小柯机器人

清华大学柴继杰等研究人员合作阐明一种微生物配糖水解酶对植物受体样蛋白的激活作用。2022年9月21日，《自然》杂志在线发表了这项成果。

据研究人员介绍，植物依靠细胞表面定位的模式识别受体来检测病原体或宿主发出的危险信号并触发免疫反应。具有富含亮氨酸重复（LRR）外域的受体样蛋白（RLP）构成了模式识别受体的一个亚组，在植物免疫中发挥着关键作用。LRR-RLP的配体识别和激活的机制仍然难以确定。

研究人员报告了来自本氏烟（Nicotiana benthamiana）的LRR-RLP RXEG1的晶体结构，它可以识别来自病原体大豆疫霉菌（Phytophthora sojae）的XEG1木葡聚糖酶。该结构显示，特定的XEG1识别主要是由RXEG1的一个氨基端和一个羧基端环出区域（RXEG1(ID)）介导的。这两个环与XEG1的活性位点槽结合，抑制其酶的活性，并抑制N. benthamiana的疫霉感染。XEG1的结合促进了RXEG1(LRR)通过RXEG1(ID)和最后四个保守的LRR与LRR型共受体BAK1的结合，从而引发RXEG1介导的免疫反应。Apo-RXEG1（LRR）、XEG1-RXEG1（LRR）和XEG1-BAK1-RXEG1（LRR）的结构比较显示，XEG1的结合诱导了RXEG1（ID）N端区域的构象变化，增强了RXEG1（LRR）的BAK1结合区域的结构灵活性。这些变化使RXEG1(ID)的褶皱切换，以便招募BAK1(LRR)。

这些数据揭示了配体诱导的LRR-RLP与BAK1异源二聚体化的保守机制，并表明LRR-RLP在植物免疫中的双重功能。

附：英文原文

Title: Plant receptor-like protein activation by a microbial glycoside hydrolase

Author: Sun, Yue, Wang, Yan, Zhang, Xiaoxiao, Chen, Zhaodan, Xia, Yeqiang, Wang, Lei, Sun, Yujing, Zhang, Mingmei, Xiao, Yu, Han, Zhifu, Wang, Yuanchao, Chai, Jijie

Issue&Volume: 2022-09-21

Abstract: Plants rely on cell-surface-localized pattern recognition receptors to detect pathogen- or host-derived danger signals and trigger an immune response1,2,3,4,5,6. Receptor-like proteins (RLPs) with a leucine-rich repeat (LRR) ectodomain constitute a subgroup of pattern recognition receptors and play a critical role in plant immunity1,2,3. Mechanisms underlying ligand recognition and activation of LRR-RLPs remain elusive. Here we report a crystal structure of the LRR-RLP RXEG1 from Nicotiana benthamiana that recognizes XEG1 xyloglucanase from the pathogen Phytophthora sojae. The structure reveals that specific XEG1 recognition is predominantly mediated by an amino-terminal and a carboxy-terminal loop-out region (RXEG1(ID)) of RXEG1. The two loops bind to the active-site groove of XEG1, inhibiting its enzymatic activity and suppressing Phytophthora infection of N. benthamiana. Binding of XEG1 promotes association of RXEG1(LRR) with the LRR-type co-receptor BAK1 through RXEG1(ID) and the last four conserved LRRs to trigger RXEG1-mediated immune responses. Comparison of the structures of apo-RXEG1(LRR), XEG1–RXEG1(LRR) and XEG1–BAK1–RXEG1(LRR) shows that binding of XEG1 induces conformational changes in the N-terminal region of RXEG1(ID) and enhances structural flexibility of the BAK1-associating regions of RXEG1(LRR). These changes allow fold switching of RXEG1(ID) for recruitment of BAK1(LRR). Our data reveal a conserved mechanism of ligand-induced heterodimerization of an LRR-RLP with BAK1 and suggest a dual function for the LRR-RLP in plant immunity.

DOI: 10.1038/s41586-022-05214-x

Source: https://www.nature.com/articles/s41586-022-05214-x

Nature：《自然》，创刊于1869年。隶属于施普林格·自然出版集团，最新IF：69.504
官方网址：http://www.nature.com/
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