Peptidoglycan pentaglycyl peptide bridge (Gly5 bridge)

The peptidoglycan pentaglycyl peptide bridge is a specialized structural element found in the cell walls of certain Gram-positive bacteria, most notably Staphylococcus aureus (Schleifer & Kandler, 1972). It consists of a chain of five glycine residues that serves to cross-link the L-lysine of one peptidoglycan stem peptide to the D-alanine of an adjacent strand, providing the cell wall with the necessary tensile strength to resist internal osmotic pressure (Bera et al., 2005). This specific bridge is a key determinant of bacterial viability and a major target for antimicrobial intervention. The enzyme lysostaphin, a glycylglycine endopeptidase, targets this structure directly by cleaving the glycine-glycine bonds, leading to rapid cell wall degradation and bacterial death (Recsei et al., 1987). Furthermore, glycopeptide antibiotics like vancomycin interfere with the incorporation of this bridge into the cell wall by binding to the D-Ala-D-Ala precursors, effectively halting the cross-linking process (Reynolds, 1989). Because the pentaglycine sequence is relatively unique to staphylococci, it allows for highly targeted therapeutic strategies with minimal impact on other bacterial species.

Other names

Pentaglycine cross-bridgePentaglycyl interpeptide bridgeStaphylococcal cross-bridgeGly5 interpeptide segmentPeptidoglycan pentaglycine bridge

Lysostaphin acts as a glycylglycine endopeptidase that specifically hydrolyzes the peptide bonds between glycine residues within the pentaglycine bridge, leading to rapid cell wall degradation and bacterial lysis (Recsei et al., 1987). Glycopeptide antibiotics like vancomycin indirectly target the utilization of this bridge by binding to the D-alanyl-D-alanine terminus of the peptidoglycan precursor, sterically blocking the transpeptidase enzymes from forming the cross-link (Reynolds, 1989).