Ligand-triggered de-repression of Arabidopsis heterotrimeric G proteins coupled to immune receptor kinases  

作　　者：Xiangxiu Liang Miaomiao Ma ,Zhaoyang Zhou Jinlong Wang Xinru Yang Shaofei Rao Guozhi Bi Lin Li Xiaojuan Zhang Jijie Chai She Chen Jian-Min Zhou 

机构地区：[1]State Key Laboratory of Plant Genomics, institute of Genetics and Developmental Biology, Chinese Academy of Sciences, 100101 Beijing, China [2]State Key Laboratory of Plant Genomics, institute of Microbiology, Chinese Academy of Sciences, 100101 Beijing, China [3]University of Chinese Academy of Sciences, 100049 Beijing, China [4]Center for Plant Biology, School of Life Sciences, Tsinghua University, 100084 Beijing, Chin [5]National Institute of Biological Sciences, 102206 Beijing, China

出　　处：《Cell Research》2018年第5期529-543,共15页细胞研究（英文版）

基　　金：The work was supported by grants from the Chinese Natural Science Foundation （31521001）, Chinese Ministry of Science and Technology （Grant No. 2015CB910200）, the Strategic Priority Research Program of the Chinese Academy of Sciences （Grant No. XDB11020200）, and the State Key Laboratory of Plant Genomics （SKLPG20168-2） to J.M.Z.

摘　　要：Arabidopsis heterotrimeric G proteins regulate diverse processes by coupling to single-transmembrane receptors. One such receptor is the FLS2 receptor kinase, which perceives bacterial flagellin epitope fig22 to activate immunity through a class of cytoplasmic kinases called BIKI/PBLs. Unlike animal and fungal heterotrimeric G proteins that are activated by a ligand-induced guanine nucleotide exchange activity of seven-transmembrane G protein-coupled receptors （GPCRs）, plant heterotrimeric G proteins are self-activating. How plant receptors regulate heterotrimeric G proteins in response to external ligands remains unknown. Here we show that RGS1, a GTPase accelerating protein, maintains Arabidopsis G proteins in an inactive state in complex with FLS2. Activation of FLS2 by fig22 induces a BIK1/PBL-mediated phosphorylation of RGS1 at Ser428 and Ser431 and that promotes RGS1 dissociation from the FLS2-G protein complex. This relieves G proteins from the RGSl-mediated repression and enables positive regulation of immune signaling. We additionally show that RGS1 is similarly regulated by multiple immune receptors. Our results uncover ligand-induced de-repression as a mechanism for G protein signaling in plants that is distinct from previously reported mechanism underlying the activation of heterotrimeric G proteins in other systems.

关 键 词：ARABIDOPSIS 蛋白质 免疫力 受体 触发 GTPASE 建筑群 激活 

分 类 号：Q51[生物学—生物化学] X173[环境科学与工程—环境科学]