Mechanism and Regulation of Ethylene Biosythesis

乙烯是一种调节植物生长发育的植物激素，在农业生产中具有重要的经济意义。 通过增加或降低乙烯产生速率来操纵植物中的乙烯水平是适用于许多农业系统优化的有用选择。 已经确定的是，乙烯是由S-腺苷甲硫氨酸（S-adenosylmethionine，S-Met）通过1-氨基环丙烷-1-羧酸（1-aminocyclopropane-1-carboxylic acid，ACC）生物合成的，并且该反应由两种独特的酶ACC合成酶和ACC氧化酶催化。 本项目的目的是获得关于乙烯生物合成的机制和调控的进一步信息，这些信息可以用于建立理论基础，从而可以通过生物技术调节作物植物的乙烯产生及其生理后果。 我们建议的项目的主要目标是：（a）表征ACC合酶在植物组织中快速周转的性质，（B）分离通过生长素施用特异性表达的番茄ACC合酶基因，并表征编码和调节序列区，（c）使用参与结合辅酶磷酸吡哆醛的氨基酸残基pu113的定点诱变来研究ACC合酶的结构和功能之间的相关性，（d）进一步研究CO_2对ACC氧化酶的激活作用并确定其激活位点;（e）研究高温和低温胁迫对ACC氧化酶的抑制方式;（f）利用胶体金免疫标记技术研究ACC氧化酶的亚细胞定位。 乙烯是一种植物激素，调节植物生长和发育的许多方面，其作用在农业中具有重要的商业意义。 通过增加或降低乙烯产生速率来操纵植物中的乙烯水平是适用于许多农业系统优化的有用选择。 已经确定的是，乙烯是由S-腺苷甲硫氨酸（S-adenosylmethionine，S-Met）通过1-氨基环丙烷-1-羧酸（1-aminocyclopropane-1-carboxylic acid，ACC）生物合成的，并且该反应由两种独特的酶ACC合成酶和ACC氧化酶催化。 本项目的目的是获得关于乙烯生物合成的机制和调控的进一步信息，这些信息可以用于建立理论基础，从而可以通过生物技术调节作物植物的乙烯产生及其生理后果。 ***

Yang 9303801 Ethylene is a plant hormone regulating many aspects of plant growth and development, and its effects are commercially important in agriculture. Manipulation of the levels of ethylene in plants, either by increasing or decreasing ethylene production rates, is a useful option applicable to the optimization of many agricultural systems. It has been established that ethylene is biosynthesized from S-adenosylmethionine (AdoMet) via 1-aminocyclopropane-1- carboxylic acid (ACC), and the reactions are catalyzed by two unique enzymes, ACC synthase and ACC oxidase. The aim of the present project is to obtain further information about the mechanism and regulation of ethylene biosynthesis which can be used to establish a theoretical basis from which ethylene production by crop plants and its physiological consequences can be regulated via biotechnology. Our primary objectives of this proposed project are: (a) to characterize the nature of the rapid turnover of ACC synthase in plant tissue, (b) to isolate tomato ACC synthase genes that are specifically expressed by auxin application, and to characterize both coding and regulatory sequence regions, (c) to study the correlation between structure and function of ACC synthase using site-directed mutagenesis of amino acid residues putatively involved in binding the coenzyme pyridoxal phosphate, (d) to further characterize the activation of Acc oxidase by Co2 and to identify the activation site of the enzyme, (e) to study the mode of high temperature and chilling stress on the inhibition of ACC oxidase, and (f) to elucidate subcellular localization of ACC oxidase using gold-immuno labeling techniques. %%% Ethylene is a plant hormone regulating many aspects of plant growth and development, and its effects are commercially important in agriculture. Manipulation of the levels of ethylene in plants, either by increasing or decreasing ethylene production rates, is a useful option applicable to the optimization of many agricultural systems. It has been established that ethylene is biosynthesized from S-adenosylmethionine (AdoMet) via 1-aminocyclopropane-1- carboxylic acid (ACC), and the reactions are catalyzed by two unique enzymes, ACC synthase and ACC oxidase. The aim of the present project is to obtain further information about the mechanism and regulation of ethylene biosynthesis which can be used to establish a theoretical basis from which ethylene production by crop plants and its physiological consequences can be regulated via biotechnology. ***