Expression of yeast lipid phosphatase Sac1p is regulated by phosphatidylinositol-4-phosphate

<p>Abstract</p> <p>Background</p> <p>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.</p> <p>Results</p> <p>Here we show that the expression of lipid phosphatase Sac1p in the yeast <it>Saccharomyces cerevisiae </it>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 <it>SAC1 </it>gene is independent of inositol levels. We identified a novel 9-bp motif within the 5' untranslated region (5'-UTR) of <it>SAC1 </it>that is responsible for PI(4)P-mediated regulation. Upregulation of <it>SAC1 </it>promoter activity correlates with elevated levels of Sac1 protein levels.</p> <p>Conclusion</p> <p>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.</p