Molecular bssis of mef-mediated antibiotic resistance in Streptococcus pneumoniae

肺炎链球菌 mef 介导的抗生素耐药性的分子基础

基本信息

批准号：
7645618
负责人：
DAVID S STEPHENS
金额：
$ 37.52万
依托单位：
EMORY UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2007
资助国家：
美国
起止时间：
2007-08-15 至 2011-07-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7645618
关键词：
Abbreviations Accounting Address Adenine Africa Alleles Antibiotic Resistance Antibiotics Antibodies Antimicrobial Resistance Asia Azithromycin Bacteria Base Sequence Be++ element Beryllium Binding Binding Sites Biological Assay Boxing Canada Cell Wall Chimera organism Clarithromycin Clinical Color Competence DNA Repair Data Direct Repeats Disease Drug Design Elements Erythromycin Escherichia coli Europe Fluoroquinolones Frameshift Mutation Funding Generations Genes Genetic Genetic Screening Genetic Structures Genome Genus staphylococcus Gram-Positive Bacteria Gray unit of radiation dose Head Health Homologous Gene Human Indium Infection Ketolides Lead Letters Macrolide-resistance Macrolides Measures Mediating Membrane Meningeal Methyltransferase Mobile Genetic Elements Molecular Mutation Open Reading Frames Operon Peptidyltransferase Pneumococcal 7-Valent Conjugate Vaccine Pneumococcal Infections Pneumococcal conjugate vaccine Pneumonia Population Predisposition Prevalence Principal Investigator Promoter Regions Proteins Proton-Motive Force Pump RNA Regulation Regulatory Element Regulon Reporter Genes Reporting Research Research Personnel Resistance Ribosomal Proteins Ribosomal RNA Role Series Serotyping Site Site-Directed Mutagenesis Son of Sevenless Proteins Staphylococcus epidermidis msrA protein Streptococcus Group B Streptococcus pneumoniae Streptococcus pyogenes Streptococcus salivarius Streptogramin B Structure Substrate Specificity System Therapeutic Intervention Transcriptional Regulation Translations Trimethoprim United States Virulence Factors Work base beta-Lactam Resistance beta-Lactams biological adaptation to stress capsule efflux pump genetic element insight lincosamide meetings mutant novel pathogen programs promoter resistance mechanism resistant strain telithromycin

项目摘要

DESCRIPTION (provided by applicant): The basis for the emergence of mefE-associated macrolide resistance in Streptococcus pneumoniae is a genetic element, mega (macrolide efflux genetic assembly). Mega initially emerged in pneumococcal serotypes (e.g., 14, 6B, 9V, 19F and 6A) and has now appeared in serotypes (e.g., 33F, 19A) causing replacement carriage and disease. We identified and characterized the mega genetic locus in S. pneumoniae. The mefE gene is found in single copy on the 5' end of a 5.5 kb or 5.4 kb chromosomal insert in the S. pneumoniae genome. At least four sites of insertion of mega have been identified. In addition to mefE, four other open reading frames (ORFs) organized into two convergent clusters are found in mega. Immediately downstream of mefE is an ORF, designated mel, that had significant homology to the erythromycin resistance ATP-binding cassette (ABC) protein, MsrA, of Staphylococcus epidermidis. The 3' end of mega contains three convergently transcribed ORFs (ORF5, ORF4, ORF3), homologous to ORFs in the 47.5 kb transposon Tn5252. In mefE-containing invasive S. pneumoniae isolates, mega is found in at least four distinct sites in the pneumococcal genome in epidemiologically and genetically unrelated strains. The gene products of mefE and mel are both required for macrolide resistance, work in concert, are coordinately regulated, and are inducible by macrolides. Mega element homologs have now been found in Tn1207.1, Tn1207.3, Tn2009 in S. pneumoniae and related elements in S. pyogenes, group B streptococci and in other Gram-positive bacteria. In two Specific Aims, we will further characterize the mega element and the genetic basis of mef-mediated macrolide resistance in S. pneumoniae. Two hypotheses will be examined: first, Mef and Mel of mega represent a novel efflux pump in Gram-positive bacteria composed of two distinct efflux proteins, an ABC membrane-bound transporter and a proton motive force transporter. Second, mega is a defective or "hitchhiker" genetic element related to conjugative transposons. The horizontal transfer and efflux activity of mega is enhanced by Tn5252 or other conjugative transposons. Also, the rapid emergence of mega and its continued spead in S. pneumoniae has been facilitated through ORFs 3-5 by competence induction and by agents, e.g., trimethoprim-sulfa, fluoroquinolones, that induce an SOS stress response in pneumococci. In Specific Aim 1, the molecular basis, regulation and substrate specificity of the efflux pump will be determined and the pump's potential role as a virulence factor assessed. In Specific Aim 2, the factors that impact the dissemination of mega (horizontal transfer) and efflux functions in the S. pneumoniae population will be determined. These studies should provide further insights into the molecular basis and mechanism(s) of dissemination of this novel genetic element and efflux pump and provide greater understanding of the emergence of antibiotic resistance in S. pneumoniae.

描述（由申请人提供）：肺炎链球菌中与MEFE相关的大花环抗性的基础是遗传元素，是Mega（Macrolide Felf遗传组装）。大型最初出现在肺炎球菌血清型（例如14、6b，9v，19f和6a）中，现在出现在血清型（例如33F，19A）中，导致替换运输和疾病。我们确定并表征了肺炎链球菌中的巨型遗传基因座。 MEFE基因在肺炎链球菌基因组中的5.5 kb或5.4 kb染色体插入的5'端单副本中发现。至少已经确定了四个插入大型插入位置。除MEFE外，在Mega中发现了其他四个开放式阅读框（ORF），分为两个收敛群。 MEFE下游的立即是指定的MEL，它与表皮葡萄球菌的红霉素耐药性ATP结合盒（ABC）蛋白MSRA具有重要同源性。巨型的3'末端包含三个收敛转录的ORF（ORF5，ORF4，ORF3），与47.5 kb Transposon TN5252中的ORF同源。在含MEFE的侵入性肺炎链球菌分离株中，在流行病学和遗传不相关菌株中的肺炎球菌基因组中的至少四个不同的位点中发现了大型。 MEFE和MEL的基因产物都是大环内酯类耐药性所必需的，协同工作，经过协调调节，并由大环内酯类诱导。现在在TN1207.1，TN1207.3，TN2009中发现了巨型元素同源物，在肺炎链球菌和相关元素中，B组B链球菌和其他革素阳性细菌中的相关元素。在两个具体的目标中，我们将进一步表征肺炎链球菌中MEF介导的大花环耐药性的巨型元素和遗传基础。将研究两个假设：首先，MEGA的MEF和MEL代表了革兰氏阳性细菌中的一种新型外排泵，该泵由两个不同的外排蛋白组成，ABC膜结合的转运蛋白和质子动力转运蛋白。其次，Mega是与共轭转座子有关的有缺陷或“搭便车”的遗传元素。 TN5252或其他共轭转座子增强了MEGA的水平转移和外排活性。同样，通过能力诱导和例如甲氧苄啶 - 硫酸盐，氟喹诺酮，通过ORFS 3-5促进了大型大型及其在肺炎链球菌中的迅速出现，从而诱导了肺炎球菌中SOS应力反应。在特定的目标1中，将确定外排泵的分子基础，调节和底物特异性，并评估泵作为毒力因子的潜在作用。在特定目标2中，将确定肺炎链球菌种群中影响大型（水平转移）和外排功能的因素。这些研究应提供对这种新型遗传元件和外排泵传播的分子基础和机制的进一步见解，并对肺炎链球菌抗生素耐药性的出现有更深入的了解。