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: 10438764
• 负责人: Shahriar Mobashery
• 金额: $ 62.9万
• 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/10438764
• 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.

项目概要/摘要 革兰氏阴性细菌已对已知类别的抗生素产生广泛耐药性。 由这些病原体引起的疾病变得越来越具有挑战性，过去二十年我们在发现 在本次拨款申请中，我们将注意力转向新型抗菌剂。 bulgecins，一组三种天然产物（bulgecins A、B 和 C）于 20 世纪 80 年代发现，可增强 制备了三种天然产物的β-内酰胺抗生素对革兰氏阴性菌的活性。 全合成，我们记录了微生物实验中的增强活性。 通过荧光显微镜和扫描电子显微镜记录表明， bulgecin A 和 β-内酰胺类抗生素（头孢他啶或美罗培南）会导致细菌包膜凸起，从而 是结构不稳定的点，会破裂并导致杀菌作用。此外，我们记录了这一点。 铜绿假单胞菌中的 11 种溶解性转糖基酶中只有两种 -Slt 和 MltD（使用头孢他啶）和 Slt 和 MltG（与美罗培南）——是 bulgecin A 的靶标。我们还报告了 Slt 与 bulgecin A 的复合物。我们在两个具体目标中公开了这项研究的下一阶段。 1 阐述了我们对最近发现的 bulgecin 生物合成簇的计划分析。 八基因簇将 L-丝氨酸和 L-天冬氨酸转化为 bulgecinine，这是 bulgecins，然后依次是 bulgecins A、B 和 C。我们建议研究这些基因 概述了制备高价值 bulgecinine 的酶学反应及其结构。 我们已经报道了使用宿主细菌作为“一锅”反应容器的化学合成。 具体方案中还提出了 bulgecinine 和第二种（较短的）合成方法。 目标 2 优化 bulgecin 模板 该过程利用了我们的复合物的 X 射线结构。 Slt 和 bulgecin A 进行计算分析，以确定与裂解物结合更有效的类似物 转糖基酶并更热切地实现对革兰氏阴性菌的渗透。 在一系列体外和体内实验中合成并充分分析，以确定合适的 bulgecin 类似物与 β-内酰胺抗生素的组合可对抗革兰氏阴性细菌感染。