Bacterial cell wall synthesis enzyme transpeptidase

Bacterial cell wall synthesis enzyme transpeptidases are a class of enzymes essential for the final stages of peptidoglycan biosynthesis in bacteria. These enzymes catalyze the formation of peptide cross-links between glycan strands, providing mechanical strength and rigidity to the bacterial cell wall. The most well-known members are penicillin-binding proteins (PBPs), particularly those with DD-transpeptidase activity. They possess a conserved serine residue at their active site that is crucial for catalysis. Transpeptidases are vital for maintaining cellular structure, enabling growth, division, and protection against osmotic stress. Inhibition by β-lactam antibiotics such as penicillins disrupts their function by acylating the active site serine residue, preventing proper cross-linking and ultimately causing bacterial lysis due to weakened cell walls. This mechanism underlies the clinical efficacy of many frontline antibiotics against a broad range of pathogenic bacteria. These enzymes belong molecularly to the penicilloyl-serine transferase superfamily and share signature sequence motifs involved in catalysis. They are considered prime therapeutic targets because their inhibition is lethal specifically to bacteria but not eukaryotic cells due to differences in cellular architecture. Resistance mechanisms include production of alternative PBPs with reduced affinity for β-lactams or expression of β-lactamases that degrade these drugs. In summary, bacterial cell wall synthesis enzyme transpeptidases play an indispensable role in prokaryotic viability and represent one of medicine’s most validated antibacterial drug targets.

Other names

Penicillin-binding protein (PBP) transpeptidaseDD-transpeptidasePeptidoglycan transpeptidaseBacterial transpeptidase

Inhibition of peptidoglycan cross-linking by covalent binding to the active site serine, leading to loss of cell wall integrity and bacterial lysis (bactericidal effect)