The role of protein phosphorylation in secretion is not well understood. Here we show that yeast lacking the Snc1,2 v-SNAREs, or bearing a temperature-sensitive mutation in the Sso2 t-SNARE, are rescued at restrictive conditions by the addition of ceramide precursors and analogs to the growth medium. Rescue results from dephosphorylation of the Sso t-SNAREs by a ceramide-activated type 2A protein phosphatase (Sit4) involved in cell cycle control. Sso t-SNARE dephosphorylation correlated with its assembly into complexes with the Sec9 t-SNARE, both in vitro and in vivo, and with an increase in protein trafficking and secretion in cells. SNARE complexes isolated under these conditions contained only Sso and Sec9, suggesting that a t-t-SNARE fusion complex is sufficient to confer exocytosis. Mutation of a single PKA site (Ser79 to Ala79) in Sso1 resulted in a decrease in phosphorylation and was sufficient to confer growth to snc cells at restrictive conditions. Thus, modulation of t-SNARE phosphorylation regulates SNARE complex assembly and membrane fusion in vivo.
|Evidence ID||Analyze ID||Interactor||Interactor Systematic Name||Interactor||Interactor Systematic Name||Type||Assay||Annotation||Action||Modification||Phenotype||Source||Reference||Note|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Gene Ontology Term||Gene Ontology Term ID||Qualifier||Aspect||Method||Evidence||Source||Assigned On||Reference||Annotation Extension|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Phenotype||Experiment Type||Experiment Type Category||Mutant Information||Strain Background||Chemical||Details||Reference|
|Evidence ID||Analyze ID||Regulator||Regulator Systematic Name||Target||Target Systematic Name||Experiment||Conditions||Strain||Source||Reference|