BAK1-mediated phosphorylation of canonical G protein alpha during flagellin signaling in Arabidopsis  

作　　者：Jiao Xue Ben-Qiang Gong Xinran Yao Xiangjuan Huang Jian-Feng Li 

机构地区：[1]Guangdong Provincial Key Laboratory of Plant Resources,State Key Laboratory of Biocontrol,MOE Key Laboratory of Gene Function and Regulation,School of Life Sciences,Sun Yat-sen University,Guangzhou 510275,China

出　　处：《Journal of Integrative Plant Biology》2020年第5期690-701,共12页植物学报（英文版）

基　　金：supported by the National Natural Science Foundation of China(31770295 and 31570276)。

摘　　要：Heterotrimeric G proteins consisting of Gα,Gβand Gγare conserved signaling hubs in eukaryotes.Without analogs to canonical animal G protein-coupled receptors,plant cells are thought to use RGS1 and a yet unknown mechanism to regulate the activity of Gα.Meanwhile,the exact role of canonical Gαin plant innate immunity remains controversial.Here,we report multiple immune deficiencies in the null allele of Arabidopsis Gα(GPA1)in response to bacterial flg22 elicitor,clarifying a positive regulatory role of GPA1 in flg22 signaling.We also detect overall increased phosphorylation of GPA1 but reduced phosphorylation at Thr^19 upon flg22 elicitation.Interestingly,flg22 could not induce phosphorylation of GPA1 T19 Aand GPA1 T19D,suggesting that the dynamic Thr^19 phosphorylation is required for GPA1 to respond to flg22.Moreover,flg22-induced GPA1 phosphorylation is largely abolished in the absence of BAK1 in vivo,and BAK1 could phosphorylate GPA1 but not GPA1^T19A in vitro at the phosphorylation sites identified in vivo,suggesting BAK1 is likely the kinase for GPA1 phosphorylation in response to flg22.Furthermore,the T19A mutation could promote flg22-induced association,rather than dissociation,between GPA1 and RGS1.Taken together,our findings shed new insights into the function and regulation of GPA1 in Arabidopsis defense signaling.

关 键 词：PHOSPHORYLATION ARABIDOPSIS IMMUNITY 

分 类 号：Q943.2[生物学—植物学]