Structural Studies of Nonribosomal Peptide Synthesis

微生物产生天然产物，在独特的环境中茁壮成长， 条件和竞争有机体的范围。这些不同的分子通常是独特的， 在细胞通讯和信号传导中发挥作用， 竞争、营养获取和毒性。天然产物的功能， 生物环境使它们成为发现新药物的有吸引力的候选者。 事实上，大约三分之二的小分子药物来自天然产物。 了解不寻常的天然产物的生物合成将有助于分析 成千上万的生物合成基因簇，没有已知的产品，并可能导致发现 新的药物活性分子。一个基于肽的天然产物家族是 由多结构域非核糖体肽合成酶（NRPS）产生。有几百 NRPS产品的主要成分是重要的肽类抗生素万古霉素和替沙菌素，β-内酰胺类抗生素 抗生素，如青霉素和头孢菌素，大肠杆菌素， 免疫抑制剂环孢菌素以及细菌铁载体如肠杆菌素，绿脓菌荧光素， 和分枝杆菌素。NRPS使用一个显着的装配线架构;多个蛋白质结构域 连接在一个单一的蛋白质，可以是数千或数万个残基的长度。 在生物合成过程中，氨基酸结构单元共价负载到载体结构域上， 递送至邻近的催化结构域用于肽延伸和修饰。使用 在核糖体和mRNA非依赖性合成中的非蛋白质氨基酸，以及 随后通过辅助结构域的化学修饰，使NRPS的惊人多样性成为可能 产品.我们建议继续进行生物化学和结构研究， NRPS功能的分子基础我们将确定管理高效的 通过NRPS结构循环的进展，以允许以一种非结构化的方式递送结合的底物。 协调、高效的过程。这些研究将确定大型多畴 酶在催化相关的构象，以了解功能，使这一点 结构周期我们还将研究不寻常的NRPS，以确定赋予NRPS的功能 具有执行意外化学反应的能力的域。我们将研究NRPS 生物合成机制尚未确定，特别关注异常催化 缩合和硫酯域的性质，并将决定产品的 来自人类病原体的未表征的NRPS。

Microbes produce natural products to thrive in unique environments where they face a wide range of conditions and competing organisms. These diverse molecules are often unique to individual species and play roles in cellular communication and signaling, interspecies competition, nutrient acquisition, and virulence. The ability of natural products to function in the biological setting make them attractive candidates for the discovery of new pharmaceuticals. Indeed, roughly two-thirds of small molecule drugs are derived from natural products. Understanding the biosynthesis of unusual natural products will facilitate the analysis of the thousands of biosynthetic gene clusters with no known product and may lead to the discovery of new pharmaceutically active molecules. One family of peptide-based natural products is produced by the multidomain nonribosomal peptide synthetases (NRPSs). Among the hundreds of NRPS products are the important peptide antibiotics vancomycin and teixobactin, β-lactam antibiotics like some penicillins and cephalosporins, the genotoxin colibactin, the immunosuppressant cyclosporin, as well as bacterial siderophores like enterobactin, pyoverdine, and mycobactin. NRPSs use a remarkable assembly line architecture; multiple protein domains are joined in a single protein that can be thousands or tens of thousands of residues in length. During biosynthesis, amino acid building blocks are covalently loaded onto a carrier domain and delivered to neighboring catalytic domains for peptide extension and modification. The use of nonproteinogenic amino acids in a ribosome- and mRNA-independent synthesis, as well as subsequent chemical modification by auxiliary domains, enables the striking diversity of NRPS products. We propose to continue our biochemical and structural studies to understand the molecular basis of NRPS function. We will identify the features that govern the efficient progression through the NRPS structural cycle to allow the delivery of bound substrates in a coordinated, efficient process. These studies will determine structures of large, multidomain enzymes in catalytically relevant conformations to understand features that enable this structural cycle. We will also examine unusual NRPSs to identify the features that endow NRPS domains with the ability to perform unexpected chemical reactions. We will examine NRPSs with undetermined biosynthetic mechanism with a particular focus on unusual catalytic properties of condensation and thioester domains, and will determine the products of uncharacterized NRPSs from human pathogens.