Individual components of paired typical NLR immune receptors are regulated by distinct E3 ligases

First author: Oliver Xiaoou Dong; Affiliations: University of British Columbia (不列颠哥伦比亚大学): Vancouver, Canada

Corresponding author: Xin Li 

In plants and animals, nucleotide-binding leucine-rich repeat (NLR; 核苷酸结合富含亮氨酸重复序列) proteins serve as intracellular immune receptors (细胞内免疫受体). Defence signalling by NLRs often requires the formation of NLR heteropairs. Our knowledge of the molecular mechanism regulating this process is limited. In a reverse genetic screen to identify the partner of the Arabidopsis typical NLR, SUPRESSOR OF NPR1, CONSTITUTIVE 1 (SNC1), we discovered three NLRs that are redundantly required for SNC1-mediated defence, which were named SIDEKICK SNC1 1 (SIKIC1), SIKIC2 and SIKIC3. Immunoprecipitation–mass spectrometry analyses (免疫沉淀-质谱分析) revealed that SIKIC2 physically associates with SNC1. We also uncovered that the protein level of SIKIC2 is under the control of two previously uncharacterized redundant E3 ubiquitin ligases MUSE1 and MUSE2. As SNC1 accumulation has previously been shown to be regulated by the E3 ubiquitin ligase SCFCPR1, this report provides evidence that the homeostasis of individual components of partnered typical NLRs is subjected to differential regulation via ubiquitin-mediated protein degradation.

在植物和动物中，核苷酸结合富含亮氨酸重复序列NLR蛋白都是作为细胞内的免疫受体。NLR所介导的防御信号通常需要不同的NLR配对形成的复合物。目前对于该过程的分子调控机制了解的还很少。本文通过反向遗传学试验鉴定了拟南芥NLR蛋白SNC1的配对蛋白，作者发现了三个NLR即SIKIC1、SIKIC2和SIKIC3均在SNC1介导的防御信号中发挥作用，且相互之间存在冗余。进一步的免疫沉淀-质谱分析显示SIKIC2能够与SNC1发生物理上的互作。作者还发现SIKIC2在蛋白水平受到两个功能冗余的E3泛素连接酶MUSE1和MUSE2调控。已有的研究表明SNC1的积累受到E3泛素连接酶SCFCPR1的调控，结合本文的研究说明NLR复合物中不同个体受到了不同的泛素介导的蛋白降解途径所调控。

通讯：Xin Li (http://www.msl.ubc.ca/faculty/li)

个人简介：复旦大学，学士；1995年，俄克拉荷马州立大学，博士；1996-1999年，杜克大学，博士后。

研究方向：植物天然免疫。

doi: https://doi.org/10.1038/s41477-018-0216-8

Journal: Nature Plants

Published date: 06 August, 2018

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