EL1-like Casein Kinases Suppress ABA Signaling and Responses by Phosphorylating and Destabilizing the ABA Receptors PYR/PYLs in Arabidopsis  

作　　者：Hu-Hui Chen Li Qu Zhi-Hong Xu Jian-Kang Zhu Hong-Wei Xue 

机构地区：[1]National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology Chinese Academy of Sciences, 300 Fenglin Road, 200032 Shanghai, China [2]University of Chinese Academy of Sciences, 100049 Beijing, China [3]Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, 200032 Shanghai, China [4]Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN, USA

出　　处：《Molecular Plant》2018年第5期706-719,共14页分子植物（英文版）

摘　　要：Unveiling the signal transduction of phytohormone abscisic acid （ABA） and its regulatory mechanisms is critical for developing the strategies toward improving plant responses to stressful environments. ABA signaling is perceived and mediated by multiple PYR/PYL receptors, whose post-translational modifications, especially phosphorylation, remain largely unknown. In this study, we demonstrate thatArabidopsis ELl-like （AEL） protein, a casein kinase that regulates various physiological processes, phosphorylate PYR/PYLs to promote their ubiquitination and degradation, resulting in suppressed ABA responses. Arabidopsis ael triple mutants display hypersensitive responses to ABA treatment, which is consistent with the suppressed degradation of PYR/PYL proteins. PYR/PYLs are phosphorylated in vivo and mutation of the conserved AEL phosphorylation sites results in reduced phosphorylation, ubiquitination, and degradation of PYR/PYLs, and hence enhanced ABA responses. Taken together, these results demonstrate that AEL-mediated phosphorylation plays crucial roles in regulating the stability and function of PYR/ PYLs, providing significant insights into the post-translational regulation of PYR/PYL receptors and ABA signaling.Unveiling the signal transduction of phytohormone abscisic acid （ABA） and its regulatory mechanisms is critical for developing the strategies toward improving plant responses to stressful environments. ABA signaling is perceived and mediated by multiple PYR/PYL receptors, whose post-translational modifications, especially phosphorylation, remain largely unknown. In this study, we demonstrate thatArabidopsis ELl-like （AEL） protein, a casein kinase that regulates various physiological processes, phosphorylate PYR/PYLs to promote their ubiquitination and degradation, resulting in suppressed ABA responses. Arabidopsis ael triple mutants display hypersensitive responses to ABA treatment, which is consistent with the suppressed degradation of PYR/PYL proteins. PYR/PYLs are phosphorylated in vivo and mutation of the conserved AEL phosphorylation sites results in reduced phosphorylation, ubiquitination, and degradation of PYR/PYLs, and hence enhanced ABA responses. Taken together, these results demonstrate that AEL-mediated phosphorylation plays crucial roles in regulating the stability and function of PYR/ PYLs, providing significant insights into the post-translational regulation of PYR/PYL receptors and ABA signaling.

关 键 词：ARABIDOPSIS ABA AEL （Arabidopsis EL1 -like） PYR/PYLs PHOSPHORYLATION degradation 

分 类 号：Q516[生物学—生物化学] X173[环境科学与工程—环境科学]