A Plant Immune Receptor Adopts a Two-Step Recognition Mechanism to Enhance Viral Effector Perception
A Plant Immune Receptor Adopts a Two-Step Recognition Mechanism to Enhance Viral Effector Perception
复制标题
植物免疫受体采用两步识别机制来增强病毒效应子感知
DOI：
10.1016/j.molp.2019.01.005
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发表时间：
2019-02-04
期刊：
影响因子：
27.5
通讯作者：
Tao, Xiaorong
中科院分区：
文献类型：
--
作者：
Li, Jia;Huang, Haining;Tao, Xiaorong
植物富含亮氨酸重复序列(NLR)的细胞内核苷酸结合免疫受体在病原菌监测中起着关键作用。到目前为止，大多数植物NLR被发现使用单一的结构域/传感器来识别病原体效应器。在这里，我们报告了Sw-5b NLR免疫受体使用两个不同的结构域来检测由TospoVirus编码的病毒运动蛋白NSM。除了先前报道的富含亮氨酸重复序列(LRR)结构域外，Sw-5b的N端茄科结构域(SD)还与NSM以及NSM的一个保守的21个氨基酸区域(NSm21)相互作用。Sw-5b SD与NSM之间的特异性相互作用需要释放螺旋线圈结构域对Nb-ARC-LRR区域的抑制作用。此外，我们还发现NSM的结合影响了Nb-ARC-LRR的体外核苷酸结合活性，而Sw-5b Nb-ARC-LRR只有在NSM和NSm21水平较高时才被激活。有趣的是，Sw-5b SD可以显著增强NB-ARC-LRR检测低水平NSM效应的能力，并促进其激活和诱导防御反应。在NSM识别中被破坏的Sw-5b SD突变体未能增强NB-ARC-LRR检测低水平NSM和NSm21的能力。综上所述，我们的结果表明，SW-5b SD作为额外的传感器，NB-ARC-LRR作为激活剂，而SW-5b NLR采用两步识别机制来增强病毒效应器的感知。
Plant intracellular nucleotide binding leucine-rich repeat (NLR) immune receptors play critical roles in pathogen surveillance. Most plant NLRs characterized so far were found to use a single domain/sensor to recognize pathogen effectors. Here we report that the Sw-5b NLR immune receptor uses two distinct domains to detect the viral movement protein NSm encoded by tospovirus. In addition to its leucine-rich repeat (LRR) domain that has been previously reported, the N-terminal Solanaceae domain (SD) of Sw-5b also interacts with NSm and a conserved 21-amino-acid region of NSm (NSm21). The specific interaction between Sw-5b SD and NSm is required for releasing the inhibitory effect of coiled-coil domain on the NB-ARC-LRR region. Furthermore, we found that the binding of NSm affects the nucleotide binding activity of the NB-ARC-LRR in vitro, while Sw-5b NB-ARC-LRR is activated only when NSm and NSm21 levels are high. Interestingly, Sw-5b SD could significantly enhance the ability of the NB-ARC-LRR to detect low levels of NSm effector and facilitate its activation and induction of defense response. An Sw-5b SD mutant that is disrupted in NSm recognition failed to enhance the ability of the NB-ARC-LRR to sense low levels of NSm and NSm21. Taken together, our results suggest that Sw-5b SD functions as an extra sensor and the NB-ARC-LRR as an activator, and that Sw-5b NLR adopts a two-step recognition mechanism to enhance viral effector perception.