How do rifamycins like rifampin inhibit bacterial RNA synthesis?

• A. They inhibit tRNA synthetases, thereby depleting charged tRNAs and halting transcription because RNA polymerase requires charged tRNA to continue elongation.
• B. They degrade ribosomal RNA directly, preventing ribosome assembly and indirectly stopping transcription.
• C. They bind to the beta subunit of bacterial RNA polymerase and block the elongation of the nascent RNA chain.
• D. They intercalate into DNA upstream of promoters preventing RNA polymerase from recognizing promoter sequences but do not bind the polymerase directly.

Answer: (C)