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全球主要的健康问题。沙门氏菌通过表达位于致病岛上的基因来引起疾病。驻留在沙门氏菌致病性岛1（SPI-1）上的基因使沙门氏菌能够粘附并侵入上皮细胞，而全身感染需要SPI-2基因。所谓的III型分泌系统的专门分泌系统都在每个致病岛上编码，这些岛提供了沙门氏菌，并将效应分子分泌到宿主中，以改变宿主功能并促进发病机理。目前的建议着重于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，但是其转录调节的复杂分子生物学，特别是在体内基因表达途径的鉴定仍然很差。我们的研究重点是用分子术语定义这些途径。 SPI-2基因表达由两组分组调节系统SSRAB控制，其表达又受其他调节网络的控制，包括Envz-OMPR两组分组，转录激活剂SLYA和全局抑制器H-NS。 SPI-2的复杂调节需要整合多个环境信号，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。在此提案中，将确定SSRA/SSRB表达在各种环境条件下的关键顺式和反式调节元件。我们假设OMPR位于该法规层次结构的顶部，激活了SSRA/B两组分组调节系统的转录。 SSRB刺激编码在感染过程中分泌的III型分泌仪和效应子的基因的表达。 SSRB在巨噬细胞感染期间没有应力来改变，这种半胱氨酸调节对SPI-2基因表达的后果将在两种小鼠巨噬细胞，巨噬细胞样细胞系和小鼠组织中使用沙门氏菌野生型和SSRB突变体链条感染。由于我们的研究，我们将增强对沙门氏菌感染导致的分子事件的了解，以及这些修饰如何改变宿主中的基因表达。 公共卫生相关性： 对退伍军人卫生退伍军人的影响遭受急性和慢性细菌感染的影响。我们的研究是机械性的，并且具有沙门氏菌以外的意义，扩展到其他病原体。 OMPR已被证明是在纤维状霍乱，志贺氏菌，Yersinia和其他传染性物种中毒力所必需的。此外，在所有医院中，耐药沙门氏菌感染都是一个问题，包括VA医院和由于沙门氏菌引起的败血病是免疫功能低下的HIV阳性患者的问题，这是退伍军人发生的高发病率。与沙门氏菌相关的急性胃肠炎是旅行者，部署军事人员和高人口密度关闭社区（例如军事基地，医院或养老院）发病的重要原因。伤寒病例的数量每年在全球范围内超过3300万，并且在先前接种疫苗的旅行者和军事人员中仍然是一个潜在的关注。