Molecular Basis for Pre-Receptor Modulation of Plant Hormones by Acyl Acid Amido Synthetases

植物需要对周围环境和环境的变化做出反应。作为这些反应的一部分，植物使用各种激素来改变它们的生长和新陈代谢，这些激素在化学上与动物体内发现的激素无关。植物激素的两种主要类型是茉莉酸盐和生长素。这些分子的存在或缺失由受体感知，如果与激素结合，受体就会触发植物的生物变化模式。这个项目的重点是GH3酶家族的蛋白质，这些蛋白质通过化学修饰激素来促进或阻止受体识别这些分子。GH3蛋白将不同的氨基酸附着在激素上，这会导致产生活性分子，就像茉莉酸盐一样，或者产生非活性分子，就像生长素一样。通过其生化活性，GH3蛋白可以控制受体的开启或关闭，并作为植物激素反应的前受体调节剂。虽然GH3蛋白在植物界广泛存在，但对其生化功能知之甚少。本项目旨在通过x射线晶体学了解GH3蛋白的分子结构，研究GH3蛋白如何催化其在化学上不同的植物激素上的反应，并深入了解每种GH3蛋白在植物激素反应中的生理作用。更广泛的影响探索植物激素作用控制的分子基础将为植物生长、害虫防御和作物可持续性分配资源的生化网络提供新的见解。例如，茉莉酸盐在改变与环境变化、害虫/病原体防御以及对生物燃料和工业原料有用的化合物的生产有关的各种化合物的代谢方面至关重要。该项目还注重培养下一代多学科科学家。本项目采用的研究方法和问题跨越了生物学、化学和物理学的界限，在实验室和教学中整合了x射线晶体学、生物化学和植物生物学。此外，培养研究生的很大一部分更广泛的影响努力集中在本科教育。PI积极通过本科论文工作（Bio200、Bio500和Chem490）、华盛顿大学HHMI-SURF、CD-BioRAP （NSF-REU项目）和大一前生物学和生物医学研究暑期学者项目招收本科生，并通过辉瑞- solutia暑期学生和教师作为研究科学家（STARS）项目指导高中生。该PI是Bio4522：蛋白质生物化学实验室的课程硕士，并在本科实验教学课程中开发了以研究为导向的项目(Jez等人，2007 Biochem。摩尔。杂志。建造。and Arkus & Jez, 2008 Biochem。摩尔。杂志。建造)。Bio4522是一个研究型实验室，旨在让学生通过不同的研究阶段来研究一个科学问题，并作为一个团队来工作。2010年春季和2011年春季班在拟南芥GH3蛋白方面的一些初步数据的成功，突出了这种方法对本科教育的价值。在本提案的时间框架内，课程的每学期将重点研究GH3蛋白功能的发展，通过检查这些酶从生命之树的不同生物体的进化。

Intellectual MeritPlants need to respond to their surroundings and changes in their environment. As part of those responses, plants use various hormones, which are chemically unrelated to those found in animals, to alter their growth and change metabolism. Two major types of plant hormones are the jasmonates and auxins. The presence or absence of these molecules is sensed by receptors, which if bound to the hormone trigger a pattern of biological changes in the plant. This project focuses on proteins of GH3 enzyme family that chemically modify the hormones to either promote or prevent the receptor from recognizing these molecules. The GH3 proteins attach different amino acids to the hormone, which can lead to production of an active molecule, as occurs with jasmonates, or an inactive molecule, as with the auxins. Through their biochemical activity, the GH3 proteins can control if the receptor is on or off and act as pre-receptor modulators of hormone responses in plants. Although the GH3 proteins are widespread across the plant kingdom, little is known about their biochemical function. This project aims to understand the molecular structure of the GH3 proteins by using x-ray crystallography, to investigate how the GH3 proteins catalyze their reactions on chemically diverse plant hormones, and to provide insight on the physiological roles of each GH3 protein in plant hormone responses.Broader ImpactExploring the molecular foundations for control of plant hormone action will provide new insight on the biochemical networks involved in allocating resources for plant growth, pest defenses, and crop sustainability. For example, jasmonates are critical in altering metabolism of various compounds related to environmental changes, pest/pathogen defenses, and production of compounds useful for biofuels and industrial feedstocks. The project also focuses on training the next generation of multidisciplinary scientists. The research methods and questions used in this project cross the boundaries between biology, chemistry, and physics by integrating x-ray crystallography, biochemistry, and plant biology in both the lab and in teaching. In addition, to training graduate students a large portion of the broader impact efforts focus on undergraduate education. The PI actively recruits undergraduate students through undergraduate thesis work (Bio200, Bio500, and Chem490), the Washington U. HHMI-SURF, CD-BioRAP (an NSF-REU program), and the pre-freshman Summer Scholars in Biology and Biomedical Research program, and mentors high school students through the Pfizer-Solutia Summer Students and Teachers as Research Scientists (STARS) program. The PI is course-master for Bio4522: Protein Biochemistry Lab and has a record of developing research-oriented projects in undergraduate teaching lab courses (Jez et al., 2007 Biochem. Mol. Biol. Educ. and Arkus & Jez, 2008 Biochem. Mol. Biol. Educ.). Bio4522 is a research-oriented lab designed to have students progress through different stages of research to examine a scientific question and to work as a team. The success of the Spring 2010 & 2011 classes in generating some of the preliminary data on the Arabidopsis GH3 proteins for this proposal highlights the value of this approach for undergraduate education. During the timeframe of this proposal, each semester of the course will focus on investigating the development of GH3 protein function across evolution by examining these enzymes from different organisms in the Tree of Life.