Linezolid, an oxazolidinone antibiotic, acts by inhibiting bacterial protein synthesis at which specific step?
- A Peptide bond formation at the A site of 50S ribosome
- B Formation of the 70S initiation complex by binding to the 23S rRNA of the 50S subunit ✓
- C Translocation of the peptidyl-tRNA from A site to P site
- D Aminoacyl-tRNA binding to the 30S ribosomal A site
Correct answer: B. Formation of the 70S initiation complex by binding to the 23S rRNA of the 50S subunit
Explanation
Linezolid binds to the 23S rRNA component of the 50S subunit and prevents formation of the 70S initiation complex (it blocks the junction where 30S and 50S associate with mRNA and initiator tRNA). This is a unique mechanism among clinically used antibiotics. It does not inhibit transpeptidation, translocation, or aminoacyl-tRNA binding per se.
Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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