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，也是一种关键的信号脂质。磷脂酸生物合成的调节机制，限速甘油3-磷酸酰基转移酶（GPAT）步骤，以及脂质代谢途径分配，才刚刚出现。克服这一知识差距是细胞生物学的核心问题。利用酿酒酵母的分子和遗传优势，我们计划确定调节GPAT的分子事件，以及它们如何影响特定的脂质代谢，脂质信号传导和脂质介导的转运过程。我们已经启动了一个全面的生化，分子和生物学特性的酵母GPAT，Gat 1和Gat 2。我们的研究表明这些酶是微粒体磷蛋白，对特定的脂质池有不同的贡献。我们计划调查 i）磷酸化在调节GPAT活性、定位和蛋白质-蛋白质相互作用中的作用; ii）Gat 1和Gat 2对线粒体脂质磷脂酰甘油和心磷脂合成的贡献。 iii）二酰基甘油库在酵母中的分布和维持这些库的途径的鉴定。 此外，将使用酵母遗传方法，以进一步表征磷脂酸转化为二酰基甘油的相互转化及其脂质运输、交易和信号传导的细胞解剖。脂质代谢在真核生物中是保守的，从酵母到人类。由于其基本性质，我们的研究与了解生物体如何控制脂质代谢与环境中营养物质的可用性有关。我们的研究结果可能会对利用脂质代谢进行石油工业生产（包括生物燃料）产生重大影响。此外，它还可以提供见解，了解由于控制脂质合成和信号传导的调节回路的改变而导致的脂质稳态的丧失如何有助于人类肥胖，糖尿病和癌症等疾病的发展。

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.