黄脂菌素生物合成基因簇中调控基因xanR3的功能

摘要

[Objective] We revealed the function of the ArsR (Arsenical resistance regulator) family regulator XanR3 in xantholipin biosynthetic gene cluster.[Methods] Genetically,the xanR3 disrupted mutant CGF03 and complementary strain CGF06 were constructed by conjugation between S.flavogriseus SIIA-A02191 and Escherichia coli ET12567/pUZ8002.The operons within xantholipin biosynthesis cluster were grouped by RT-PCR and the transcriptional level was analyzed in the mutant CGF-3 by quantitative real-time RT-PCR.[Results] Inactivation of the xanR3 gene dramatically reduced xantholipin biosynthesis,and its complementation partially restored xantholipin production.Totally,genes in xantholipin biosynthetic gene cluster were assigned into 18 co-transcription units,and the disruption of xanR3 directly down-regulated the transcription of four operons as xanO1-xanS1,xanB1-xanB3,xanT-xanO9 and xanO10-xanC3.[Conclusion] XanR3,a ArsR family transcriptional regulator,is an activator of xantholipin biosynthesis.%[目的]研究黄脂菌素产生菌灰黄链霉菌中编码ArsR家族转录调控蛋白(Arsenical resistanceregulator)的xanR3基因的功能.[方法]利用大肠杆菌和链霉菌双亲本接合转移的方法,构建xanR3基因缺失突变株及回补突变株.利用cDNA在相邻同方向的基因间隔区进行PCR确定黄脂菌素生物合成基因簇中的转录单元.利用荧光定量RT-PCR方法进行突变株中黄脂菌素生物合成基因簇转录水平的检测.[结果]对得到的xanR3基因缺失突变株及回补突变株进行发酵,发现xanR3基因缺失突变株产黄脂菌素能力下降,回补菌株中黄脂菌素产量相比缺失突变株有一定程度的恢复,但仍未达到野生型水平.经鉴定,黄脂菌素生物合成基因簇中共有18个共转录单元,其中4个共转录单元在△xanR3突变株中转录水平明显下降.[结论]ArsR家族转录调控基因xanR3是黄脂菌素生物合成的正调控基因.