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Deleting the DAG kinase Dgk1 augments yeast vacuole fusion through increased Ypt7 activity and altered membrane fluidity
Author(s) -
Miner Gregory E.,
Starr Matthew L.,
Hurst Logan R.,
Fratti Rutilio A.
Publication year - 2017
Publication title -
traffic
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.677
H-Index - 130
eISSN - 1600-0854
pISSN - 1398-9219
DOI - 10.1111/tra.12479
Subject(s) - diacylglycerol kinase , vacuole , biology , phosphatidic acid , phosphatidylinositol , lipid bilayer fusion , microbiology and biotechnology , biochemistry , phosphatase , contractile vacuole , saccharomyces cerevisiae , phospholipase d , inositol , phospholipase c , yeast , kinase , cytoplasm , signal transduction , protein kinase c , enzyme , membrane , phospholipid , receptor
Diacylglycerol ( DAG ) is a fusogenic lipid that can be produced through phospholipase C activity on phosphatidylinositol 4,5‐bisphosphate [ PI (4,5) P 2 ], or through phosphatidic acid ( PA ) phosphatase activity. The fusion of Saccharomyces cerevisiae vacuoles requires DAG , PA and PI (4,5) P 2 , and the production of these lipids is thought to provide temporally specific stoichiometries that are critical for each stage of fusion. Furthermore, DAG and PA can be interconverted by the DAG kinase Dgk1 and the PA phosphatase Pah1. Previously we found that pah1 Δ vacuoles were fragmented, blocked in SNARE priming and showed arrested endosomal maturation. In other pathways the effects of deleting PAH1 can be compensated for by additionally deleting DGK1 ; however, deleting both genes did not rescue the pah1 Δ vacuolar defects. Deleting DGK1 alone caused a marked increase in vacuole fusion that was attributed to elevated DAG levels. This was accompanied by a gain in resistance to the inhibitory effects of PA as well as inhibitors of Ypt7 activity. Together these data show that Dgk1 function can act as a negative regulator of vacuole fusion through the production of PA at the cost of depleting DAG and reducing Ypt7 activity.