The Antibiotic Rifamycin Is Selectively Toxic in Blocking Protein Synthesis

question 82

Multiple Choice

The antibiotic rifamycin is selectively toxic in blocking protein synthesis in Mycobacterium tuberculosis because

• A)the drug binds to the initiator tRNA, preventing the formation of the protein synthesis initiation complex in the bacterial cell.
• B)it binds preferentially to bacterial RNA polymerase rather than the eukaryotic protein, effectively halting transcription in the pathogen but not the host.
• C)the antibiotic binds to the mRNA once synthesized, preventing it from participating in the initiation complex with the ribosome.
• D)bacterial ribosomes are 70s whereas host ribosome are 80s, thus the antibiotic binds to the M.tuberculosis ribosome but does not bind to the eukaryotic machinery.