Molecular Characterization of the Ethylene Receptor ETRI from Arabidopsis

在高等植物中，气体激素乙烯调节着许多重要的发育过程。在拟南芥中，参与乙烯感知的初始生化事件正在被研究。植物的ETR1基因编码一种与细菌感觉受体蛋白序列同源的蛋白。ETR1基因的突变使其对乙烯不敏感。通过在酵母中表达ETR1基因，发现转化后的酵母将乙烯与ETR1蛋白结合，证实了ETR1编码蛋白作为乙烯受体的作用。利用酵母表达系统，将表达ETR1蛋白的改变形式，以研究其结合和信号转导的机制。利用体外诱变技术，对该蛋白的单个氨基酸残基进行特异性改变，分析改变后的蛋白在转基因酵母中表达时结合乙烯的能力，并将乙烯信号转导转基因植物。结合其他来源资助的从酵母中纯化ETR1蛋白的工作，拟议的研究将用于构建该植物激素受体作用机制的分子模型。此外，在这项研究中发现的ETR1基因的新突变形式将为生物技术专家提供基因工程改变经济上重要植物物种的乙烯敏感性的能力。＊＊＊

9513463 Bleecker The gaseous hormone ethylene regulates a number of important developmental processes in higher plants. The initial biochemical events involved in ethylene perception are being investigated in the plant Arabidopsis thaliana. The ETR1 gene in the plant codes for a protein with sequence homology to sensory receptor proteins of bacteria. Mutations in the ETR1 gene confer dominant insensitivity to ethylene. The role of the protein coded by ETR1 as an ethylene receptor was confirmed by expressing the ETR1 gene in yeast and finding that the transformed yeast binds ethylene to the ETR1 protein. Using the yeast expression system, altered forms of the ETR1 protein will be expressed to investigate the mechanism of binding and signal transduction. Using in vitro mutagenesis, effects of specific changes in single amino acid residues of the protein will be followed by analysis of the ability of the altered protein to bind ethylene when expressed in transgenic yeast, and to transduce the ethylene signal transgenic plants. In conjunction with work funded by other sources on the purification of the ETR1 protein from yeast, the proposed research will be used to construct a molecular model for the mechanism of action of this plant hormone receptor. In addition the novel mutant forms of the ETR1 gene identified in this study will provide biotechnologists with the ability to genetically engineer alterations in ethylene sensitivity in economically important plant species. ***