Collaborative Research: Unveiling the Enigmatic Biosynthetic Machinery of the Azinomycins

通过这一奖项，生命过程化学项目资助德克萨斯农工大学的Coran Watanabe博士和康奈尔大学的Stephen Ealick博士合作从功能和结构上表征阿奇霉素生物合成途径的酶。具体地说，该项目旨在评估硫酯酶结构域的相互作用伙伴和迭代聚酮合成酶Azib的结构特征，以及AziA2和AziB的功能特征，以及氮杂双环生物合成酶的结构特征。该项目还旨在了解参与构建环氧阿奇霉素的细菌I型迭代聚酮合成酶(PKS)的结构。虽然长期以来人们一直认为所有的细菌芳香族聚酮都来自II型PKS，但现在很明显情况并非如此，阿奇霉素PKS就是一个具体的例子。因此，阿奇霉素PKS将作为I型细菌迭代PKS类的模型系统。实验将阐明一个不同寻常的非核糖体多肽合成酶(NRPS)模块的关键作用，该模块具有前所未有的结构域结构(C-PCP-C)。氮菌素还含有一个氮杂环系统，对其生物合成知之甚少。这些研究将通过这一途径的四种酶的功能特征来研究氮杂环丙啶的形成途径和机制。天然产物或次生代谢物是由特定有机体产生的化合物，但对宿主的生存不是必需的。这类化合物通常具有很强的生物活性，并作为开发治疗剂的先导化合物。这里正在研究氮菌素的生物合成。链霉素类是一类具有抗肿瘤活性的DNA交联剂。了解大自然是如何构建这些紧张的环系统的，应该会揭示生物合成中的一个基本机制问题，并为长期用于治疗目的的途径基因工程铺平道路。该项目还包括一个外展部分，本科生和高中生都将接触到天然产品研究。

With this award, the Chemistry of Life Processes Program is funding Dr. Coran Watanabe from Texas A&M University and Dr. Stephen Ealick of Cornell University to collaboratively characterize enzymes of the azinomycin biosynthetic pathway both functionally and structurally. Specifically, this project is directed at the evaluation of thioesterase-domain interacting partners and structural characterization of the iterative polyketide synthase (PKS) AziB, as well as functional characterization of both AziA2, and the of azabicycle biosynthetic enzymes. This project also aims at a structural understanding of the bacterial Type I iterative polyketide synthase (PKS) involved in the construction of the azinomycin naphthoate. While it was long thought that all bacterial aromatic polyketides are derived from Type II PKSs, it is now clear that this is not the case and the azinomycin PKS serves as a specific example. The azinomycin PKS will thus serve as a model system for this bacterial Type I iterative PKS class. Experiments will elucidate the key role of an unusual non-ribosomal peptide synthetase (NRPS) module of unprecedented domain architecture (C-PCP-C). The azinomycins also contain an aziridine ring system, the biosynthesis of which is poorly understood. These studies should provide inroads into the route and mechanism of aziridine formation through the functional characterization of four enzymes of this pathway. Natural products or secondary metabolites are compounds that are produced by a given organism but are not essential to the survival of the host. Such compounds often possess potent bioactivities and serve as lead compounds for the development of therapeutic agents. The biosynthesis of the azinomycins is under investigation here. The azinomycins are a family of DNA crosslinking agents with demonstrated anti-tumor activity. Understanding how nature constructs these strained ring systems should shed light on a fundamental mechanistic question in biosynthesis and also pave the way for the engineering of the pathway genes for therapeutic purposes, in the longer term. This project also includes an outreach component where both undergraduate and high school students will be exposed to natural products research.