清华大学柴继杰等研究人员合作发现，病原体能够直接诱导NLR免疫受体复合物组装形成全酶。该项研究成果发表在2020年12月4日出版的《科学》杂志上。

研究人员表示，通过植物核苷酸结合的亮氨酸富含重复序列（LRR）受体（NLR）直接或间接识别病原体来源的效应蛋白能够启动先天免疫应答。病原体Hyaloperonospora arabidopsidis效应蛋白ATR1激活拟南芥NLR RPP1的N端Toll-白介素1受体（TIR）域。

研究人员报告了ATR1结合时的RPP1冷冻电镜。该结构揭示了一个C-JID结构域（C-terminal jelly roll/Ig-like domain），用于特定的ATR1识别。生化和功能分析表明，ATR1与C-JID和LRR结合，来诱导烟酰胺腺嘌呤二核苷酸水解酶（NADase）活性所需的RPP1四聚体组装。RPP1四聚产生两个潜在的活性位点，每个活性位点由不对称的TIR同型二聚体形成。

这些数据定义了一种直接的效应子识别机制，这是通过一种植物NRL导致的信号活化型全酶的形成来实现。

附：英文原文

Title: Direct pathogen-induced assembly of an NLR immune receptor complex to form a holoenzyme

Author: Shoucai Ma, Dmitry Lapin, Li Liu, Yue Sun, Wen Song, Xiaoxiao Zhang, Elke Logemann, Dongli Yu, Jia Wang, Jan Jirschitzka, Zhifu Han, Paul Schulze-Lefert, Jane E. Parker, Jijie Chai

Issue&Volume: 2020/12/04

Abstract: Direct or indirect recognition of pathogen-derived effectors by plant nucleotide-binding leucine-rich repeat (LRR) receptors (NLRs) initiates innate immune responses. The Hyaloperonospora arabidopsidis effector ATR1 activates the N-terminal Toll–interleukin-1 receptor (TIR) domain of Arabidopsis NLR RPP1. We report a cryo–electron microscopy structure of RPP1 bound by ATR1. The structure reveals a C-terminal jelly roll/Ig-like domain (C-JID) for specific ATR1 recognition. Biochemical and functional analyses show that ATR1 binds to the C-JID and the LRRs to induce an RPP1 tetrameric assembly required for nicotinamide adenine dinucleotide hydrolase (NADase) activity. RPP1 tetramerization creates two potential active sites, each formed by an asymmetric TIR homodimer. Our data define the mechanism of direct effector recognition by a plant NLR leading to formation of a signaling-active holoenzyme.

DOI: 10.1126/science.abe3069

Source: https://science.sciencemag.org/content/370/6521/eabe3069