BAK1-mediated phosphorylation of canonical G protein alpha during flagellin signaling in Arabidopsis.
BAK1-mediated phosphorylation of canonical G protein alpha during flagellin signaling in Arabidopsis.
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DOI：
10.1111/jipb.12824
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发表时间：
2020-05
影响因子：
11.4
通讯作者：
Jiao Xue;Ben-Qiang Gong;Xinran Yao;Xiangjuan Huang;Jian-Feng Li
中科院分区：
文献类型：
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作者：
Jiao Xue;Ben-Qiang Gong;Xinran Yao;Xiangjuan Huang;Jian-Feng Li
异源三聚体G蛋白是由Gα、Gβ和Gγ组成的真核生物中保守的信号中枢。在没有典型的动物G蛋白偶联受体类似物的情况下，植物细胞被认为采用RGS1和未知的机制来调节Gα的活性。同时，经典Gα在植物天然免疫中的确切作用仍存在争议。在这里，我们报告了拟南芥Gα（GPA 1）的无效等位基因在响应细菌flg22激发子的多重免疫缺陷，阐明了GPA 1在flg22信号传导中的正调控作用。我们还检测到flg22诱导后GPA 1磷酸化总体增加，但Thr19磷酸化减少。有趣的是，flg22不能诱导GPA 1T19A和GPA 1T19D的磷酸化，这表明动态Thr 19磷酸化是GPA 1响应flg22所必需的。此外，在体内不存在BAK1的情况下，flg22诱导的GPA 1磷酸化在很大程度上被消除，并且BAK1可以在体外在体内鉴定的磷酸化位点磷酸化GPA 1而不是GPA 1T19A，这表明BAK1可能是响应flg22的GPA 1磷酸化的激酶。此外，T19A突变可促进flg22诱导的GPA 1和RGS1之间的结合，而不是解离。综上所述，我们的研究结果揭示了新的见解GPA1在拟南芥防御信号的功能和调节。本文受版权保护。All rights reserved.
Heterotrimeric G proteins consisting of Gα, Gβ and Gγ are conserved signaling hubs in eukaryotes. Without analogs to canonical animal G protein-coupled receptors, plant cells are thought to employ RGS1 and yet unknown mechanism to regulate the activity of Gα. Meanwhile, the exact role of canonical Gα in 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 Thr19 upon flg22 elicitation. Interestingly, flg22 could not induce phosphorylation of GPA1T19A and GPA1T19D , suggesting that the dynamic Thr19 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 GPA1T19A 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. This article is protected by copyright. All rights reserved.