Mechanistic studies of thioether crosslink formation in peptides

项目总结 生活的所有领域都会产生多肽类天然产物，它们的作用就像Quorum一样多种多样 传感分子和氧化还原辅因子。这些多肽发挥作用的能力 抗菌、抗病毒或抗癌药物使人们了解它们的生物合成 当代研究的重要领域。基于多肽的次生代谢物是 由不同的生物合成途径产生，这些途径在多肽是否是 由非核糖体多肽合成酶(NRP)或核糖体合成 由基因编码的ORF产生。这些多肽通常广泛存在于 修改过的。而在NRPS系统中，许多修改与 多肽合成，核糖体编码的多肽经历翻译后 修改。这些所谓的核糖体编码的翻译后修饰 多肽是一类新兴的多肽，具有广泛的生物活性。 由机制引入的修改，这些修改大多鲜为人知。 这一应用将集中在酶的引入上，将硫磺转化为α-碳硫醚 与核糖体编码的多肽发生交联，从而产生活性多肽。这些联系 不同于研究得很好的羊硫肽，在这些肽之间形成硫醚交联剂 一个半胱氨酸残基和一个脱水苏氨酸/丝氨酸。活性多肽成熟酶是 自由基SAM家族的酶和催化硫醚交联的自由基- 不被理解的中介反应。而生化、光谱和 结构研究在这一方面的应用将导致对这一重要的机械范式的研究 一类酶。虽然活性多肽本身有各种治疗用途， 了解这些酶的底物分布和机制将提供一种 用于合成交联肽的工具，这增加了在临床上的发现效用。

PROJECT SUMMARY All domains of life produce peptidic natural products that play roles as diverse as quorum sensing molecules and redox cofactors. The ability of these peptides to function as antibacterial, antiviral, or anticancer agents makes understanding their biosynthesis an important area of contemporary research. Peptide-based secondary metabolites are produced by distinct biosynthetic pathways that differ in whether the peptide is synthesized by the action of non-ribosomal peptide synthetases (NRPS), or ribosomally produced from a genomically encoded orf. These peptides are often extensively modified. While in the NRPS systems many of the modifications occur concurrently with peptide synthesis, the ribosomally encoded peptides undergo posttranslational modification. These so-called ribosomally encoded posttranslationally modified polypeptides (RiPP) are a new emerging class of polypeptides that have extensive modifications that are introduced by mechansims that are mostly poorly understood. This application will focus on enzymes introduce sulfur-to-alpha carbon thioether crosslinks into ribosomally encoded peptides to produce sactipeptides. These linkages are distinct from the well-studied lanthipeptide, where thioether crosslinks form between a Cys residue and a dehydrated Thr/Ser. The sactipeptide maturases are members of the radical SAM family of enzymes and catalyze thioether crosslinks by a radical- mediated reaction that is not understood. While The biochemical, spectroscopic, and structural studies in this application will lead to a mechanistic paradigm for this important class of enzymes. While sactipeptides themselves have various therapeutic uses, understanding the substrate profiles and mechanisms of these enzymes would provide a tool for synthesis of crosslinked peptides, which are increasing finding utility in the clinic.