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Yeast Pah1 Phosphatidate Phosphatase Regulates the Expression of Phosphatidylserine Synthase for Membrane Phospholipid Synthesis
Author(s) -
Han GilSoo,
Carman George M.
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.lb226
Subject(s) - phosphatidate , atp synthase , derepression , phosphatidylserine , biochemistry , biology , enzyme , chemistry , phospholipid , microbiology and biotechnology , psychological repression , gene expression , gene , membrane , phosphatidic acid
Pah1 phosphatidate phosphatase (PAP), which catalyzes a committed step for the synthesis of triacylglycerol in Saccharomyces cerevisiae , exerts a negative regulatory effect on the level of PA required for de novo phospholipid synthesis. In this study, we examined the Pah1 PAP‐mediated regulation of phosphatidylserine (PS) synthase, which catalyzes a committed step for the synthesis of major membrane phospholipids. PS synthase activity was highly increased by the lack of Pah1 PAP with a growth‐dependent upregulation from the exponential to the stationary phase. Immunoblot analysis showed that the elevation of PS synthase activity results from an increase in the level of the enzyme encoded by CHO1 . By promoter truncation analysis and site‐directed mutagenesis, the induced expression of CHO1 in the pah1 Δ mutant was shown to occur through the inositol‐sensitive upstream activation sequence (UAS INO , −163 ~ −154), a cis ‐acting element for the PA‐controlled Ino2‐Ino4/Opi1 regulatory circuit. The abrogation of CHO1 induction by the UAS INO mutation suppressed the pah1 Δ phenotypes related to the increase of PA levels (e.g., increased phospholipid synthesis, nuclear/ER membrane expansion, and reduced lipid droplet formation) with its effect stronger in the exponential phase than in the stationary phase. These results demonstrate that Pah1 PAP regulates the expression of PS synthase through its control on the PA level. Support or Funding Information Supported by NIH grant GM028140