Biosynthesis of Pyrrolo[1,4]benzodiazepines, potent antitumor antibiotics

描述（由申请人提供）：次生代谢物通常由生物体产生，作为防御机制的一部分或促进繁殖。次生代谢物的化学多样性反映了生物合成途径中存在的酶促反应的多样性。因此，这些途径是令人兴奋的新转化和前所未有的酶的持续和丰富的来源。此外，通过阐明生物合成途径获得的遗传和酶学知识可以用于化学变化的次生代谢物的生产。Pyrrolo[1,4]苯二氮卓类药物是一类发现于放线菌中的有效抗肿瘤抗生素，是序列选择性DNA烷基化剂。SJG-136用于治疗转移性或不可切除实体瘤的一期人体临床试验于2004年开始。本文将利用微生物学、分子生物学和酶学技术来阐明吡咯[1,4]苯二氮生成的生物化学基础。具体来说，我们建议1)鉴定托马霉素和西比霉素的生物合成基因簇，2)生产新的糖基化PBD和PBD二聚体，以及3)表征生物合成途径中存在的独特酶转化。公共

DESCRIPTION (provided by applicant): Secondary metabolites are usually produced by an organism as part of a defense mechanism or to facilitate reproduction. The chemical diversity of secondary metabolites mirrors the variety of enzymatic reactions present in the biosynthetic pathways. Therefore, these pathways are a constant and rich source of exciting novel transformations and unprecedented enzymes. In addition, the genetic and enzymatic knowledge acquired by elucidating the biosynthetic pathways can be exploited for the production of chemically varied secondary metabolites. Pyrrolo[1,4]benzodiazepines, a class of potent antitumor antibiotics found in actinomycetes, are sequence selective DNA alkylating agents. Phase 1 human clinical trials of SJG-136 for the treatment of metastatic or unresectable solid tumors were started in 2004. Microbiology, molecular biology and enzymological techniques will be used in this proposal to elucidate the biochemistry underlying pyrrolo[1,4]benzodiapines' production. Specifically, we propose to 1) identify the biosynthetic gene clusters for tomaymycin and sibiromycin, 2) produce novel glycosylated PBDs and PBD dimers, and 3) characterize the unique enzymatic transformations present in the biosynthetic pathway. PUBLIC HEALTH RELEVANCE Pyrrolobenzodiazepines (PBDs) are compounds naturally produced by bacteria with potent antitumor properties. PBDs' remarkable broad spectrum of activities and effectiveness against a wide variety of cancers encourages the development of new PBDs. For instance, SJG-136 is currently in phase I clinical trials against metastatic and unresectable solid tumors. We are proposing to study how nature carries out the synthesis of these compounds. The genetic and enzymological knowledge so obtained can then be used for production of new analogs of these compounds. Examples of such application are discussed in this proposal.