Mechanisms and Impacts of De-regulating Aromatic Amino Acid Biosynthesis in Plants

植物从简单的前体产生芳香族氨基酸（AAAs），并使用它们来产生蛋白质、许多天然产物，包括生物碱、酚类和具有药用、营养和其他有用特性的附加有机化合物。了解和改善AAAs的生物合成将提高食品的营养质量，实现具有成本效益的药品生产，并实现工业材料的可持续生产。本研究的目的是获得有关植物如何调节AAAs生产的基础知识，以精确控制AAAs衍生的植物天然产物的生产。“颜料艺术+”外展活动将与K-12学生及其家长进行，以提高对植物天然产品重要性的认识。在这个项目中，来自AAAs的彩色植物色素被用作向公众宣传植物天然产品的营养和药理价值的工具。这些活动的对象是来自低收入和科学代表性不足社区的父母。该项目还培养不同背景的学生和博士后，进行整合生物化学、结构和定量生物学以及植物化学的跨学科合作研究。植物特别适合生产AAA及其衍生物，因为它们天然合成并积累大量AAA衍生物。植物如何调节AAA生物合成和协调整个代谢网络以有效地产生AAA仍然是难以捉摸的。 最近的一个项目鉴定了分别由3-脱氧-D-阿拉伯庚酮糖酸-7-磷酸合酶（DHS）和arogenate脱氢酶（TyrA）催化的解除调节AAA生物合成的进入和最终反应的植物酶。这些新的AAA生物合成的调节酶用于调节连接中心碳代谢和许多植物天然产物代谢途径的关键中间途径。该提案的主要目标是确定植物AAA生物合成失调的分子机制，并确定其对整个植物代谢网络的定量影响。该项目专门研究了DHS和TyrA变体的反馈调节，并定量测试了它们在控制AAA前体供应中的作用。动态碳-13 CO2标记将用于代谢通量分析。将使用随时间变化的碳-13富集数据，根据对代谢网络模型拟合的优化来估计通量。这种整合的分子到网络水平的分析将提供一系列去调控的DHS和TyrA变体，这些变体将在植物中进行测试。 这些实验将产生原型植物化学平台，将显示增强AAA前体供应。该奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

Plants produce aromatic amino acids (AAAs) from simple precursors, and use them to produce proteins, numerous natural products, including alkaloids, phenolics and additional organic compounds that have medicinal, nutritional and other useful properties. Understanding and improving the biosynthesis of AAAs will enhance the nutritional quality of food, achieve cost-effective production of medicines and enable sustainable production of industrial materials. The aims of this research are to gain fundamental knowledge concerning how plants regulate the production of AAAs, in order to precisely control the production of plant natural products that are derived from AAAs. "Pigment Art+" outreach activities will be conducted with K-12 students and their parents as a means of increasing the awareness of the importance of plant natural products. Colorful plant pigments derived from AAAs are used in this project as tools to inform the general public about the nutritional and pharmacological values of plant natural products. The activities are targeted for parents from communities that are low-income and underrepresented in science. This project also trains students and postdocs of diverse backgrounds, in collaborative interdisciplinary research that integrates biochemistry, structural and quantitative biology and the chemistry of plants.Plants are particularly suited to produce AAAs and their derivatives since they naturally synthesize and accumulate a large quantity of AAA-derived compounds. How plants regulate AAA biosynthesis and coordinate the overall metabolic network to efficiently produce AAAs remains elusive. A recent project identified plant enzymes that de-regulate the entry and final reactions of AAA biosynthesis, catalyzed by 3-deoxy-D-arabinoheptulosonate 7-phosphate synthase (DHS) and arogenate dehydrogenase (TyrA), respectively. Such novel regulatory enzymes of AAA biosynthesis are used to modulate this key intermediary pathway that connects central carbon metabolism and numerous plant natural product metabolic pathways. The major goals of this proposal are to define molecular mechanisms underlying the de-regulation of plant AAA biosynthesis and to determine their quantitative impacts on overall plant metabolic networks. The project specifically investigates the feedback regulation of DHS and TyrA variants, and quantitatively test their in planta roles in controlling AAA precursor supply. Dynamic carbon-13 CO2 labeling will be used for metabolic flux analysis. Time-dependent carbon-13 enrichment data will be used to estimate fluxes based on optimization of fit to a metabolic network model. This integrated molecular to network level analyses will provide a series of de-regulated DHS and TyrA variants, which will be tested in planta. These experiments will generate prototype plant chemical platforms that will display enhanced AAA precursor supply.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.