Abstract
The DPP1 gene, encoding diacylglycerol pyrophosphate (DGPP) phosphatase from Saccharomyces cerevisiae, has recently been identified as a zinc-regulated gene, and it contains a putative zinc-responsive element (UAS(ZRE)) in its promoter. In this work we examined the hypothesis that expression of DGPP phosphatase was regulated by zinc availability. The deprivation of zinc from the growth medium resulted in a time- and dose-dependent induction of beta-galactosidase activity driven by a P(DPP1)-lacZ reporter gene. This regulation was dependent on the UAS(ZRE) in the DPP1 promoter and was mediated by the Zap1p transcriptional activator. Induction of the DGPP phosphatase protein and activity by zinc deprivation was demonstrated by immunoblot analysis and measurement of the dephosphorylation of DGPP. The regulation pattern of DGPP phosphatase in mutants defective in plasma membrane (Zrt1p and Zrt2p) and vacuolar membrane (Zrt3p) zinc transporters indicated that enzyme expression was sensitive to the cytoplasmic levels of zinc. DGPP phosphatase activity was inhibited by zinc by a mechanism that involved formation of DGPP-zinc complexes. Studies with well characterized subcellular fractions and by indirect immunofluorescence microscopy revealed that the DGPP phosphatase enzyme was localized to the vacuolar membrane.
Highlights
The DPP1-encoded diacylglycerol pyrophosphate (DGPP)1 phosphatase [1] is a membrane-associated enzyme from the yeast Saccharomyces cerevisiae that catalyzes the removal of the -phosphate from DGPP to form PA and removes the phosphate from PA to form DG [2]
Activity in Cells Bearing the PDPP1-lacZ Reporter Gene—Yuan [46] recently identified the DPP1 gene in a genetic screen designed to identify genes that are regulated by zinc deprivation
Inspection of the DPP1 gene revealed that it contains a sequence (ACCTGAAAGGT) in its promoter (Ϫ442 to Ϫ452) that is closely related to a consensus UASZRE [47]
Summary
The DPP1-encoded diacylglycerol pyrophosphate (DGPP) phosphatase [1] is a membrane-associated enzyme from the yeast Saccharomyces cerevisiae that catalyzes the removal of the -phosphate from DGPP to form PA and removes the phosphate from PA to form DG [2]. DGPP phosphatase expression is greater in stationary phase cells, and the inositoland growth phase-dependent regulation of the enzyme is additive [23]. These growth conditions have profound effects on the expression of many phospholipid biosynthetic enzymes and on the regulation of phosphatidylinositol metabolism (5, 24 –26). DGPP phosphatase regulation by inositol occurs in a manner that is opposite that of many phospholipid biosynthetic enzymes [23]. Zinc deprivation induced DGPP phosphatase in wild-type cells This regulation was mediated by the Zap1p transcriptional activator through a zinc-responsive element (UASZRE) in the promoter of the DPP1 gene. The pattern of DGPP phosphatase regulation in mutants defective in plasma membrane and vacuolar membrane zinc
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