Lantibiotic biosynthetic enzymes and autoimmunity

描述(申请人提供)：这项研究提案的长期目标是对细菌中抗生素生物合成的分子基础提供见解，这将作为设计新型抗生素的框架。最近在生物合成组合化学技术方面的工作已经确立了细菌聚酮合成酶和非核糖体多肽合成酶在产生具有抗生素能力的天然和非天然产物方面的应用。我们试图通过提供使用抗生素的框架来扩大治疗药物的生物合成生产的研究，抗生素是一类核糖体合成的但翻译后修饰的多肽。这些抗生素的工程是复杂的，因为在多肽前体中产生的任何修饰都可能影响其作为翻译后修饰酶底物的功能，并损害这一方法的有效性。为了描述翻译后修饰酶对底物的要求，我们的目标是确定许多抗生素修饰酶的高分辨晶体结构。这些酶的晶体结构将被用来识别和设计特定位点的变体。我们将通过将结构与我们合作者实验室产生的功能数据相关联来测试我们基于结构的假设。此外，我们将确定免疫成分的晶体结构，该成分保护产生抗生素的细菌免受其自身产生的药物的作用。我们试图理解为什么序列上几乎相同的抗生素使用的免疫成分没有同源性，而且大小差异很大。最后，我们将利用研究计划前几部分中产生的机理和结构数据来设计新型抗生素的生产。在这最后一个目标中，我们将寻求利用生物合成组合化学的原理来回答这样一个问题：新的含羊毛硫氨酸的抗生素能从基于结构的原理设计出来吗？

DESCRIPTION (provided by applicant): The long-term goal of this research proposal is to provide insights into the molecular basis for antibiotic biosynthesis in bacteria, which will serve as a framework for the design of novel antibiotics. Recent work in biosynthetic combinatorial chemistry technology has already established the utility of bacterial polyketide synthases and nonribosomal peptide synthases in generating natural and un-natural products with antibiotic capabilities. We seek to extend the research of biosynthetic production of therapeutics by providing a framework for the use of lantibiotics, a family of ribosomally synthesized but post-translationally modified peptides. The engineering of these lantibiotics is complicated by the fact that any modification that are generated in the peptide precursor may affect its function as a substrate for the post-translational modification enzymes, and compromise the effectiveness of this approach. In order to delineate the substrate requirements for the post-translation modification enzyme, we aim to determine the high-resolution crystal structures of many of the lantibiotic modification enzymes. The crystal structures of these enzymes will be used to identify and design site-specific variants. We will test our structure-based hypothesis by correlating the structure with functional data generated in the laboratory of our collaborator. Additionally, we will determine the crystal structure of the immunity component that protects the lantibiotic-producing bacteria from the action of its self-produced drug. We seek to understand why lantibiotics that are nearly identical in sequence utilize immunity components that share no homology and vary drastically in size. Finally, we will utilize the mechanistic and structural data generated in the previous components of the research plan to engineer the production of novel lantibiotics. In this last aim, we will seek to utilize the principles of biosynthetic combinatorial chemistry to answer the question "Can novel lanthionine-bearing lantibiotics be designed from structure-based principles?"