Penicillin-binding proteins 3, 1A, 1B, 2 (PBP3, PBP1A, PBP1B, PBP2)

Penicillin-binding proteins are critical bacterial enzymes involved in the late stages of peptidoglycan biosynthesis, which is essential for bacterial viability and maintenance of cell shape[1][3][6]. PBP1A and PBP1B (class A) are bifunctional enzymes with both transglycosylase and transpeptidase activities and contribute to the synthesis and integrity of the cell wall[5][3]. PBP2 and PBP3 (class B) primarily possess transpeptidase activity, with PBP2 involved in maintaining rod shape and PBP3 in septum formation and cell division[6][1]. β-lactam antibiotics target these proteins by mimicking their D-Ala-D-Ala substrate, resulting in covalent acylation of the active site serine residue and inhibition of enzymatic activity, leading to cell lysis. PBPs differ in their essentiality: for example, PBP3 is essential in *Pseudomonas aeruginosa* and *Escherichia coli*, while others are partially redundant[6][1][5]. Resistance to β-lactam drugs is frequently caused by mutations in PBPs that reduce antibiotic binding[6].

Other names

FtsIPonAMrcBPbpA

Irreversible covalent inhibition of transpeptidase or glycosyltransferase domains by β-lactam antibiotics, leading to loss of cell wall integrity and bacterial cell death