Molecular Targets in Peptidoglycan Synthesis

肽聚糖合成中的分子靶标

• 批准号: 7261521
• 负责人: Christopher Davies
• 金额: $ 30.35万
• 依托单位: MEDICAL UNIVERSITY OF SOUTH CAROLINA
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-02-01 至 2011-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7261521
• 关键词: Acylation; Address; Amidohydrolases; Amino Acids; Anabolism; Antibiotic Resistance; Antibiotic Therapy; Antibiotics; Autolysin; Bacteria; Bambermycins; Biochemical; Biochemical Genetics; Biology; Boronic Acids; Cefixime; Ceftriaxone; Cell Wall; Cell division; Cells; Cephalosporins; Ciprofloxacin; Class; Complex; Development; Disease; Drug Delivery Systems; Drug Design; Enzymes; Escherichia coli; Generations; Genetic; Goals; Gonorrhea; Infection; Intermediate resistance; Lactams; Lytic; Mediating; Metabolism; Molecular; Molecular Target; Monobactams; Multienzyme Complexes; Multiprotein Complexes; Mutation; Neisseria gonorrhoeae; Numbers; Organism; Penicillin-Binding Proteins; Penicillins; Peptides; Peptidoglycan; Peptidyltransferase; Pharmaceutical Preparations; Polysaccharides; Proteins; Public Health; Rate; Research Personnel; Resistance; Role; Scaffolding Protein; Sexually Transmitted Diseases; Structure; Tetracycline; Tetracyclines; Therapeutic Agents; Variant; X-Ray Crystallography; amidase; antimicrobial; base; boronic acid; crosslink; drug development; drug discovery; enzyme mechanism; fluoroquinolone resistance; glycosyltransferase; improved; insight; mimetics; mutant; novel; pathogenic bacteria; polymerization; programs

Beta-lactam antibiotics, which target the essential transpeptidases (penicillin-binding proteins or PBPs) that cross-link peptidoglycan strands, are important drugs in the treatment of bacterial diseases. Unfortunately, the emergence of antibiotic-resistant pathogenic bacteria is a growing problem and threatens to make these and other antibiotics obsolete. Penicillin and tetracycline are no longer used to treat gonococcal infections due to the emergence of resistant strains of N. gonorrhoeae. Moreover, resistance to fluoroquinolones and third-generation cephalosporins, the two classes of antibiotics current recommended in the treatment of gonorrhea, is increasing. Clearly there is an urgent need to develop new antimicrobials directed both against well-known molecular targets, such as PBPs, but also against novel targets such as transglycosylases (TGases), which catalyze the polymerization of glycan stands, and autolysins, which break down peptidoglycan during biosynthesis. Development of new antibiotics, however, has been hindered by a dearth of mechanistic information for these enzymes. In this proposal we describe genetic, biochemical and structural studies of three classes of enzyme involved in peptidoglycan metabolism in N. gonorrhoeae. Each has been selected to address one or more of the following aims: (a) to understand the biology of peptidoglycan synthesis, (b) to explore their interactions with antibiotics, (c) to elucidate the molecular basis for antibiotic resistance and (d) to examine their potential as targets for drug development. The molecular basis for antibiotic resistance will be investigated by structural and biochemical studies of a unique variant of PBP 2 from strains of N. gonorrhoeae with intermediate-level resistance to ceftriaxone. The role of the lytic TGase MltA as part of a multienzyme complex involved in cell division will be investigated by genetic studies. The suitability of the amidase AmiC as a novel target for antimicrobials will be examined both genetically and by solving its crystal structure. Finally, the crystal structure of a TGase domain will reveal the catalytic mechanism of these enzymes and pave the way for drug design. Together, these studies will provide insight into the functional roles of these proteins in peptidoglycan metabolism but also the essential molecular information needed to bolster the current repertoire of antimicrobials directed against pathogenic bacteria. The sexually transmitted disease gonorrhea is a growing public-health problem due to the emergence of strains harboring resistance to antibiotics such as penicillin. The development of new treatments for gonococcal disease requires detailed, three-dimensional pictures of essential proteins in these bacteria for use in drug discovery. This project will use X-ray crystallography to provide such information for a number of key proteins in N. gonorrhoeae that are involved in cell wall synthesis.

β-内酰胺抗生素以交联肽聚糖链的必需转肽酶（青霉素结合蛋白或 PBP）为目标，是治疗细菌性疾病的重要药物。不幸的是，抗生素耐药病原菌的出现是一个日益严重的问题，并有可能使这些抗生素和其他抗生素过时。由于淋病奈瑟菌耐药菌株的出现，青霉素和四环素不再用于治疗淋球菌感染。此外，对氟喹诺酮类和第三代头孢菌素（目前推荐用于治疗淋病的两类抗生素）的耐药性正在增加。显然，迫切需要开发新的抗菌药物，既针对众所周知的分子靶标，例如 PBP，又针对新靶标，例如催化聚糖链聚合的转糖基酶 (TGase) 和在生物合成过程中分解肽聚糖的自溶素。然而，由于缺乏这些酶的机制信息，新抗生素的开发受到阻碍。在本提案中，我们描述了淋病奈瑟菌中参与肽聚糖代谢的三类酶的遗传、生化和结构研究。每一个都被选择来解决以下一个或多个目标：（a）了解肽聚糖合成的生物学，（b）探索它们与抗生素的相互作用，（c）阐明抗生素耐药性的分子基础，以及（d）检查它们作为药物开发目标的潜力。抗生素耐药性的分子基础将通过对来自对头孢曲松具有中等耐药性的淋病奈瑟菌菌株的 PBP 2 独特变体进行结构和生化研究来研究。裂解性 TGase MltA 作为参与细胞分裂的多酶复合物的一部分，其作用将通过遗传学研究进行研究。酰胺酶 AmiC 作为抗菌药物新靶点的适用性将通过遗传学和解析其晶体结构进行检验。最后，TGase结构域的晶体结构将揭示这些酶的催化机制，并为药物设计铺平道路。总之，这些研究将深入了解这些蛋白质在肽聚糖代谢中的功能作用，同时也提供支持当前针对病原菌的抗菌药物库所需的基本分子信息。 由于对青霉素等抗生素具有耐药性的菌株的出现，性传播疾病淋病已成为一个日益严重的公共卫生问题。淋球菌疾病新疗法的开发需要这些细菌中必需蛋白质的详细三维图像，以用于药物发现。该项目将利用 X 射线晶体学为淋病奈瑟菌中参与细胞壁合成的许多关键蛋白质提供此类信息。