6sRNA对Pseudomonas protegensH78抗生素合成的调控

The Regulation of 6S RNA on Antibiotic Synthesis of Pseudomonas protegens H78

Pseudomonas protegens H78是本实验室从上海奉贤油菜根际分离得到的一株生防菌株,可以分泌多种抗生素和铁载体等次级代谢产物,6S RNA(ssrS编码产物)主要调控细菌DNA的转录过程。以H78菌株基因组DNA为模板,体外缺失体内同源重组构建H78 ssrS突变菌株,KMB培养基中测定菌体生长,进行藤黄绿菌素(Plt)发酵分析和pltL'-、prnA'-、pchD'-'lacZ表达酶活测定,分析6S RNA对H78抗生素生物合成等次级代谢的调控作用。与H78野生型比较,ssrS突变菌株Plt产量下降大约50%,pltL、pchD基因表达没有明显变化,prnA表达约为野生型的1.5倍,表明6S RNA对H78菌株的抗生素合成存在部分但不显著的调控作用。

Pseudomonas protegens H78 is a biocontrol strain isolated from rape rhizosphere in Fengxian, Shanghai, which can produce a variety of antibiotics and secondary metabolites such as iron carrier. 6S RNA （the encoded product of ssrS gene） mainly regulates DNA transcription process in bacteria. The ssrS mutant strain of H78 was constructed by homologous recombination in vitro deletant with the genomic DNA of H78 strain as template. We measured the cell growth, analyzed Pit fermentation, and assayed pltL＇-, prnA ＇-, pchD＇-＇lacZ fusion expression in KMB medium to analyze the regulatory action of 6S RNA on secondary metabolism of H78 antibiotic biosynthesis. The result showed that when compared with widetype H78, Pit production of ssrS mutant strain decreased about 50%, but no obvious difference was observed in the expression ofpltL and pchD genes, and the prnA expression was about 1.5 times of that of wildtype, which indicated that 6S RNA had partial but not significant regulation influence on the antibiotic biosynthesis of H78 strain.