Suppression of innate immunity by an ADP-ribosyltransferase type III effector

ADP-核糖基转移酶 III 型效应子对先天免疫的抑制

• 批准号: 7751271
• 负责人: JAMES Robert ALFANO
• 金额: $ 35.95万
• 依托单位: UNIVERSITY OF NEBRASKA LINCOLN
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-12-15 至 2012-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7751271
• 关键词: ADP Ribose Transferases; ADP ribosylation; Active Sites; Affect; Animals; Arabidopsis; Award; Binding; Biochemical; Biological; Chloroplasts; Cholera Toxin; Data; Disease; Eukaryota; Gene Expression Profile; Genes; Glycine; Grant; Immune response; Immune system; In Vitro; Inflammatory; Journals; Mammals; Manuscripts; Mass Spectrum Analysis; Metabolism; Microbe; Mission; Modeling; Molecular; Natural Immunity; Nature; Pathogenesis; Plant Proteins; Plants; Play; Predisposition; Principal Investigator; Production; Protein Secretion; Proteins; Pseudomonas syringae; Publishing; RNA; RNA Splicing; RNA-Binding Proteins; Research; Research Personnel; Resources; Role; Shigella flexneri; System; Tomatoes; Toxin; Type III Epithelial Receptor Cell; United States National Institutes of Health; Update; base; cost efficient; cytokine; interest; mutant; novel; pathogen; programs; research study; response

DESCRIPTION (provided by applicant): The eukaryotic innate immune system represents an important barrier that pathogens need to circumvent in order to cause disease. Several components of this system are conserved in eukaryotes. Recently, bacterial pathogen effectors that are injected into host cells by type III protein secretion systems (TTSSs) have been shown to be capable of suppressing innate immunity in eukaryotes. The bacterial plant pathogen Pseudomonas syringae is dependent on a TTSS to cause disease on plants. The P. s. pv. tomato DC3000 effector gene hopU1 resembles ADP ribosyltransferases (ADP-RTs) genes. These genes encode some of the best understood toxins in bacterial pathogens of animals (e. g., cholera toxin). Preliminary data within this proposal show that HopU1 is an active ADP-RT and that it ADP-riboslylates several plant proteins. Mass spectrometry determined that chloroplast and glycine-rich RNA-binding proteins acted as in vitro substrates for HopU1. These are novel substrates for ADP-RTs. Moreover, HopU1 has the ability to suppress several responses of the plant innate immune system in a manner that is dependent on its ADP-RT active site. An Arabidopsis mutant lacking one HopU1 substrate, AtGRP7, displayed enhanced susceptibility to P. syringae suggesting that it is a component of innate immunity. AtGRP7 is a glycine-rich RNA-binding protein, which suggests this pathogen targets proteins involved in RNA metabolism to suppress innate immunity. The central hypothesis of the proposed experiments is that AtGRP7 and perhaps other targets of the HopU1 ADP-RT type III effector are components of innate immunity. Several of the experiments seek to elucidate the role AtGRP7 plays in innate immunity using biochemical and molecular biological approaches. The P. syringae-Arabidopsis pathosystem is an excellent model to study the innate immune system because of the resources available, the similarities between innate immune systems between eukaryotes, and the cost efficient research. These experiments will contribute to a fundamental understanding of the molecular mechanism of bacterial pathogenesis and innate immunity. The Specific Aims are the following: (1) Determine the molecular consequence of ADP- ribosylation on the function of AtGRP7 and elucidate the role this protein plays in innate immunity; (2) Identify additional substrates of HopU1 and verify their involvement in innate immunity; (3) Analyze the affect that HopU1 has on host-microbe interactions. Project Narrative: Identifying the eukaryotic targets for the P. syringae HopU1 ADP-ribosyltransferase will contribute to our understanding of bacterial pathogenesis and will likely reveal important components of the innate immune system. One HopU1 target belongs to a large group of proteins called glycine-rich RNA binding proteins, which are not well understood, and this research will likely increase our understanding of these proteins. Because there are considerable similarities between the innate immune systems in plants and mammals we expect that our findings will be relevant to the mission of the NIH and be broadly interesting to researchers studying molecular mechanisms of bacterial pathogenesis and innate immunity.

描述（由申请人提供）：真核先天免疫系统代表了一个重要的障碍，病原体需要规避才能引起疾病。该系统的几个组成部分在真核生物中保存。最近，通过III型蛋白质分泌系统（TTSS）注射到宿主细胞中的细菌病原体效应子已证明能够抑制真核生物中的先天免疫力。细菌植物病原体假单胞菌丁香依赖于TTSS引起植物疾病。 P. s。 PV。番茄DC3000效应基因HOPU1类似于ADP核糖基转移酶（ADP-RTS）基因。这些基因在动物的细菌病原体中编码一些最好的毒素（例如，霍乱毒素）。该提案中的初步数据表明，hopu1是一种活跃的ADP-RT，并且ADP-丝酰基磷酸化几种植物蛋白。质谱法确定叶绿体和富含甘氨酸的RNA结合蛋白充当hopu1的体外底物。这些是ADP-RT的新型底物。此外，Hopu1具有依赖于其ADP-RT活性部位的方式抑制植物先天免疫系统的多种反应。缺乏一种HOPU1底物ATGRP7的拟南芥突变体显示出对丁香假单胞菌的敏感性增强，这表明它是先天免疫的组成部分。 ATGRP7是一种富含甘氨酸的RNA结合蛋白，这表明该病原体靶向参与RNA代谢的蛋白质以抑制先天免疫。提出的实验的中心假设是ATGRP7以及HOPU1 ADP-RT III型效应子的其他靶标是先天免疫的组成部分。一些实验旨在使用生化和分子生物学方法阐明ATGRP7在先天免疫中的作用。丁香假单胞菌 - 阿拉伯p。病原系统是研究先天免疫系统的绝佳模型，因为可用的资源，真核生物之间的先天免疫系统与具有成本效益的研究之间的相似之处。这些实验将有助于对细菌发病机理和先天免疫的分子机制的基本理解。 具体目的是：（1）确定ADP-核糖基化对ATGRP7功能的分子后果，并阐明该蛋白质在先天免疫中的作用； （2）确定Hopu1的其他底物并验证其参与先天免疫力； （3）分析Hopu1对宿主 - 微生物相互作用的影响。 项目叙述：确定丁香假单胞菌hopu1 ADP-核糖基转移酶的真核靶标将有助于我们对细菌发病机理的理解，并可能揭示了先天免疫系统的重要组成部分。一个HOPU1靶标属于一大群称为富含甘氨酸RNA的RNA结合蛋白的蛋白质，这些蛋白质尚不清楚，这项研究可能会增加我们对这些蛋白质的理解。由于植物和哺乳动物的先天免疫系统之间存在相当大的相似性，因此我们期望我们的发现与NIH的使命相关，对于研究细菌发病机理和先天免疫的分子机制的研究人员来说，这很有趣。