深海放线菌Streptomyces sp. SCSIO 03032抗肿瘤天然产物Spiroindimicins生物合成研究

Spiroindimicins是本课题组从一株深海链霉菌Streptomyces sp. SCSIO 03032中分离的新天然产物，含有独特的螺环结构。spiroindimicins B-D对测定的肿瘤细胞显示良好选择性细胞毒性，对于抗肿瘤药物研发具有重要意义。至今spiroindimicins生物合成研究尚未开展。本项目拟对Streptomyces sp. SCSIO 03032全基因组测序及构建全基因组文库，结合生物信息学分析，克隆完整的spiroindimicins生物合成基因簇；利用敲除和回补技术，鉴定spiroindimicins生物合成基因的体内功能；利用体外异源过表达技术，挖掘负责螺环等特殊结构单元生物合成的新颖功能酶；阐明spiroindimicins的生物合成机制；探索组合生物合成，为理性创造基于spiroindimicins的新型高效抗肿瘤先导化合物，提供新策略。

Spiroindimicins A-D, four new natural products of indolocarbazole family, were isolated from deep sea actinomycetes Streptomyces sp. SCSIO 03032 in our research group. The structures of these compounds contain rare spiro unit. All compounds except spiroindimicin A exhibited in vitro selective cytotoxicities against several human cancer cell lines HepG2, CCRF-CEM, NCI-H460, and MCF-7 and the mouse melanoma cell line B16. As far as we know, chemical synthesis or biosynthesis of spiroindimicins has not been reported. In this project, whole genome of Streptomyces sp. SCSIO 03032 is sequenced and its genomic library is also constructed. The whole sequence of predicted spiroindimicins gene cluster is obtained with the aid of bioinformatics. Gene knockout and complementation analysis is used to indentify in vivo function of genes involved in spiroindimicins biosynthesis. Heterologous expression of the genes is used to elucidate novel catalysis mechanism of key enzymes that are responsible for biosynthesis of some important spiro unit. Combinatorial biosynthesis of spiroindimicins provides a new blueprint for rational generation of some new spiroindimicins derivatives as lead drugs with improved antitumor effect.