RESUMO
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.