REGULATION OF PHOSPHOLIPID SYNTHESIS

磷脂合成的调控

• 批准号: 6918236
• 负责人: GEORGE M. CARMAN
• 金额: $ 28.13万
• 依托单位: RUTGERS, THE STATE UNIV OF N.J.
• 依托单位国家: 美国
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-05-01 至 2009-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6918236
• 关键词: Saccharomyces cerevisiae; alcohol phosphotransferase; chemical stability; cytosine nucleotides; diacylglycerols; enzyme activity; enzyme mechanism; gene expression; lipid biosynthesis; membrane lipids; messenger RNA; microorganism metabolism; mutant; phosphatidylcholines; phospholipids; phosphorylation; protein kinase A; protein kinase C; transcription factor

DESCRIPTION (provided by applicant): 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.

描述（由申请人提供）：在酿酒酵母中，膜磷脂通过互补（CDP-二酰基甘油和Kennedy）途径合成，这些途径中的基因和酶受遗传和生化机制的调节。本申请中提出的工作的主要假设是磷脂合成受磷酸化和mRNA稳定性调节。我们将重点关注胆碱激酶和转录因子Opi 1 p的磷酸化。胆碱激酶通过Kennedy途径的CDP-胆碱分支催化磷酸胆碱合成中的关键步骤。了解其调节强调了这样一个事实，即胆碱激酶活性的不受调节的水平是人类各种癌症的共同特性。Opi 1 p是一种负性转录因子，它控制着几种磷脂生物合成基因在补充肌醇时的表达。胆碱激酶被蛋白激酶A磷酸化，我们将检验这种酶也被蛋白激酶C磷酸化的假设。蛋白激酶C磷酸化缺陷的突变体将被用来检查结果 蛋白激酶C磷酸化对胆碱激酶活性的影响，以及对磷脂酰胆碱合成的调节。将检查蛋白激酶A和蛋白激酶C位点的分级磷酸化。Opi 1 p被蛋白激酶A和C磷酸化，我们将研究Opi 1 p也被酪蛋白激酶II磷酸化的假设。将构建磷酸化缺陷突变体，并用于检查酪蛋白激酶II磷酸化对Opi 1 p阻遏物功能的作用。蛋白激酶A和C的靶位点突变体将纳入本分析中。将检查蛋白激酶A、蛋白激酶C和酪蛋白激酶II的分级磷酸化。mRNA稳定性是当Kennedy途径被阻断时CDP-二酰甘油途径被激活的机制。使用磷脂代谢缺陷的突变体，我们将研究的假设，即通过mRNA稳定性的CDP-甘油二酯途径的调节信号是肯尼迪途径的最终产物，肯尼迪途径的水溶性中间体，或来自通过肯尼迪途径合成的磷脂的周转的分子。将检查CHO 1 mRNA（CDP-二酰基甘油途径转录物）降解的机制。