Mechanisms of Antibiotic Efflux in Campylobacter

弯曲杆菌中抗生素流出的机制

• 批准号: 7844924
• 负责人: Qijing Zhang
• 金额: $ 26.06万
• 依托单位: IOWA STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-04-01 至 2012-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7844924
• 关键词: ATP-Binding Cassette Transporters; Animal Model; Animals; Antibiotic Resistance; Antibiotic Therapy; Antimicrobial Resistance; Bacteria; Bile fluid; Binding; Biochemical; C-terminal; Campylobacter; Campylobacter jejuni; Categories; Cell Survival; Child; Complex; DNA; DNA Binding Domain; Developed Countries; Developing Countries; Diarrhea; Effectiveness; Enteral; Environment; Family; Funding; Genes; Genomics; Goals; Grant; In Vitro; Intestines; Laboratories; Ligand Binding Domain; Mediating; Membrane Transport Proteins; Molecular; Molecular Genetics; Molecular Target; Multi-Drug Resistance; N-terminal; National Institute of Allergy and Infectious Disease; Organism; Oxygen; Oxygen measurement, partial pressure, arterial; Physiological; Physiological Processes; Physiology; Play; Poison; Positioning Attribute; Promoter Regions; Reagent; Regulation; Repression; Research Personnel; Resistance; Resources; Role; Structure; System; United States; Work; X-Ray Crystallography; antibiotic efflux; base; bile salts; design; dicarboxylate; dicarboxylate-binding protein; efflux pump; enteric pathogen; environmental change; fluoroquinolone resistance; foodborne; in vivo; mutant; novel; pathogen; prevent; programs; promoter; resistance mechanism; uptake

DESCRIPTION (provided by applicant): Bacterial antibiotic efflux transporters are important players in conferring intrinsic and acquired resistance to antimicrobials. According to the genomic sequence, Campylobacter jejuni, a leading bacterial cause of foodborne diarrhea in the United States and an agent included in the NIAID Category B Priority Pathogens list, harbors multiple antibiotic efflux transporters of different families. During the previous application period, we determined the function and regulation of two efflux pumps (CmeABC and CmeDEF) of the resistance- nodulation-division (RND) family in Campylobacter. Our findings indicate the efflux system not only contributes to antimicrobial resistance, but also has important physiological functions in facilitating Campylobacter colonization in animal intestinal tract. We have also found that CmeR, a transcriptional factor, represses cmeABC and that bile salts (normally present in the gut) induce the expression of cmeABC by inhibiting the binding of CmeR to the promoter of cmeABC. Our recent preliminary studies also strongly suggest that CmeR is a global regulator and modulates the expression of the MF (major facilitator) and MATE (multidrug and toxic compound extrusion) transporters as well as the C4-dicarboxylate transporters potentially involved in Campylobacter adaptation to oxygen-limited environments, which exist in the niches occupied by Campylobacter in animal hosts. These findings clearly indicate that the modulated expression of the antibiotic efflux system plays important roles in antimicrobial resistance and in facilitating Campylobacter adaptation to environmental changes. Despite these recent advances, the majority of the CmeR-regulated efflux transporters in Campylobacter have not been functionally characterized, and the molecular mechanisms governing the expression of the transporters and the structural basis of CmeR regulation remain to be determined. To close these important gaps in our understanding of the active efflux system in Campylobacter, we plan to pursue 3 specific aims in this application to 1) determine the regulatory mechanisms and functions of the MF and MATE transporters in C. jejuni, 2) define the roles of the CmeR-regulated C4-dicarboxylate transport system in facilitating Campylobacter adaptation to oxygen-limited environments, and 3) elucidate the structural basis of CmeR regulation and the induction mechanisms of bile salts using X-ray crystallography. The proposed studies take advantage of unique resources available in our laboratory and utilize contemporary molecular, genetic, and biochemical approaches as well as an established animal model. Once completed, the proposed work together with the studies conducted in the previous application period will reveal novel information on the functions and regulatory mechanisms of antibiotic efflux transporters in bacteria. The findings will also help to identify potential molecular targets for the control and treatment of antibiotic resistant Campylobacter.

描述（由申请人提供）：细菌抗生素外流转运蛋白在赋予抗菌药物内在和获得性耐药性方面发挥着重要作用。根据基因组序列，空肠弯曲菌是美国食源性腹泻的主要原因，也是 NIAID B 类优先病原体清单中的一种病原体，它拥有不同家族的多种抗生素外排转运蛋白。在之前的应用期间，我们确定了弯曲杆菌中抗性结瘤分裂（RND）家族的两个外排泵（CmeABC和CmeDEF）的功能和调节。我们的研究结果表明，外排系统不仅有助于抗菌素耐药性，而且在促进弯曲杆菌在动物肠道定植方面具有重要的生理功能。我们还发现转录因子 CmeR 抑制 cmeABC，胆盐（通常存在于肠道中）通过抑制 CmeR 与 cmeABC 启动子的结合来诱导 cmeABC 的表达。我们最近的初步研究还强烈表明，CmeR 是一种全局调节剂，调节 MF（主要促进剂）和 MATE（多药和有毒化合物挤出）转运蛋白以及可能参与弯曲杆菌对氧的适应的 C4-二羧酸转运蛋白的表达。有限的环境，存在于动物宿主中弯曲杆菌占据的生态位中。这些发现清楚地表明，抗生素流出系统的调节表达在抗菌素耐药性和促进弯曲杆菌适应环境变化方面发挥着重要作用。尽管最近取得了这些进展，但弯曲杆菌中大多数 CmeR 调节的外排转运蛋白尚未得到功能表征，并且控制转运蛋白表达的分子机制和 CmeR 调节的结构基础仍有待确定。为了弥补我们对弯曲杆菌主动外排系统的理解中的这些重要差距，我们计划在此应用中追求 3 个具体目标：1) 确定空肠弯曲杆菌中 MF 和 MATE 转运蛋白的调节机制和功能，2) 定义CmeR调节的C4-二羧酸转运系统在促进弯曲杆菌适应限氧环境中的作用，以及3）阐明CmeR调节的结构基础和诱导机制使用 X 射线晶体学分析胆汁盐。拟议的研究利用我们实验室的独特资源，并利用当代分子、遗传和生化方法以及已建立的动物模型。一旦完成，拟议的工作与之前申请期间进行的研究将揭示有关细菌中抗生素外排转运蛋白的功能和调节机制的新信息。这些发现还将有助于确定控制和治疗抗生素耐药性弯曲杆菌的潜在分子靶点。