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的化学物质的抗生素。 与目前的临床抗生素武器装备相比，具有新的靶点。高度修改 抑制参与细胞壁生物合成的细菌转位酶I(TL1)的核苷抗生素适合 这两种描述都具有极好的潜力，部分原因是它们是(I)纳米分子 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点， 如果不是所有细菌，(Iii)在体外和体内模型中都是有效的抗生素，以及(Iv)没有 对小鼠的明显毒性。我们已经定义了导致核心的生物合成机制 A-90289等几种有前景的核苷类抗生素的二糖基核苷结构 从链霉菌属(Streptomyces sp.)沉降率为60405，产孢链霉菌的溶菌素和 从链霉菌(Streptomyces sp.)LL-AA896采用体内和体外结合的方法。 结果已经定义了一种多酶途径，突出表现为与主要的 构建块UMP并重新聚合，形成核心核苷。该数据被用来扫描 丰富的基因组信息来鉴定一种新的主要抗生素，球菌素，它是 分离和揭示的核苷核心结构相同，但有几个独特的特征 包括来源不明的二羟基哌啶环。我们现在将完成以下工作 具体目标：(1)确定3-氨基-3-羧丙基的键合机理 (3A3CP)在A-90289的生物合成中产生最后一个共享中间体的部分， 溶菌素、溶菌素和球菌素，推测是通过一种新的酶产生的。 由依赖于吡哆醛-5‘-磷酸的蛋白催化的策略和(Ii)描述 生物合成机制，用于与上一个共享中间体的分歧，以产生独特的， 进一步修饰脂肪酸、聚酮、非核糖体的核苷核心支架 多肽和/或糖类。A-90289的二氮杂环的生物合成机理 并将定义Sphaerimicin中非常不寻常的稠合哌啶环系。

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.