Expression of yeast lipid phosphatase Sac1p is regulated by phosphatidylinositol-4-phosphate
1 Division of Nephrology and Hypertension, Oregon Health & Science University, Portland OR 97239, USA
2 Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), 69120 Heidelberg, Germany
BMC Molecular Biology 2008, 9:16 doi:10.1186/1471-2199-9-16Published: 28 January 2008
Phosphoinositides play a central role in regulating processes at intracellular membranes. In yeast, a large number of phospholipid biosynthetic enzymes use a common mechanism for transcriptional regulation. Yet, how the expression of genes encoding lipid kinases and phosphatases is regulated remains unknown.
Here we show that the expression of lipid phosphatase Sac1p in the yeast Saccharomyces cerevisiae is regulated in response to changes in phosphatidylinositol-4-phosphate (PI(4)P) concentrations. Unlike genes encoding enzymes involved in phospholipid biosynthesis, expression of the SAC1 gene is independent of inositol levels. We identified a novel 9-bp motif within the 5' untranslated region (5'-UTR) of SAC1 that is responsible for PI(4)P-mediated regulation. Upregulation of SAC1 promoter activity correlates with elevated levels of Sac1 protein levels.
Regulation of Sac1p expression via the concentration of its major substrate PI(4)P ensures proper maintenance of compartment-specific pools of PI(4)P.