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

• 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
• 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

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）：肺炎链球菌出现与mefe相关的大环内酯耐药的基础是一个遗传因素，mega（大环内酯外排遗传组装）。Mega最初出现在肺炎球菌血清型（如14、6B、9V、19F和6A）中，现在出现在血清型（如33F、19A）中，导致替代携带和疾病。我们鉴定并鉴定了肺炎链球菌的大基因位点。mefE基因位于肺炎链球菌基因组5.5 kb或5.4 kb染色体插入体的5'端。目前已经确定了至少4个mega插入位点。除了mefE，在mega中还发现了另外四个被组织成两个收敛簇的开放阅读框架（orf）。mefE的下游是一个ORF，命名为mel，它与表皮葡萄球菌的红霉素耐药atp结合盒（ABC）蛋白MsrA具有显著的同源性。mega的3'端包含3个聚合转录的orf (ORF5, ORF4, ORF3)，与47.5 kb转座子Tn5252中的orf同源。在含有mefe的侵袭性肺炎链球菌分离株中，在流行病学和遗传学不相关的菌株中，至少在肺炎球菌基因组的四个不同位点发现mega。mefE和mel的基因产物都是大环内酯类耐药所必需的，它们协同工作，协调调节，并被大环内酯类诱导。目前已在肺炎链球菌的Tn1207.1、Tn1207.3、Tn2009以及化脓性链球菌、B群链球菌和其他革兰氏阳性细菌的相关元素中发现兆元同源物。在两篇文章中，我们将进一步描述肺炎链球菌mef介导的大环内酯类耐药的mega元素和遗传基础。本文将研究两种假设：首先，Mef和Mel代表革兰氏阳性细菌中的一种新的外排泵，由两种不同的外排蛋白组成，一种是ABC膜结合转运蛋白，另一种是质子动力转运蛋白。其次，mega是一种与共轭转座子相关的有缺陷或“搭便车”的遗传元件。Tn5252或其他共轭转座子增强了mega的水平转移和外排活性。此外，通过能力诱导和药物（如甲氧苄啶-磺胺、氟喹诺酮类药物）在肺炎球菌中诱导SOS应激反应，orf 3-5促进了mega的迅速出现及其在肺炎链球菌中的持续传播。在Specific Aim 1中，将确定外排泵的分子基础、调控和底物特异性，并评估该泵作为毒力因子的潜在作用。在具体目标2中，将确定影响肺炎链球菌人群中mega（水平转移）传播和外排功能的因素。这些研究将进一步深入了解这种新型遗传元件和外排泵传播的分子基础和机制，并为肺炎链球菌抗生素耐药性的出现提供更好的理解。