SEC14-dependent Secretion inSaccharomyces cerevisiae
| Autor: | Daryll B. DeWald, Stephen D. Stock, Hiroko Hama, Jon Y. Takemoto |
|---|---|
| Rok vydání: | 1999 |
| Předmět: |
biology
Mutant Saccharomyces cerevisiae Cell Biology Golgi apparatus biology.organism_classification Biochemistry Sphingolipid symbols.namesake chemistry.chemical_compound Secretory protein chemistry symbols Phosphatidylinositol Molecular Biology Phosphatidylinositol transfer protein Diacylglycerol kinase |
| Zdroj: | Journal of Biological Chemistry. 274:12979-12983 |
| ISSN: | 0021-9258 |
| Popis: | The SEC14 gene in Saccharomyces cerevisiae encodes a phosphatidylinositol transfer protein required for secretory protein movement from the Golgi. Mutation ofSAC1, a gene of unknown function, restores secretory flow in sec14-1 ts strains. The existing model for the bypass of the sec14-1 ts defect bysac1-22 involves stimulation of sphingolipid biosynthesis and, in particular, the synthesis of mannosyl-diinositolphosphoryl-ceramide with concomitant increases in Golgi diacylglycerol levels. To test this model, we disruptedIPT1, the mannosyl-diinositolphosphoryl-ceramide synthase of S. cerevisiae. Disruption of the IPT1 gene had no effect on the ability of sac1-22 to bypasssec14-1 ts. Furthermore, sphingolipid analysis of sec14-1 ts and sec14-1 ts sac1-22 strains showed that mannosyl-diinositolphosphoryl-ceramide synthesis was not stimulated in the bypass mutant. However, thesec14-1 ts strain had elevated mannosyl-monoinositolphosphoryl-ceramide levels, and thesec14-1 ts sac1-22 strain showed an 8-fold increase in phosphatidylinositol 4-phosphate along with a decrease in phosphatidylinositol 4,5-bisphosphate. Cellular diacylglycerol levels, measured by [14C]acetate incorporation, did not differ between thesec14-1 ts and the sec14-1 sac1-22bypass strains, although disruption of IPT1 in the bypass strain resulted in reduced levels. These data indicate that phosphatidylinositol 4-phosphate, rather than mannosyl-diinositolphosphoryl-ceramide, accumulates in thesec14-1 ts sac1-22 bypass strain, and that Golgi diacylglycerol accumulation is not required for bypass of the sec14-1 ts growth and secretory phenotypes. |
| Databáze: | OpenAIRE |
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