Penicillin-binding protein 3 of Pseudomonas aeruginosa (PBP3)

Penicillin-binding protein 3 of Pseudomonas aeruginosa (PBP3) is an essential, high-molecular-mass transpeptidase enzyme located in the inner membrane of *P. aeruginosa* that catalyzes the final cross-linking step of peptidoglycan biosynthesis during cell division[1][3][4][6]. PBP3 is encoded by the ftsI gene and is the primary and only essential penicillin-binding protein for cell division in this species[3][6]. It is the principal target for several β-lactam antibiotics, including ceftazidime, carbenicillin, cefepime, meropenem, and aztreonam, which bind covalently to its active site serine and block cell wall synthesis, leading to cell death in actively dividing bacteria[1][4][5][8]. Mutations in PBP3 (notably F533L and R504C) are associated with clinical resistance to multiple β-lactams by reducing drug affinity for the enzyme, contributing to the challenge of treating infections caused by multidrug-resistant *P. aeruginosa*[5][6]. Structural studies of PBP3-antibiotic complexes have provided molecular insight for antibiotic development and resistance mechanisms[1][4][9].

Other names

PBP3FtsI (*gene name*)Penicillin-binding protein 3

Covalent inhibition of transpeptidase activity by β-lactam antibiotics Blocking cell wall biosynthesis leading to lysis and death of dividing bacteria