Molecular Targets in Peptidoglycan Synthesis

肽聚糖合成中的分子靶标

基本信息

批准号：
8245454
负责人：
Christopher Davies
金额：
$ 34.79万
依托单位：
MEDICAL UNIVERSITY OF SOUTH CAROLINA
依托单位国家：
美国
项目类别：
财政年份：
2003
资助国家：
美国
起止时间：
2003-02-01 至 2015-12-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8245454
关键词：
Active Sites Acylation Address Alanine Amidohydrolases Amino Acids Antibiotic Resistance Antibiotics Autolysin Biochemical Biological Process C-terminal Catalytic Domain Cefixime Ceftriaxone Cell Wall Cell division Centers for Disease Control and Prevention (U.S.)Cephalosporin Resistance Cephalosporins Clinical Complex Data Development Dose Drug Delivery Systems Enzymes Exhibits Fluoroquinolones Goals Gonorrhea Infection Investigation Kinetics Lactams Light Lytic Mediating Metabolism Methods Molecular Molecular Target Monobactams Mutation N-terminal Neisseria gonorrhoeae Organism Penicillin Binding Protein 2 Penicillin Resistance Penicillin-Binding Proteins Penicillins Peptides Peptidoglycan Peptidyltransferase Positioning Attribute Predisposition Protein Dynamics Proteins Public Health Relaxation Reporting Resistance Role Series Sexually Transmitted Diseases Specificity Staging Structural Protein Structure Substrate Specificity Tertiary Protein Structure Testing Therapeutic Treatment Failure Variant Withdrawal X-Ray Crystallography amidase antimicrobial base crosslink drug discovery enzyme activity inhibitor/antagonist mutant novel protein structure research study resistant strain

项目摘要

DESCRIPTION (provided by applicant): Neisseria gonorrhoeae is the causative agent for the sexually transmitted disease gonorrhea and was responsible for over 350,000 infections in the U.S. in 2007. The steady and inexorable increase of resistance in this organism toward multiple classes of antibiotics has severely limited treatment options for gonococcal infections and, after the recent withdrawal of fluoroquinolones, the expanded-spectrum cephalosporin ceftriaxone is now the only single-dose treatment recommended by the CDC in the U.S. Unfortunately, new strains of N. gonorrhoeae have emerged that exhibit resistance to cefixime and ceftriaxone, and treatment failures are now being reported. This precarious position endangers public health and demands a better understanding of antibiotic resistance at the molecular level, as well as strategies to develop new antimicrobials directed against N. gonorrhoeae. This renewal application will address this need by investigating two enzymes of N. gonorrhoeae involved in peptidoglycan synthesis. One is penicillin-binding protein 2 (PBP 2), a transpeptidase that forms peptide cross-links during the latter stages of cell wall synthesis, and the clinical target for ?-lactam antibiotics directed against this organism. Cephalosporin-resistant strains of N. gonorrhoeae harbor mutations in PBP 2 and a key goal is to determine the structural mechanisms that lower reactivity of PBP 2 with these antibiotics. We will also apply NMR relaxation methods to test the hypothesis that the molecular mechanism governing penicillin and cephalosporin resistance mediated by PBP 2 involves dynamic states of the protein. In recognition that other enzymes involved in peptidoglycan metabolism are potential targets for antimicrobials, we will also investigate N-acetylmuramyl-L-alanine amidase (AmiC), an autolysin that is required for proper cell division of N. gonorrhoeae. We have discovered that this enzyme exhibits autolytic activity in its N-terminal domain in addition to its known amidase activity in the C-terminal domain and therefore is a bifunctional autolysin. To understand the functional role of AmiC in peptidoglycan breakdown, but also to pave the way for drug discovery against its two active sites, we will obtain essential structural and biochemical information for AmiC. PUBLIC HEALTH RELEVANCE: The steady and inexorable increase of antibiotic resistance in N. gonorrhoeae, the causative agent for the sexually transmitted disease gonorrhea, has severely limited treatment options for gonococcal infections such that the expanded-spectrum cephalosporin ceftriaxone is now the only single-dose treatment recommended by the CDC in the U.S. Unfortunately, new strains of N. gonorrhoeae have emerged that exhibit marked increases in resistance to the expandedspectrum cephalosporins, cefixime and ceftriaxone, and are now overcoming established breakpoints for these antibiotics. This application will address this impending crisis in public health by elucidating the molecular mechanism of antibiotic resistance caused by mutations in a penicillin-binding protein and by investigation of an autolysin required for cell division as a potential new target for antimicrobial development.

描述（由申请人提供）：淋病奈瑟氏菌是性传播疾病淋病的病原体，2007 年在美国造成了超过 350,000 例感染。这种生物体对多种抗生素的耐药性稳定且不可阻挡地增加，严重限制了该病的治疗。淋球菌感染的治疗选择，以及最近停用氟喹诺酮类药物后，广谱头孢菌素头孢曲松目前是美国疾病预防控制中心推荐的唯一单剂量治疗方法。不幸的是，新的淋病奈瑟菌菌株已经出现，对头孢克肟和头孢曲松具有耐药性，目前有治疗失败的报告。这种不稳定的状况危及公共健康，需要在分子水平上更好地了解抗生素耐药性，以及开发针对淋病奈瑟菌的新型抗菌药物的策略。该更新申请将通过研究淋病奈瑟菌中涉及肽聚糖合成的两种酶来满足这一需求。其中之一是青霉素结合蛋白 2 (PBP 2)，这是一种在细胞壁合成后期形成肽交联的转肽酶，也是针对该生物体的 β-内酰胺抗生素的临床靶点。淋病奈瑟菌的头孢菌素耐药菌株含有 PBP 2 突变，关键目标是确定降低 PBP 2 与这些抗生素反应性的结构机制。我们还将应用 NMR 弛豫方法来检验以下假设：PBP 2 介导的青霉素和头孢菌素耐药性的分子机制涉及蛋白质的动态状态。认识到参与肽聚糖代谢的其他酶是抗菌药物的潜在靶标，我们还将研究 N-乙酰胞壁酰-L-丙氨酸酰胺酶 (AmiC)，这是一种淋病奈瑟菌正常细胞分裂所需的自溶素。我们发现，该酶除了在 C 端结构域中具有已知的酰胺酶活性外，还在其 N 端结构域中表现出自溶活性，因此是一种双功能自溶素。为了了解 AmiC 在肽聚糖分解中的功能作用，同时也为针对其两个活性位点的药物发现铺平道路，我们将获得 AmiC 的重要结构和生化信息。公共卫生相关性：淋病奈瑟菌（性传播疾病淋病的病原体）的抗生素耐药性稳步且不可阻挡地增加，严重限制了淋球菌感染的治疗选择，例如广谱头孢菌素头孢曲松钠现在是唯一的单剂量药物美国疾病预防控制中心推荐的治疗方法不幸的是，新的淋病奈瑟菌菌株已经出现，其数量显着增加对广谱头孢菌素、头孢克肟和头孢曲松具有耐药性，目前正在克服这些抗生素的既定突破点。该申请将通过阐明青霉素结合蛋白突变引起的抗生素耐药性的分子机制，并研究细胞分裂所需的自溶素作为抗菌药物开发的潜在新靶点，解决这一迫在眉睫的公共卫生危机。