Mechanism and Spread of Qnr-Mediated Resistance

Qnr介导的耐药机制和传播

• 批准号: 7334159
• 负责人: David C Hooper
• 金额: $ 20.35万
• 依托单位: MASSACHUSETTS GENERAL HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-01-01 至 2009-07-09
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7334159
• 关键词: Affinity; Animals; Anti-Bacterial Agents; Area; Bacteria; Bacterial Chromosomes; Binding; Cells; Clinical; Complex; Crystallography; DNA Gyrase; DNA Topoisomerase IV; Disruption; Elements; Escherichia coli; Europe; Evolution; Family; Far East; Gelshift Analysis; Genes; Genetic; High Prevalence; Holoenzymes; Hospitals; Human; Integrons; Kinetics; Klebsiella pneumonia bacterium; Link; Measures; Mediating; Modeling; Molecular; Molecular Epidemiology; Molecular Structure; Mutation; Numbers; Pharmaceutical Preparations; Plasmids; Prevalence; Principal Investigator; Protein Family; Proteins; Quinolones; Relative (related person); Research Design; Research Personnel; Resistance; Site; Structure; Superhelical DNA; Surface Plasmon Resonance; Testing; Thinking; Topoisomerase; Toxic effect; Toxin; United States; antimicrobial drug; base; gel displacement assay; genetic element; inhibitor/antagonist; instrument; microcin; pathogen; programs; protein function; protein protein interaction; quinolone resistance; resistance mechanism

DESCRIPTION (provided by applicant): Mechanism and Spread of Qnr-Mediated Resistance. Quinolones are widely used antimicrobial agents because of their broad antibacterial spectrum, low toxicity, and reliable action against otherwise resistant pathogens. Bacterial resistance to quinolones, however, is increasing and has reached alarming levels in some parts of Europe and the Far East. Various chromosomal mutations contribute to this resistance. Plasmid-mediated resistance was long thought not to exist. We discovered a plasmid-encoded protein termed Qnr that protects DNA gyrase from quinolone inhibition. Qnr acts additively with chromosomal mechanisms for quinolone resistance, belongs to the pentapeptide repeat family of proteins and, by a gel displacement assay, binds to the gyrase tetramer as well as to the GyrA and GyrB subunits with differing affinities. Although initially found at a single hospital in the United States, the qnr gene has recently been discovered in clinical Escherichia coli isolates from the Far East and in about 10% of quinolone resistant Klebsiella pneumoniae strains from the US. The aims of this proposal are to explore the hypothesis that Qnr blocks quinolone binding to gyrase, to study Qnr binding kinetics by surface plasmon resonance, to investigate whether Qnr can also protect gyrase from such protein inhibitors as MccB17, CcdB, and Gyrl, to study further the prevalence of qnr and the genetic basis of its acquisition by plasmids, and to explore whether Qnr and an active gyrase fragment can co-crystallize for structural analysis by x-ray diffraction. These studies are important not only for understanding an emerging resistance mechanism but should also reveal details of how DNA gyrase and related topoisomerases function and how proteins in the pentapeptide family interact with and regulate the activity of other proteins.

描述（由申请人提供）：QNR介导的电阻的机理和扩散。喹诺酮是广泛使用的抗菌剂，因为它们的抗菌光谱，低毒性和对其他耐药性病原体的可靠作用。然而，对喹诺酮类的细菌耐药性正在增加，并且在欧洲和远东的某些地区达到了令人震惊的水平。各种染色体突变有助于这种抗性。长期以来，质粒介导的抗性不存在。我们发现了一种称为QNR的质粒编码的蛋白质，可保护DNA旋酶免受喹诺酮抑制作用。 QNR与喹诺酮耐药性的染色体机制相加的作用，属于蛋白质的五肽重复家族，并且通过凝胶位移测定法，与Gyrase Tetramer以及Gyra和Gyrb亚基结合，具有不同的亲密亲密关系。尽管最初在美国的一家医院发现了QNR基因，但最近在远东地区的临床大肠杆菌分离株中发现了QNR基因，在美国，约有10％的Quinolone耐药性克雷伯氏菌肺炎菌株来自美国。该提议的目的是探讨QNR阻塞奎诺酮与陀螺酶结合的假设，研究QNR通过表面等离子体共振的结合动力学，以研究QNR是否也可以通过MCCB17，CCDB，ccdb和Gyrl和gyrl的预期和QNR和QNR的预期来保护Gyrase免受此类蛋白质抑制剂的侵害，以进行QNR和QNR的蛋白质抑制剂。探索QNR和活动的回旋酶片段是否可以通过X射线衍射进行结构分析。这些研究不仅对于理解新出现的抗性机制也很重要，还应揭示DNA旋酶和相关拓扑异构酶的功能以及五肽家族中的蛋白质如何与其他蛋白质的活性相互作用和调节的细节。