title: Arabidopsis heterotrimeric G proteins regulate immunity by directly coupling to the FLS2 receptor.
abstract: The Arabidopsis immune receptor FLS2 perceives bacterial flagellin epitope flg22 to activate defenses through the central cytoplasmic kinase BIK1. The heterotrimeric G proteins composed of the non-canonical Gα protein XLG2, the Gβ protein AGB1, and the Gγ proteins AGG1 and AGG2 are required for FLS2-mediated immune responses through an unknown mechanism. Here we show that in the pre-activation state, XLG2 directly interacts with FLS2 and BIK1, and it functions together with AGB1 and AGG1/2 to attenuate proteasome-mediated degradation of BIK1, allowing optimum immune activation. Following the activation by flg22, XLG2 dissociates from AGB1 and is phosphorylated by BIK1 in the N terminus. The phosphorylated XLG2 enhances the production of reactive oxygen species (ROS) likely by modulating the NADPH oxidase RbohD. The study demonstrates that the G proteins are directly coupled to the FLS2 receptor complex and regulate immune signaling through both pre-activation and post-activation mechanisms.
authors.affiliation: State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China.
authors.forename: Xiangxiu
authors.initials: X
authors.lastname: Liang
authors.affiliation: Department of Botany, University of British Columbia, Vancouver, Canada.
authors.forename: Pingtao
authors.identifier: http://orcid.org/0000-0002-3535-6053
authors.initials: P
authors.lastname: Ding
authors.affiliation: Department of Botany, University of British Columbia, Vancouver, Canada.
authors.forename: Kehui
authors.initials: K
authors.lastname: Lian
authors.affiliation: State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China.
authors.forename: Jinlong
authors.initials: J
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China.
authors.forename: Miaomiao
authors.initials: M
authors.lastname: Ma
authors.affiliation: National Institute of Biological Sciences, Beijing, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Li
authors.affiliation: State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Li
authors.affiliation: State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China.
authors.forename: Meng
authors.initials: M
authors.lastname: Li
authors.affiliation: State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China.
authors.forename: Xiaojuan
authors.initials: X
authors.lastname: Zhang
authors.affiliation: National Institute of Biological Sciences, Beijing, China.
authors.forename: She
authors.initials: S
authors.lastname: Chen
authors.affiliation: Department of Botany, University of British Columbia, Vancouver, Canada.
authors.forename: Yuelin
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China.
authors.forename: Jian-Min
authors.identifier: http://orcid.org/0000-0002-9943-2975
authors.initials: JM
authors.lastname: Zhou
mesh_terms: D000942:Antigens, Bacterial / Q000276:immunology; D017360:Arabidopsis / Q000276:immunology*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D005408:Flagellin / Q000276:immunology; D020962:Heterotrimeric GTP-Binding Proteins / Q000378:metabolism*; D011485:Protein Binding; D011494:Protein Kinases / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D000942:Antigens, Bacterial; D029681:Arabidopsis Proteins; D017382:Reactive Oxygen Species; D005408:Flagellin; D011494:Protein Kinases; C411853:FLS2 protein, Arabidopsis; D020962:Heterotrimeric GTP-Binding Proteins
keywords: <i>a. thaliana</i>; cell biology; heterotrimeric G proteins; oxidative burst; phosphorylation; plant biology; plant immunity