Biosynthesis of nucleoside antibiotics targeting bacterial translocase

描述（由申请人提供）：多种耐药病原体的出现在全球范围内成为问题，新抗生素的发现持续下降。广泛的，长期的目标，这项建议是发现，表征，并开发一种新的结构类的抗生素核苷类抗生素，目标是参与肽聚糖细胞壁生物合成的细菌移位酶I。该提议的具体目的是（I）表征脂肽基-核苷抗生素家族内发现的氨基核糖基部分的组装和掺入，和（II）功能上和机理上表征催化本文所代表的新的或不寻常的生化反应的酶，所述酶由丝氨酸羟甲基转移酶样酶的新家族表示，所述丝氨酸羟甲基转移酶样酶被假设催化羟醛缩合反应。型缩合形成不寻常的非蛋白质氨基酸。具体目标I和II将通过使用为脂肽基核苷A-90289生产菌株开发的稳健遗传系统实现，用于采用基因失活和交叉互补的体内研究，重组蛋白将用于体外功能和机制研究。这一结果将为核糖基单元整合到天然产物支架中建立一种新的机制，并将为进入高碳核苷类抗生素领域建立一个范例。这些结果对于我们使用遗传信息（基因型到化学型方法）寻找新的核苷抗生素的长期目标至关重要，将允许使用组合生物合成和全合成的母体支架的结构多样化，并将为设计具有改善的生物相容性和药理学特性的第二代抗生素提供基础。

DESCRIPTION (provided by applicant): The emergence of multiple drug resistant pathogens is becoming problematic worldwide, and the discovery of new antibiotics continues to decline. The broad, long-term objective of this proposal is to discover, characterize, and develop a new structural class of antibiotics-nucleoside antibiotics-that target bacterial translocase I involved in peptidoglycan cell wall biosynthesis. The specific aims of this proposal are (I) to characterize the assembly and incorporation of the aminoribosyl moiety found within the family of lipopeptidyl-nucleoside antibiotics and (II) to functionally and mechanistically characterize enzymes catalyzing novel or unusual biochemical reactions represented herein by a new family of serine hydroxymethyltransferase-like enzymes that are hypothesized to catalyze an aldol-type condensation to form unusual nonproteinogenic amino acids. Specific Aim I and II will be achieved by using the robust genetic system developed for the lipopeptidyl nucleoside A-90289-producing strain for in vivo studies employing gene inactivation and cross-complementation, and recombinant proteins will be exploited for functional and mechanistic studies in vitro. The results will establish a new mechanism for incorporating ribosyl units into natural product scaffolds and will establish a paradigm for the entry into high-carbon nucleoside antibiotics. The results will be essential for our long-term goals of searching for new nucleoside antibiotics using genetic information (a genotype-to-chemotype approach), will allow for the structural diversification of the parent scaffolds using combinatorial biosynthesis and total synthesis, and will provide the basis for the design of second generation antibiotics with improved biocompatibility and pharmacological properties.