Regulation of the yeast DPP1-encoded diacylglycerol pyrophosphate phosphatase by transcription factor Gis1p

The Saccharomyces cerevisiae DPP1-encoded diacylglycerol pyrophosphate phosphatase catalyzes the dephosphorylation of diacylglycerol pyrophosphate to form phosphatidate and P-i. The enzyme also dephosphorylates phosphatidate to form diacylglycerol and P-i. Because diacylglycerol pyrophosphate, phosphatidate, and diacylglycerol have roles as lipid signal molecules in higher eukaryotic cells, it is important to understand how diacylglycerol pyrophosphate phosphatase is regulated. Analysis of DPP1 expression using P-DPP1-lacZ reporter genes with a series of deletions from the 5' end of the promoter indicated sequences responsible for enzyme expression. Three binding sites (URSPDS) for transcription factor Gis1p were identified in the DPP1 promoter (consensus sequence of 5'-T(A/T)AGGGAT-3'). A gis1Delta mutant exhibited elevated levels of DPP1 expression and diacylglycerol pyrophosphate phosphatase activity. Direct interaction between Gis1p and DPP1 promoter elements was demonstrated by electrophoretic mobility shift assays. Mutations in the three URSPDS elements within the DPP1 promoter abolished Gis1p-DNA interactions in vitro and abolished the regulation of DPP1 in vivo. These data indicated that Gis1p was a repressor of DPP1 expression. Phospholipid composition analysis of the gis1Delta mutant showed that Gis1p played a role in regulating the cellular level of diacylglycerol pyrophosphate, as well as the levels of the major phospholipids phosphatidylethanolamine and phosphatidylcholine.