Regulation of plant phospholipid biosynthesis

磷脂是构建真核生物细胞膜所必需的，而真核生物细胞膜在生命的生物化学划分中起着重要作用。磷脂的数量和组成在生长发育过程和环境变化中受到严格调节，使膜始终保持其结构和功能。在哺乳动物和酵母（Saccharomyces cerevisiae）的研究中，发现了优雅的代谢物信号传导机制，包括转录和翻译后，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（和转换）。类似的机制也可能存在于植物中，但令人惊讶的是，它们尚未被阐明。因为磷脂是必需的，通过功能丧失对其调控的遗传分析是有问题的。然而，我们最近分离出了拟南芥两种磷脂磷酸酶（pah1 pah2）的双突变体，其叶片中产生的磷脂大约是野生型植物的两倍。据我们所知，这是第一个过量产生磷脂的植物突变体，功能获得表型提供了一个独特的工具。本课题的目的是利用pah1 pah2突变体（及相应基因）来发现拟南芥中磷脂的生物合成是如何调控的，并研究它是如何与需要膜生物发生的细胞周期进程协调的。这一发现将具有根本性的科学意义，特别是已有证据表明，植物调控机制的许多关键要素肯定不同于哺乳动物或酵母。

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.