The Role of TamAB in Salmonella Pathogenesis

TamAB 在沙门氏菌发病机制中的作用

• 批准号: 10287293
• 负责人: JAMES M. SLAUCH
• 金额: $ 18.7万
• 依托单位: UNIVERSITY OF ILLINOIS AT URBANA-CHAMPAIGN
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-06-01 至 2023-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10287293
• 关键词: Affect; Attenuated; Bacteria; Biochemical; Cell Membrane Permeability; Cells; Complex; Data; Defect; Disease; Environment; Future; Gammaproteobacteria; Genes; Genetic; Goals; Growth; Heat shock proteins; Homologous Gene; Immune; Immune system; In Vitro; Infection; Life; Mass Spectrum Analysis; Membrane; Membrane Proteins; Molecular; Monitor; Mus; Mutation; Nature; Pathogenesis; Phagosomes; Phenotype; Proteins; Regulation; Regulon; Research; Role; Salmonella; Salmonella enterica; Salmonella infections; Salmonella typhimurium; Stress; Suppressor Mutations; System; Vancomycin; Virulence; Virulence Factors; antimicrobial; beta barrel; biological adaptation to stress; combat; foodborne; foodborne pathogen; improved; macrophage; member; membrane assembly; mutant; pathogenic bacteria; tissue culture; translocase

ABSTRACT Salmonella Typhimurium is a major food-borne pathogen that propagates within macrophages, leading to life-threatening disease. The long-term objectives of our research are to understand the molecular mechanisms by which Salmonella circumvents the host immune system to cause disease. The outer membrane of the bacterium is the interface with the immune system. Outer membrane beta- barrel proteins are normally assembled by the Bam complex. A homolog of Bam, the TamAB translocation module is highly conserved in the Gammaproteobacteria. Originally proposed as a system for assembly of a subset of beta-barrel proteins, the so-called autotransporter proteins, the actual function of TamAB is unknown. We have discovered that tamAB is a previously unrecognized member of the PhoPQ regulon and is induced when Salmonella is replicating in macrophages, suggesting that this system is important for virulence. Indeed, our preliminary data strongly support our primary hypothesis that TamAB is induced to assist Bam function under the stressful conditions in the phagosome. Our secondary hypothesis is that TamAB is required for proper assembly of particular proteins in the outer membrane under the conditions in the phagosome, and that decreases or loss of these proteins attenuate Salmonella virulence. In Aim 1, we will determine outer membrane composition using mass spectrometry, and monitor expression of envelope stress response systems, to determine the biochemical and regulatory effects caused by loss of TamAB, thereby identifying proteins that directly or indirectly require TamAB for proper assembly. We will also isolate mutations that suppress in vitro defects in outer membrane permeability conferred or exacerbated by loss of TamAB. In Aim 2, we will characterize identified loci and their role in macrophage survival and virulence. The overall role of the identified factors in macrophage survival will be revealed by genetic interactions with tamAB. Understanding the roles of TamAB will inform us about the conditions in the phagosome leading to outer membrane assembly stress and the mechanisms used by Salmonella to combat them. Identifying the specific proteins affected by loss of TamAB also identifies additional virulence factors critical for Salmonella pathogenesis.

抽象的 鼠伤寒沙门氏菌是一种主要的粮食传播病原体，在巨噬细胞中传播， 导致威胁生命的疾病。我们研究的长期目标是了解 沙门氏菌绕过宿主免疫系统引起疾病的分子机制。 细菌的外膜是与免疫系统的界面。外膜β- 枪管蛋白通常由BAM复合物组装。 tamab的BAM同源物 易位模块在γ-细菌中高度保守。最初建议作为系统 为了组装β-桶蛋白的子集，所谓的自动转移蛋白，实际 TAMAB的功能未知。我们发现塔玛布是以前未被认可的成员 在沙门氏菌在巨噬细胞中复制时，phopq的调节剂被诱导，表明 该系统对于毒力很重要。确实，我们的初步数据强烈支持我们的主要数据 假设TAMAB被诱导在压力条件下有助于BAM功能 吞噬体。我们的次要假设是tamab是正确组装的 在吞噬体的条件下，外膜中的特定蛋白质， 这些蛋白质减少或丧失减弱沙门氏菌的毒力。在AIM 1中，我们将确定 使用质谱法的外膜组成，并监测包膜应力的表达 响应系统，以确定由TAMAB丢失引起的生化和调节作用， 从而识别直接或间接需要TAMAB才能适当组装的蛋白质。我们也会 抑制外膜渗透率抑制体外缺陷的分离株突变赋予或 因tamab的损失而加剧。在AIM 2中，我们将表征已确定的基因座及其在 巨噬细胞存活和毒力。鉴定因子在巨噬细胞存活中的总体作用 将通过与TAMAB的遗传相互作用来揭示。了解Tamab的角色将通知我们 关于导致外膜组装应力的吞噬体的条件和 沙门氏菌用来对抗它们的机制。识别受损失影响的特定蛋白质 TAMAB还鉴定出对沙门氏菌发病机理至关重要的其他毒力因子。