title: Two proteins homologous to the N- and C-terminal domains of the bacterial glycosyltransferase Murg are required for the second step of dolichyl-linked oligosaccharide synthesis in Saccharomyces cerevisiae.
abstract: Two highly conserved eukaryotic gene products of unknown function showing homology to glycosyltransferases involved in the second steps of bacterial peptidoglycan (Murg) and capsular polysaccharide (Cps14f/Cps14g) biosynthesis have been identified in silico. The amino acid sequence of the eukaryotic protein that is homologous to the lipid acceptor- and membrane-associating N-terminal domain of Murg and the Cps14f beta4-galactosyltransferase enhancer protein is predicted to possess a cleavable signal peptide and transmembrane helices. The other eukaryotic protein is predicted to possess neither transmembrane regions nor a signal peptide but is homologous to the UDP-sugar binding C-terminal domain of Murg and the Cps14g beta4-galactosyltransferase. Both the eukaryotic proteins are encoded by essential genes in Saccharomyces cerevisiae, and down-regulation of either causes growth retardation, reduced N-glycosylation of carboxypeptidase Y, and accumulation of dolichyl-PP-GlcNAc. In vitro studies demonstrate that these proteins are required for transfer of [3H]GlcNAc from UDP-[3H]GlcNAc onto dolichyl-PP-GlcNAc. To conclude, two gene products showing homology to bacterial glycosyltransferases are required for the second step in dolichyl-PP-oligosaccharide biosynthesis.
authors.affiliation: Institut National de la Santé et de la Recherche Médicale, U504, Bâtiment INSERM, 16 avenue Paul Vaillant-Couturier, 94807 Villejuif, France.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Chantret
authors.forename: Julia
authors.initials: J
authors.lastname: Dancourt
authors.forename: Alain
authors.initials: A
authors.lastname: Barbat
authors.forename: Stuart E H
authors.initials: SE
authors.lastname: Moore
mesh_terms: D000595:Amino Acid Sequence; D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism; D006017:Glycolipids / Q000096:biosynthesis; D006031:Glycosylation; D007700:Kinetics; D008861:Microsomes / Q000201:enzymology; D008969:Molecular Sequence Data; D017351:N-Acetylglucosaminyltransferases / Q000378:metabolism*; D009844:Oligosaccharides / Q000096:biosynthesis*; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013296:Streptococcus pneumoniae / Q000201:enzymology
chemical_list: D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D006017:Glycolipids; D009844:Oligosaccharides; D029701:Saccharomyces cerevisiae Proteins; D017351:N-Acetylglucosaminyltransferases; C064057:UDP-N-acetylglucosamine-N-acetylmuramyl-(pentapeptide)pyrophosphoryl-undecaprenol N-acetylglucosamine transferase