Dissection of AvrBsT-BST defense pathway in Arabidopsis

拟南芥 AvrBsT-BST 防御途径的剖析

• 批准号: 7116258
• 负责人: Mary Beth MUDGETT
• 金额: $ 26.66万
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-09-30 至 2009-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7116258
• 关键词: Arabidopsis; Pseudomonadaceae; bacteria infection mechanism; bacterial cytopathogenic effect; bacterial genetics; bacterial proteins; biological signal transduction; endopeptidases; enzyme substrate; gene expression; genetic regulation; genetically modified plants; host organism interaction; plant diseases; plant genetics; plant proteins; posttranslational modifications; protein localization; protein structure function; ubiquitin; western blottings; yeast two hybrid system

DESCRIPTION (provided by applicant): This project will further dissect the molecular and cellular basis of Xanthomonas campestris pathovar vesicatoria (Xcv) pathogenesis in plants. This bacterium uses a specialized secretory system to orchestrate cell-to-cell communication during the early stages of plant infection. The type III secretion system (TTSS) enables direct secretion and translocation of bacterial proteins into host plant cells. Once inside the host, TTSS effectors, acting presumably as virulence proteins, collectively modulate the cell to initiate disease symptoms in susceptible plants and to activate defense responses in resistant plants. To date, the mechanisms by which XcvTTSS effectors modulate plant physiology are virtually unknown. However, our work has provided important insights to the potential mechanisms used by the YopJ-like effectors, a family that is prevalent in Xanthomonas and conserved amongst plant and animal bacterial pathogens. Such conservation implies that pathogenic microbes use a specific mechanism to interfere with host cell signaling. We have shown that Xcv effectors in the YopJ and XopD family function as cysteine proteases inside plant and animal cells. The substrates for these effectors are highly conserved small ubiquitin-like modifiers (SUMO) that are covalently added to a number of regulatory proteins. Thus, we predict that YopJ-like effectors exert their pathogenic effect on host cells by disrupting posttranslational SUMO modification of proteins. The overall goal of this study is to identify and study the plant signal transduction pathways that are affected by the YopJ-like effector AvrBsT during Xanthomonas pathogenesis. Specifically, we will: (1) explore the effect of AvrBsT proteolysis on the SUMO pathway in Arabidopsis by isolating SUMOylated plant targets, (2) isolate the Arabidopsis bst disease resistance gene that provides protection against AvrBsT, and (3) use genetic screens to dissect the AvrBsTBST disease resistance signal transduction pathway in Arabidopsis. We believe our findings will reveal common mechanisms used by SUMO proteases conserved in both plant and animal pathogens to control eukaryotic physiology during bacterial-host interactions.

描述（由申请人提供）：该项目将进一步剖析植物中野油菜黄单胞菌致病性囊泡病（Xcv）发病机制的分子和细胞基础。这种细菌在植物感染的早期阶段使用专门的分泌系统来协调细胞间的通讯。 III 型分泌系统 (TTSS) 能够将细菌蛋白直接分泌并易位到宿主植物细胞中。一旦进入宿主体内，TTSS效应子（可能充当毒力蛋白）共同调节细胞，在易感植物中引发疾病症状，并在抗性植物中激活防御反应。迄今为止，XcvTTSS 效应器调节植物生理学的机制几乎未知。然而，我们的工作为 YopJ 样效应器使用的潜在机制提供了重要的见解，YopJ 样效应器是黄单胞菌中普遍存在的家族，并且在植物和动物细菌病原体中保守。这种保守性意味着病原微生物使用特定的机制来干扰宿主细胞信号传导。我们已经证明 YopJ 和 XopD 家族中的 Xcv 效应子在植物和动物细胞内充当半胱氨酸蛋白酶。这些效应子的底物是高度保守的小泛素样修饰物 (SUMO)，它们共价添加到许多调节蛋白上。因此，我们预测 YopJ 样效应子通过破坏蛋白质的翻译后 SUMO 修饰对宿主细胞发挥致病作用。 本研究的总体目标是识别和研究黄单胞菌发病过程中受 YopJ 样效应子 AvrBsT 影响的植物信号转导途径。具体来说，我们将：(1) 通过分离 SUMO 化植物靶标，探索 AvrBsT 蛋白水解对拟南芥 SUMO 途径的影响，(2) 分离提供针对 AvrBsT 保护的拟南芥 bst 抗病基因，以及 (3) 使用遗传筛选剖析拟南芥中 AvrBsTBST 抗病信号转导途径。我们相信我们的研究结果将揭示植物和动物病原体中保守的 SUMO 蛋白酶在细菌与宿主相互作用期间控制真核生理学的常见机制。