In the yeast Saccharomyces cerevisiae, membrane phospholipids are synthesized by complementary (CDP-diacylglycerol and Kennedy) pathways, and the genes and enzymes in these pathways are regulated by genetic and biochemical mechanisms. The major hypotheses of the work proposed in this application are that phospholipid synthesis is regulated by phosphorylation and by mRNA stability. We will focus on the phosphorylation of choline kinase and the transcription factor Opi1p. Choline kinase catalyzes the committed step in phosphatdylcholine synthesis via the CDP-choline branch of the Kennedy pathway. Understanding its regulation is emphasized by the fact that unregulated levels of choline kinase activity is a common property of various cancers in humans. Opi1p is a negative transcription factor that controls expression of several phospholipid biosynthetic genes in response to inositol supplementation. Choline kinase is phosphorylated by protein kinase A, and we will examine the hypothesis that the enzyme is also phosphorylated by protein kinase C. Mutants defective in protein kinase C phosphorylation will be used to examine the consequences of protein kinase C phosphorylation on choline kinase activity, and on the regulation of phosphatidylcholine synthesis. Hierarchical phosphorylation of the protein kinase A and protein kinase C sites will be examined. Opi1p is phosphorylated by protein kinases A and C, and we will examine the hypothesis that Opi1p is also phosphoylated by casein kinase II. Mutants defective in phosphorylation will be constructed and used to examine the role of casein kinase II phosphoylation on Opi1p repressor function. Target site mutants for protein kinases A and C will be included in this analysis. Hierarchical phosphorylation of the protein kinase A, protein kinase C, and casein kinase II will be examined. mRNA stability is a mechanism by which the CDP-diaclyglycerol pathway is activated when the Kennedy pathway is blocked. Using mutants defective in phospholipid metabolism, we will examine the hypothesis that the signal for regulation of the CDP-diacylglycerol pathway by mRNA stability is a Kennedy pathway end product, a water-soluble intermediate of the Kennedy pathway, or a molecule derived from the turnover of a phospholipid synthesized via the Kennedy pathway. The mechanism for CHO1 mRNA (a CDP-diacylgylcerol pathway transcript) degradation will be examined.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM050679-14
Application #
7228607
Study Section
Physiological Chemistry Study Section (PC)
Program Officer
Jones, Warren
Project Start
1994-05-01
Project End
2009-04-30
Budget Start
2007-05-01
Budget End
2008-04-30
Support Year
14
Fiscal Year
2007
Total Cost
$267,010
Indirect Cost
Name
Rutgers University
Department
Nutrition
Type
Schools of Earth Sciences/Natur
DUNS #
001912864
City
New Brunswick
State
NJ
Country
United States
Zip Code
08901
Carman, George M (2018) Discoveries of the phosphatidate phosphatase genes in yeast published in the Journal of Biological Chemistry. J Biol Chem :
Su, Wen-Min; Han, Gil-Soo; Dey, Prabuddha et al. (2018) Protein kinase A phosphorylates the Nem1-Spo7 protein phosphatase complex that regulates the phosphorylation state of the phosphatidate phosphatase Pah1 in yeast. J Biol Chem 293:15801-15814
Carman, George M; Han, Gil-Soo (2018) Phosphatidate phosphatase regulates membrane phospholipid synthesis via phosphatidylserine synthase. Adv Biol Regul 67:49-58
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
Hsieh, Lu-Sheng; Su, Wen-Min; Han, Gil-Soo et al. (2016) Phosphorylation of Yeast Pah1 Phosphatidate Phosphatase by Casein Kinase II Regulates Its Function in Lipid Metabolism. J Biol Chem 291:9974-90
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
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
Sahu-Osen, Anita; Montero-Moran, Gabriela; Schittmayer, Matthias et al. (2015) CGI-58/ABHD5 is phosphorylated on Ser239 by protein kinase A: control of subcellular localization. J Lipid Res 56:109-21
Barbosa, Antonio Daniel; Sembongi, Hiroshi; Su, Wen-Min et al. (2015) Lipid partitioning at the nuclear envelope controls membrane biogenesis. Mol Biol Cell 26:3641-57
Su, Wen-Min; Han, Gil-Soo; Carman, George M (2014) Yeast Nem1-Spo7 protein phosphatase activity on Pah1 phosphatidate phosphatase is specific for the Pho85-Pho80 protein kinase phosphorylation sites. J Biol Chem 289:34699-708

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