Penicillin-binding protein 1A and Penicillin-binding protein 2B (PBP1A, PBP2B)

Penicillin-binding proteins are a group of membrane-associated bacterial enzymes involved in the last steps of peptidoglycan biosynthesis, which is essential for bacterial cell wall integrity and viability[9][6]. PBP1A is a bifunctional high-molecular-weight enzyme, performing both glycosyltransferase (polymerization of the glycan backbone) and transpeptidase (cross-linking of peptide chains) activities, while PBP2B is a monofunctional high-molecular-weight enzyme acting mainly as a transpeptidase[3][9][1][4]. These proteins are key targets for β-lactam antibiotics (penicillins, cephalosporins): drugs bind covalently to the active site serine of PBPs, inhibiting their catalytic function and blocking cell wall synthesis, resulting in bacterial death[9][6]. In *Streptococcus pneumoniae* and many other bacterial pathogens, mutations or recombination in pbp1a/pbp2b genes can confer significant resistance to β-lactams by lowering their binding affinity, making these PBPs crucial molecular determinants of antibiotic resistance[1][5][10]. Experimental evidence supports their essential roles in cell division (septum formation for PBP1A) and elongation (PBP2B), and mutations are major resistance determinants in clinical isolates of *S. pneumoniae*[1][5][10].

Other names

PBP1APBP2Bpbp1a (gene)pbp2b (gene)Class A penicillin-binding protein (for PBP1A)Class B penicillin-binding protein (for PBP2B)

Inhibition of transpeptidase (cross-linking of peptidoglycan strands); Inhibition of glycosyltransferase (PBP1A: polymerization of glycan chains)