Penicillin-binding protein 1B (PBP1B) (PBP1B)

Penicillin-binding protein 1B (PBP1B) is a critical bifunctional enzyme in Salmonella enterica responsible for the synthesis and maintenance of the bacterial peptidoglycan cell wall (Uddin et al., 2016). Encoded by the mrcB gene, PBP1B exhibits both transglycosylase activity, which polymerizes glycan chains, and transpeptidase activity, which cross-links these chains to provide structural integrity (Sun et al., 2014). While PBP1B is partially redundant with PBP1A, it is particularly important for Salmonella survival under environmental stressors such as high osmotic pressure and exposure to bile in the host's gallbladder (Garcia-del Portillo et al., 2020). As a primary target for beta-lactam antibiotics, including cephalosporins and penicillins, PBP1B's inhibition leads to the loss of cell wall stability and subsequent bacterial lysis (El-Fateh et al., 2024). However, the therapeutic efficacy of targeting PBP1B is increasingly challenged by the rise of multidrug-resistant (MDR) strains and the pathogen's ability to express alternative, low-affinity PBPs in intracellular niches (Garcia-del Portillo et al., 2020). Understanding the role of PBP1B in Salmonella pathogenesis is essential for developing next-generation antimicrobials and overcoming antibiotic resistance.

Other names

PBP1bmrcBPeptidoglycan glycosyltransferase/transpeptidase PBP1b

Inhibition of peptidoglycan transpeptidation by covalent binding to the active site serine residue, leading to cell wall destabilization and bacterial lysis.