Yeast cell death caused by mutation of the OST2 gene encoding the epsilon-subunit of Saccharomyces cerevisiae oligosaccharyltransferase.
An essential epsilon-subunit of oligosaccharyltransferase Ost2 is a yeast homolog of mammalian highly conserved DAD1 (defender against apoptotic death). In hamster cells, the Gly38Arg mutation in DAD1 causes apoptosis at restrictive temperatures due to a defect in N-linked glycosylation. To analyze the function of Ost2 in yeast cell death, we constructed Saccharomyces cerevisiae strains expressing Gly58Arg (corresponding to the Gly38Arg mutation in hamster DAD1), Gly86Arg, and Glu113Val mutant Ost2. At elevated temperatures, ost2 mutants arrested growth by decreasing cell viability. Phosphatidylserine exposure, a phenotypic marker of apoptosis in mammalian cells, was found in ost2 mutant cells at 37 degrees C, although DNA fragmentation was not clearly detected. A high concentration of sorbitol compensates for the temperature sensitivity of the ost2 mutant. These results suggest that apoptosis-like cell death in ost2 mutants is caused by the secondary effect of overall reduced protein N-linked glycosylation.
Sugiura
Masaharu
M
Department of Bioscience, Fukui Prefectural University, Fukui, Japan.
Takagi
Hiroshi
H
D000595:Amino Acid Sequence; D017209:Apoptosis / Q000235:genetics*; D002473:Cell Wall / Q000235:genetics; D053938:DNA Fragmentation / Q000235:genetics; D005804:Genes, Lethal; D006031:Glycosylation; D006602:Hexosyltransferases / Q000235:genetics*; D008565:Membrane Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation; D010718:Phosphatidylserines / Q000494:pharmacology; D021122:Protein Subunits; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000201:enzymology / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics*; D013696:Temperature
D008565:Membrane Proteins; D010718:Phosphatidylserines; D021122:Protein Subunits; D029701:Saccharomyces cerevisiae Proteins; D006602:Hexosyltransferases; C025620:dolichyl-diphosphooligosaccharide - protein glycotransferase