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Elife. 2016 Apr 4;5:e13568. doi: 10.7554/eLife.13568.

Arabidopsis heterotrimeric G proteins regulate immunity by directly coupling to the FLS2 receptor.

Author information

1
State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China.
2
Department of Botany, University of British Columbia, Vancouver, Canada.
3
National Institute of Biological Sciences, Beijing, China.

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.

KEYWORDS:

<i>a. thaliana</i>; cell biology; heterotrimeric G proteins; oxidative burst; phosphorylation; plant biology; plant immunity

PMID:
27043937
PMCID:
PMC4846371
DOI:
10.7554/eLife.13568
[Indexed for MEDLINE]
Free PMC Article

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