Question

What is the effect of rifamycin on transcription?

1) Rifamycin binds to sigma factors to prevent initiation.
2) Rifamycin inhibits translation but has no effect on transcription.
3) Rifamycin binds to the beta subunit of RNA polymerase and blocks the exit channel.
4) Rifamycin mimics a DNA base and intercalates between GC base pairs; it blocks transcription in all domains of life.

Answer 1

Rifamycin inhibits transcription by binding to the beta-subunit of bacterial RNA polymerase, thus preventing the initiation of transcription and offering selective toxicity against bacteria, useful in treating tuberculosis.

Step-by-step explanation:

The effect of rifamycin on transcription is that it binds to the beta-subunit of RNA polymerase and blocks the exit channel, which prevents initiation of transcription. Specifically, rifampin, a semisynthetic member of the rifamycin family, inhibits bacterial RNA polymerase activity by binding to this subunit. The selectivity of this mechanism allows it to be used as a treatment against infections, particularly for mycobacteria that cause tuberculosis, while providing selective toxicity against bacterial cells over eukaryotic cells.