The Sw-5b NLR nucleotide-binding domain plays a role in oligomerization, and its self-association is important for activation of cell death signaling

文献类型： 外文期刊

第一作者： Zhao, Xiaohui

作者： Zhao, Xiaohui;Chen, Zhengqiang;Wu, Qian;Cai, Yazhen;Zhang, Yu;Zhao, Ruizhen;Yan, Jiaoling;Qian, Xin;Li, Jia;Zhu, Min;Ding, Xin Shun;Tao, Xiaorong;Zhao, Xiaohui;Hong, Lizhou;Xing, Jincheng;Khan, Nasr Ullah;Ji, Yinghua;Wu, Peijun;Huang, Changjun;Zhang, Hui

作者机构：

关键词： HR-associated cell death; NLR; nucleotide binding domain; oligomerization; self-association; Sw-5b

期刊名称：JOURNAL OF EXPERIMENTAL BOTANY （ 影响因子：6.992； 五年影响因子：7.86 ）

ISSN： 0022-0957

年卷期： 2021 年 72 卷 18 期

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收录情况： SCI

摘要： Plant and animal intracellular nucleotide-binding and leucine-rich repeat (NLR) receptors play important roles in sensing pathogens and activating defense signaling. However, the molecular mechanisms underlying the activation of host defense signaling by NLR proteins remain largely unknown. Many studies have determined that the coil-coil (CC) or Toll and interleukin-1 receptor/resistance protein (TIR) domain of NLR proteins and their dimerization/oligomerization are critical for activating downstream defense signaling. In this study, we demonstrated that, in tomato, the nucleotide-binding (NB) domain Sw-5b NLR alone can activate downstream defense signaling, leading to elicitor-independent cell death. Sw-5b NB domains can self-associate, and this self-association is crucial for activating cell death signaling. The self-association was strongly compromised after the introduction of a K568R mutation into the P-loop of the NB domain. Consequently, the NBK568R mutant induced cell death very weakly. The NBC Delta 20 mutant lacking the C-terminal 20 amino acids can self-associate but cannot activate cell death signaling. The NBC Delta 20 mutant also interfered with wild-type NB domain self-association, leading to compromised cell death induction. By contrast, the NBK568R mutant did not interfere with wild-type NB domain self-association and its ability to induce cell death. Structural modeling of Sw-5b suggests that NB domains associate with one another and likely participate in oligomerization. As Sw-5b-triggered cell death is dependent on helper NLR proteins, we propose that the Sw-5b NB domain acts as a nucleation point for the assembly of an oligomeric resistosome, probably by recruiting downstream helper partners, to trigger defense signaling.

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