卡伍尔氏链霉菌NA4的Ⅱ型聚酮基因簇的靶向激活及其产物鉴定

【目的】以基因组信息为导向，定向激活海洋来源卡伍尔氏链霉菌（Streptomyces cavourensis） NA4中沉默的Ⅱ型聚酮类次级代谢产物生物合成基因簇，鉴定新产生的次级代谢产物的结构和抑菌活性。【方法】通过添加启动子和敲除负调控基因的方法激活实验室培养条件下沉默或低表达的生物合成基因簇，并完成目标化合物的分离与纯化，通过电喷雾质谱（electrospray ionization-mass spectrometry，ESI-MS）和核磁共振（nuclear magnetic resonance，NMR）数据分析鉴定目标化合物结构，对目标化合物进行抑菌活性鉴定，基于生物信息学信息推导化合物的生物合成途径。【结果】根据基因组生物信息学分析，从海洋来源链霉菌Streptomyces cavourensis NA4中选取一个编码PKSⅡ型次级代谢产物的生物合成基因簇开展研究，成功激活目标基因簇，从中分离到1个PKSⅡ型化合物，推导了其生物合成途径并进行了抑菌活性鉴定。【结论】基因组导向下的天然产物挖掘，可以目标明确地分离产物，充分挖掘链霉菌编码次级代谢产物的潜力。

Targeted activation and product identification of the type II polyketone gene cluster of Streptomyces cavourensis NA4

Objective] To activate the silenced gene cluster for the biosynthesis of type II polyketides in Streptomyces cavourensis NA4 isolated from a marine environment, and identify the structure and antibacterial activity of the newly produced secondary metabolite. Methods] The silenced or low-expressed biosynthetic gene cluster under laboratory culture conditions was activated by the addition of promoters and the knockout of negative regulator genes. The target compound was separated. The structure of the target compound was identified by electrospray ionization-mass spectrometry (ESI-MS) and nuclear magnetic resonance (NMR). Furthermore, the antibacterial activity of the target compound was determined, and the biosynthetic pathway of the compound was deduced based on bioinformatics information. Results] A biosynthetic gene cluster encoding type II polyketides was mined from the genome of S. cavourensis NA4 and successfully activated. A type II polyketide was separated from the expression products. The biosynthetic pathway of this compound was deduced and the antibacterial activity was determined. Conclusion] Genome-oriented natural product mining can facilitate the separation of target products and fully tap the potential of Streptomyces in the production of secondary metabolites.