Molecular Diversification of Plant Hormone Modification by Acyl Acid Amido Synthetases

植物需要对周围的环境和环境的变化做出反应。为了做到这一点，植物使用各种激素来控制它们在正常和压力条件下的生长方式，例如干旱、营养匮乏、阳光变化以及害虫和病原体的攻击。这些小分子也会影响作物产量。将小分子激素与植物发育变化联系起来的复杂系统才刚刚开始被理解。控制植物激素反应的一种方法是改变激素的化学结构；这提供了一个分子开/关开关。这个项目的重点是一系列植物蛋白质，这些蛋白质可以改变植物激素的开关，并将使用新发现的途径来改变主要植物激素生长素的水平。了解植物如何控制它们的生长发育，特别是提高它们在胁迫条件下的生存能力，对于提高作物产量和满足未来生物经济的潜力是至关重要的。该项目还将为各级科学家提供一个跨学科的培训环境，从博士后研究人员到高中生，结合结构生物学、生物化学和植物生物学的实验方法。受体前和受体后代谢和信号通路的整合控制植物生长和发育的激素反应。生长素在植物发育过程中的代谢和定位是建立活性激素反应和生物效应的关键。作为调节植物激素的系统的一部分，GH3酰基酸氨基合成酶控制主要植物激素的水平，包括茉莉酸和生长素，并调节与植物生长发育、种子发育、光信号、干旱反应和抗病有关的途径。在生物化学方面，GH3蛋白催化氨基酸结合成酰基酸，以调节茉莉酸和生长素的活性和非活性形式的水平。该酶家族酰基底物的多样性允许茉莉酸和吲哚乙酸以外的生物合成途径中代谢产物的改变，如内源生长素吲哚-3-丁酸(IBA)，以及合成生长素的修饰，这表明可能在除草剂耐受机制中的应用。本项目将确定IBA特异的Gretchen Hagen(GH3)蛋白在植物幼苗生长中的作用，研究GH3蛋白对不同生长素的专一性的分子基础，并评价GH3蛋白对苯氧基烷酸的修饰作为除草剂耐受机制。该项目得到了生物科学局分子和细胞生物科学司分子生物物理组的支持。

Plants need to respond to their surroundings and changes in their environment. To do that, plants use various hormones to control how they grow under normal and stress conditions, such as drought, nutrient starvation, sunlight changes, and attack by pests and pathogens. These small molecules also influence crop productivity. The intricate systems that link small molecule hormones to developmental changes in plants are just beginning to be understood. One way of controlling responses to plant hormones is to alter the chemical structure of the hormone; this provides a molecular on/off switch. This project focuses on a family of plant proteins that modify plant hormones to turn them on and off and will use newly identified route for altering levels of the major plant hormone auxin. Understanding how plants control their growth and development, especially to improve their ability to survive under stress conditions, is essential for improving crop yields and for meeting the potential of a bio-based economy in the future. This project will also provide an interdisciplinary training environment for scientists at all levels from postdoctoral researchers to high school students that combines experimental approaches from structural biology, biochemistry, and plant biology.The integration of pre- and post-receptor metabolic and signaling pathways controls hormone responses for plant growth and development. Metabolism and localization of auxin during plant development is critical for establishing active hormone responses and biological effects. As part of the system that regulates plant hormones, GH3 acyl acid amido synthetases control levels of major plant hormones, including jasmonic acid and auxin, and modulate pathways responsible for plant growth and development, seed development, light signaling, drought response, and pathogen resistance. Biochemically, the GH3 proteins catalyze the conjugation of amino acids to acyl acids to regulate levels of active and inactive forms of jasmonates and auxins. Diversification of acyl acid substrate specificity in this enzyme family allows for alteration of metabolites in biosynthetic pathways beyond jasmonate and indole acetic acid, such as the endogenous auxin indole-3-butyric acid (IBA), and for the modification of synthetic auxins, which suggests possible uses in herbicide tolerance mechanisms. This project will determine the role of an IBA-specific Gretchen Hagen (GH3) protein in plant seedling growth, investigate the molecular basis of GH3 protein specificity for different auxins and evaluate the modification of phenoxyalkanoic acids by GH3 proteins as an herbicide tolerance mechanism. This project is supported by the Molecular Biophysics Cluster of the Molecular and Cellular Biosciences Division in the Directorate for Biological Sciences.