A type III effector ADP-ribosylates RNA-binding proteins and quells plant immunity
A type III effector ADP-ribosylates RNA-binding proteins and quells plant immunity
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DOI：
10.1038/nature05737
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发表时间：
2007-05-17
期刊：
影响因子：
64.8
通讯作者：
Alfano, James R.
中科院分区：
文献类型：
--
作者：
Fu, Zheng Qing;Guo, Ming;Alfano, James R.
细菌植物病原体假单胞菌丁香病通过III型蛋白质分泌系统将效应蛋白注射到宿主细胞中，以引起疾病。大多数丁香假单胞菌效应子及其靶标的酶促活性仍然晦涩。在这里，我们表明III型效应子Hopu1是单个ADP-核糖基转移酶（ADP-RT）。 HOPU1以依赖ADP-RT活性部位的方式抑制植物先天免疫。拟南芥提取物中的HOPU1底物是具有RNA识别基序（RRMS）的RNA结合蛋白。 A. thaliana敲除线在富含甘氨酸的RNA结合蛋白GRP7（也称为ATGRP7）中有缺陷（一种hopu1底物）比野生型植物对丁香菌的植物更容易受到敏感。 HOPU1对GRP7的ADP-核糖基化需要在RRM内进行两种精氨酸，这表明这种修饰可能会干扰GRP7结合RNA的能力。我们的结果表明了一种致病策略，其中RNA结合蛋白的ADP-核糖基化通过影响RNA代谢和植物防御转录组来激发免疫。
The bacterial plant pathogen Pseudomonas syringae injects effector proteins into host cells through a type III protein secretion system to cause disease. The enzymatic activities of most of P. syringae effectors and their targets remain obscure. Here we show that the type III effector HopU1 is a mono-ADP-ribosyltransferase (ADP-RT). HopU1 suppresses plant innate immunity in a manner dependent on its ADP-RT active site. The HopU1 substrates in Arabidopsis thaliana extracts were RNA-binding proteins that possess RNA-recognition motifs (RRMs). A. thaliana knockout lines defective in the glycine-rich RNA-binding protein GRP7 ( also known as AtGRP7), a HopU1 substrate, were more susceptible than wild-type plants to P. syringae. The ADP-ribosylation of GRP7 by HopU1 required two arginines within the RRM, indicating that this modification may interfere with GRP7' s ability to bind RNA. Our results suggest a pathogenic strategy where the ADP-ribosylation of RNA-binding proteins quells host immunity by affecting RNA metabolism and the plant defence transcriptome.