Purification and properties of DNA-dependent RNA polymerase from Mycobacterium tuberculosis H37RV

RNA polymerase (nucleosidetriphosphate: RNA nucleotidyltransferase DNA-dependent), EC 2.7.7.6) was purified approximately 200 fold from Mycobacterium tuberculosis H37RV cells. The purified enzyme has a molecular weight of about 330 000-350 000 and is composed of four subunits. The subunits beta', beta and sigma have molecular weights different from those of Escherichia coli polymerase; the fourth, alpha subunit has a similar weight. The purified enzyme is a thousand-fold more sensitive to rifampicin, a potent antitubercular drug than the E. coli RNA polymerase, probably because of the difference in the beta subunits. This, with other data presented in this paper, indicate that the RNA polymerase of M. tuberculosis differs in its properties from that of E. coli.