Molecular and Structural Bases of Polymyxin Resistance

多粘菌素耐药性的分子和结构基础

• 批准号: 7163518
• 负责人: Eduardo Groisman
• 金额: $ 20.91万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-02-01 至 2008-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7163518
• 关键词: Acids; Antibiotics; Antisense RNA; Binding; Biochemical; Biological Assay; Chickens; Cues; Cytoplasmic Granules; Development; Event; Exhibits; Gene Expression; Genes; Genetic; Genetic Screening; Genetic screening method; Goals; Growth; Human; Infection; Iron; Lipopolysaccharides; Mediating; Methods; Modification; Molecular; Mus; Pattern; Peptide Antibiotics; Peptides; Physiological; Polymyxin B; Polymyxin Resistance; Polymyxins; Process; Property; Proteins; Regulation; Resistance; Role; Salmonella; Signal Transduction; Soil; System; Virulence; aminoarabinose; antimicrobial; antimicrobial drug; antimicrobial peptide; base; cell envelope; extracellular; genetic regulatory protein; in vivo; killings; macrophage; microbicide; microorganism; mutant; neutrophil; novel; novel therapeutics; pathogen; periplasm; phosphoethanolamine; polymyxin B(1); promoter; protein expression; research study; sensor

DESCRIPTION (provided by applicant): The unremitting isolation of bacterial pathogens exhibiting resistance to multiple antibiotics demands the development of novel therapeutic strategies. This entails not only identifying resistance determinants but also understanding the environmental cues that regulate expression of such determinants. The Salmonella PmrA/PmrB two-component system is required for resistance to the peptide antibiotic polymyxin B and to several antimicrobial proteins from human polymorphonuclear leukocytes. The regulatory protein PmrA governs expression of proteins mediating modifications of the lipopolysaccharide (LPS) with 4-aminoarabinose, which confers polymyxin resistance, and with phosphoethanolamine, the significance of which has remained unknown. We have established that: (1) the PmrB protein is a sensor that responds to extracellular levels of Fe 3+ by activating the PmrA protein, (2) low Mg2+ can also activate the PmrA protein in a process mediated by the PmrD protein, and (3) mutants defective in the pmrA or pmrB genes are hypersensitive to killing by Fe3+. This proposal describes experiments aimed at understanding the cascade of events by which multiple environmental cues activate the PmrA/PmrB two-component system to promote resistance to different compounds. We will examine the molecular mechanism by which low pH activates the PmrA protein; investigate how the PmrD protein can activate the PmrA protein at a posttranscriptional level; identify the PmrA-regulated determinants mediating resistance to polymyxin and to Fe3+; and define the physiological role of PmrA-controlled phosphoethanolamine modification of the LPS. An accomplishment of these goals will uncover the molecular bases for bacterial signal transduction and antimicrobial peptide resistance. Moreover, as a variety of peptides and proteins are currently being developed as novel antimicrobial agents, the proposed experiments may help in our understanding of how these compounds exert their microbicidal properties.

描述（由申请人提供）：对多种抗生素表现出抗性的细菌病原体的不断分离需要开发新的治疗策略。这不仅需要识别抗性决定因素，还需要了解调节此类决定因素表达的环境线索。沙门氏菌 PmrA/PmrB 双组分系统是对肽抗生素多粘菌素 B 和来自人多形核白细胞的几种抗菌蛋白产生耐药性所必需的。调节蛋白 PmrA 控制介导脂多糖 (LPS) 修饰的蛋白质表达，其中 4-氨基阿拉伯糖赋予多粘菌素抗性，而磷酸乙醇胺的意义仍不清楚。我们已经确定：(1) PmrB 蛋白是一种传感器，通过激活 PmrA 蛋白来响应细胞外 Fe 3+ 水平，(2) 低 Mg2+ 也可以在 PmrD 蛋白介导的过程中激活 PmrA 蛋白，并且(3) pmrA 或 pmrB 基因缺陷的突变体对 Fe3+ 杀伤高度敏感。该提案描述了旨在了解多种环境因素激活 PmrA/PmrB 双组分系统以促进对不同化合物的抗性的级联事件的实验。我们将研究低pH值激活PmrA蛋白的分子机制；研究 PmrD 蛋白如何在转录后水平激活 PmrA 蛋白；确定介导多粘菌素和 Fe3+ 抗性的 PmrA 调节决定因素；并定义了 PmrA 控制的 LPS 磷酸乙醇胺修饰的生理作用。这些目标的实现将揭示细菌信号转导和抗菌肽耐药性的分子基础。此外，由于目前正在开发多种肽和蛋白质作为新型抗菌剂，所提出的实验可能有助于我们了解这些化合物如何发挥其杀菌特性。