The yeast Saccharomyces cerevisiae responds to a variety of stress conditions (e.g., zinc depletion) by regulating the expression of several enzyme activities including those involved in phospholipid synthesis. Zinc is an essential nutrient required for the growth and metabolism of S. cerevisiae, and of higher eukaryotic cells. The work proposed in this application will address mechanisms by which the expression of key phospholipid biosynthetic enzyme activities is regulated in response to zinc depletion. We will examine the hypothesis that zinc depletion induces a cytosolic Mg2+dependent and NEM-sensitive phosphatidate phosphatase that reduces phosphatidate concentration in the ER. This in turn, triggers the Opi 1p-mediated repression of CHO1 (encodes phosphatidylserine synthase) and other UASINO-containing genes. This question will be addressed using a phosphatase mutant that will be isolated by a reverse genetic approach requiring the purification of the cytosolic Mg2+dependent phosphatidate phosphatase enzyme. The regulation of expression of this phosphatase gene by zinc depletion will be examined, along with the biochemical properties of the purified enzyme. We will examine the hypothesis that E/C/7-encoded ethanolamine kinase and CK/t-encoded choline kinase are induced in response to zinc depletion. Mechanisms responsible for the zinc-mediated regulation of the EKI1 and CKI1 genes will be examined, and the biological relevance of regulation for each gene will be examined using selective promoter mutations that affect their expression. The biological relevance of the Opi 1p-mediated repression of CHO1 and the Zap1p-mediated induction of PIS1 (encodes phosphatidylinositol synthase) will be explored with mutants that are unable to down-regulate phosphatidylserine synthase or up-regulate phosphatidylinositol synthase activities, respectively, in response to zinc depletion. We will examine the hypothesis that the function of the high-affinity plasma membrane zinc transporter Zrt1 p is regulated by changes in phospholipid composition brought about by phospholipid synthesis regulation by zinc depletion. Zinc transport function will be addressed with mutants defective in phospholipid synthesis, and with Zrt1p reconstituted into unilamellar vesicles with varying phospholipid composition.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
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Biochemistry and Biophysics of Membranes Study Section (BBM)
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Chin, Jean
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Rutgers University
Schools of Earth Sciences/Natur
New Brunswick
United States
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Carman, George M; Han, Gil-Soo (2018) Phosphatidate phosphatase regulates membrane phospholipid synthesis via phosphatidylserine synthase. Adv Biol Regul 67:49-58
Park, Yeonhee; Han, Gil-Soo; Carman, George M (2017) A conserved tryptophan within the WRDPLVDID domain of yeast Pah1 phosphatidate phosphatase is required for its in vivo function in lipid metabolism. J Biol Chem 292:19580-19589
Hassaninasab, Azam; Han, Gil-Soo; Carman, George M (2017) Tips on the analysis of phosphatidic acid by the fluorometric coupled enzyme assay. Anal Biochem 526:69-70
Dey, Prabuddha; Su, Wen-Min; Han, Gil-Soo et al. (2017) Phosphorylation of lipid metabolic enzymes by yeast protein kinase C requires phosphatidylserine and diacylglycerol. J Lipid Res 58:742-751
Han, Gil-Soo; Carman, George M (2017) Yeast PAH1-encoded phosphatidate phosphatase controls the expression of CHO1-encoded phosphatidylserine synthase for membrane phospholipid synthesis. J Biol Chem 292:13230-13242
Qiu, Yixuan; Hassaninasab, Azam; Han, Gil-Soo et al. (2016) Phosphorylation of Dgk1 Diacylglycerol Kinase by Casein Kinase II Regulates Phosphatidic Acid Production in Saccharomyces cerevisiae. J Biol Chem 291:26455-26467
Park, Ki-Sook; Dubon, Maria Jose; Gumbiner, Barry M (2015) N-cadherin mediates the migration of MCF-10A cells undergoing bone morphogenetic protein 4-mediated epithelial mesenchymal transition. Tumour Biol 36:3549-56
Barneda, David; Planas-Iglesias, Joan; Gaspar, Maria L et al. (2015) The brown adipocyte protein CIDEA promotes lipid droplet fusion via a phosphatidic acid-binding amphipathic helix. Elife 4:e07485
Hsieh, Lu-Sheng; Su, Wen-Min; Han, Gil-Soo et al. (2015) Phosphorylation regulates the ubiquitin-independent degradation of yeast Pah1 phosphatidate phosphatase by the 20S proteasome. J Biol Chem 290:11467-78
Park, Yeonhee; Han, Gil-Soo; Mileykovskaya, Eugenia et al. (2015) Altered Lipid Synthesis by Lack of Yeast Pah1 Phosphatidate Phosphatase Reduces Chronological Life Span. J Biol Chem 290:25382-94

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