Molecular, regulatory and functional properties of key enzymes of plant carbohydrate and phosphate metabolism

我的长期研究目标是确定植物碳水化合物和磷酸盐(PI)代谢的关键酶的分子、调节和功能特性。我们对纯化酶的详细生化特征最近通过各种创新的蛋白质组和基因组学工具得到了增强，导致了一些有趣的发现，涉及到发育中的蓖麻种子富含甘油三酯的胚乳中磷酸烯醇式丙酮酸(PEP)代谢的控制，以及PI缺乏(-PI)的拟南芥的生化适应。PEP羧化酶(PEPC)是一种重要的、多方面的变构酶，位于植物初级代谢的核心，参与控制种子碳水化合物分配给重要的农艺终产物，如储藏油和蛋白质，但也帮助植物应对次优PI，这是许多土壤中可利用的最低常量营养素之一。拟议的研究集中在：(A)发育中油籽的新型1类和2类PEPC同工酶的功能特性、蛋白质相互作用和亚细胞定位；&(B)由-PI拟南芥可逆积累和磷酸化的PEPC同工酶的性质和清除PI的功能(假设导致-PI植物根部分泌溶解PI的有机酸)，以及由-PI拟南芥上调的主要细胞内和细胞外紫色酸性磷酸酶同工酶(假设有助于从细胞内和土壤定位的PI酯中回收PI)。我们的研究对加拿大农业中的问题有着重要的应用，包括：(I)有针对性地修改油料种子(如油菜籽或大豆)中的储油与蛋白质水平，以及(Ii)开发高效PI转基因作物，以减少人类猖獗但低效地使用不可再生、不可持续和污染的PI肥料。在此授权期内，我们将继续将新的蛋白质组和基因组学工具整合到我们的研究中。这些创新需要重新装备、培训和优化，但在我们可以收集的数据类型方面提供了量化进展，并为现代植物代谢生物化学中的HQP培训奠定了坚实的基础。

My long-term research goal is to identify the molecular, regulatory, and functional properties of key enzymes of plant carbohydrate and phosphate (Pi) metabolism. Our detailed biochemical characterization of purified enzymes was recently augmented by various innovative proteomic and genomic tools, resulting in several fascinating discoveries concerning the control of phosphoenolpyruvate (PEP) metabolism in the triglyceride-rich endosperm of developing castor oilseeds, and the biochemical adaptations of Pi-deprived (-Pi) Arabidopsis thaliana. PEP carboxylase (PEPC) is an important and 'multi-faceted' allosteric enzyme situated at the core of primary plant metabolism that participates in the control of seed carbohydrate partitioning to agronomically important end-products such as storage oils and proteins, but also helps plants to cope with suboptimal Pi, one of the least available macronutrients in many soils. Proposed research is focused on the: (A) functional properties, protein interactions, and subcellular localization of novel Class-1 & Class-2 PEPC isoforms of developing oilseeds, & (B) properties and Pi-scavenging functions of a PEPC isozyme that is reversibly accumulated and phosphorylated by -Pi Arabidopsis (hypothesized to result in excretion of Pi-solubilizing organic acids by roots of -Pi plants), as well as the predominant intra- & extracellular purple acid phosphatase isozymes upregulated by -Pi Arabidopsis (hypothesized to help recycle Pi from intracellular and soil-localized Pi-esters). Our studies have significant applications to problems in Canadian agriculture including the: (i) targeted modification of storage oil vs. protein levels in oilseeds such as canola or soybean, & (ii) development of Pi-efficient transgenic crops, urgently needed to reduce mankind's rampant but inefficient use of non-renewable, unsustainable, and polluting Pi fertilizers. During this granting period we will continue to integrate new proteomic and genomic tools into our research. These innovations require retooling, training, and optimization, but provide quantitative advances in the types of data that we can gather, and a solid foundation for HQP training in modern plant metabolic biochemistry.