Mechanism and Regulation of Ethylene Biosythesis

乙烯是一种调节植物生长发育的激素，在农业上具有重要的商业价值。通过提高或降低乙烯生产速率来控制植物中的乙烯水平，是一种适用于许多农业系统优化的有用选择。以1-氨基环丙烷-1-羧酸（ACC）为原料，以s -腺苷蛋氨酸（AdoMet）为原料合成乙烯，并由ACC合成酶和ACC氧化酶两种独特的酶催化。本项目旨在进一步了解乙烯生物合成的机制和调控，为通过生物技术调控作物的乙烯生产及其生理后果奠定理论基础。我们这个拟议项目的主要目标是：(a)表征ACC合酶在植物组织中快速转换的性质，(b)分离出通过生长素特异性表达的番茄ACC合酶基因，并对编码区和调控序列区进行表征，(c)利用位点定向诱变技术研究ACC合酶结构与功能之间的相关性，这些氨基酸残基被认为与磷酸吡多醛辅酶结合有关。(d)进一步表征Co2对Acc氧化酶的激活作用，确定Acc氧化酶的激活位点；(e)研究高温低温胁迫对Acc氧化酶抑制的模式；(f)利用金免疫标记技术阐明Acc氧化酶的亚细胞定位。乙烯是一种调节植物生长发育许多方面的植物激素，它在农业上具有重要的商业作用。通过提高或降低乙烯生产速率来控制植物中的乙烯水平，是一种适用于许多农业系统优化的有用选择。以1-氨基环丙烷-1-羧酸（ACC）为原料，以s -腺苷蛋氨酸（AdoMet）为原料合成乙烯，并由ACC合成酶和ACC氧化酶两种独特的酶催化。本项目旨在进一步了解乙烯生物合成的机制和调控，为通过生物技术调控作物的乙烯生产及其生理后果奠定理论基础。＊＊＊

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. ***