Molecular mechanism of cephalosporin resistance of N. gonorrhoeae conferred by mutated PBP2

项目摘要 淋病奈瑟菌是性传播感染淋病的病原体， 美国每年有超过80万例感染，全球有7800万例感染。未处理或 无法治疗的感染可导致不孕症，女性盆腔炎（PID），淋球菌性关节炎 感染和传播艾滋病毒的风险增加。在过去几十年中， 这种生物体对多种抗生素的抗性的不可阻挡的增加严重限制了 淋球菌感染的治疗选择。最令人担忧的是，对超广谱抗生素的抵抗 头孢菌素（ESC）头孢曲松对公众健康构成严重威胁。这种情况需要一个 在分子水平上了解抗生素耐药性，以便能够设计新的抗菌剂。 N.淋病由青霉素结合蛋白2（PBP 2）的突变形式赋予。 在本申请中，我们建议阐明抗性的分子机制， 假设PBP 2中的突变限制了蛋白质的分子动力学。它建立在我们最近的 了解野生型PBP 2与ESCs结合时的相互作用以及构象如何改变 与结合和酰化相关的变化似乎在来源于ESCR菌株的PBP 2中受到限制。的 研究包括三个目标：具体目标1是野生型PBP 2的结构-功能分析， 研究当PBP 2被结合和酰化时形成的特异性相互作用的重要性， 头孢菌素。在具体目标2中，我们将阐明来自ESCR菌株的PBP 2中存在的关键突变是如何发生的。 N.淋病减少头孢菌素的灭活，同时保留足够的生物功能， 有机体的生长。最后，具体目标3将检查PBP 2变体在溶液中的行为， 确定突变是否阻碍蛋白质动力学。通过揭示分子机制 PBP 2的突变克服了β-内酰胺的致命作用，这些研究将使新的策略， 开发替代性抗淋球菌药物。

Project Summary Neisseria gonorrhoeae, the causative agent for the sexually transmitted infection gonorrhea, is responsible for over 800,000 infections annually in the U.S. and 78 million cases worldwide. Untreated or untreatable infections can lead to infertility, pelvic inflammatory disease (PID) in females, gonococcal arthritis in both sexes, and an increased risk of both contracting and transmitting HIV. Over the past several decades, the inexorable increase of resistance in this organism toward multiple classes of antibiotics has severely limited treatment options for gonococcal infections. Most alarmingly, resistance against the extended-spectrum cephalosporin (ESC) ceftriaxone poses a serious threat to public health. This situation requires an understanding of antibiotic resistance at the molecular level in order to enable design of new antimicrobials. ESC resistance of N. gonorrhoeae is conferred by mutated forms of penicillin-binding protein 2 (PBP2). In this application, we propose to elucidate the molecular mechanism of resistance, with the overarching hypothesis that mutations in PBP2 restrict the molecular dynamics of the protein. It builds upon our recent understanding of the interactions made by wild-type PBP2 when bound by ESCs and how conformational changes associated with binding and acylation appear restricted in PBP2 derived from ESCR strains. The investigation comprises three aims: Specific Aim 1 is a structure-function analysis of wild-type PBP2 to investigate the importance of specific interactions formed when PBP2 is bound and acylated by cephalosporins. In Specific Aim 2, we will elucidate how key mutations present in PBP2 from ESCR strains of N. gonorrhoeae reduce inactivation by cephalosporins while retaining sufficient biological function to support growth of the organism. Finally, Specific Aim 3 will examine the behavior of PBP2 variants in solution to determine whether mutations hinder protein dynamics. By revealing the molecular mechanisms of how mutations in PBP2 overcome the lethal action of β-lactams, these investigations will enable new strategies for the development of replacement anti-gonococcal agents.