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。 已经从拟南芥中鉴定出作为乙烯受体的蛋白质家族。 这项研究的重点是了解该受体家族感知和转导乙烯信号的机制。 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。 ETR 1的乙烯结合结构域的定点诱变和对酵母中乙烯结合活性的影响的评估提供了用于测试和改进乙烯结合结构域的结构模型的方法。 在酵母中的表达也将继续提供ETR 1蛋白的来源，用于受体功能的直接生化分析，包括继续分析铜作为结合的辅因子的参与和研究乙烯结合与受体的递质结构域的信号输出之间的关系。 在同一酵母系中的受体的不同亚型的共表达将允许研究受体亚型的异源二聚化是否在信号传导中起作用。在酵母中的工作将通过在突变体和转基因植物中进行的实验来补充，所述实验将提供用于测试关于受体功能的假设的功能背景。 将通过将受体的改变形式转移到野生型植物中并使用幼苗生长响应测定评估对体内乙烯信号传导的影响来评估受体同种型中引入突变的显性效应。 受体无效突变体背景提供了一种以类似方式评估隐性突变影响的方法。 在受体无效的遗传背景下的植物组织中的乙烯结合测定将提供关于每个异构体对植物组织的总体结合活性的贡献的信息。这些实验将得到亚型特异性抗体开发的支持。这项对第一个可用的植物激素受体的研究将提供关于乙烯如何作为激素信号工作的新信息，并将为植物中其他激素受体的研究提供模型。

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.