Gram-negative bacterial peptidoglycan (PGN)

Gram-negative bacterial peptidoglycan is a vital structural polymer located within the periplasmic space, situated between the inner cytoplasmic membrane and the outer membrane. It is composed of alternating residues of N-acetylglucosamine and N-acetylmuramic acid, which are cross-linked by pentapeptide side chains to form a resilient, mesh-like layer (Vollmer et al., 2008). The primary biological role of this molecule is to maintain cell shape and provide the mechanical strength necessary to withstand high internal osmotic pressure, thereby preventing bacterial lysis (Silhavy et al., 2010). During bacterial growth and division, the peptidoglycan layer undergoes constant remodeling, a process that is highly regulated by various enzymes. In the context of infectious disease, peptidoglycan serves as a major pathogen-associated molecular pattern (PAMP); specifically, its breakdown products (muropeptides) are recognized by host intracellular receptors like NOD1 to initiate an immune response (Girardin et al., 2003). Because peptidoglycan is unique to prokaryotes, it is the primary target for several classes of antibiotics, most notably the beta-lactams, which inhibit the transpeptidation enzymes required for its synthesis (Kohanski et al., 2010). Therapeutic challenges include the presence of the Gram-negative outer membrane, which acts as a permeability barrier, and the rapid evolution of resistance mechanisms such as beta-lactamases that degrade drugs targeting this structure.

Other names

MureinPeptidoglycan layerBacterial cell wall polymerPG

Inhibition of peptidoglycan biosynthesis and cross-linking by targeting enzymes such as penicillin-binding proteins (PBPs) or Mur ligases.