权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Defining the molecular mechanisms of MacAB in protection of Salmonella from oxidative stress

定义 MacAB 保护沙门氏菌免受氧化应激的分子机制

基本信息

批准号：
9092827
负责人：
HELENE L ANDREWS-POLYMENIS
金额：
$ 22.28万
依托单位：
TEXAS A&M UNIVERSITY HEALTH SCIENCE CTR
依托单位国家：
美国
项目类别：
财政年份：
2016
资助国家：
美国
起止时间：
2016-02-01 至 2018-01-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9092827
关键词：
Address Affect Animal Model Antibiotics Antioxidants Attenuated Bacteria Bacterial Infections Biology Cause of Death Cells Cleaved cell Co-Immunoprecipitations Coculture Techniques Colitis Data Detergents Development Disease Disinfectants Drug Efflux Drug Metabolic Detoxication Dyes E coli tolC protein Enterobactin Epitopes Gastroenteritis Generations Genes Genetic Genome Goals Growth Heating Homologous Gene Human Hydrogen Peroxide Immunocompromised Host In Vitro Infection Intestines Livestock Macrolide Antibiotics Macrolides Mediating Membrane Membrane Proteins Modeling Molecular Mus Mutation Nature Organism Oxidative Stress Parasites Pathway interactions Peptide Synthesis Peroxides Persons Phenotype Play Positioning Attribute Proteins Public Health Publishing Pump Reactive Oxygen Species Regulation Resistance Resistance development Role Salmonella Salmonella enterica Salmonella infections Salmonella typhimurium Serine Siderophores Staging Stress Structure Substrate Specificity System Testing United States Virulence Virus Work antibiotic efflux antimicrobial base dimer efflux pump enteritis esterase extracellular foodborne foodborne illness hydroxyl group killings macrophage monomer mouse model mutant neutrophil novel novel therapeutics novel vaccines pathogen prevent public health relevance response tool transmission process

项目摘要

DESCRIPTION (provided by applicant): Salmonella enterica is the leading cause of bacterial food borne enteritis and the leading cause of death from food borne disease in the United States. Salmonella Typhimurium (STm) encodes at least 11 multidrug efflux systems (MES), known to export antibiotics and a few other substrates from the cell, with high redundancy in substrate specificity for antibiotics. Mutants lacking MacAB, an ABC-type MES known to weakly efflux macrolide antibiotics, are avirulent in animal models suggesting an important role in infection. In published work we have shown that MacAB protects STm from peroxide mediated killing by secreting a heat stable compound that detoxifies extracellular reactive oxygen species (ROS). ROS are antimicrobial compounds produced in abundance by host neutrophils and macrophages in response to STm and other bacterial infections. Our unpublished genetic evidence strongly suggest that one or more linear metabolite(s) of enterobactin (DHBS3, DHBS2, DHBS) are likely the natural antioxidant substrates secreted by MacAB that protect Salmonella against ROS. Mutants that cannot produce DHBS trimers, dimers or monomers share the phenotypes of a macAB mutant during ROS exposure, and cannot rescue the macAB mutant from peroxide mediated killing when co-cultured. Although the outer membrane partner for MacAB function during macrolide efflux is TolC, this protein does not appear to function with MacAB for secretion of antioxidant compounds during oxidative stress. Two other putative outer membrane proteins, STM2172 and STM2690, share peroxide sensitivity of macAB mutants during oxidative stress when these outer membrane proteins are deleted together, and the double mutant fails to rescue a macAB mutant from ROS mediated killing. In order to develop a molecular and mechanistic understanding of the function and components of the MacAB system in H2O2 resistance, we have developed two hypotheses addressed in two specific aims. First, (Aim I) we hypothesize that linear products of enterobactin (DHBS3, DHBS2, DHBS) are the substrates of the MacAB system that detoxify peroxide. Second, (Aim II) we hypothesize that STM2172 and STM2690 are the outer membrane components that complete the MacAB apparatus allowing export of the substrate out of the bacterium. We are uniquely positioned to address these hypotheses because we possess critical preliminary data, expertise and the tools necessary to complete the work we propose. Our studies described here on MacAB, and our long-term goal to understand the natural functions of multi-drug efflux systems, address a key gap in our understanding bacterial efflux pumps: their natural role in the biology of these organisms. Finally, a detailed understanding of MacAB function, and MES function more broadly, will provide new targets for the development of novel antimicrobial therapy.