Singh Amit, Jain Shruti, Gupta Seema, Das Taposh, Tyagi Anil K
Department of Biochemistry, University of Delhi South Campus, Benito Juarez Road, New Delhi, 110021, India.
FEMS Microbiol Lett. 2003 Oct 10;227(1):53-63. doi: 10.1016/S0378-1097(03)00648-7.
Mycobacterium tuberculosis faces various stressful conditions inside the host and responds to them through a coordinated regulation of gene expression. We had previously reported identification of the virS gene of M. tuberculosis (Rv3082c) belonging to the AraC family of transcriptional regulators. In the current study, we show that the seven genes (Rv3083-Rv3089) which are present divergently to virS (Rv3082c) constitute an operon designated the mymA operon. Further investigation on the regulation of this operon showed that transcription of the mymA operon is dependent on the presence of VirS protein. A four-fold induction of the mymA operon promoter occurs specifically in wild-type M. tuberculosis and not in the virS mutant of M. tuberculosis (MtbDeltavirS) when exposed to acidic pH. Expression of the mymA operon was also induced in infected macrophages by 10-fold over a 6-day period. To gain an insight into the function of the proteins encoded by this operon, we carried out a bioinformatic analysis, which suggested the involvement of these proteins in the modification of fatty acids required for cell envelope. This was supported by altered colony morphology and cell envelope structure displayed by the virS mutant of M. tuberculosis (MtbDeltavirS).
结核分枝杆菌在宿主体内面临各种应激条件，并通过基因表达的协调调控对其作出反应。我们之前曾报道过鉴定出结核分枝杆菌的virS基因（Rv3082c），它属于转录调节因子的AraC家族。在当前研究中，我们表明与virS（Rv3082c）呈反向排列的七个基因（Rv3083 - Rv3089）构成了一个名为mymA操纵子的操纵子。对该操纵子调控的进一步研究表明，mymA操纵子的转录依赖于VirS蛋白的存在。当暴露于酸性pH值时，mymA操纵子启动子在野生型结核分枝杆菌中特异性地出现四倍诱导，而在结核分枝杆菌的virS突变体（MtbDeltavirS）中则没有。在感染的巨噬细胞中，mymA操纵子的表达在6天内也被诱导了10倍。为了深入了解该操纵子编码的蛋白质的功能，我们进行了生物信息学分析，结果表明这些蛋白质参与了细胞壁所需脂肪酸的修饰。结核分枝杆菌的virS突变体（MtbDeltavirS）所显示的菌落形态和细胞壁结构的改变支持了这一点。
