The Experts below are selected from a list of 3783 Experts worldwide ranked by ideXlab platform
Carolyn R. Bertozzi - One of the best experts on this subject based on the ideXlab platform.
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Probing mucin-type O-Linked Glycosylation in living animals
Proceedings of the National Academy of Sciences of the United States of America, 2006Co-Authors: Danielle H. Dube, Jennifer A. Prescher, Chi N. Quang, Carolyn R. BertozziAbstract:Changes in O-Linked protein Glycosylation are known to correlate with disease states but are difficult to monitor in a physiological setting because of a lack of experimental tools. Here, we report a technique for rapid profiling of O-Linked glycoproteins in living animals by metabolic labeling with N-azidoacetylgalactosamine (GalNAz) followed by Staudinger ligation with phosphine probes. After injection of mice with a peracetylated form of GalNAz, azide-labeled glycoproteins were observed in a variety of tissues, including liver, kidney, and heart, in serum, and on isolated splenocytes. B cell glycoproteins were robustly labeled with GalNAz but T cell glycoproteins were not, suggesting fundamental differences in Glycosylation machinery or metabolism. Furthermore, GalNAz-labeled B cells could be selectively targeted with a phosphine probe by Staudinger ligation within the living animal. Metabolic labeling with GalNAz followed by Staudinger ligation provides a means for proteomic analysis of this posttranslational modification and for identifying O-Linked glycoprotein fingerprints associated with disease.
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The chemistry and biology of mucin-type O-Linked Glycosylation.
Bioorganic & Medicinal Chemistry, 2005Co-Authors: Howard C. Hang, Carolyn R. BertozziAbstract:Mucin-type O-Linked Glycosylation is a fundamental post-translational modification that is involved in a variety of important biological processes. However, the lack of chemical tools to study mucin-type O-Linked Glycosylation has hindered our molecular understanding of O-Linked glycans in many biological contexts. The review discusses the significance of mucin-type O-Linked Glycosylation initiated by the polypeptide N-acetylgalactosaminyltransferases in biology and development of chemical tools to study these enzymes and their substrates.
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An inhibitor of O-Glycosylation induces apoptosis in NIH3T3 cells and developing mouse embryonic mandibular tissues.
Journal of Biological Chemistry, 2004Co-Authors: E Tian, Howard C. Hang, Carolyn R. Bertozzi, Kelly G. Ten Hagen, Lillian Shum, Yoannis Imbert, William W. Young, Lawrence A. TabakAbstract:Abstract The family of UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferases (ppGaNTases) is responsible for initiating mucin-type O-Linked Glycosylation in higher eukaryotes. To begin to examine the biological role of O-Linked Glycosylation, mammalian cells were treated with a small molecule inhibitor (designated 1–68A, Ref. 15) of ppGaNTase activity. NIH3T3 cells exposed to the inhibitor were shown to undergo a significant reduction in cell surface O-Glycosylation as detected by staining with jacalin and peanut agglutinin lectins after 30 min of treatment; no reduction in staining using antibodies to O-Linked N-acetylglucosamine or the lectin concanavalin A was detected. Apoptosis was also observed in treated cells after 45 min of exposure, ostensibly following the O-Glycosylation reduction. Overexpression of several different ppGaNTase isoforms restored cell surface O-Glycosylation and rescued inhibitor-induced apoptosis. Additionally, mouse embryonic mandibular organ cultures exposed to 1–68A developed abnormally, presumably because of epithelial and mesenchymal apoptosis that followed a reduction in jacalin and peanut agglutinin staining. Our studies suggest that mucin-type O-Linked Glycosylation may be required for normal development and that ppGaNTases may play a role in the regulation of apoptosis.
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Small Molecule Inhibitors of Mucin-Type O-Linked Glycosylation from a Uridine-Based Library
Chemistry & Biology, 2004Co-Authors: Howard C. Hang, Chong Yu, Kelly G. Ten Hagen, E Tian, Katharine A. Winans, Lawrence A. Tabak, Carolyn R. BertozziAbstract:Abstract The polypeptide N -acetyl-α-galactosaminyltransferases (ppGalNAcTs, also abbreviated ppGaNTases) initiate mucin-type O -linked Glycosylation and therefore play pivotal roles in cell-cell communication and protection of tissues. In order to develop new tools for studying mucin-type O -linked Glycosylation, we screened a 1338 member uridine-based library to identify small molecule inhibitors of ppGalNAcTs. Using a high-throughput enzyme-linked lectin assay (ELLA), two inhibitors of murine ppGalNAcT-1 ( K I ∼8 μM) were identified that also inhibit several other members of the family. The compounds did not inhibit other mammalian glycosyltransferases or nucleotide sugar utilizing enzymes, suggesting selectivity for the ppGalNAcTs. Treatment of cells with the compounds abrogated mucin-type O -linked Glycosylation but not N -linked Glycosylation and also induced apoptosis. These uridine analogs represent the first generation of chemical tools to study the functions of mucin-type O -linked Glycosylation.
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A metabolic labeling approach toward proteomic analysis of mucin-type O-Linked Glycosylation
Proceedings of the National Academy of Sciences of the United States of America, 2003Co-Authors: Howard C. Hang, Chong Yu, Darryl L. Kato, Carolyn R. BertozziAbstract:Mucin-type O-Linked glycoproteins are involved in a variety of biological interactions in higher eukaryotes. The biosynthesis of these glycoproteins is initiated by a family of polypeptide N-acetyl-α-galactosaminyltransferases (ppGalNAcTs) that modify proteins in the secretory pathway. The lack of a defined consensus sequence for the ppGalNAcTs makes the prediction of mucin-type O-Linked Glycosylation difficult based on primary sequence alone. Herein we present a method for labeling mucin-type O-Linked glycoproteins with a unique chemical tag, the azide, which permits their selective covalent modification from complex cell lysates. From a panel of synthetic derivatives, we identified an azido GalNAc analog (N-azidoacetylgalactosamine, GalNAz) that is metabolized by numerous cell types and installed on mucin-type O-Linked glycoproteins by the ppGalNAcTs. The azide serves as a bioorthogonal chemical handle for selective modification with biochemical or biophysical probes using the Staudinger ligation. The approach was validated by labeling a recombinant glycoprotein that is known to possess O-Linked glycans with GalNAz. In addition, GalNAz efficiently labeled mucin-type O-Linked glycoproteins expressed at endogenous levels. The ability to label mucin-type O-Linked glycoproteins with chemical tags should facilitate their identification by proteomic strategies.
Sigvard Olofsson - One of the best experts on this subject based on the ideXlab platform.
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O-Linked Glycosylation of the mucin domain of the herpes simplex virus type 1-specific glycoprotein gC-1 is temporally regulated in a seed-and-spread manner.
Journal of Biological Chemistry, 2014Co-Authors: Rickard Nordén, Adnan Halim, Kristina Nyström, Eric P. Bennett, Ulla Mandel, Sigvard Olofsson, Jonas Nilsson, Göran LarsonAbstract:The herpes simplex virus type 1 (HSV-1) glycoprotein gC-1, participating in viral receptor interactions and immunity interference, harbors a mucin-like domain with multiple clustered O-Linked glycans. Using HSV-1-infected diploid human fibroblasts, an authentic target for HSV-1 infection, and a protein immunoaffinity procedure, we enriched fully glycosylated gC-1 and a series of its biosynthetic intermediates. This fraction was subjected to trypsin digestion and a LC-MS/MS glycoproteomics approach. In parallel, we characterized the expression patterns of the 20 isoforms of human GalNAc transferases responsible for initiation of O-Linked Glycosylation. The gC-1 O-Glycosylation was regulated in an orderly manner initiated by synchronous addition of one GalNAc unit each to Thr-87 and Thr-91 and one GalNAc unit to either Thr-99 or Thr-101, forming a core glycopeptide for subsequent additions of in all 11 GalNAc residues to selected Ser and Thr residues of the Thr-76–Lys-107 stretch of the mucin domain. The expression patterns of GalNAc transferases in the infected cells suggested that initial additions of GalNAc were carried out by initiating GalNAc transferases, in particular GalNAc-T2, whereas subsequent GalNAc additions were carried out by followup transferases, in particular GalNAc-T10. Essentially all of the susceptible Ser or Thr residues had to acquire their GalNAc units before any elongation to longer O-Linked glycans of the gC-1-associated GalNAc units was permitted. Because the GalNAc occupancy pattern is of relevance for receptor binding of gC-1, the data provide a model to delineate biosynthetic steps of O-Linked Glycosylation of the gC-1 mucin domain in HSV-1-infected target cells.
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Basic amino acids as modulators of an O-Linked Glycosylation signal of the herpes simplex virus type 1 glycoprotein gC: functional roles in viral infectivity
Glycobiology, 2004Co-Authors: Kristina Mårdberg, Kristina Nyström, Mads Agervig Tarp, Edward Trybala, Henrik Clausen, Tomas Bergström, Sigvard OlofssonAbstract:The herpes simplex virus type 1 (HSV-1) glycoprotein gC-1 is engaged both in viral attachment and viral immune evasion mechanisms in the infected host. Besides several N-linked glycans, gC-1 contains numerous O-Linked glycans, mainly localized in two pronase-resistant clusters in the N-terminal domain of gC-1. In the present study we construct and characterize one gC-1 mutant virus, in which two basic amino acids (114K and 117R) in a putative O-Glycosylation sequon were changed to alanine. We found that this modification did not modify the N-linked Glycosylation but increased the content of O-Linked glycans considerably. Analysis of the OGlycosylation capacity of wild-type and mutant gC-1 was performed by in vitro Glycosylation assays with synthetic peptides derived from the mutant region predicted to present new O-Glycosylation sites. Thus the mutant peptide region served as a better substrate for polypeptide GalNActransferase 2 than the wild-type peptide, resulting in increased rate and number of O-glycan attachment sites. The predicted increase in O-Linked Glycosylation resulted in two modifications of the biological properties of mutant virus—that is, an impaired binding to cells expressing chondroitin sulfate but not heparan sulfate on the cell surface and a significantly reduced plaque size in cultured cells. The results suggested that basic amino acids present within O-Glycosylation signals may down-regulate the amount of O-Linked glycans attached to a protein and that substitution of such amino acid residues may have functional consequences for a viral glycoprotein involving virus attachment to permissive cells as well as viral cell-to-cell spread.
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Early steps in O-Linked Glycosylation and clustered O-Linked glycans of herpes simplex virus type 1 glycoprotein C: effects on glycoprotein properties
Glycobiology, 2000Co-Authors: Marlene Biller, Kristina Mårdberg, Henrik Clausen, Tomas Bergström, Helle Hassan, Anders Bolmstedt, Sigvard OlofssonAbstract:: The pathogenesis of herpes simplex virus type 1 (HSV-1) implies the sequential infection of many cell types from mucosal cells to neurons, each having a unique pattern of protein Glycosylation. The HSV-1 glycoprotein gC-1 is highly glycosylated and contains not only N-linked glycans but also a large number of O-Linked glycans, some of which are clustered into two pronase-resistant arrays in the vicinity of the HSV-1 receptor-binding domain of gC-1. The aim of the present study was to characterize gC-1 signals for addition of clustered glycans, to determine the efficacy of synthetic peptides, representing putative O-Glycosylation signals, as substrates for a panel of GalNAc transferases, and to identify possible effects of early O-Linked Glycosylation on the biological functions of gC-1. Gel filtration analysis of the pronase-resistant gC-1 O-glycan clusters from a glycoprotein mutant, lacking a site for N-linked Glycosylation at Asn 73 in the vicinity of the O-Glycosylation signal, suggested that one function of this N-linked glycan was to modulate the access for GalNAc transferases to one particular O-Glycosylation peptide signal (aa 80-104). The ability of four GalNAc-transferase isoenzymes with different cell type expression patterns to initialize O-Glycosylation of synthetic gC-1 derived peptides was analyzed. Two synthetic gC-1 peptides (aa 55-69 and aa 80-104) were excellent substrates for all four GalNAc-transferases, suggesting that cell types expressing less frequent GalNAc transferase species with unusual acceptor peptide sequence specificities may also produce a highly O-glycosylated gC-1 after HSV-1 infection. The O-Linked glycans were not essential for cell surface expression of gC-1, but monoclonal antibody-assisted epitope analysis of N-acetylgalactosaminidase-treated gC-1 showed that the O-Linked monosaccharide GalNAc contributed to expression of a three-dimensional epitope overlapping the heparan sulfate-binding domain of gC-1.
Kristina Mårdberg - One of the best experts on this subject based on the ideXlab platform.
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Basic amino acids as modulators of an O-Linked Glycosylation signal of the herpes simplex virus type 1 glycoprotein gC: functional roles in viral infectivity
Glycobiology, 2004Co-Authors: Kristina Mårdberg, Kristina Nyström, Mads Agervig Tarp, Edward Trybala, Henrik Clausen, Tomas Bergström, Sigvard OlofssonAbstract:The herpes simplex virus type 1 (HSV-1) glycoprotein gC-1 is engaged both in viral attachment and viral immune evasion mechanisms in the infected host. Besides several N-linked glycans, gC-1 contains numerous O-Linked glycans, mainly localized in two pronase-resistant clusters in the N-terminal domain of gC-1. In the present study we construct and characterize one gC-1 mutant virus, in which two basic amino acids (114K and 117R) in a putative O-Glycosylation sequon were changed to alanine. We found that this modification did not modify the N-linked Glycosylation but increased the content of O-Linked glycans considerably. Analysis of the OGlycosylation capacity of wild-type and mutant gC-1 was performed by in vitro Glycosylation assays with synthetic peptides derived from the mutant region predicted to present new O-Glycosylation sites. Thus the mutant peptide region served as a better substrate for polypeptide GalNActransferase 2 than the wild-type peptide, resulting in increased rate and number of O-glycan attachment sites. The predicted increase in O-Linked Glycosylation resulted in two modifications of the biological properties of mutant virus—that is, an impaired binding to cells expressing chondroitin sulfate but not heparan sulfate on the cell surface and a significantly reduced plaque size in cultured cells. The results suggested that basic amino acids present within O-Glycosylation signals may down-regulate the amount of O-Linked glycans attached to a protein and that substitution of such amino acid residues may have functional consequences for a viral glycoprotein involving virus attachment to permissive cells as well as viral cell-to-cell spread.
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Early steps in O-Linked Glycosylation and clustered O-Linked glycans of herpes simplex virus type 1 glycoprotein C: effects on glycoprotein properties
Glycobiology, 2000Co-Authors: Marlene Biller, Kristina Mårdberg, Henrik Clausen, Tomas Bergström, Helle Hassan, Anders Bolmstedt, Sigvard OlofssonAbstract:: The pathogenesis of herpes simplex virus type 1 (HSV-1) implies the sequential infection of many cell types from mucosal cells to neurons, each having a unique pattern of protein Glycosylation. The HSV-1 glycoprotein gC-1 is highly glycosylated and contains not only N-linked glycans but also a large number of O-Linked glycans, some of which are clustered into two pronase-resistant arrays in the vicinity of the HSV-1 receptor-binding domain of gC-1. The aim of the present study was to characterize gC-1 signals for addition of clustered glycans, to determine the efficacy of synthetic peptides, representing putative O-Glycosylation signals, as substrates for a panel of GalNAc transferases, and to identify possible effects of early O-Linked Glycosylation on the biological functions of gC-1. Gel filtration analysis of the pronase-resistant gC-1 O-glycan clusters from a glycoprotein mutant, lacking a site for N-linked Glycosylation at Asn 73 in the vicinity of the O-Glycosylation signal, suggested that one function of this N-linked glycan was to modulate the access for GalNAc transferases to one particular O-Glycosylation peptide signal (aa 80-104). The ability of four GalNAc-transferase isoenzymes with different cell type expression patterns to initialize O-Glycosylation of synthetic gC-1 derived peptides was analyzed. Two synthetic gC-1 peptides (aa 55-69 and aa 80-104) were excellent substrates for all four GalNAc-transferases, suggesting that cell types expressing less frequent GalNAc transferase species with unusual acceptor peptide sequence specificities may also produce a highly O-glycosylated gC-1 after HSV-1 infection. The O-Linked glycans were not essential for cell surface expression of gC-1, but monoclonal antibody-assisted epitope analysis of N-acetylgalactosaminidase-treated gC-1 showed that the O-Linked monosaccharide GalNAc contributed to expression of a three-dimensional epitope overlapping the heparan sulfate-binding domain of gC-1.
Howard C. Hang - One of the best experts on this subject based on the ideXlab platform.
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The chemistry and biology of mucin-type O-Linked Glycosylation.
Bioorganic & Medicinal Chemistry, 2005Co-Authors: Howard C. Hang, Carolyn R. BertozziAbstract:Mucin-type O-Linked Glycosylation is a fundamental post-translational modification that is involved in a variety of important biological processes. However, the lack of chemical tools to study mucin-type O-Linked Glycosylation has hindered our molecular understanding of O-Linked glycans in many biological contexts. The review discusses the significance of mucin-type O-Linked Glycosylation initiated by the polypeptide N-acetylgalactosaminyltransferases in biology and development of chemical tools to study these enzymes and their substrates.
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An inhibitor of O-Glycosylation induces apoptosis in NIH3T3 cells and developing mouse embryonic mandibular tissues.
Journal of Biological Chemistry, 2004Co-Authors: E Tian, Howard C. Hang, Carolyn R. Bertozzi, Kelly G. Ten Hagen, Lillian Shum, Yoannis Imbert, William W. Young, Lawrence A. TabakAbstract:Abstract The family of UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferases (ppGaNTases) is responsible for initiating mucin-type O-Linked Glycosylation in higher eukaryotes. To begin to examine the biological role of O-Linked Glycosylation, mammalian cells were treated with a small molecule inhibitor (designated 1–68A, Ref. 15) of ppGaNTase activity. NIH3T3 cells exposed to the inhibitor were shown to undergo a significant reduction in cell surface O-Glycosylation as detected by staining with jacalin and peanut agglutinin lectins after 30 min of treatment; no reduction in staining using antibodies to O-Linked N-acetylglucosamine or the lectin concanavalin A was detected. Apoptosis was also observed in treated cells after 45 min of exposure, ostensibly following the O-Glycosylation reduction. Overexpression of several different ppGaNTase isoforms restored cell surface O-Glycosylation and rescued inhibitor-induced apoptosis. Additionally, mouse embryonic mandibular organ cultures exposed to 1–68A developed abnormally, presumably because of epithelial and mesenchymal apoptosis that followed a reduction in jacalin and peanut agglutinin staining. Our studies suggest that mucin-type O-Linked Glycosylation may be required for normal development and that ppGaNTases may play a role in the regulation of apoptosis.
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Small Molecule Inhibitors of Mucin-Type O-Linked Glycosylation from a Uridine-Based Library
Chemistry & Biology, 2004Co-Authors: Howard C. Hang, Chong Yu, Kelly G. Ten Hagen, E Tian, Katharine A. Winans, Lawrence A. Tabak, Carolyn R. BertozziAbstract:Abstract The polypeptide N -acetyl-α-galactosaminyltransferases (ppGalNAcTs, also abbreviated ppGaNTases) initiate mucin-type O -linked Glycosylation and therefore play pivotal roles in cell-cell communication and protection of tissues. In order to develop new tools for studying mucin-type O -linked Glycosylation, we screened a 1338 member uridine-based library to identify small molecule inhibitors of ppGalNAcTs. Using a high-throughput enzyme-linked lectin assay (ELLA), two inhibitors of murine ppGalNAcT-1 ( K I ∼8 μM) were identified that also inhibit several other members of the family. The compounds did not inhibit other mammalian glycosyltransferases or nucleotide sugar utilizing enzymes, suggesting selectivity for the ppGalNAcTs. Treatment of cells with the compounds abrogated mucin-type O -linked Glycosylation but not N -linked Glycosylation and also induced apoptosis. These uridine analogs represent the first generation of chemical tools to study the functions of mucin-type O -linked Glycosylation.
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A metabolic labeling approach toward proteomic analysis of mucin-type O-Linked Glycosylation
Proceedings of the National Academy of Sciences of the United States of America, 2003Co-Authors: Howard C. Hang, Chong Yu, Darryl L. Kato, Carolyn R. BertozziAbstract:Mucin-type O-Linked glycoproteins are involved in a variety of biological interactions in higher eukaryotes. The biosynthesis of these glycoproteins is initiated by a family of polypeptide N-acetyl-α-galactosaminyltransferases (ppGalNAcTs) that modify proteins in the secretory pathway. The lack of a defined consensus sequence for the ppGalNAcTs makes the prediction of mucin-type O-Linked Glycosylation difficult based on primary sequence alone. Herein we present a method for labeling mucin-type O-Linked glycoproteins with a unique chemical tag, the azide, which permits their selective covalent modification from complex cell lysates. From a panel of synthetic derivatives, we identified an azido GalNAc analog (N-azidoacetylgalactosamine, GalNAz) that is metabolized by numerous cell types and installed on mucin-type O-Linked glycoproteins by the ppGalNAcTs. The azide serves as a bioorthogonal chemical handle for selective modification with biochemical or biophysical probes using the Staudinger ligation. The approach was validated by labeling a recombinant glycoprotein that is known to possess O-Linked glycans with GalNAz. In addition, GalNAz efficiently labeled mucin-type O-Linked glycoproteins expressed at endogenous levels. The ability to label mucin-type O-Linked glycoproteins with chemical tags should facilitate their identification by proteomic strategies.
Kristina Nyström - One of the best experts on this subject based on the ideXlab platform.
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O-Linked Glycosylation of the mucin domain of the herpes simplex virus type 1-specific glycoprotein gC-1 is temporally regulated in a seed-and-spread manner.
Journal of Biological Chemistry, 2014Co-Authors: Rickard Nordén, Adnan Halim, Kristina Nyström, Eric P. Bennett, Ulla Mandel, Sigvard Olofsson, Jonas Nilsson, Göran LarsonAbstract:The herpes simplex virus type 1 (HSV-1) glycoprotein gC-1, participating in viral receptor interactions and immunity interference, harbors a mucin-like domain with multiple clustered O-Linked glycans. Using HSV-1-infected diploid human fibroblasts, an authentic target for HSV-1 infection, and a protein immunoaffinity procedure, we enriched fully glycosylated gC-1 and a series of its biosynthetic intermediates. This fraction was subjected to trypsin digestion and a LC-MS/MS glycoproteomics approach. In parallel, we characterized the expression patterns of the 20 isoforms of human GalNAc transferases responsible for initiation of O-Linked Glycosylation. The gC-1 O-Glycosylation was regulated in an orderly manner initiated by synchronous addition of one GalNAc unit each to Thr-87 and Thr-91 and one GalNAc unit to either Thr-99 or Thr-101, forming a core glycopeptide for subsequent additions of in all 11 GalNAc residues to selected Ser and Thr residues of the Thr-76–Lys-107 stretch of the mucin domain. The expression patterns of GalNAc transferases in the infected cells suggested that initial additions of GalNAc were carried out by initiating GalNAc transferases, in particular GalNAc-T2, whereas subsequent GalNAc additions were carried out by followup transferases, in particular GalNAc-T10. Essentially all of the susceptible Ser or Thr residues had to acquire their GalNAc units before any elongation to longer O-Linked glycans of the gC-1-associated GalNAc units was permitted. Because the GalNAc occupancy pattern is of relevance for receptor binding of gC-1, the data provide a model to delineate biosynthetic steps of O-Linked Glycosylation of the gC-1 mucin domain in HSV-1-infected target cells.
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Basic amino acids as modulators of an O-Linked Glycosylation signal of the herpes simplex virus type 1 glycoprotein gC: functional roles in viral infectivity
Glycobiology, 2004Co-Authors: Kristina Mårdberg, Kristina Nyström, Mads Agervig Tarp, Edward Trybala, Henrik Clausen, Tomas Bergström, Sigvard OlofssonAbstract:The herpes simplex virus type 1 (HSV-1) glycoprotein gC-1 is engaged both in viral attachment and viral immune evasion mechanisms in the infected host. Besides several N-linked glycans, gC-1 contains numerous O-Linked glycans, mainly localized in two pronase-resistant clusters in the N-terminal domain of gC-1. In the present study we construct and characterize one gC-1 mutant virus, in which two basic amino acids (114K and 117R) in a putative O-Glycosylation sequon were changed to alanine. We found that this modification did not modify the N-linked Glycosylation but increased the content of O-Linked glycans considerably. Analysis of the OGlycosylation capacity of wild-type and mutant gC-1 was performed by in vitro Glycosylation assays with synthetic peptides derived from the mutant region predicted to present new O-Glycosylation sites. Thus the mutant peptide region served as a better substrate for polypeptide GalNActransferase 2 than the wild-type peptide, resulting in increased rate and number of O-glycan attachment sites. The predicted increase in O-Linked Glycosylation resulted in two modifications of the biological properties of mutant virus—that is, an impaired binding to cells expressing chondroitin sulfate but not heparan sulfate on the cell surface and a significantly reduced plaque size in cultured cells. The results suggested that basic amino acids present within O-Glycosylation signals may down-regulate the amount of O-Linked glycans attached to a protein and that substitution of such amino acid residues may have functional consequences for a viral glycoprotein involving virus attachment to permissive cells as well as viral cell-to-cell spread.
