Bacterial peptidoglycan cell wall (PGN)

The bacterial peptidoglycan cell wall, also known as murein, is an essential and unique structural component found in the cell envelope of nearly all bacteria (Vollmer et al., 2008). It consists of a mesh-like polymer of amino sugars cross-linked by short peptide chains, providing the mechanical strength necessary to withstand high internal osmotic pressure and maintain cell shape (Silhavy et al., 2010). Because this structure is absent in human cells, it represents one of the most successful and selective targets for antimicrobial therapy. Major classes of antibiotics, such as beta-lactams and glycopeptides, exert their bactericidal effects by disrupting the synthesis or assembly of the peptidoglycan layer (Kohanski et al., 2010). For instance, penicillins inhibit the transpeptidase enzymes responsible for cross-linking, while vancomycin prevents the incorporation of new subunits into the growing polymer. The integrity of the peptidoglycan cell wall is critical for bacterial survival, and its disruption leads to cell lysis and death. However, the clinical utility of targeting this structure is constantly challenged by the evolution of bacterial resistance mechanisms, such as the production of beta-lactamases or the modification of the peptidoglycan precursors themselves (Bush & Bradford, 2016).

Other names

MureinPeptidoglycan layerBacterial cell wallPeptidoglycan

Inhibition of cell wall biosynthesis through various mechanisms: beta-lactams (e.g., penicillins, cephalosporins) inhibit transpeptidation by binding to penicillin-binding proteins (PBPs); glycopeptides (e.g., vancomycin) bind to the D-Ala-D-Ala terminus of the peptidoglycan precursor to prevent cross-linking; fosfomycin inhibits MurA, an enzyme involved in the early stages of precursor synthesis; and bacitracin prevents the dephosphorylation of the lipid carrier required for transporting precursors across the membrane (Kohanski et al., 2010; Silver, 2011).