Role of bacterial virulence proteins in plant cell death

细菌毒力蛋白在植物细胞死亡中的作用

• 批准号: 7088156
• 负责人: Gregory B Martin
• 金额: $ 21.81万
• 依托单位: BOYCE THOMPSON INST FOR PLANT RESEARCH
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-05-01 至 2010-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7088156
• 关键词: Pseudomonas; apoptosis; bacteria infection mechanism; bacterial proteins; gene induction /repression; genetic screening; mitogen activated protein kinase; plant diseases; plant physiology; posttranslational modifications; protein localization; protein protein interaction; tomato; ubiquitin protein ligase; virulence

DESCRIPTION (provided by investigator): This project uses the interaction between tomato leaves and Pseudomonas syringae as a model system to investigate the molecular basis of bacterial pathogenesis and host responses to bacterial infection. To understand bacterial pathogenesis, we focus on a key virulence protein, AvrPtoB, that is secreted into host cells by the bacterial type III secretion system. To explore the host response, we focus on the rapid programmed cell death (PCD) that is associated with plant immunity. We have found that AvrPtoB acts to suppress PCD in both plants and in yeast indicating that AvrPtoB likely targets a highly conserved eukaryotic process. AvrPtoB is a modular protein: the N-terminal domain interacts with the host kinase Pto to elicit immunity, whereas the C-terminus is required for PCD inhibition. In preliminary work, we have discovered that in the host cell AvrPtoB is likely ubiquitinated, cleaved, and the cleavage products are localized to different subcellular compartments. As part of a collaboration, the structure of the AvrPtoB anti-PCD domain has been solved and shown to have homology to E3 ubiquitin ligases; determination of the N-terminal structure is underway. Possible host targets of AvrPtoB anti-PCD activity, including MEK1, a MAPKK, have been identified. Finally, we have developed a gene silencing screen for use in identifying genes that play a role in host PCD. We propose to: 1) Investigate the role in pathogenesis of AvrPtoB post-translational modifications; 2) Determine if AvrPtoB is an E3 ubiquitin ligase; 3) Characterize the interaction of AvrPtoB with MEK1; 4) Examine the role of differential subcellular localization of AvrPtoB cleavage products; and 5) Use AvrPtoB to identify novel components of host PCD pathways. Our research takes advantage of two experimentally tractable organisms to elucidate host PCD and an important pathogen virulence mechanism, PCD-suppression, - processes which impact both plant agriculture and human health. Our studies are relevant to U.S. biosecurity concerns because type III effector proteins, such as AvrPtoB, occur in many potentially weaponizable human pathogens such as Yersinia and understanding their virulence mechanisms could lead to specific intervention strategies.

描述（研究人员提供）：该项目使用番茄叶和丁香假单胞菌之间的相互作用作为模型系统，以研究细菌发病机理的分子基础和宿主对细菌感染的反应。为了了解细菌的发病机理，我们专注于关键的毒力蛋白AVRPTOB，该蛋白通过细菌III型分泌系统分泌到宿主细胞中。为了探索宿主反应，我们专注于与植物免疫相关的快速程序性细胞死亡（PCD）。我们发现，AVRPTOB的作用是抑制两种植物和酵母中的PCD，表明Avrptob可能针对高度保守的真核过程。 AVRPTOB是一种模块化蛋白：N末端结构域与宿主激酶PTO相互作用以引起免疫力，而C末端是PCD抑制所必需的。在初步工作中，我们发现在宿主细胞中，avrptob可能是泛素化的，裂解的，并且裂解产物位于不同的亚细胞隔室中。作为协作的一部分，已经解决了AVRPTOB抗PCD结构域的结构，并证明与E3泛素连接酶具有同源性。 N末端结构的确定正在进行中。已经确定了包括MEK1（MAPKK）的AVRPTOB抗PCD活性的可能的主机靶标。最后，我们开发了一个基因沉默屏幕，用于识别在宿主PCD中起作用的基因。我们建议：1）研究AVRPTOB后翻译后修饰的发挥作用； 2）确定AVRPTOB是否是E3泛素连接酶； 3）表征Avrptob与MEK1的相互作用； 4）检查Avrptob裂解产品的差分亚细胞定位的作用； 5）使用AVRPTOB识别宿主PCD途径的新组件。我们的研究利用了两种实验可牵引的生物来阐明宿主PCD和一种重要的病原体毒力机制，即PCD支持，即影响植物农业和人类健康的过程。我们的研究与美国的生物安全问题有关，因为III型效应子蛋白（例如AVRPTOB）出现在许多潜在的可武器的人类病原体（例如耶尔森氏菌）中，并了解其毒力机制可能会导致特定的干预策略。