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Gene Review:

OST2 - Ost2p

Saccharomyces cerevisiae S288c

Synonyms: Dolichyl-diphosphooligosaccharide--protein glycosyltransferase subunit OST2, Oligosaccharyl transferase 16 kDa subunit, Oligosaccharyl transferase subunit OST2, Oligosaccharyl transferase subunit epsilon, YOR103C, ...

Silberstein, S. et al., Sugiura, M. et al., Fu, J. et al., Hauptmann, P. et al., Yan, A. et al.

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High impact information on OST2

The protein sequence of ost2 mutant alleles revealed mutations at highly conserved residues in the Ost2p/DAD1 protein sequence [1].
Microsomal membranes isolated from ost2 mutant yeast show marked reductions in the in vitro transfer of high mannose oligosaccharide from exogenous lipid-linked oligosaccharide to a glycosylation site acceptor tripeptide [1].
Overexpression of the Ost2 protein suppresses the temperature-sensitive phenotype of the wbp1-2 allele and increases in vivo and in vitro oligosaccharyltransferase activity in a wbp1-2 strain [1].
Genomic disruption of the OST2 locus was lethal in haploid yeast showing that expression of the Ost2 protein is essential for viability [1].
These findings also suggested that Ost2p, Stt3p, Ost5p, and Ost6p do not have a cleavable N-terminal signal sequence [2].

Biological context of OST2

Surprisingly, the Ost2 protein was found to be 40% identical to the DAD1 protein (defender against apoptotic cell death), a highly conserved protein initially identified in vertebrate organisms [1].
In addition, sequence homology between the Ost2 subunit of the yeast OST complex and Dad1 (defender against apoptotic death) suggests that Dad1 may represent a fourth subunit of the mammalian OST complex [3].
Here we show that ost mutants, such as ost2 and wbp1-1, display morphological and biochemical features of apoptosis upon induction of the glycosylation defect [4].
These results suggest that apoptosis-like cell death in ost2 mutants is caused by the secondary effect of overall reduced protein N-linked glycosylation [5].
At elevated temperatures, ost2 mutants arrested growth by decreasing cell viability [5].

Associations of OST2 with chemical compounds

A high concentration of sorbitol compensates for the temperature sensitivity of the ost2 mutant [5].
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 [5].

References

The essential OST2 gene encodes the 16-kD subunit of the yeast oligosaccharyltransferase, a highly conserved protein expressed in diverse eukaryotic organisms. Silberstein, S., Collins, P.G., Kelleher, D.J., Gilmore, R. J. Cell Biol. (1995) [Pubmed]
Studies of yeast oligosaccharyl transferase subunits using the split-ubiquitin system: topological features and in vivo interactions. Yan, A., Wu, E., Lennarz, W.J. Proc. Natl. Acad. Sci. U.S.A. (2005) [Pubmed]
Interactions among subunits of the oligosaccharyltransferase complex. Fu, J., Ren, M., Kreibich, G. J. Biol. Chem. (1997) [Pubmed]
Defects in N-glycosylation induce apoptosis in yeast. Hauptmann, P., Riel, C., Kunz-Schughart, L.A., Fröhlich, K.U., Madeo, F., Lehle, L. Mol. Microbiol. (2006) [Pubmed]
Yeast cell death caused by mutation of the OST2 gene encoding the epsilon-subunit of Saccharomyces cerevisiae oligosaccharyltransferase. Sugiura, M., Takagi, H. Biosci. Biotechnol. Biochem. (2006) [Pubmed]

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AGOS_ADL261C	Ashbya gossypii ATCC 10895
KLLA0C13365g	Kluyveromyces lactis NRRL Y-1140

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