D-alanyl-D-alanine-containing cell wall precursor

D-alanyl-D-alanine-containing cell wall precursors are essential intermediates in the biosynthesis of bacterial peptidoglycan. These precursors consist of a pentapeptide chain ending with a terminal D-alanyl-D-alanine sequence attached to N-acetylmuramic acid within the growing peptidoglycan structure. The presence of this dipeptide is critical for proper cross-linking during cell wall assembly—a process catalyzed by transpeptidase enzymes (penicillin-binding proteins). Glycopeptide antibiotics such as vancomycin exert their antibacterial effect by binding specifically to this terminal motif on nascent peptidoglycan chains. This interaction blocks further extension and cross-linking steps required for mature cell wall formation, ultimately resulting in bacterial death due to loss of structural integrity. Resistance mechanisms include modification or replacement of the terminal dipeptide (e.g., substitution with D-lactate), which reduces antibiotic binding affinity and confers drug resistance[2][3][5].

Other names

D-Ala-D-Ala-ended peptidoglycan precursorD-Ala-D-Ala-terminated Lipid IIpeptidoglycan pentapeptide precursorterminal D-alanyl-D-alanine motif

Inhibition of cell wall synthesis by binding to the terminal D-Ala-D-Ala motif, preventing cross-linking and polymerization of peptidoglycan strands[2]