Biosynthesis of nucleoside antibiotics targeting bacterial translocase I

需要新的抗生素，特别是那些可以被视为新化学实体的抗生素 并且相对于当前的临床抗生素武器具有新的靶点。高度修饰 抑制参与细胞壁生物合成的细菌移位酶I（TL1）的核苷类抗生素 这两种描述，并有很好的潜力，部分是因为他们是（i）纳摩尔 TL1的抑制剂，（ii）抑制已被证明对大多数人的生存至关重要的靶标， 如果不是全部，细菌，（iii）在体外和体内模型中都是有效的抗生素，和（iv）没有 小鼠明显毒性。我们已经确定了导致核心的生物合成机制 包括A-90289在内的几种有前途的核苷类抗生素的二乙酰核苷结构 来自链霉菌属SANK 60405的胞壁霉素， 使用组合的体内和体外方法从链霉菌属LL-AA 896中获得Muraymycin。 这些结果已经定义了一个多酶途径，突出显示了与主要酶的分歧。 构建块UMP和再会聚以形成核心核苷。这些数据用于扫描 丰富的基因组信息，以确定一种新的领先抗生素，球孢菌素，这是 分离并显示共享核苷核心结构，但具有几个独特的特征 包括来源不明的二羟基化哌啶环。我们现在将完成以下工作 具体目的：（i）确定3-氨基-3-羧基丙基的连接机制， （3A3CP）部分，其在A-90289的生物合成中产生最后的共享中间体， Muraminomicin、Muraymycin和sphaerimicin，假设其通过一种新的酶发生 策略催化的吡哆醛-5 ′-磷酸依赖性蛋白质和（ii）描绘 生物合成机制的分歧，从最后，共享中间产生独特的， 核苷核心支架进一步被脂肪酸、聚酮化合物、非核糖体 肽和/或肽。A-90289二氮杂环庚烷酮环的生物合成机理 并定义了球孢霉素中高度不寻常的稠合哌啶环系统。

New antibiotics are needed, particularly those that can be considered as new chemical entities and have novel targets relative to the current, clinical armament of antibiotics. Highly modified nucleoside antibiotics that inhibit bacterial translocase I (TL1) involved in cell wall biosynthesis fit both these descriptions, and have excellent potential in part because they are (i) nanomolar inhibitors of TL1, (ii) inhibit a target that has been proven to be essential for the survival of most, if not all, bacteria, (iii) are effective antibiotics in both in vitro and in vivo models, and (iv) have no apparent toxicity in mice. We have defined the biosynthetic mechanism leading to the core disaccharyl-nucleoside structure of several promising nucleoside antibiotics including A-90289 from Streptomyces sp. SANK 60405, muraminomicin from Streptosporangium sp, and muraymycin from Streptomyces sp. LL-AA896 using a combined in vivo and in vitro approach. The results have defined a multi-enzyme pathway highlighted by divergence from the primary building block UMP and reconvergence to form the core nucleoside. This data was utilized to scan the wealth of genomic information to identify a new lead antibiotic, sphaerimicin, which was isolated and revealed to share the nucleoside core structure but have several unique features including a dihydroxylated piperidine ring of unknown origin. We will now accomplish the following specific aims: (i) to define the mechanism for the attachment of the 3-amino-3-carboxypropyl (3A3CP) moiety that generates the last, shared intermediate in the biosynthesis of A-90289, muraminomicin, muraymycin, and sphaerimicin, which is hypothesized to occur via a new enzyme strategy catalyzed by a pyridoxal-5′-phosphate-dependent protein and (ii) to delineate the biosynthetic mechanism for divergence from the last, shared intermediate to generate unique, nucleoside core scaffolds that are further decorated by fatty acids, polyketides, nonribosomal peptides, and/or saccharides. A biosynthetic mechanism for the diazepanone ring for A-90289 and the highly unusual fused piperidine ring system in sphaerimicin will be defined.