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科学家揭示了NPR1激活植物免疫力的结构基础
2022-05-15 14:14

美国杜克大学医学院Pei Zhou和美国杜克大学Xinnian Dong共同合作,近期取得重要工作进展。他们研究揭示了NPR1激活植物免疫的结构基础。这一成果2022年5月11日在线发表于《自然》杂志上。

在这里,研究人员报告了拟南芥NPR1及其与转录因子TGA3的复合物的低温电子显微镜和晶体结构。冷冻电镜分析显示,NPR1是一个鸟形的同源二聚体,包括一个中央的Broad-complex、Tramtrack和Bric-à-brac(BTB)结构域,一个BTB和羧基端Kelch螺旋束,四个ankyrin重复序列和一个无序的水杨酸结合结构域。晶体结构分析揭示了BTB中独特的锌指基序,用于与锚蛋白重复序列相互作用并介导NPR1寡聚化。研究人员发现,在刺激后,水杨酸诱导的水杨酸结合域折叠和对接至锚蛋白重复序列是NPR1的转录辅因子活性所必需的,这从结构上解释了水杨酸在调节NPR1依赖的基因表达方面的直接作用。

此外,他们的TGA32-NPR12-TGA32复合物结构、DNA结合分析和遗传数据表明,二聚体NPR1通过桥接两个与脂肪酸结合的TGA3二聚体形成增强体来激活转录。NPR1-TGA复合物的逐步组装表明可能与其他转录因子形成异源寡聚复合物,揭示了NPR1是如何对防御转录组进行重新编程的。

据介绍,NPR1是植物免疫信号水杨酸诱导的防御转录组的主要调控因子。尽管NPR1在植物免疫中发挥了重要作用,但由于缺乏结构信息,对其调控机制的了解一直受到阻碍。

附:英文原文

Title: Structural basis of NPR1 in activating plant immunity

Author: Kumar, Shivesh, Zavaliev, Raul, Wu, Qinglin, Zhou, Ye, Cheng, Jie, Dillard, Lucas, Powers, Jordan, Withers, John, Zhao, Jinshi, Guan, Ziqiang, Borgnia, Mario J., Bartesaghi, Alberto, Dong, Xinnian, Zhou, Pei

Issue&Volume: 2022-05-11

Abstract: NPR1 is a master regulator of the defence transcriptome induced by the plant immune signal salicylic acid1,2,3,4. Despite the important role of NPR1 in plant immunity5,6,7, understanding of its regulatory mechanisms has been hindered by a lack of structural information. Here we report cryo-electron microscopy and crystal structures of Arabidopsis NPR1 and its complex with the transcription factor TGA3. Cryo-electron microscopy analysis reveals that NPR1 is a bird-shaped homodimer comprising a central Broad-complex, Tramtrack and Bric-à-brac (BTB) domain, a BTB and carboxyterminal Kelch helix bundle, four ankyrin repeats and a disordered salicylic-acid-binding domain. Crystal structure analysis reveals a unique zinc-finger motif in BTB for interacting with ankyrin repeats and mediating NPR1 oligomerization. We found that, after stimulation, salicylic-acid-induced folding and docking of the salicylic-acid-binding domain onto ankyrin repeats is required for the transcriptional cofactor activity of NPR1, providing a structural explanation for a direct role of salicylic acid in regulating NPR1-dependent gene expression. Moreover, our structure of the TGA32–NPR12–TGA32 complex, DNA-binding assay and genetic data show that dimeric NPR1 activates transcription by bridging two fatty-acid-bound TGA3 dimers to form an enhanceosome. The stepwise assembly of the NPR1–TGA complex suggests possible hetero-oligomeric complex formation with other transcription factors, revealing how NPR1 reprograms the defence transcriptome.

DOI: 10.1038/s41586-022-04699-w

Source: https://www.nature.com/articles/s41586-022-04699-w

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/
投稿链接:http://www.nature.com/authors/submit_manuscript.html


本期文章:《自然》:Online/在线发表

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