The PMT gene family: protein O-glycosylation in Saccharomyces cerevisiae is vital.
The transfer of mannose to seryl and threonyl residues of secretory proteins is catalyzed by a family of protein mannosyltransferases coded for by seven genes (PMT1-7). Mannose dolichylphosphate is the sugar donor of the reaction, which is localized at the endoplasmic reticulum. By gene disruption and crosses all single, double and triple mutants of genes PMT1-4 were constructed. Two of the double and three of the triple mutants were not able to grow under normal conditions; three of these mutants could grow, however, when osmotically stabilized. The various mutants were extensively characterized concerning growth, morphology and their sensitivity to killer toxin K1, caffeine and calcofluor white. O-Mannosylation of gp115/Gas1p was affected only in pmt4 mutants, whereas glycosylation of chitinase was mainly affected in pmt1 and pmt2 mutants. The results show that protein O-glycosylation is essential for cell wall rigidity and cell integrity and that this protein modification, therefore, is vital for Saccharomyces cerevisiae.
Gentzsch
M
M
Lehrstuhl für Zellbiologie und Pflanzenphysiologie, Universität Regensburg, Germany.
Tanner
W
W
D005656:Fungal Proteins / Q000737:chemistry / Q000378:metabolism; D005800:Genes, Fungal; D006031:Glycosylation; D008364:Mannosyltransferases / Q000235:genetics* / Q000378:metabolism*; D008969:Molecular Sequence Data; D005810:Multigene Family; D009154:Mutation; D010641:Phenotype; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*
D005656:Fungal Proteins; D008364:Mannosyltransferases; C082696:protein O-mannosyltransferase