卡西霉素生物合成调控基因calR2的功能

Function of the regulatory gene calR2 involved in calcimycin biosynthesis

摘要:

【背景】卡西霉素(Calcimycin)是由教酒链霉菌NRRL3882产生的吡咯聚醚类抗生素，结构独特且具有广泛的生物活性，但其生物合成调控机制尚不清楚。【目的】研究卡西霉素生物合成基因簇上编码LuxR家族同源蛋白的潜在调控基因calR2的功能。【方法】通过PCR-targeting的方法对卡西霉素基因簇上的calR2基因进行中断，HPLC对突变株及回补菌株的代谢产物进行分析。利用荧光定量RT-PCR分析ΔcalR2突变菌株和野生菌株的基因转录水平差异。【结果】calR2基因中断的突变株不能产生卡西霉素，回补菌株则恢复产生卡西霉素的能力。RT-PCR结果表明卡西霉素生物合成的一些重要骨架基因在ΔcalR2突变株中的转录水平明显降低。【结论】LuxR家族转录调控基因calR2在卡西霉素生物合成过程中起正调控作用。

Abstract:

[Background] Calcimycin is a structural unique pyrrole polyether antibiotic produced by Streptomyces chartreusis NRRL3882, and exhibits multiple biological effects, but the regulatory mechanism of calcimycin biosynthesis remains unclear. [Objective] To study on the function of the potential regulatory gene calR2 encoding LuxR family homologous protein in calcimycin biosynthesis gene cluster. [Methods] The calR2 gene on calcimycin biosynthesis gene cluster was disrupted by PCR-targeting, and metabolites of the ΔcalR2 mutant and complementation strain were analyzed by HPLC. The calcimycin biosynthesis gene expression levels of ΔcalR2 mutant compared with the wild-type strain was analyzed by RT-qPCR. [Results] HPLC analysis of the fermentation products showed that the ΔcalR2 mutant could not produce calcimycin and the complementation strain restored the production of calcimycin. Gene expression analysis showed that the transcription levels of some essential genes in calcimycin biosynthesis obviously declined in ΔcalR2 mutant. [Conclusion] The putative LuxR family homologous protein CalR2 acts as a positive regulator involved in calcimycin biosynthesis.