Rifamycin and actinomycin D are two antibiotics derived from the bacterium Streptomyces. Rifamycin binds to the ? subunit of E. coli RNA polymerase and interferes with the formation of the first phosphodiester bond in the RNA chain. Actinomycin D bind to double stranded DNA by intercalation (slipping in between neighboring base pairs).
Which of the four stages in transcription would you expect rifamycin to affect primarily?
The four stages that my professor gave me was Binding, Intiation, Elongation, and Termination. Of the four stages I choose intiation because the rifamycin inferes with formation of the first phosphodiester bond in the RNA chain, and in intiation stage calls for the joining of two free NTP's. So if the first phosphodiester bond isn't formed wouldn't it mess up the intiation process.
Is this a correct