A Plant Immune Receptor Adopts a Two-Step Recognition Mechanism to Enhance Viral Effector Perception  

作　　者：Jia Li Haining Huang Min Zhu Shen Huang Wenhua Zhang Savithramma P. Dinesh-Kumar Xiaorong Tao 

机构地区：[1]Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, P. R. China [2]College of Life Science, Nanjing Agricultural University, Nanjing 210095, P. R. China [3]Department of Plant Biology and The Genome Center, College of Biological Sciences, University of California, Davis, CA, USA

出　　处：《Molecular Plant》2019年第2期248-262,共15页分子植物（英文版）

基　　金：the National Natural Science Foundation, China (31630062, 31801705 and 31870143);the National Program on Key Basic Research Project, China (973 Program, 2014CB138400);the Youth Talent Support Program, China and Distinguished Professor of Jiangsu Province, China to X.T.;the Natural Science Foundation of Jiangsu Province, China (BK20180532);the Postdoctoral Science Foundation, China (2018M642269) to J.L.;the National Science Foundation grants, United States (NSF-IOS-1354434 and NSF-IOS-1339185) to S.P.D.-K. The materials of tomato wild species were obtained from the UC Davis/C.M;maintained by the Department of Plant Sciences, University of California, Davis, CA.

摘　　要：Plant intracellular nucleotide binding leucine-rich repeat (NLR) immune receptors play critical roles in pathoge n 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 (NSm^21). The specific interaction between Sw-5b SD and NSm is required for releasing the inhibitory effect of coiled-coil domain on the NBARC- 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 NSm^21 levels are high. Interestingly, Sw-5b SD could significantly enhanee 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 NSm^21 . 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 recog nition mechanism to enhance viral effector perception.

关 键 词：plant INNATE immunity nucleotide binding leucine-rich repeat (NLR) immune receptors SOLANACEAE domain (SD) pathogen PERCEPTION TWO-STEP recognition defense response 

分 类 号：Q[生物学]