title: Identification and characterization of a gene required for alpha1,2-mannose extension in the O-linked glycan synthesis pathway in Schizosaccharomyces pombe.
abstract: The KTRalpha1,2-mannosyltransferase gene family of Saccharomyces cerevisiae is responsible not only for outer-chain modifications of N-linked oligosaccharides but also for elongation of O-linked mannose residues. To identify genes involved in the elongation step of O-linked oligosaccharide chains in Schizosaccharomyces pombe, we characterized six genes, omh1(+)-omh6(+), that share significant sequence similarity to the S. cerevisiae KTR family. Six deletion strains were constructed, each carrying a single disrupted omh allele. All strains were viable, indicating that none of the omh genes was essential. Heterologous expression of a chitinase from S. cerevisiae in the omh mutants revealed that O-glycosylation of chitinase had decreased in omh1Delta cells, but not in the other mutants, indicating that the other omh genes do not appear to be required for O-glycan synthesis. Addition of the second alpha1,2-linked mannose residue was blocked in omh1Delta cells. An Omh1-GFP fusion protein was found to be localized in the Golgi apparatus. These results indicate that Omh1p plays a major role in extending alpha1,2-linked mannose in the O-glycan pathway in S. pombe.
authors.affiliation: Department of Life Sciences, Faculty of Agriculture, Kagawa University, Kagawa, Japan.
authors.forename: Yuka
authors.initials: Y
authors.lastname: Ikeda
authors.forename: Takao
authors.initials: T
authors.lastname: Ohashi
authors.forename: Naotaka
authors.initials: N
authors.lastname: Tanaka
authors.forename: Kaoru
authors.initials: K
authors.lastname: Takegawa
mesh_terms: D002688:Chitinases / Q000378:metabolism; D017353:Gene Deletion; D017930:Genes, Reporter; D006031:Glycosylation; D006056:Golgi Apparatus / Q000737:chemistry; D049452:Green Fluorescent Proteins / Q000032:analysis / Q000235:genetics; D008358:Mannose / Q000378:metabolism*; D008364:Mannosyltransferases / Q000235:genetics* / Q000378:metabolism*; D050296:Microbial Viability; D008856:Microscopy, Fluorescence; D011134:Polysaccharides / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000032:analysis / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism*; D012568:Schizosaccharomyces / Q000201:enzymology* / Q000235:genetics* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
chemical_list: D011134:Polysaccharides; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D049452:Green Fluorescent Proteins; C068701:KRE2 protein, S cerevisiae; D008364:Mannosyltransferases; D002688:Chitinases; D008358:Mannose