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

描述(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反应的多样性。因此，这些途径是令人兴奋的新颖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生产化学变化的次生代谢物。吡咯并[1，4]苯并二氮卓类化合物是一类从放线菌中发现的有效的抗肿瘤抗生素，是DNA的序列选择性烷基化试剂。SJG-136用于治疗转移性或不可切除实体肿瘤的第一阶段人体临床试验于2004年开始。微生物学、分子生物学和酶学技术将被用于阐明吡咯并[1，4]苯并二平生产的生物化学。具体地说，我们建议1)鉴定托马霉素和西比罗霉素的生物合成基因簇，2)产生新的糖基化PBD和PBD二聚体，以及3)表征生物合成途径中存在的独特的酶转化。公众 与健康相关的吡咯洛苯并二氮卓类化合物(PBDS)是由细菌自然产生的化合物，具有强大的抗肿瘤特性。PBDS对多种癌症具有显著的广谱活性和有效性，这鼓励了新PBD的开发。例如，SJG-136目前正处于治疗转移性和不可切除实体瘤的I期临床试验。我们建议研究自然界是如何合成这些化合物的。这样获得的遗传和酶学知识可以用于生产这些化合物的新类似物。在本提案中讨论了这种应用的例子。

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.