Molecular Characterization of the Ethylene Receptor ETR1 From Arabidopsis

植物激素乙烯调节生长和发育的许多方面。已从拟南芥中鉴定出一类作为乙烯受体的蛋白质家族。这项研究的重点是了解这一受体家族感知和传递乙烯信号的机制。ETR-1受体蛋白在酵母中的表达为研究乙烯结合位点的结构/功能关系提供了一个模型系统。ETR1的乙烯结合域的定点突变和对酵母中乙烯结合活性的影响的评估为测试和提纯乙烯结合域的结构模型提供了一种方法。在酵母中的表达也将继续为受体功能的直接生化分析提供ETR1蛋白的来源，包括继续分析铜作为结合的辅助因子的参与，以及研究乙烯结合与受体的传递器域信号输出之间的关系。不同受体异构体在同一酵母系中的共表达将允许研究受体异构体的异二聚化是否在信号传递中发挥作用。在酵母中的工作将得到在突变和转基因植物上进行的实验的补充，这些实验将为测试关于受体功能的假说提供功能背景。通过将改变的受体形式转移到野生型植物中，并使用幼苗生长反应试验在体内评估对乙烯信号的影响，将评估受体异构体引入的突变的显性效应。受体零突变背景为以类似的方式评估隐性突变的影响提供了一种方法。在受体缺失的遗传背景中，植物组织中的乙烯结合分析将提供关于每种异构体对植物组织整体结合活性的贡献的信息。这些实验将得到异构体特异性抗体开发的支持。对第一个可用的植物激素受体的研究将为乙烯如何作为激素信号提供新的信息，并将为植物中其他激素受体的研究提供一个模型。

The plant hormone ethylene regulates many aspects of growth and development. A family of proteins that act as receptors for ethylene have been identified from Arabidopsis. This research is focused on gaining an understanding of the mechanism by which this family of receptors perceives and transduces the ethylene signal. Expression of the ETR 1 receptor protein in yeast provides a model system in which to study the structure/function relationships of the ethylene binding site. Site directed mutagenesis of the ethylene binding domain of ETR1 and assessment of effects on ethylene binding activity in yeast provides a method for testing and refining a structural model of the ethylene binding domain. Expression in yeast will also continue to provide a source of the ETR1 protein for direct biochemical analysis of receptor function, including continuing analysis of the involvement of copper as a co-factor for binding and investigations into the relationship between ethylene binding and signal output by the transmitter domain of the receptor. Co-expression of different isoforms of the receptor in the same yeast line will allow the investigation of whether heterodimerization of receptor isoforms plays a role in signaling The work in yeast will be complemented by experiments performed in mutant and transgenic plants that will provide a functional context for testing hypotheses concerning receptor function. Dominant effects of introduced mutations in receptor isoforms will be assessed by transferring altered forms of the receptor into wild-type plants and evaluating the effects on the ethylene signaling in vivo using a seedling growth-response assay. Receptor-null mutant backgrounds provide a method for evaluating the effects of recessive mutations in a similar way. Ethylene binding assays in plant tissues in the receptor-null genetic backgrounds will provide information on the contribution each isoform makes to the overall binding activity of plant tissues. These experiments will be supported by the development of isoform-specific antibodies. This research on the first available plant hormone receptor will provide novel information on how ethylene works as a hormone signal and will provide a model for the investigation of other hormone receptors in plants.