红球菌新结构非核糖体肽的发掘与合成途径的解析

许多临床上的重要抗生素来源于微生物生产的非核糖体肽。最近新分子结构的天然产物（包括非核糖体肽）的发掘越来越困难，一个原因是大部分研究集中在链霉菌上，菌株来源的单一性导致发掘的天然产物分子结构具有类似性。最近关于一株红球菌基因组序列的报道和本课题组的初步研究结果表明红球菌应该是非核糖体肽潜在的重要来源。本项目分离培养土壤等复杂环境中的细菌，通过16S rDNA 测序筛选出红球菌；通过全基因组测序和生物信息学分析发掘新结构的非核糖体肽合成基因簇，并预测这些基因簇合成产物分子的骨架结构；通过分子遗传学技术激活或异源表达这些基因簇，通过化学技术分离纯化并鉴定这些基因簇合成的产物；通过生物化学技术表征这些生物合成途径中的新机制和关键步骤；在分子水平或细胞水平上研究这些产物的生物活性。本项目的研究结果一方面丰富非核糖体肽类天然产物库，一方面建立基于全基因组测序发掘新天然产物的策略。

Many important clinical antibiotics are derived from microbial non-ribosomal peptides. Recently, it becomes more and more difficult to find new natural products with structural and functional diversity, including non-ribosomal peptides, because most of antibiotics come from Streptomyces. Rhodococcus should be a potential important source for new structural non-ribosomal peptides based on our preliminary results and the recent report about the genome sequence of one Rhodococcus strain. In this project, Rhodococcus strains will be screened out from soil and identified by sequencing their 16S rDNA. The gene clusters encoding non-ribosomal peptide synthetases (NRPSs) with new domain organizations will be predicted by bioinformatic analysis of genome sequence. Structures of these NRPS products will be predicted by bioinformatic analysis of domain organizations. Then these NRPS gene clusters will be activated by molecular genetic techniques. NPRS products will be isolated and identified by chemical techniques. Finally, their biosynthetic pathways and their biological activities will be characterized by both in vitro and in vivo assays. Our results will not only expand NRPS natural product library, but also establish a strategy to identify new molecular structural natural products based on genomic DNA sequence.