Heterotrimeric G Proteins Serve as a Converging Point in Plant Defense Signaling Activated by Multiple Receptor-Like Kinases
Heterotrimeric G Proteins Serve as a Converging Point in Plant Defense Signaling Activated by Multiple Receptor-Like Kinases
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DOI：
10.1104/pp.112.212431
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发表时间：
2013-04-01
期刊：
影响因子：
7.4
通讯作者：
Zhang, Yuelin
中科院分区：
文献类型：
--
作者：
Liu, Jinman;Ding, Pingtao;Zhang, Yuelin
在真菌和后生动物中，细胞外信号通常被 G 蛋白偶联受体 (GPCR) 感知，并通过异源三聚体 G 蛋白复合物转导至下游靶标。植物异三聚体 G 蛋白也参与多种生物过程，但对其上游受体知之甚少。此外，植物中是否存在真正的 GPCR 尚未确定。在拟南芥 (Arabidopsis thaliana) 中，异三聚体 G 蛋白由 1 个 G α 亚基 (G PROTEIN α-SUBUNIT1)、1 个 G β 亚基 (ARABIDOPSIS G PROTEIN beta-SUBUNIT1 [AGB1]) 和 3 个 G gamma s 亚基 (ARABIDOPSIS G PROTEIN gamma-SUBUNIT1 [AGG1]、AGG2 和 AGG3) 组成。我们从 BAK1 相互作用受体样激酶 1-1 (bir1-1) 的抑制子筛选中鉴定出了 AGB1，bir1-1 是一种突变体，可激活 BIR1-1 受体样激酶 (RLK) 抑制剂介导的细胞死亡和防御反应。 AGB1 突变抑制 bir1-1 和过度表达 SUPPRESSOR OF BIR1-1 的转基因植物中的细胞死亡和防御反应。此外，agb1突变体植物在由其他三种RLK介导的免疫方面受到严重损害，分别是FLAGELLIN-SENSITIVE2（FLS2）、Elongation Factor-TU RECEPTOR（EFR）和几丁质诱导剂受体激酶1（CERK1）。相比之下，bir1-1 中的细胞死亡或由 FLS2、EFR 和 CERK1 介导的病原体相关分子模式触发的免疫不需要 G 蛋白 α-SUBUNIT1。对 agg1 和 agg2 突变植物的进一步分析表明，AGG1 和 AGG2 也是由 FLS2、EFR 和 CERK1 介导的病原体相关分子模式触发的免疫反应以及 bir1-1 中的细胞死亡和防御反应所必需的。我们假设拟南芥异三聚体 G 蛋白通过介导多个 RLK 引发的反应，充当植物防御信号的汇聚点，这可能与真菌和动物中的 GPCR 发挥相同的作用。
In fungi and metazoans, extracellular signals are often perceived by G-protein-coupled receptors (GPCRs) and transduced through heterotrimeric G-protein complexes to downstream targets. Plant heterotrimeric G proteins are also involved in diverse biological processes, but little is known about their upstream receptors. Moreover, the presence of bona fide GPCRs in plants is yet to be established. In Arabidopsis (Arabidopsis thaliana), heterotrimeric G protein consists of one G alpha subunit (G PROTEIN alpha-SUBUNIT1), one G beta subunit (ARABIDOPSIS G PROTEIN beta-SUBUNIT1 [AGB1]), and three G gamma s subunits (ARABIDOPSIS G PROTEIN gamma-SUBUNIT1 [AGG1], AGG2, and AGG3). We identified AGB1 from a suppressor screen of BAK1-interacting receptor-like kinase1-1 (bir1-1), a mutant that activates cell death and defense responses mediated by the receptor-like kinase (RLK) SUPPRESSOR OF BIR1-1. Mutations in AGB1 suppress the cell death and defense responses in bir1-1 and transgenic plants overexpressing SUPPRESSOR OF BIR1-1. In addition, agb1 mutant plants were severely compromised in immunity mediated by three other RLKs, FLAGELLIN-SENSITIVE2 (FLS2), Elongation Factor-TU RECEPTOR (EFR), and CHITIN ELICITOR RECEPTOR KINASE1 (CERK1), respectively. By contrast, G PROTEIN alpha-SUBUNIT1 is not required for either cell death in bir1-1 or pathogen-associated molecular pattern-triggered immunity mediated by FLS2, EFR, and CERK1. Further analysis of agg1 and agg2 mutant plants indicates that AGG1 and AGG2 are also required for pathogen-associated molecular pattern-triggered immune responses mediated by FLS2, EFR, and CERK1, as well as cell death and defense responses in bir1-1. We hypothesize that the Arabidopsis heterotrimeric G proteins function as a converging point of plant defense signaling by mediating responses initiated by multiple RLKs, which may fulfill equivalent roles to GPCRs in fungi and animals.