Bulgecin Template for Potentiation of beta-Lactam Antibiotics

用于增强 β-内酰胺抗生素的 Bulgecin 模板

• 批准号: 10040793
• 负责人: Shahriar Mobashery
• 金额: $ 50.2万
• 依托单位: UNIVERSITY OF NOTRE DAME
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-07-01 至 2025-06-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10040793
• 关键词: Address; Anti-Bacterial Agents; Antibiotics; Applications Grants; Aspartate; Aspartic Acid; Attention; Bacteria; Binding; Ceftazidime; Chemosensitization; Clinical; Complex; Computer Analysis; Cytolysis; Event; Exhibits; Failure; Fluorescence Microscopy; Gene Cluster; Genes; Gram-Negative Bacteria; Gram-Negative Bacterial Infections; Host resistance; In Vitro; Infection; Lead; Lytic; Meropenem; Methodology; Methods; Microbiology; Monobactams; Natural Products; Organism; Pathway interactions; Penetration; Phase; Preparation; Process; Production; Property; Pseudomonas aeruginosa; Pseudomonas aeruginosa infection; Reaction; Reporting; Research; Resistance; Rodent Model; Roentgen Rays; Scanning Electron Microscopy; Series; Serine; Site; Structure; Work; analog; bactericide; beta-Lactams; chemical synthesis; experimental study; fighting; human pathogen; in vivo; lead optimization; novel; novel strategies; pathogen; periplasm; resistance mechanism

Project Summary/Abstract Gram-negative bacteria have become broadly resistant to known classes of antibiotics. Treatment of infections by these pathogens has become increasingly challenging and efforts in the past two decades in discoveries of new classes of antibacterial agents have failed. In this grant application, we have turned our attention to bulgecins, a group of three natural products (bulgecins A, B and C) discovered in the 1980s, which potentiate the activities of b-lactam antibiotics to Gram-negative bacteria. The three natural products were prepared by total synthesis and we documented the potentiation activity in microbiological experiments. Furthermore, we documented by both fluorescence microscopy and by scanning-electron microscopy that the combination of bulgecin A and a b-lactam antibiotic (ceftazidime or meropenem) cause bulges in the bacterial envelope, which are points of structural instability that burst and lead to bactericidal effect. In addition, we documented that merely two lytic transglycosylases out of 11 in Pseudomonas aeruginosa—Slt and MltD (with ceftazidime) and Slt and MltG (with meropenem)—are the targets of bulgecin A. We also report the X-ray structure for the complex of Slt with bulgecin A. We disclose the next phase of this research in two Specific Aims. Specific Aim 1 addresses our planned analysis of the bulgecin-biosynthetic cluster, which we discovered recently. The eight-gene cluster converts L-serine and L-aspartic acid to bulgecinine, a key structural component of bulgecins, and then in turn, to bulgecins A, B and C. We propose to study these genes both for their enzymological reactions and for their structures. A proposal is outlined to prepare the high-value bulgecinine using a host bacterium as a “one-pot” reaction vessel. We already have reported a chemical synthesis for bulgecinine and a second (shorter) synthetic approach is also proposed. A detailed plan is outlined in Specific Aim 2 to optimize the bulgecin template. The process takes advantage of our X-ray structure for the complex of Slt and bulgecin A in a computational analysis to identify analogs that will bind more potently to lytic transglycosynases and achieve penetration into Gram-negatives more avidly. The proposed targets will be synthesized and fully analyzed in a series of both in vitro and in vivo experiments in identification of a suitable combination of a bulgecin analog with a b-lactam antibiotic in fighting Gram-negative bacterial infections.

项目总结/摘要 革兰氏阴性菌已经对已知种类的抗生素产生了广泛的耐药性。治疗感染 在过去的二十年里， 新型抗菌剂已经失败。在这份拨款申请中，我们将注意力转向了 bulgecins是在20世纪80年代发现的一组三种天然产物（bulgecins A、B和C），其增强 β-内酰胺类抗生素对革兰阴性菌的抗菌活性。这三种天然产物通过以下步骤制备： 全合成，我们在微生物实验中记录了增强活性。而且我们 通过荧光显微镜和扫描电子显微镜记录， bulgecin A和b-内酰胺抗生素（头孢他啶或美罗培南）引起细菌包膜的隆起， 是结构不稳定的点，破裂并导致杀菌作用。此外，我们还记录了 铜绿假单胞菌中11种酶中仅有两种溶解性转糖基酶-Slt和MltD（头孢他啶）， Slt和MltG（与美罗培南）-是bulgecin A的靶点。我们还报告了X射线结构的 Slt与bulgecin A的复合物。我们在两个具体目标中披露了这项研究的下一阶段。具体目标 1解决了我们计划的bulgecin生物合成集群，我们最近发现的分析。的 八个基因簇将L-丝氨酸和L-天冬氨酸转化为bulgecinine，bulgecinine是一种关键的结构成分， bulgecins，然后依次转化为bulgecins A、B和C。我们建议研究这些基因， 酶反应及其结构。本文提出了制备高价值的Bulgecinine的建议 使用宿主细菌作为“一锅法”反应容器。我们已经报道了一种化学合成方法， bulgecinine和第二个（较短）的合成方法也提出了。详细的计划概述在具体 目的2优化bulgecin模板。该过程利用了我们的X射线结构的复杂性， Slt和bulgecin A进行计算分析，以鉴定将更有效地结合裂解的类似物。 转糖苷酶和实现渗透到革兰氏阴性菌更贪婪。拟议的目标将是 合成并在一系列体外和体内实验中充分分析，以鉴定合适的 bulgecin类似物与b-内酰胺抗生素的组合在对抗革兰氏阴性细菌感染中的应用。