Linezolid's pharmacological activity differs from all earlier protein synthesis inhibitors in that it:
- A Inhibits peptidyl transferase activity of the 50S subunit identical to chloramphenicol
- B Binds to 23S rRNA of the 50S ribosomal subunit and blocks the very first step of translation — formation of the 70S initiation complex ✓
- C Blocks translocation of tRNA from A-site to P-site like fusidic acid
- D Binds 30S ribosomal subunit and causes misreading of mRNA codons
Explanation
Linezolid, the prototype oxazolidinone, binds the V domain of 23S rRNA on the 50S subunit. Crucially, it prevents assembly of the functional 70S initiation complex by blocking the binding of formyl-methionyl tRNA to the P-site during initiation — a mechanistically unique step not targeted by any prior class. This novel target means there is no pre-existing cross-resistance with macrolides, chloramphenicol, or aminoglycosides. Chloramphenicol inhibits peptidyl transferase; fusidic acid blocks EF-G and translocation; aminoglycosides cause misreading at the 30S subunit.
Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.