An ATPase promotes autophosphorylation of the pattern recognition receptor XA21 and inhibits XA21-mediated immunity

Xuewei Chen, Mawsheng Chern, Patrick E. Canlas, Deling Ruan, Caiying Jiang, Pamela C. Ronald
Proc Natl Acad Sci USA, 2010, 107(17): 8029-8034  DOI: 10.1073/pnas.0912311107     追溯原文......本站官方QQ群:62473826
non-RD kinase; pathogen-associated molecular pattern; pattern recognition receptor; ATPase; rice

Cell-surface pattern recognition receptors (PRRs) are key components of the innate immune response in animals and plants. These receptors typically carry or associate with non-RD kinases to control early events of innate immunity signaling. Despite their importance, the mode of regulation of PRRs is largely unknown. Here we show that the rice PRR, XA21, interacts with XA21 binding protein 24 (XB24), a previously undescribed ATPase. XB24 promotes autophosphorylation of XA21 through its ATPase activity. Rice lines silenced for Xb24 display enhanced XA21-mediated immunity, whereas rice lines overexpressing XB24 are compromised for immunity. XB24 ATPase enzyme activity is required for XB24 function. XA21 is degraded in the presence of the pathogen-associated molecular pattern Ax21 when XB24 is overexpressed. These results demonstrate a function for this large class of broadly conserved ATPases in PRR-mediated immunity.

一个促进模式识别受体XA21自身磷酸化并抑制XA21介导的免疫反应的ATP酶的研究

细胞表面的模式识别受体(PRRs)是动植物先天免疫反应的关键组成部分。这些受体通常都带有非RD(精氨酸,天冬氨酸)激酶(非RD激酶在激酶亚结构域VI缺乏保守的R)或与之相关,从而控制先天免疫信号传导的早期事件。尽管这些受体非常重要,但人们关于PPRs的调控却知之甚少。Chen等(2010)报道了与水稻模式识别受体XA21互作的结合蛋白24(XB24),XB24之前是一个未知功能的ATP酶。XB24通过其ATP酶活性可以促进XA21的自身磷酸化,同时,当Xb24被沉默的转基因植株表现出了增强的XA21介导的免疫反应,而过表达XB24的株系则表现为减弱的抗性反应。实验证明XB24的ATP酶活性是其功能不可或缺的。在XB24过表达,且存在病原相关分子模式Ax21时,XA21被降解。这些结果都说明了这类广泛保守的ATP酶在PRR介导的免疫反应中的作用。
结果 XB24与XA21在体内存在直接相互作用 在PXO99接种下,XB24从XA21上解离 XB24拥有ATP酶活性 ATP酶XB24增强了XA21K668的自身磷酸化 沉默Xb24,则增强了XA21介导的抗性反应 XB24的过表达减弱了XA21介导的抗性 ATP酶活性是XB24调控XA21功能所必需的 XB24的过表达会引起识别Ax21后XA21的不稳定
讨论 XB24介导的调控XA21的模型 XB24是一类之前未知的ATP酶


本文涉及的功能基因
  白叶枯病抗性基因 Xa21; Xa-21
  XA21结合蛋白基因 XB24