The antibiotic rifamycin is selectively toxic in blocking protein synthesis in M

Question

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

Select one:

a. 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.

b. the drug binds to the initiator tRNA, preventing the formation of the protein synthesis initiation complex in the bacterial cell.

c. the antibiotic binds to the mRNA once synthesized, preventing it from participating in the initiation complex with the ribosome.

d. it binds preferentially to bacterial RNA polymerase rather than the eukaryotic protein, effectively halting transcription in the pathogen but not the host.

Explanation / Answer

Answer: Option D is correct.

Explanation:

Rifampicin is a polyketide compound belonging to the class of Anasmycins. It specifically binds to bacterial RNA polymerase and inhibits RNA synthesis.

The critical components of rifampicin inhibitory binding to the bacterial RNA polymerase are naphthol ring and four hydroxyl groups.

Rifampicin binds to the RNA polymerase and blocks the beta subunit within the DNA/RNA channel and thereby exerts steric exclusion and inhibition of elongation step in the RNA synthesis.

It is effective against leprosy, Legionnaire's disease, and tuberculosis.

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