Characterization of O-mannosyltransferase family in Schizosaccharomyces pombe.
Protein O-glycosylation is an essential protein modification in eukaryotic cells. In Saccharomyces cerevisiae, O-mannosylation is initiated in the lumen of the endoplasmic reticulum by O-mannosyltransferase gene products (Pmt1p-7p). A search of the Schizosaccharomyces pombe genome database revealed a total of three O-glycoside mannosyltransferase homologs (ogm1+, ogm2+, and ogm4+), closely related to Saccharomyces cerevisiae PMT1, PMT2, and PMT4. Although individual ogm genes were not found to be essential, ogm1Delta and ogm4Delta mutants exhibited aberrant morphology and failed to agglutinate during mating. The phenotypes of the ogm4Delta mutant were not complemented by overexpression of ogm1+ or ogm2+, suggesting that each of the Ogm proteins does not have overlapping functions. Heterologous expression of a chitinase from S. cerevisiae in the ogm mutants revealed that O-glycosylation of chitinase had decreased in ogm1Delta cells. A GFP-tagged Fus1p from S. cerevisiae was specifically not glycosylated and accumulated in the Golgi in ogm4Delta cells. These results indicate that O-glycosylation initiated by Ogm proteins plays crucial physiological roles and can serve as a sorting determinant for protein transport of membrane glycoproteins in S. pombe.
Tanaka
Naotaka
N
Department of Life Sciences, Faculty of Agriculture, Kagawa University, Miki-cho, Kagawa 761-0795, Japan.
Fujita
Yasuko
Y
Suzuki
Shotaro
S
Morishita
Masayo
M
Giga-Hama
Yuko
Y
Shimoda
Chikashi
C
Takegawa
Kaoru
K
D000818:Animals; D002455:Cell Division / Q000235:genetics; D002688:Chitinases / Q000378:metabolism; D006031:Glycosylation; D006056:Golgi Apparatus / Q000378:metabolism; D006801:Humans; D008358:Mannose / Q000378:metabolism; D008364:Mannosyltransferases / Q000145:classification* / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D010802:Phylogeny; D021381:Protein Transport; D012441:Saccharomyces cerevisiae / Q000201:enzymology; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D012568:Schizosaccharomyces / Q000201:enzymology* / Q000235:genetics
C490024:FUS1 protein, S cerevisiae; D008565:Membrane Proteins; D029701:Saccharomyces cerevisiae Proteins; D008364:Mannosyltransferases; D002688:Chitinases; D008358:Mannose