A Pseudomonas syringae effector inactivates MAPKs to suppress PAMP-Induced immunity in plants
A Pseudomonas syringae effector inactivates MAPKs to suppress PAMP-Induced immunity in plants
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DOI：
10.1016/j.chom.2007.03.006
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发表时间：
2007-05-01
影响因子：
30.3
通讯作者：
Zhou, Jian-Min
中科院分区：
文献类型：
--
作者：
Zhang, Jie;Shao, Feng;Zhou, Jian-Min
病原体相关分子模式（pathogen associated molecular patterns, PAMPs）在植物中引发基础防御反应，反过来，病原体已经进化出克服这些PAMPs诱导的防御机制。为了抑制免疫，植物致病菌丁香假单胞菌分泌效应蛋白，其生化功能和毒力靶点尚不清楚。我们发现，在植物和动物细菌病原体中广泛保守的效应物HopAll可以抑制暴露于PAMPs激活的拟南芥丝裂原活化蛋白激酶（MAPKs）。HopAll通过独特的磷酸苏氨酸裂解酶活性从磷酸苏氨酸中去除磷酸基团，从而使MAPKs失活，这是HopAll功能所必需的。HopAl对MAPKs的抑制抑制了两个独立的下游事件，即细胞壁防御的增强和PAMP应答基因的转录激活。MAPKs MPK3和MPK6与HopAll相互作用，表明它们是HopAll的直接靶点。这些发现揭示了丁香假单胞菌克服宿主先天免疫促进发病的机制。
Pathogen-associated molecular patterns (PAMPs) elicit basal defense responses in plants, and, in turn, pathogens have evolved mechanisms to overcome these PAMP-induced defenses. To suppress immunity, the phytopathogenic bacterium Pseudomonas syringae secretes effector proteins, the biochemical function and virulence targets of which remain largely unknown. We show that HopAll, an effector widely conserved in both plantand animal bacterial pathogens, inhibits the Arabidopsis mitogen-activated protein kinases (MAPKs) activated by exposure to PAMPs. HopAll inactivates MAPKs by removing the phosphate group from phosphothreonine through a unique phosphothreonine lyase activity, which is required for HopAll function. The inhibition of MAPKs by HopAl suppresses two independent downstream events, namely the reinforcement of cell wall defense and transcriptional activation of PAMP response genes. The MAPKs MPK3 and MPK6 physically interact with HopAll indicating that they are direct targets of HopAll. These findings uncover a mechanism by which Pseudomonas syringae overcomes host innate immunity to promote pathogenesis.