Penicillin-binding protein-associated <p>This entry represents a structural motif found at the C-terminal of penicillin-binding proteins 4 (PBP4) and 5 (PBP5), as well as at the C-terminal of D-Ala-D-Ala carboxypeptidase A, a member of the MEROPS S11 peptidase family (PBP4 and PBP5 also belong to this peptidase family). These domains share a similar structure, consisting of a beta-sandwich of six strands in two sheets [<cite idref="PUB00022291"/>, <cite idref="PUB00032485"/>].</p><p>Penicillin-binding proteins are beta-lactam antibiotic-sensitive bacterial enzymes required for the growth and maintenance of the peptidoglycan layer of the bacterial cell wall that protects the cell from osmotic stress. PBP4 functions as a transpeptidase, acting co-operatively with PBP2 in staphylococcal cell wall biosynthesis and susceptibility to antimicrobial agents [<cite idref="PUB00035543"/>].</p>