Rifampidn inhibition of RNA synthesis by destabilisation of DNA-RNA polymerase-oligonucleotide-complexes

Although the antibiotic rifampicin inhibits the transcription of poly[d(A-T)] by E.coli RNA polymerase, a series of short oligonucleotides is produced. It is claimed that the overall inhibition of RNA synthesis by rifampicin is caused by a destabilising effect on the binding of the intermediate oligonucleotides to the active enzyme-DNA complex. Rifampicin itself can only interact specifically with RNA polymerase if the enzyme is free or in a binary complex with DNA. However, the enzyme is not susceptible in a ternary complex, even if the "RNA" is as short as a trinucleotide.