Regulation of ACC Synthase Protein Stability

气体激素乙烯对植物的生长发育有着深远的影响。这种激素的生物合成的限速和关键调控步骤是由ACC合成酶（ACS）催化的。先前的研究表明，ACS的c端结构域针对该蛋白进行快速降解，并且已经确定了几个参与调节这种降解的因素。本研究的主要目的是进一步阐明调节ACS蛋白周转的机制。为此，将开展以下研究：1)研究蛋白磷酸化在控制ACS蛋白稳定性中的作用，并确定ACS蛋白快速降解所需的精确部分；2)在与乙烯生物合成增加相关的各种发育事件或对外源线索的反应中，将检查ACS蛋白的稳定性，以确定在这些条件下，ACS蛋白稳定性的改变是否在控制乙烯生物合成中起作用；3)研究两个拟南芥DnaJ（又名HSP40）同源物在调节ACS周转中的作用；4)先前确定的参与乙烯生物合成调控的基因CIN2将被克隆并鉴定；5)将进行基因筛选，以确定参与调节ACS蛋白周转的新元件。这些研究将揭示调节ACS蛋白稳定性的机制以及这如何有助于控制乙烯的生物合成。这项研究也将增加我们对DnaJ在高等真核生物中的作用的理解，以及这种普遍存在的蛋白质的作用机制。这些研究的结果将导致对乙烯生物合成的调控有更深的了解，这可能导致在农业环境中操纵这种激素的生产的能力，从而提高各种农产品的质量和寿命。此外，蛋白质周转的调节已经成为多种生物系统的核心机制。这项研究将阐明这一基本过程，并通过为本科生、研究生和博士后研究人员提供实践培训，加强研究和教育的基础设施。此外，它还将允许与DESTINY旅行科学学习计划合作，协助创建和维护一个基于植物的学习模块，旨在促进K-12年级的科学教育。

The gaseous hormone ethylene has profound effects on plant growth and development. The rate-limiting and key regulatory step in the biosynthesis of this hormone is catalyzed by ACC synthase (ACS). Previous studies have shown that the C-terminal domain of ACS targets this protein for rapid degradation, and several factors involved in regulating this degradation have been identified. The primary goal of this research is to further elucidate the mechanisms regulating ACS protein turnover. To these ends, the following lines of investigation will be pursued: 1) The role of protein phosphorylation in controlling ACS protein stability will be examined, and the precise portion of the ACS protein required for its rapid degradation will be delineated; 2) The stability of ACS protein during various developmental events that are associated with a rise in ethylene biosynthesis or in response to exogenous cues will be examined to determine if altered ACS protein stability plays a role in controlling ethylene biosynthesis under these conditions; 3) The role that two Arabidopsis DnaJ (a.k.a. HSP40) orthologs play in regulating ACS turnover will be studied; 4) The CIN2 gene, which was previously identified as a gene that is involved in controlling ethylene biosynthesis, will be cloned and characterized; 5) A genetic screen will be performed to identify novel elements involved in regulating ACS protein turnover. These studies will shed light on the mechanism regulating the stability of ACS proteins and how this contributes to the control of the biosynthesis of ethylene. This research will also increase our understanding of the role of DnaJ in higher eukaryotic organisms, and on the mechanism by which this ubiquitous protein acts.Results from these studies will lead to a deeper understanding of the regulation of ethylene biosynthesis, which may lead to the ability to manipulate the production of this hormone in an agricultural setting and hence improve the quality and longevity of various agricultural products. Furthermore, the regulation of protein turnover has emerged as a central mechanism underlying a variety of biological systems. This research will shed light on this fundamental process and enhance the infrastructure of research and education by providing hands-on training for undergraduate students, graduate students, and post-doctoral researchers. In addition, it will also allow collaboration with the DESTINY Traveling Science Learning Program to assist in the creation and maintenance of a plant based learning module aimed at fostering science education in grades K-12.