Listeria virulence gene expression within host cells

宿主细胞内李斯特菌毒力基因的表达

• 批准号: 8524135
• 负责人: Nancy Elizabeth Freitag
• 金额: $ 39.88万
• 依托单位: UNIVERSITY OF ILLINOIS AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-08-16 至 2013-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8524135
• 关键词: Adult; Aging; Bacteria; Bacterial Meningitis; Bacterial Physiology; Biochemical; Cells; Cessation of life; Chemicals; Complex; Cytosol; Disease Reservoirs; Drug Delivery Systems; Environment; Equilibrium; Food; Free Radicals; Gene Expression; Genetic; Goals; Growth; Health; Human; Immune response; Immunocompromised Host; In Vitro; Incidence; Infection; Inflammatory Response; Island; Life; Link; Lipoproteins; Listeria; Listeria monocytogenes; Mammalian Cell; Maps; Mediating; Metabolic; Molecular; Molecular Chaperones; Mutation Analysis; North America; Organ; Organism; Oxidative Stress; Oxygen; Pathogenesis; Pathway interactions; Pheromone; Play; Predisposition; Production; Proteins; Recording of previous events; Regulation; Research; Resistance; Role; Severities; Signal Transduction; Sodium Chloride; Soil; Spin Trapping; Stress; Suppressor Mutations; Virulence; Virulence Factors; Work; acid stress; bacterial resistance; base; biological adaptation to stress; cell transformation; cofactor; defined contribution; effective therapy; foodborne infection; foodborne outbreak; genetic regulatory protein; in vivo; interest; macrophage; novel; oxidative damage; pathogen; research study; small molecule

DESCRIPTION (provided by applicant): The long-term objective of this research is to understand how an environmental bacterium gains the ability to transition from soil organism to life within mammalian cells. Listeria monocytogenes (Lm) is a facultative intra- cytosolic bacterium that is an increasingly important agent of serious food-borne infections and has been responsible for some of the largest food recalls in US history. The focus of this proposal is on an essential virulence regulatory protein known as PrfA that coordinates the complex and multifaceted Lm transition from life in the outside environment to life within an infected host. Critical to PrfA function is the shift from the low PrfA activity state found in bacteria replicatig outside of host cells to a high activity state following bacterial entry into the host cell. Cytosoic activation of PrfA has profound effects not only on the expression and secretion of Lm virulence gene products, but also on the metabolic state of Lm and on the ability of the bacterium to respond to conditions of stress. The central hypothesis of this proposal is that the regulation of PrfA activation is critical for Lm to successfully balance bacterial survival in the outside environment with life within mammalian cells. A combination of genetic, biochemical, and in vivo approaches will be used to elucidate the mechanisms that regulate PrfA activation status as well as to functionally decipher how PrfA activation coordinates different aspects of Lm stress resistance, bacterial cell signaling, and bacterial physiology to enhance bacterial growth and viability within the cytosol. Aim 1 will elucidate the mechanistic links between PrfA activation an different facets of Lm stress susceptibility and resistance. Experiments will clarify how PrfA activation selectively influences stress resistance to enhance bacterial survival within host cells and will identify targets of free radical damage that occur as a result of host inflammatory responses. The focus of Aim 2 is on mechanisms that promote bacterial viability in the cytosol under conditions of PrfA activation. Experiments will functionally define the contributions of two secretion chaperones and a pheromone-encoding lipoprotein known as Lmo2637 to pathogenesis; the secretion of these gene products is induced by PrfA activation and all have apparent roles in maintaining Lm viability within the cytosol. Aim 3 will clarify the molecular pathways leading to PrfA activation within the host and will seek to identify the cofactor that triggers PrfA activation. The ultimate goal of this proposal will be to elucidate the molecular pathways that promote Lm survival within host cells and the transformation of a soil dweller into a cell invader.

描述（由申请人提供）：这项研究的长期目标是了解环境细菌如何获得从土壤生物转变为哺乳动物细胞内生命的能力。单核细胞增生李斯特菌 (Lm) 是一种兼性胞浆内细菌，是严重食源性感染的日益重要的病原体，并导致了美国历史上一些最大规模的食品召回。该提案的重点是 称为 PrfA 的重要毒力调节蛋白，可协调从外部环境中的生命到受感染宿主体内生命的复杂且多方面的 Lm 转变。 PrfA 功能的关键是从细菌在宿主细胞外复制时发现的低 PrfA 活性状态转变为细菌进入宿主细胞后的高活性状态。 PrfA 的胞浆激活不仅对 Lm 毒力基因产物的表达和分泌具有深远的影响，而且对 Lm 的代谢状态和细菌响应应激条件的能力也有深远的影响。该提议的中心假设是，PrfA 激活的调节对于 Lm 成功平衡外部环境中的细菌生存与哺乳动物细胞内的生命至关重要。将结合遗传、生化和体内方法来阐明调节 PrfA 激活状态的机制，并从功能上解读 PrfA 激活如何协调 Lm 应激抵抗、细菌细胞信号传导和细菌生理学的不同方面，以增强细胞质内的细菌生长和活力。目标 1 将阐明 PrfA 激活与 Lm 应激敏感性和抵抗力不同方面之间的机制联系。实验将阐明 PrfA 激活如何选择性地影响应激抵抗力，以增强宿主细胞内细菌的存活，并将确定因宿主炎症反应而发生的自由基损伤的目标。目标 2 的重点是在 PrfA 激活条件下促进细胞质中细菌活力的机制。实验将在功能上定义两种分泌伴侣和一种称为 Lmo2637 的信息素编码脂蛋白对发病机制的贡献；这些基因产物的分泌是由 PrfA 激活诱导的，并且在维持细胞质内的 Lm 活力方面都具有明显的作用。目标 3 将阐明导致宿主内 PrfA 激活的分子途径，并寻求识别触发 PrfA 激活的辅因子。该提案的最终目标是阐明促进 Lm 在宿主细胞内存活以及将土壤居民转变为细胞入侵者的分子途径。