resulted in increased resistance to DPS. Exposure to DPS caused extensive depolarization of the actin cytoskeleton. We found that tao3-516 is resistant to latrunculin, a specific inhibitor of actin polymerization, and that ram, Deltaace2, and Deltacts1 mutants are resistant to benomyl, a microtubule-destabilizing drug. Since septum build-up depends on the organization of cytoskeletal proteins, the resistance to cytoskeletal stress of Cts1p-deficient mutants might relate to bypass for abnormal septum-associated protein sorting. The broad resistance toward oxidants (DPS, diamide and H(2)O(2)) of the Deltacts1 strain links cell wall function to the resistance to oxidative stress and suggests the existence of targets that are common for these oxidants.
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Gao XD, Sperber LM, Kane SA, Tong Z, Tong AHY, Boone C, Bi E. Sequential and distinct roles of the cadherin domain-containing protein Axl2p in cell polarization in yeast cell cycle. Mol Biol Cell 2007; 18:2542-60. [PMID: 17460121 PMCID: PMC1924817 DOI: 10.1091/mbc.e06-09-0822] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2006] [Revised: 04/10/2007] [Accepted: 04/18/2007] [Indexed: 11/11/2022] Open
Abstract
Polarization of cell growth along a defined axis is essential for the generation of cell and tissue polarity. In the budding yeast Saccharomyces cerevisiae, Axl2p plays an essential role in polarity-axis determination, or more specifically, axial budding in MATa or alpha cells. Axl2p is a type I membrane glycoprotein containing four cadherin-like motifs in its extracellular domain. However, it is not known when and how Axl2p functions together with other components of the axial landmark, such as Bud3p and Bud4p, to direct axial budding. Here, we show that the recruitment of Axl2p to the bud neck after S/G2 phase of the cell cycle depends on Bud3p and Bud4p. This recruitment is mediated via an interaction between Bud4p and the central region of the Axl2p cytoplasmic tail. This region of Axl2p, together with its N-terminal region and its transmembrane domain, is sufficient for axial budding. In addition, our work demonstrates a previously unappreciated role for Axl2p. Axl2p interacts with Cdc42p and other polarity-establishment proteins, and it regulates septin organization in late G1 independently of its role in polarity-axis determination. Together, these results suggest that Axl2p plays sequential and distinct roles in the regulation of cellular morphogenesis in yeast cell cycle.
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Affiliation(s)
- Xiang-Dong Gao
- *Department of Cell and Developmental Biology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6058; and
| | - Lauren M. Sperber
- *Department of Cell and Developmental Biology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6058; and
| | - Steven A. Kane
- *Department of Cell and Developmental Biology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6058; and
| | - Zongtian Tong
- *Department of Cell and Developmental Biology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6058; and
| | - Amy Hin Yan Tong
- Banting and Best Department of Medical Research, University of Toronto, Toronto, Ontario M5S 3E1, Canada
| | - Charles Boone
- Banting and Best Department of Medical Research, University of Toronto, Toronto, Ontario M5S 3E1, Canada
| | - Erfei Bi
- *Department of Cell and Developmental Biology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6058; and
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20
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Meitzler JL, Gray JJ, Hendrickson TL. Truncation of the caspase-related subunit (Gpi8p) of Saccharomyces cerevisiae GPI transamidase: Dimerization revealed. Arch Biochem Biophys 2007; 462:83-93. [PMID: 17475206 DOI: 10.1016/j.abb.2007.03.035] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2007] [Revised: 03/15/2007] [Accepted: 03/16/2007] [Indexed: 11/24/2022]
Abstract
Eukaryotic proteins can be post-translationally modified with a glycosylphosphatidylinositol (GPI) membrane anchor. This modification reaction is catalyzed by GPI transamidase (GPI-T), a multimeric, membrane-bound enzyme. Gpi8p, an essential component of GPI-T, shares low sequence similarity with caspases and contains all or part of the enzyme's active site [U. Meyer, M. Benghezal, I. Imhof, A. Conzelmann, Biochemistry 39 (2000) 3461-3471]. Structural predictions suggest that the soluble portion of Gpi8p is divided into two domains: a caspase-like domain that contains the active site machinery and a second, smaller domain of unknown function. Based on these predictions, we evaluated a soluble truncation of Gpi8p (Gpi8(23-306)). Dimerization was investigated due to the known proclivity of caspases to homodimerize; a Gpi8(23-306) homodimer was detected by native gel and confirmed by mass spectrometry and N-terminal sequencing. Mutations at the putative caspase-like dimerization interface disrupted dimer formation. When combined, these results demonstrate an organizational similarity between Gpi8p and caspases.
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Affiliation(s)
- Jennifer L Meitzler
- Department of Chemistry, Remsen Hall, Johns Hopkins University, Baltimore, MD 21218, USA
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21
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Orlean P, Menon AK. Thematic review series: lipid posttranslational modifications. GPI anchoring of protein in yeast and mammalian cells, or: how we learned to stop worrying and love glycophospholipids. J Lipid Res 2007; 48:993-1011. [PMID: 17361015 DOI: 10.1194/jlr.r700002-jlr200] [Citation(s) in RCA: 273] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Glycosylphosphatidylinositol (GPI) anchoring of cell surface proteins is the most complex and metabolically expensive of the lipid posttranslational modifications described to date. The GPI anchor is synthesized via a membrane-bound multistep pathway in the endoplasmic reticulum (ER) requiring >20 gene products. The pathway is initiated on the cytoplasmic side of the ER and completed in the ER lumen, necessitating flipping of a glycolipid intermediate across the membrane. The completed GPI anchor is attached to proteins that have been translocated across the ER membrane and that display a GPI signal anchor sequence at the C terminus. GPI proteins transit the secretory pathway to the cell surface; in yeast, many become covalently attached to the cell wall. Genes encoding proteins involved in all but one of the predicted steps in the assembly of the GPI precursor glycolipid and its transfer to protein in mammals and yeast have now been identified. Most of these genes encode polytopic membrane proteins, some of which are organized in complexes. The steps in GPI assembly, and the enzymes that carry them out, are highly conserved. GPI biosynthesis is essential for viability in yeast and for embryonic development in mammals. In this review, we describe the biosynthesis of mammalian and yeast GPIs, their transfer to protein, and their subsequent processing.
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Affiliation(s)
- Peter Orlean
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
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22
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Pittet M, Conzelmann A. Biosynthesis and function of GPI proteins in the yeast Saccharomyces cerevisiae. Biochim Biophys Acta Mol Cell Biol Lipids 2007; 1771:405-20. [PMID: 16859984 DOI: 10.1016/j.bbalip.2006.05.015] [Citation(s) in RCA: 163] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2006] [Revised: 05/20/2006] [Accepted: 05/22/2006] [Indexed: 11/28/2022]
Abstract
Like most other eukaryotes, Saccharomyces cerevisiae harbors a GPI anchoring machinery and uses it to attach proteins to membranes. While a few GPI proteins reside permanently at the plasma membrane, a majority of them gets further processed and is integrated into the cell wall by a covalent attachment to cell wall glucans. The GPI biosynthetic pathway is necessary for growth and survival of yeast cells. The GPI lipids are synthesized in the ER and added onto proteins by a pathway comprising 12 steps, carried out by 23 gene products, 19 of which are essential. Some of the estimated 60 GPI proteins predicted from the genome sequence serve enzymatic functions required for the biosynthesis and the continuous shape adaptations of the cell wall, others seem to be structural elements of the cell wall and yet others mediate cell adhesion. Because of its genetic tractability S. cerevisiae is an attractive model organism not only for studying GPI biosynthesis in general, but equally for investigating the intracellular transport of GPI proteins and the peculiar role of GPI anchoring in the elaboration of fungal cell walls.
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Affiliation(s)
- Martine Pittet
- Department of Medicine, Division of Biochemistry, Chemin du Musée 5, CH-1700 Fribourg, Switzerland
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23
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Walsh CJ. The role of actin, actomyosin and microtubules in defining cell shape during the differentiation of Naegleria amebae into flagellates. Eur J Cell Biol 2007; 86:85-98. [PMID: 17189659 DOI: 10.1016/j.ejcb.2006.10.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2006] [Revised: 10/17/2006] [Accepted: 10/18/2006] [Indexed: 11/18/2022] Open
Abstract
Differentiation of Naegleria amebae into flagellates was used to examine the interaction between actin, actomyosin and microtubules in defining cell shape. Amebae, which lack microtubules except during mitosis, differentiate into flagellates with a fixed shape and a complex microtubule cytoskeleton in 120 min. Based on earlier models of ameboid motility it has been suggested that actomyosin is quiescent in flagellates. This hypothesis was tested by following changes in the cytoskeleton using three-dimensional reconstructions prepared by confocal microscopy of individual cells stained with antibodies against actin and tubulin as well as with phalloidin and DNase I. F-actin as defined by phalloidin staining was concentrated in expanding pseudopods. Most phalloidin staining was lost as cells rounded up before the onset of flagellum formation. Actin staining with a Naegleria-specific antibody that recognizes both F- and G-actin was confined to the cell cortex of both amebae and flagellates. DNase I demonstrated G-actin throughout all stages. Most of the actin in the cortex was not bound by phalloidin yet was resistant to detergent extraction suggesting that it was polymerized. The microtubule cytoskeleton of flagellates was intimately associated with this actin cortex. Treatment of flagellates with cytochalasin D produced a rapid loss of flagellate shape and the appearance of phalloidin staining while latrunculin A stabilized the flagellate shape. These results suggest that tension produced by an actomyosin network is required to maintain the flagellate shape. The rapid loss of the flagellate shape induced by drugs, which specifically block myosin light chain kinase, supports this hypothesis.
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Affiliation(s)
- Charles J Walsh
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA.
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24
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Hardwidge PR, Donohoe S, Aebersold R, Finlay BB. Proteomic analysis of the binding partners to enteropathogenic Escherichia coli virulence proteins expressed in Saccharomyces cerevisiae. Proteomics 2006; 6:2174-9. [PMID: 16552782 DOI: 10.1002/pmic.200500523] [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: 11/11/2022]
Abstract
Enteropathogenic Escherichia coli (EPEC) is an enteric human pathogen responsible for much worldwide morbidity and mortality. EPEC uses a type III secretion system to inject bacterial proteins into the cytosol of intestinal epithelial cells to cause diarrheal disease. We are interested in determining the host proteins to which EPEC translocator and effector proteins bind during infection. To facilitate protein enrichment, we created fusions between GST and EPEC virulence proteins, and expressed these fusions individually in Saccharomyces cerevisiae. The biology of S. cerevisiae is well understood and often employed as a model eukaryote to study the function of bacterial virulence factors. We isolated the yeast proteins that interact with individual EPEC proteins by affinity purifying against the GST tag. These complexes were subjected to ICAT combined with ESI-MS/MS. Database searching of sequenced peptides provided a list of proteins that bound specifically to each EPEC virulence protein. The dataset suggests several potential mammalian targets of these proteins that may guide future experimentation.
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Affiliation(s)
- Philip R Hardwidge
- Veterinary Science Department, South Dakota State University, Brookings, SD, USA.
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25
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Zhu Y, Fraering P, Vionnet C, Conzelmann A. Gpi17p does not stably interact with other subunits of glycosylphosphatidylinositol transamidase in Saccharomyces cerevisiae. Biochim Biophys Acta Mol Cell Biol Lipids 2005; 1735:79-88. [PMID: 15939668 DOI: 10.1016/j.bbalip.2005.05.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2005] [Revised: 04/30/2005] [Accepted: 05/02/2005] [Indexed: 10/25/2022]
Abstract
Homologues of Gpi8p, Gaa1p, Gpi16p, Gpi17p, and Cdc91p are essential components of the GPI transamidase complex that adds glycosylphosphatidylinositols (GPIs 1) to newly synthesized proteins in the ER. In mammalian cells, these five subunits remain stably associated with each other in detergent. In yeast, we find no stable stoichiometric association of Gpi17p with the Gpi8p-Gpi16p-Gaa1p core in detergent extracts. Random and site-directed mutagenesis generated mutations in several highly conserved amino acids but did not yield nonfunctional alleles of Gpi17p and a saturating screen did not yield any dominant negative alleles of Gpi17p. Moreover, Gpi8p becomes unstable when any one of the other subunits is depleted, whereas Gpi17p is slightly affected only by the depletion of Gaa1p. These data suggest that yeast Gpi17p may be able to exert its GPI anchoring function without interacting in a stable and continuous manner with the other GPI-transamidase subunits. Shutting down ER-associated and vacuolar protein degradation pathways has no effect on the levels of Gpi17p or other transamidase subunits.
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Affiliation(s)
- Yonghua Zhu
- Department of Medicine/Biochemistry, University of Fribourg, Division of Biochemistry, Chemin du Musée 5, CH-1700 Fribourg, Switzerland
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26
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Vainauskas S, Menon AK. Endoplasmic Reticulum Localization of Gaa1 and PIG-T, Subunits of the Glycosylphosphatidylinositol Transamidase Complex. J Biol Chem 2005; 280:16402-9. [PMID: 15713669 DOI: 10.1074/jbc.m414253200] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
After integration into the endoplasmic reticulum (ER) membrane, ER-resident membrane proteins must be segregated from proteins that are exported to post-ER compartments. Here we analyze how human Gaa1 and PIG-T, two of the five subunits of the ER-localized glycosylphosphatidylinositol transamidase complex, are retained in the ER. Neither protein contains a known ER localization signal. Gaa1 is a polytopic membrane glycoprotein with a cytoplasmic N terminus and a large luminal loop between its first two transmembrane spans; PIG-T is a type I membrane glycoprotein. To simplify our analyses, we studied Gaa1 and PIG-T constructs that could not interact with other subunits of the transamidase. We now show that Gaa1(282), a truncated protein consisting of the first TM domain and luminal loop of Gaa1, is correctly oriented, N-glycosylated, and ER-localized. Removal of a potential ER localization signal in the form of a triple arginine cluster near the N terminus of Gaa1 or Gaa1(282) had no effect on ER localization. Fusion proteins consisting of different elements of Gaa1(282) appended to alpha2,6-sialyltransferase or transferrin receptor could exit the ER, indicating that Gaa1(282), and by implication Gaa1, does not contain any dominant ER-sorting determinants. The data suggest that Gaa1 is passively retained in the ER by a signalless mechanism. In contrast, similar analyses of PIG-T revealed that it is ER-localized because of information in its transmembrane span; fusion of the PIG-T transmembrane span to Tac antigen, a plasma membrane-localized protein, caused the fusion protein to remain in the ER. These data are discussed in the context of models that have been proposed to account for retention of ER membrane proteins.
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Affiliation(s)
- Saulius Vainauskas
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706-1544, USA.
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