Phosphatidic Acid Biosynthesis and Signalling in Eukaryotes

磷脂酸不仅是所有甘油脂生物合成的前体，而且也是关键的信号脂质。磷脂酸生物合成的调控、3-磷酸甘油酰基转移酶(GPAT)的限速步骤以及脂质代谢途径的划分等机制才刚刚出现。克服这一知识鸿沟是细胞生物学的一个中心问题。利用酿酒酵母的分子和遗传优势，我们计划确定调节GPATs的分子事件及其如何影响特定的脂类代谢、脂类信号转导和脂类介导的转运过程。我们已经开始对酵母GPATs、Gat1和Gat2进行全面的生化、分子和生物学特性研究。我们的研究表明，这些酶是微粒体磷酸蛋白，对特定的脂类有不同的贡献。我们计划研究*i)磷酸化在调节GPAT活性、定位和蛋白质-蛋白质相互作用中所起的作用；*ii)Gat1和Gat2在线粒体脂类磷脂酰甘油和心磷脂合成中的作用。*iii)酵母中二酰甘油池的分布和维持这些池的途径的鉴定。*此外，酵母遗传方法将被用来进一步表征磷脂酸到二酰甘油的相互转化以及它们的脂类运输、交易和信号的细胞解剖。从酵母到人类，真核生物的脂肪代谢都是保守的。由于它的基本性质，我们的研究与了解生物如何控制与环境中营养物质的可获得性有关的脂肪代谢有关。我们的研究结果可能会对开发脂代谢用于包括生物燃料在内的石油工业生产产生重大影响。此外，它还可以为理解由于控制脂质合成和信号传递的调节电路改变而导致的脂稳态丧失如何促进人类肥胖、糖尿病和癌症等疾病的发展提供洞察力。

Phosphatidic acid is not only the precursor for the biosynthesis of all glycerolipids but is also a key signaling lipid. The mechanisms of the regulation of phosphatidic acid biosynthesis, the rate limiting glycerol 3-phosphate acyltransferase (GPAT) step, as well as lipid metabolic pathway partitioning, are just emerging. Overcoming this gap in knowledge is a central issue in cell biology. Exploiting the molecular and genetic advantages of Saccharomyces cerevisiae, we plan to identify molecular events that regulate GPATs and how they affect specific lipid metabolic, lipid signaling and lipid mediated transport processes. We have initiated a comprehensive biochemical, molecular and biological characterization of the yeast GPATs, Gat1 and Gat2. Our studies indicated these enzymes are microsomal phosphoproteins with differential contributions to specific lipid pools. We plan to investigate ***i) the role that phosphorylation plays in regulating GPAT activity, localization, and protein-protein interactions; ***ii) the contribution of Gat1 and Gat2 to the synthesis of the mitochondrial lipids phosphatidylglycerol and cardiolipin.***iii) the distribution of diacylglycerol pools in yeast and the identification of pathways that maintain these pools.***In addition, yeast genetic approaches will be used in order to further characterize the inter-conversion of phosphatidic acid to diacylglycerol and the cell anatomy of their lipid traffic, trading and signaling. Lipid metabolism is conserved in eukaryotes, from yeast to humans. Due to its fundamental nature, our research is relevant to understand how organisms control lipid metabolism in relation to the availability of nutrients in the environment. The outcome of our investigations could have a significant impact in the exploitation of lipid metabolism for industrial production of oils, which includes biofuels. In addition, it could also provide insights into understanding how loss of lipid homeostasis due to alterations of the regulatory circuits that control lipid synthesis and signalling contributes to the development of diseases such as obesity, diabetes, and cancer in humans.**