四对结核分枝杆菌毒素-抗毒素系统基因功能的初步研究

目的探讨结核分枝杆菌毒素-抗毒素(toxin-antitoxin,TA)系统中的4对基因的功能,为研究结核分枝杆菌的传播机制提供基础科学数据。方法选取结核分枝杆菌TA系统VapBC家族中4对基因,包括VapC 4个毒素基因(Rv1720c、Rv2103c、Rv2494和Rv3408)和VapB4个抗毒素基因(Rv1721c、Rv2104c、Rv2493、Rv3407),在大肠杆菌和耻垢分枝杆菌中分别构建严谨型阿拉伯糖诱导质粒体系及乙酰胺诱导穿梭质粒体系观察VapC对细菌生长的抑制作用,及其对应的VapB解除抑制作用。结果在大肠杆菌和耻垢分枝杆菌的实验结果一致,Rv2103c具有一定抑制作用和Rv2104c具有消除抑制作用,其余3对毒素-抗毒素基因未见到明显的对细菌生长的抑制和消除抑制的作用。结论成功构建了VapBC家族在大肠杆菌及耻垢分枝杆菌中的表达体系,并发现了一对TA系统基因对细菌生长的抑制和消除抑制的作用。

Function of four pairs of genes in toxin-antitoxin system of Mycobacterium tuberculosis

We discussed the function of four pairs of genes in the toxin-antitoxin system of Mycobacterium tuberculosis,providing theoretical foundation and scientific basis for studying the transmission mechanism of Mycobacterium tuberculosis.Four pairs of genes which belong to VapBC family,including four VapC genes (Rv1720c,Rv2103c,Rv2494,Rv3408) and four VapB genes (Rv1721c,Rv2104c,Rv2493,Rv3407) were chosen.We constructed a serial of arabinose-induced hybrid plasmid system in Escherichia coli and a serial of acetamide-induced hybrid plasmid system in Mycobacterium smegmatis respectively,in order to observe the potential inhibition effect of VapC and the release inhibition of homologous VapB.Results showed that only one toxin gene(Rv2103c) showed the function of bacteriostasis in both E.coli and M.smegmatis and the homologous antitoxin gene(Rv2104c) could release the inhibition of growth.We built the inducible systems of VapBC family in both E.coli and M.smegmatis respectively and found only a pair of toxin and antitoxin genes(Rv2103c,Rv2104c) had the function of inhibition and release for the growth of bacteria.And two pairs of toxin genes(Rv1720c,Rv2494) did not have the function of inhibition for the growth of both E.coli and M.smegmatis.Whereas,another toxin gene VapC47(Rv3408) also did not have the bacteriostastic activity,only this result was not consistent with the existing literature.We speculated that the reason for this kind of difference may be the different inducible systems we used.Cause the other three results were consistent with all existing literature and the doubtful result also appeared in other reports,so our protocol could be confirmed as reliable,and we would use it to build inducible systems and make further functional identification of certain toxin and antitoxin genes that we are interested in.