Mechanistic studies of thioether crosslink formation in peptides

项目摘要 生命的所有领域都产生肽类天然产物，它们发挥的作用与法定人数一样多样化。 传感分子和氧化还原辅因子。这些肽的功能， 抗细菌、抗病毒或抗癌药物的研究，使得了解它们的生物合成， 当代研究的重要领域。基于肽的次级代谢产物是 由不同的生物合成途径产生，不同的生物合成途径在于肽是否是 通过非核糖体肽合成酶（NRPS）的作用合成，或通过核糖体 由基因组编码的ORF产生。这些肽通常广泛地 修改.虽然在NRPS系统中，许多修饰同时发生， 在肽合成中，核糖体编码的肽经历翻译后 改性这些所谓的核糖体编码后修饰的 多肽（RiPP）是一类新出现的多肽，其具有广泛的生物活性。 由大多数知之甚少的机制引入的修饰。 本申请将集中在酶引入硫到α-碳硫醚 交联成核糖体编码的肽以产生sactipeptide。这些联系 与充分研究的羊毛硫肽不同，其中硫醚交联形成于 半胱氨酸残基和脱水的Thr/Ser。 自由基SAM家族的酶和催化硫醚交联的自由基- 不被理解的介导反应。虽然生物化学，光谱学， 在这种应用中的结构研究将导致这一重要的机械范式 类酶。虽然乳糖肽本身具有各种治疗用途， 了解这些酶的底物分布和机制将提供一个 用于合成交联肽的工具，其在临床上的应用越来越多。

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.