Plasmid-Mediated Quinolone Resistance

质粒介导的喹诺酮耐药性

• 批准号: 6732154
• 负责人: GEORGE A JACOBY
• 金额: $ 16.95万
• 依托单位: LAHEY CLINIC
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-03-15 至 2008-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6732154
• 关键词: DNA gyrase; DNA topoisomerases; Escherichia coli; Klebsiella pneumoniae; X ray crystallography; adenosinetriphosphatase; bacterial proteins; chemical binding; crystallization; drug resistance; endopeptidases; enzyme activity; enzyme inhibitors; microorganism culture; molecular cloning; plasmids; polymerase chain reaction; protein binding; protein protein interaction; protein structure function; proteolysis; quinoline; surface plasmon resonance; transfection /expression vector

DESCRIPTION (provided by applicant): 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 in a limited number of isolates in the United States, the qnr gene has recently been discovered in a larger group of isolates from the Far East. The aims of this proposal are: to elucidate the structural requirements for Qnr binding to gyrase, to establish the gyrase activities that Qnr can protect from quinolone inhibition, to determine whether Qnr can also protect the related quinolone target topoisomerase IV, to explore the hypothesis that Qnr blocks quinolone binding to gyrase, to study Qnr binding quantitatively using surface plasmon resonance, to investigate whether Qnr can also protect gyrase from such protein inhibitors as MccB17, CcdB, and Gyrl, to determine whether Qnr and an active gyrase fragment can co-crystallize for structural analysis by x-ray diffraction, and to study the detailed molecular structure of Qnr plasmids to elucidate how this novel property has been acquired. Qnr prevalence will also be explored utilizing samples from parts of the world where quinolone resistance has become common and also from food animal sources. 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）：喹诺酮是由于其广泛的抗菌光谱，低毒性和对其他耐药性病原体的可靠作用，因此是广泛使用的抗菌剂。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。尽管最初在美国有限的分离株中发现了QNR基因，但最近在远东的一组较大的分离株中发现了QNR基因。 The aims of this proposal are: to elucidate the structural requirements for Qnr binding to gyrase, to establish the gyrase activities that Qnr can protect from quinolone inhibition, to determine whether Qnr can also protect the related quinolone target topoisomerase IV, to explore the hypothesis that Qnr blocks quinolone binding to gyrase, to study Qnr binding quantitatively using surface plasmon resonance,调查QNR是否还可以保护回旋酶免受MCCB17，CCDB和GYRL等蛋白抑制剂的影响，以确定QNR和活性Gyrase片段是否可以通过X射线衍射进行结构分析，并研究QNR质量的详细分子结构，以实现这种新颖的特性。还将利用来自世界各地的样品QNR患病率探索奎诺酮耐药性已变得普遍，也是食用动物来源的样本。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。