RNA Polymerase: Interaction of RNA and Rifampicin with the Subassembly &alpha2β.

We studied the inhibition of tryptic digestion of the subassembly α₂β of Escherichia coli DNA-dependent RNA polymerase to investigate its interaction with RNA and rifampicin. Both agents decreased distinctly the cleavage of subunit β in the subassembly as well as the degradation of the transiently formed polypeptides (M_r > 80000). Short RNAs with a chain length of approximately 35 nucleotides were most protective at a concentration of 1 mg/ml while long RNAs were less effective at the same concentration. DNA did not exert any observable protective effects. The association of RNA with α₂β was shown by chromatography on phosphocellulose. which separates α₂β bound to RNA from free α₂β. The association of α₂β with RNA was inhibited by rifampicin. [ABSTRACT FROM AUTHOR]