What is the primary mechanism of action of Rifampin?

What is the primary mechanism of action of Rifampin?

• A. Prevents cell wall synthesis
• B. Prevents mRNA synthesis by binding to RNA polymerase
• C. Inhibits bacterial protein synthesis
• D. Inhibits DNA replication

Answer: (B)

Rifampin’s primary action is to inhibit transcription by binding the bacterial DNA-dependent RNA polymerase, which prevents initiation of mRNA synthesis. By occupying the RNA polymerase, it blocks the enzyme from forming the first phosphodiester bonds needed to start mRNA production, so no mRNA is made and protein synthesis cannot proceed. This mechanism is distinct from agents that disrupt cell wall synthesis, protein synthesis at the ribosome, or DNA replication. Clinically, rifampin is especially used against mycobacteria and is a key part of TB therapy, often in combination to prevent resistance. Resistance typically arises from mutations in the RNA polymerase beta subunit.

Rifampin’s primary action is to inhibit transcription by binding the bacterial DNA-dependent RNA polymerase, which prevents initiation of mRNA synthesis. By occupying the RNA polymerase, it blocks the enzyme from forming the first phosphodiester bonds needed to start mRNA production, so no mRNA is made and protein synthesis cannot proceed. This mechanism is distinct from agents that disrupt cell wall synthesis, protein synthesis at the ribosome, or DNA replication. Clinically, rifampin is especially used against mycobacteria and is a key part of TB therapy, often in combination to prevent resistance. Resistance typically arises from mutations in the RNA polymerase beta subunit.