Regulation of plant phospholipid biosynthesis

磷脂是构建真核细胞膜所必需的，真核细胞膜在划分生命的生物化学中起着重要作用。磷脂的数量和组成在生长和发育过程中受到严格调节，并响应环境变化，因此膜始终保持其结构和功能。对哺乳动物和酵母（酿酒酵母）的研究发现了转录和翻译后的代谢物信号传导机制，使细胞能够感知关键脂质中间体的变化，并相应地调整磷脂合成（和周转）。类似的机制也可能存在于植物中，但令人惊讶的是，它们尚未得到阐明。由于磷脂是必不可少的，通过功能丧失对其调节进行遗传分析是有问题的。然而，我们最近已经分离出一个拟南芥双突变体中的两个磷脂酸磷酸酶（pah1 pah2），产生约两倍的磷脂在其叶片中的野生型植物。据我们所知，这是第一个过度生产磷脂的植物突变体，功能获得表型提供了一个独特的工具。这项资助提案的目的是使用pah1 pah2突变体（和相应的基因）来发现磷脂生物合成是如何在拟南芥中调节的，并研究它是如何与细胞周期进程协调的，这需要膜生物发生。这一发现将具有根本的科学意义，特别是因为已经有证据表明，植物中调节机制的许多关键要素必须与哺乳动物或酵母中描述的那些不同。

Phospholipids are essential for the construction of eukaryotic cell membranes, which play a fundamental role in compartmentalising the biochemistry of life. The quantity and composition of phospholipids are tightly regulated during growth and development, and in response to environmental change, so that membranes always maintain their structure and function. Research in mammals and yeast (Saccharomyces cerevisiae) has uncovered elegant metabolite signaling mechanisms, both transcriptional and post-translational, that allow the cell to sense changes in key lipid intermediates and adjust phospholipid synthesis (and turnover) accordingly. Analogous mechanisms are also likely to exist in plants but surprisingly they have not been elucidated. Because phospholipids are essential, genetic analysis of their regulation through loss-of-function is problematic. However, we have recently isolated an Arabidopsis thaliana double mutant in two phosphatidate phosphatases (pah1 pah2) that produces approximately twice as much phospholipid in its leaves as wild type plants. To our knowledge this is the first plant mutant to over-produce phospholipids and the gain-of-function phenotype provides a unique tool. The objective of this grant proposal is to use the pah1 pah2 mutant (and corresponding genes) to discover how phospholipid biosynthesis is regulated in Arabidopsis and to investigate how it is coordinated with cell cycle progression, which requires membrane biogenesis. This discovery will be of fundamental scientific interest, particularly as there is already evidence to show that many key elements of the regulatory mechanism(s) in plants must differ from those described in mammals or yeast.