Biosynthesis of Sibiromycin, a Potent Antitumor Antibiotic
Biosynthesis of Sibiromycin, a Potent Antitumor Antibiotic
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DOI：
10.1128/aem.02326-08
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发表时间：
2009-05-01
影响因子：
4.4
通讯作者：
Gerratana, Barbara
中科院分区：
文献类型：
--
作者：
Li, Wei;Khullar, Ankush;Gerratana, Barbara
吡咯并苯并二氮杂卓类化合物是一类由放线菌产生的具有序列选择性的DNA烷基化化合物，具有显著的抗肿瘤活性。在吡咯并[1，4]苯并二氮杂卓类药物中，西比罗霉素是两种糖基化的吡咯并[1，4]苯并二氮杂卓类药物之一，它对DNA的亲和力最高，抗肿瘤活性最强。尽管西比罗霉素具有很好的抗肿瘤特性，但由于C-9羟基的存在而导致的动物心脏毒性作用，使西比罗霉素的临床试验无法进行。作为对sibiromycin类似物的发展的第一步，我们已经克隆和本地化sibiromycin基因簇的32.7 kb的连续DNA区域。通过基因替换实验验证了比较基因组学初步确定的聚类边界。由26个开放阅读框组成的西比罗霉素基因簇揭示了一种“模块化”策略，其中邻氨基苯甲酸和二氢吡咯部分的合成在通过非核糖体肽合成酶组装之前完成。此外，所鉴定的基因簇包括编码参与西比糖胺生物合成的酶以及调节和抗性蛋白的开放阅读框。基因置换和化学互补的研究报告，以支持拟议的生物合成途径。
Pyrrolobenzodiazepines, a class of natural products produced by actinomycetes, are sequence selective DNA alkylating compounds with significant antitumor properties. Among the pyrrolo[1,4]benzodiazepines (PBDs) sibiromycin, one of two identified glycosylated PBDs, displays the highest affinity for DNA and the most potent antitumor properties. Despite the promising antitumor properties clinical trials of sibiromycin were precluded by the cardiotoxicity effect in animals attributed to the presence of the C-9 hydroxyl group. As a first step toward the development of sibiromycin analogs, we have cloned and localized the sibiromycin gene cluster to a 32.7-kb contiguous DNA region. Cluster boundaries tentatively assigned by comparative genomics were verified by gene replacement experiments. The sibiromycin gene cluster consisting of 26 open reading frames reveals a "modular" strategy in which the synthesis of the anthranilic and dihydropyrrole moieties is completed before assembly by the nonribosomal peptide synthetase enzymes. In addition, the gene cluster identified includes open reading frames encoding enzymes involved in sibirosamine biosynthesis, as well as regulatory and resistance proteins. Gene replacement and chemical complementation studies are reported to support the proposed biosynthetic pathway.