Discovery and Characterization of Natural Product Systems

项目摘要。在R35 GM 118101的竞争性更新中，我们建议重点调查和 开发生物催化系统，产生具有高治疗潜力的复杂天然产物 剂.在过去的四年里，该方案取得了很高的成果，出版了34篇出版物。重大进展 继续对来自细菌的模块化聚酮酶（PKS）的功能和结构进行研究。一 第二个主题领域涉及对不同细菌和真菌吲哚生物碱途径的研究， 已经报道了在表征催化周环（e. G. 科普，狄尔斯-阿尔德）反应。我们计划在这些研究的基础上，扩大有关剪裁反应的工作 吲哚生物碱结构多样化。 我们在I型PKS领域的工作将集中在我们所拥有的关键催化结构域的功能和结构上 被认为是催化循环中的看门人。通过使用天然和非天然的高级聚酮链 延伸中间体与后期阶段PKS模块，我们计划开发方法，以扩大生物催化 这些卓越的分子机器组装大环内酯结构的潜力。进一步糖基化 和后期羟基化/环氧化方法将用于产生下一代大环内酯， 对一系列具有抗药性的人类病原体进行测试。 我们在微生物吲哚生物碱方面的工作将集中在核环系统衍生的天然产物上 来自于生物催化的周环反应。对这些不寻常过程的机械理解正在迅速出现， 并且它们明显的灵活性表明代谢物结构多样化的高潜力。这些努力将 通过探索能够进一步修饰核心吲哚生物碱结构的后期剪裁酶来增强 以产生一系列具有显著制药潜力的生物活性产品。

Project Summary. In this competing renewal of R35 GM118101, we propose to focus on investigating and developing biocatalytic systems that generate complex natural products with high potential as therapeutic agents. This program has been highly productive with 34 publications over the past four years. Major progress continues toward studies on the function and structure of modular polyketide synthases (PKSs) from bacteria. A second thematic area involves studies on diverse bacterial and fungal indole alkaloid pathways for which we have reported important achievements on characterizing biosynthetic enzymes that catalyze pericyclic (e. g. Cope, Diels-Alder) reactions. We plan to build on these studies and also expand work on allied tailoring reactions for indole alkaloid structural diversification. Our work in the type I PKS area will focus on function and structure of key catalytic domains that we have identified to be gatekeepers in the catalytic cycle. By employing natural and unnatural advanced polyketide chain elongation intermediates with late stage PKS modules, we plan to develop methods to expand the biocatalytic potential of these remarkable molecular machines for assembly of macrolactone structures. Further glycosylation and late-stage hydroxylation/epoxidation methods will be employed to generate next generation macrolides for testing against a range of antibiotic-resistant human pathogens. Our work in the microbial indole alkaloids will focus on natural products whose core ring systems are derived from biocatalytic pericyclic reactions. Mechanistic understanding of these unusual processes is rapidly emerging, and their apparent flexibility indicates high potential for metabolite structural diversification. These efforts will be augmented by exploring late-stage tailoring enzymes capable of further modifying core indole alkaloid structures to generate a range of biologically active products with significant pharmaceutical potential.