一个甲基转移酶基因lomo3在洛蒙真菌素生物合成途径中的功能

Function of a methyltransferase gene lomo3 involved in the biosynthesis of lomofungin

摘要:

【目的】洛蒙真菌素是在洛蒙德链霉菌(Streptomyces lomondensis)中生物合成的一种具有广谱抑菌活性的吩嗪类抗生素，但其合成机理仍不清晰。在洛蒙德链霉菌S015的洛蒙真菌素生物合成核心基因簇下游，有一甲基转移酶基因——lomo3，研究该基因对洛蒙真菌素生物合成的影响。【方法】对lomo3基因进行无痕敲除得到基因缺失突变株S015Δlomo3，再过表达重组质粒构建回补突变株S015Δlomo3::lomo3，比较两株突变株与野生型S015的发酵产物的变化。【结果】发现基因缺失菌株S015Δlomo3不能合成洛蒙真菌素，而基因回补菌株S015Δlomo3::lomo3则可恢复洛蒙真菌素的合成能力。【结论】甲基转移酶基因lomo3在洛蒙真菌素生物合成过程中起着重要的作用，但该基因的具体功能还有待深入研究。研究对于阐明洛蒙真菌素的生物合成途径具有一定的指导作用。

Abstract:

[Objective] Lomofungin is a phenazine antibiotic with broad-spectrum anti-bacterial activity and is biosynthesized by Streptomyces lomondensis. In the lomofungin producing strain, S. lomondensis S015, a methyltransferase gene lomo3 at the downstream of the phenazine biosynthesis core gene cluster was studied. [Methods] we inactivated lomo3 by in-frame partial deletion and obtained strain S015Δlomo3. Complementary strain S015Δlomo3::lomo3 was then constructed. To investigate the function of lomo3, we analyzed the metabolites in the fermentation broth of S015, S015Δlomo3 and S015Δlomo3::lomo3. [Results] Inactivation of lomo3 in S. lomondensis S015 resulted in the absence of lomofungin production. The lomo3 complementary strain S015Δlomo3::lomo3 regained the biosynthesis of lomofungin. [Conclusion] This methyltransferase gene lomo3 plays an important role in the biosynthesis of lomofungin. The information obtained in this study laid a theoretical foundation for the biosynthesis of lomofungin.