Ethylene Controls Autophosphorylation of the Histidine Kinase Domain in Ethylene Receptor ETR1  

作　　者：Jan Voet-van-Vormizeele Georg Groth 

机构地区：[1]Heinrich-Heine-Universitat, Biochemie der Pflanzen, Universitatsstr. 1, 40225 Duisseldorf, Germany

出　　处：《Molecular Plant》2008年第2期380-387,共8页分子植物（英文版）

摘　　要：Perception of the phytohormone ethylene is accomplished by a small family of integral membrane receptors. In Arabidopsis, five ethylene receptor proteins are known, including ethylene resistant I （ETR1）. The hydrophobic aminoterminal domain of these receptors contains the ethylene-binding site while the carboxyl-terminal part consists of a histidine kinase domain and a response regulator domain, which are well known elements found in bacterial two-component signaling. The soluble membrane-extrinsic carboxyl-terminal part of the receptor, which is likely to play an important role in signal transduction, showed intrinsic kinase activity when expressed and purified on its own. However, a correlation between signal input and autokinase activity was not established in these studies, as receptors were missing the trans- membrane amino-terminal sensor domain. Thus, it is still unclear whether autophosphorylation occurs in response to perception of the ethylene signal. Here, we report on autophosphorylation studies of purified full-length ETR1. Autoki- nase activity of the purified receptor is controlled by ethylene or by ethylene agonists like the π-acceptor compound cyanide. In fact, both signal molecules were able to completely turn off the intrinsic kinase activity, Furthermore, the observed inhibition of autophosphorylation in ETR1 by both molecules could be prevented when the ethylene antagonist 1-methyl-cyclopropene （MOP） was applied.Perception of the phytohormone ethylene is accomplished by a small family of integral membrane receptors. In Arabidopsis, five ethylene receptor proteins are known, including ethylene resistant I （ETR1）. The hydrophobic aminoterminal domain of these receptors contains the ethylene-binding site while the carboxyl-terminal part consists of a histidine kinase domain and a response regulator domain, which are well known elements found in bacterial two-component signaling. The soluble membrane-extrinsic carboxyl-terminal part of the receptor, which is likely to play an important role in signal transduction, showed intrinsic kinase activity when expressed and purified on its own. However, a correlation between signal input and autokinase activity was not established in these studies, as receptors were missing the trans- membrane amino-terminal sensor domain. Thus, it is still unclear whether autophosphorylation occurs in response to perception of the ethylene signal. Here, we report on autophosphorylation studies of purified full-length ETR1. Autoki- nase activity of the purified receptor is controlled by ethylene or by ethylene agonists like the π-acceptor compound cyanide. In fact, both signal molecules were able to completely turn off the intrinsic kinase activity, Furthermore, the observed inhibition of autophosphorylation in ETR1 by both molecules could be prevented when the ethylene antagonist 1-methyl-cyclopropene （MOP） was applied.

关 键 词：ethylene pathway phytohormone receptor membrane protein two-component system SIGNALTRANSDUCTION Arabidopsis thaliana 

分 类 号：Q946.885[生物学—植物学] TQ221.211[化学工程—有机化工]