Biosynthesis of the Leinamycin Family of Natural Products: Mechanistic Studies and Chemoenzymatic Analog Synthesis

项目总结/摘要 化疗一直是现代社会癌症治疗的核心，并将继续如此。 可预见的未来。在这方面，DNA损伤化合物在历史上使用最多，这是由于 癌细胞相对于正常健康细胞的生长和增殖速率增加。但这些 治疗常常引起脱靶效应和抗性发展。因此，可以损害 以选择性方式和与当前临床治疗互补的机制来治疗癌细胞DNA 为这两个问题提供解决方案。天然产物来那霉素（LNM）是一种DNA损伤化合物 其仅在被硫醇活化时增强其DNA损伤作用，并且具有纳摩尔的抗肿瘤活性， 对临床使用的药物有抵抗力的细胞。LNM E1是一种工程化的LNM类似物，其在被反应性激活后， 氧物种（ROS）通过与LNM正交的机制发挥其抗肿瘤活性。一个脚手架， 可以以两种互补的方式引发DNA损伤，这是这组化合物所独有的， 在抗癌活性方面进一步优化LNM支架的阶段。LNM的生物合成来源 在链霉菌中的生物合成是一个深入研究的领域，许多生物合成步骤已经阐明 并导致了涉及前所未有的化学步骤的发现。该项目的长期目标是 利用对LNM生物合成的机械理解的力量， 用于生产具有改善的治疗性质的类似物的生物。这项建议有两个目的： 研究一个关键的生物合成步骤的机制和（ii）访问合理设计的LNM类似物 和LNM E1来回答关于化合物的生物活性的具体问题。的中心假设 这一建议是，LNM化合物可以通过合理的调节和改善稳定性和效力， 设计这一假设是合理的，自然的能力，以产生一系列的LNM型化合物， 对本文提出的结构改革起到了启发作用。该应用程序的结果将 是LNM生物合成的关键步骤之一的机制理解和获得新的LNM类似物 可以用来回答关于LNM DNA损伤和抗癌活性的关键问题。这些发现 可以应用于合理的生物合成操作的长期目标，以产生靶向结构LNM 用于进一步抗癌开发的类似物。

PROJECT SUMMARY/ABSTRACT Chemotherapy has been the centerpiece of cancer treatment in modern society, and will remain so for the foreseeable future. DNA-damaging compounds have seen the most use historically in this regard, due to cancer cells’ increased rates of growth and proliferation relative to normal, healthy cells. However, these treatments often cause off-target effects and resistance development. Therefore, compounds that can damage cancer cell DNA in a selective fashion and with a mechanism complementary to current clinical treatments offer solutions to both of these issues. The natural product leinamycin (LNM) is a DNA-damaging compound that only elicits its DNA-damaging effects upon activation by thiols, and has nanomolar activity against tumor cells resistant to clinically utilized drugs. LNM E1 is an engineered LNM analog that upon activation by reactive oxygen species (ROS) exerts its antitumor activity via a mechanism orthogonal to LNM. A single scaffold that can be primed for DNA damage in two complementary ways is unique to this set of compounds, and sets the stage for further optimization of the LNM scaffold in terms of anticancer activity. The biosynthetic origin of LNM in Streptomyces has been an area of intense study, and many of the biosynthetic steps have been elucidated and led to discoveries involving unprecedented chemical steps. The long-term goals of this project are to harness the power of a mechanistic understanding of LNM biosynthesis to genetically alter producing organisms for production of analogs with improved therapeutic properties. This proposal contains two aims: (i) investigate the mechanism of a key biosynthetic step and (ii) access rationally-designed analogs of both LNM and LNM E1 to answer specific questions about the compounds’ biological activities. The central hypothesis of this proposal is that LNM compounds can be tuned and improved in both stability and potency through rational design. This hypothesis is rationalized by Nature’s ability to produce an array of LNM-type compounds, which have served as the inspiration for the structural changes proposed herein. The outcomes of this application will be a mechanistic understanding of one of the key steps of LNM biosynthesis and access to novel LNM analogs that can be used to answer key questions about LNM DNA-damaging and anticancer activity. These findings can be applied to the long-term goal of rational biosynthetic manipulation to produce targeted structural LNM analogs for further anticancer development.