Rifampicin

Rifampicin is an antibiotic used to treat tuberculosis. It was discovered by Hermes Pagani from a soil actinomycete. Rifampicin inhibits transcription. Rifampicin binds to the \(\beta \) subunit deep within the DNA/RNA channel of bacterial RNA polymerase, thereby directly blocking the elongation of RNA. Rifampicin binding to RNA polymerase can be confirmed by intrinsic fluorescence quenching experiments. Rifampicin causes abortive initiation or the release of short RNA fragments rather than full m-RNA transcripts. Radiolabeled abortive initiation transcripts are detectable on a PAGE gel. The X-ray crystal structure of the rifampicin-RNA polymerase complex confirms that it binds to the \(\beta \) subunit of Thermus aquaticus RNA polymerase. Mutations to the rpoG gene, which encodes the \(\beta \) subunit, confer rifampicin resistance. Multidrug efflux pumps can also remove intracellular rifampicin.