OmpR and SsrB Regulation of Salmonella Virulence

OmpR 和 SsrB 对沙门氏菌毒力的调节

• 批准号: 7689637
• 负责人: Linda J. Kenney
• 金额: --
• 依托单位: JESSE BROWN VA MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-04-01 至 2013-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7689637
• 关键词: Acute; Bacteria; Bacterial Infections; Binding; Binding Sites; Cells; Chronic; Communities; Complex; Cysteine; DNA Binding; Defect; Dimerization; Disease; Drug resistance; Ensure; Epithelial Cells; Event; Figs - dietary; Gastroenteritis; Gene Expression; Genes; Genetic Transcription; Growth; HIV Seropositivity; Health; Hospitals; Hour; Immune; In Vitro; Incidence; Infection; Invaded; Laboratories; Military Personnel; Modification; Molecular; Molecular Biology; Morbidity - disease rate; Mouse Cell Line; Mus; Nursing Homes; Pathogenesis; Pathogenicity Island; Pathway interactions; Patients; Phagosomes; Physiological; Play; Population Density; Recovery; Regulation; Regulatory Element; Reporter; Research; Role; Salmonella; Salmonella infections; Septicemia; Shigella; Signal Transduction; Stress; System; Systemic infection; Testing; Time; Tissues; Transcription Coactivator; Transcriptional Regulation; Type III Secretion System Pathway; Typhoid Fever; Vaccinated; Veterans; Vibrio cholerae; Virulence; Yersinia; base; dimer; in vivo; macrophage; mutant; pathogen; prevent; promoter; public health relevance; response

DESCRIPTION (provided by applicant): PROJECT SUMMARY Salmonella infections are a major health problem worldwide. Salmonella causes disease by expressing genes that are located on pathogenicity islands. Genes that reside on Salmonella Pathogenicity Island-1 (SPI-1) enable Salmonella to adhere to and invade epithelial cells, whereas SPI-2 genes are required for systemic infection. Specialized secretory systems termed type III secretion systems are encoded on each pathogenicity island that provide Salmonella with the means to secrete effector molecules into the host that alter host functions and promote pathogenesis. The present proposal focuses on the control of SPI-2 gene expression. It is one of the most critical virulence determinants of Salmonella, yet the complex molecular biology of its transcriptional regulation, in particular the identification of the pathways for gene expression in vivo, remains poorly defined. Our research is focused on defining these pathways in molecular terms. SPI-2 gene expression is controlled by a two-component regulatory system SsrAB, whose expression is in turn controlled by additional regulatory networks, including the EnvZ-OmpR two-component system, the transcriptional activator SlyA and the global repressor H-NS. The complex regulation of SPI-2 requires integration of multiple environmental signals to ensure that these important virulence genes are expressed at the appropriate time within the macrophage phagosome. In this proposal, critical cis and trans regulatory elements for ssrA/ssrB expression under a variety of environmental conditions will be identified. We hypothesize that OmpR lies at the top of this regulatory hierarchy, activating transcription of the ssrA/B two-component regulatory system. SsrB stimulates expression of the genes encoding the type III secretory apparatus and effectors that are secreted during infection. SsrB is modified by NO stress during macrophage infection, the consequences of this cysteine-modification to expression of SPI-2 genes will be examined in both mouse macrophages, a macrophage-like cell line and mouse tissues upon infection with Salmonella wild type and ssrB mutant strains. As a result of our studies, we will have an enhanced understanding of the molecular events that occur as a result of Salmonella infection and how these modifications alter gene expression in the host. PUBLIC HEALTH RELEVANCE: Impact on Veteran's Health Veterans suffer from both acute and chronic bacterial infections. Our studies are mechanistic and have implications beyond Salmonella, extending to other pathogens. OmpR has been shown to be required for virulence in Vibrio cholerae, Shigella, Yersinia and other infectious species. Furthermore, drug-resistant Salmonella infections are a problem in all hospitals, including VA hospitals and septicemia due to Salmonella is a problem in immune-compromised HIV positive patients, a high incidence which occurs in veterans. Salmonella-associated acute gastroenteritis is a significant cause of morbidity among travelers, deployed military personnel and high population density closed communities (e.g. military bases, hospitals or nursing homes). The number of typhoid fever cases exceeds 33 million per year worldwide and remains a potential concern among previously vaccinated travelers and military personnel.

描述（由申请人提供）： 项目摘要 沙门氏菌感染是世界范围内的一个主要健康问题。沙门氏菌通过表达位于致病岛的基因引起疾病。沙门氏菌致病岛 1 (SPI-1) 上的基因使沙门氏菌能够粘附并侵入上皮细胞，而 SPI-2 基因是全身感染所必需的。每个致病岛上编码了称为 III 型分泌系统的专门分泌系统，为沙门氏菌提供了将效应分子分泌到宿主中的方法，从而改变宿主功能并促进发病机制。本提案的重点是 SPI-2 基因表达的控制。它是沙门氏菌最关键的毒力决定因素之一，但其转录调控的复杂分子生物学，特别是体内基因表达途径的鉴定，仍然知之甚少。我们的研究重点是用分子术语定义这些途径。 SPI-2基因表达由双组分调控系统SsrAB控制，其表达又由其他调控网络控制，包括EnvZ-OmpR双组分系统、转录激活子SlyA和全局阻遏物H-NS。 SPI-2的复杂调节需要整合多种环境信号，以确保这些重要的毒力基因在巨噬细胞吞噬体内的适当时间表达。在本提案中，将确定在各种环境条件下 ssrA/ssrB 表达的关键顺式和反式调控元件。我们假设 OmpR 位于该调控层次的顶部，激活 ssrA/B 双组分调控系统的转录。 SsrB 刺激编码 III 型分泌装置和感染期间分泌的效应器的基因的表达。 SsrB 在巨噬细胞感染期间受到 NO 应激的修饰，这种半胱氨酸修饰对 SPI-2 基因表达的影响将在小鼠巨噬细胞、巨噬细胞样细胞系和沙门氏菌野生型和 ssrB 突变株感染后的小鼠组织中进行检查。通过我们的研究，我们将对沙门氏菌感染所发生的分子事件以及这些修饰如何改变宿主的基因表达有更深入的了解。 公共卫生相关性： 对退伍军人健康的影响退伍军人患有急性和慢性细菌感染。我们的研究是机械性的，其影响不仅限于沙门氏菌，还扩展到其他病原体。 OmpR 已被证明是霍乱弧菌、志贺氏菌、耶尔森氏菌和其他传染性物种的毒力所必需的。此外，耐药沙门氏菌感染是所有医院（包括退伍军人管理局医院）的一个问题，沙门氏菌引起的败血症是免疫功能低下的艾滋病毒阳性患者的一个问题，在退伍军人中发生率很高。沙门氏菌相关的急性胃肠炎是旅行者、部署的军事人员和人口密度高的封闭社区（例如军事基地、医院或疗养院）发病的重要原因。全球每年伤寒病例数超过 3300 万例，对于之前接种过疫苗的旅行者和军事人员来说，这仍然是一个潜在的担忧。