D-alanyl-D-alanine carboxypeptidase DacA

D-alanyl-D-alanine carboxypeptidase DacA, also known as penicillin-binding protein 5 (PBP5), is a membrane-bound, penicillin-sensitive enzyme involved in bacterial cell wall synthesis. It specifically trims the C-terminal D-alanyl residues from peptidoglycan pentapeptides during the final stages of peptidoglycan biosynthesis. This activity is crucial for proper cell wall maturation and regulation of cell shape. It is a key target for beta-lactam antibiotics, and mutations can lead to antibiotic resistance.

Other names

Penicillin-binding protein 5 (PBP5)DD-carboxypeptidaseDD-peptidaseSerine-type D-Ala-D-Ala carboxypeptidases

Beta-lactam antibiotics bind covalently to PBPs like DacA, leading to enzyme deactivation and ultimately bacterial death due to defective cell wall synthesis.