Suppressor of G2 allele of skp1 (SGT1) is a highly conserved eukaryotic protein that plays a vital role in growth, development, and immunity in both animals and plants. Although some SGT1 interactors have been identified, the molecular regulatory network of SGT1 remains unclear. SGT1 serves as a co-chaperone to stabilize protein complexes such as the nucleotide-binding leucine-rich repeat (NLR) class of immune receptors, thereby positively regulating plant immunity. SGT1 has also been found to be associated with the SKP1-Cullin-F-box (SCF) E3 ubiquitin ligase complex. However, whether SGT1 targets immune repressors to coordinate plant immune activation remains elusive. In this study, we constructed a toolbox for TurboID- and split-TurboID-based proximity labeling (PL) assays in and used the PL toolbox to explore the SGT1 interactome during pre- and post-immune activation. The comprehensive SGT1 interactome network we identified highlights a dynamic shift from proteins associated with plant development to those linked with plant immune responses. We found that SGT1 interacts with Necrotic Spotted Lesion 1 (NSL1), which negatively regulates salicylic acid-mediated defense by interfering with the nucleocytoplasmic trafficking of non-expressor of pathogenesis-related genes 1 (NPR1) during N NLR-mediated response to tobacco mosaic virus. SGT1 promotes the SCF-dependent degradation of NSL1 to facilitate immune activation, while salicylate-induced protein kinase-mediated phosphorylation of SGT1 further potentiates this process. Besides N NLR, NSL1 also functions in several other NLR-mediated immunity. Collectively, our study unveils the regulatory landscape of SGT1 and reveals a novel SGT1-NSL1 signaling module that orchestrates plant innate immunity.

中文翻译：

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近端组分析揭示了一个保守的 SGT1-NSL1 信号转导模块，可激活 NLR 介导的免疫


skp1 的 G2 等位基因抑制因子 （SGT1） 是一种高度保守的真核蛋白，在动植物的生长、发育和免疫中起着至关重要的作用。尽管已经鉴定出一些 SGT1 相互作用子，但 SGT1 的分子调控网络仍不清楚。SGT1 作为辅助伴侣稳定蛋白质复合物，例如核苷酸结合亮氨酸富集重复序列 （NLR） 类免疫受体，从而正向调节植物免疫。SGT1 还被发现与 SKP1-Cullin-F-box （SCF） E3 泛素连接酶复合物相关。然而，SGT1 是否靶向免疫抑制因子以协调植物免疫激活仍然难以捉摸。在这项研究中，我们构建了一个基于 TurboID 和分裂 TurboID 的邻近标记 （PL） 分析工具箱，并使用 PL 工具箱来探索免疫前和免疫后激活期间的 SGT1 相互作用组。我们确定的综合 SGT1 相互作用组网络突出了从与植物发育相关的蛋白质到与植物免疫反应相关的蛋白质的动态转变。我们发现 SGT1 与坏死斑点病变 1 （NSL1） 相互作用，后者通过干扰 N NLR 介导的烟草花叶病毒反应期间非发病机制相关基因 1 （NPR1） 的核质运输来负向调节水杨酸介导的防御。SGT1 促进 NSL1 的 SCF 依赖性降解以促进免疫激活，而水杨酸诱导的蛋白激酶介导的 SGT1 磷酸化进一步增强了这一过程。除了 N NLR，NSL1 还在其他几种 NLR 介导的免疫中发挥作用。总的来说，我们的研究揭示了 SGT1 的调控前景，并揭示了一种协调植物先天免疫的新型 SGT1-NSL1 信号传导模块。