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，调控和功能特性。最近，我们通过各种创新的蛋白质组学和基因组学工具增强了纯化酶的详细生化表征，从而在发育中的蓖麻油籽富含甘油三酯的胚乳中控制磷酸烯醇丙酮酸（PEP）代谢以及pi剥夺（-Pi）拟南芥的生化适应方面取得了一些令人着迷的发现。PEP羧化酶（PEP carboxylase， 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到农学上重要的最终产物，如储存油和蛋白质，但也帮助植物应对非最佳Pi，这是许多土壤中最缺乏的常量营养素之一。建议研究的重点是：(A)发育中的油籽中新型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) PEPC同工酶的特性和pi清除功能，该酶可被-Pi拟南芥可逆积累和磷酸化（假设导致-Pi植物的根分泌溶解pi的有机酸）。以及主要的细胞内和细胞外紫色酸性磷酸酶同工酶被拟南芥-Pi上调（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存在的问题具有重要的应用价值，包括：(i)有针对性地改变油籽（如油菜或大豆）中的储油和蛋白质水平；（ii）开发高效的Pi转基因作物，迫切需要减少人类对不可再生、不可持续和污染的Pi肥料的大量低效使用。在此授权期内，我们将继续将新的蛋白质组学和基因组学工具整合到我们的研究中。这些创新需要重组工具、培训和优化，但提供了我们可以收集的数据类型的定量进步，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.