Glycopeptide antibiotics (vancomycin, teicoplanin) inhibit bacterial cell wall synthesis by binding to which specific target?

• A Penicillin-binding proteins (transpeptidases) directly
• B Beta-1,4-glycosidic bonds in the glycan backbone of peptidoglycan
• C MurA enzyme in the cytoplasm preventing UDP-MurNAc synthesis
• D D-Ala-D-Ala terminus of the lipid II peptidoglycan precursor ✓

Explanation

Vancomycin and teicoplanin bind non-covalently to the D-Ala-D-Ala terminus of the lipid II pentapeptide peptidoglycan precursor on the outer leaflet of the bacterial membrane, physically blocking transglycosylation and transpeptidation. This mechanism is entirely different from beta-lactams that covalently acylate transpeptidases (PBPs). VRE acquires resistance by substituting D-Ala-D-Lac, reducing vancomycin binding 1000-fold. Lysozyme cleaves the glycan backbone; fosfomycin inhibits MurA.

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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