Peptidoglycan precursor Lipid II (Lipid II)

Peptidoglycan precursor Lipid II is a fundamental component of the bacterial cell wall synthesis machinery, acting as the essential carrier and substrate for the assembly of the peptidoglycan layer (Nature Reviews Microbiology, 2008). It is composed of a N-acetylglucosamine (GlcNAc) and N-acetylmuramic acid (MurNAc) disaccharide, a pentapeptide, and a C55-undecaprenyl pyrophosphate anchor. Lipid II is synthesized in the cytoplasm and flipped across the plasma membrane to the periplasmic space, where it is utilized by penicillin-binding proteins (PBPs) for transglycosylation and transpeptidation (UniProt, 2024). This molecule is the specific target for glycopeptide antibiotics, such as vancomycin and teicoplanin, which bind with high affinity to the D-alanyl-D-alanine (D-Ala-D-Ala) terminus of the pentapeptide (PubChem, 2024). This binding event sterically hinders the enzymatic incorporation of the precursor into the cell wall, leading to structural failure and bacterial cell death. Because Lipid II is highly conserved across Gram-positive bacteria and absent in human cells, it remains a cornerstone target for treating multi-drug resistant infections like MRSA (NIH, 2022).

Other names

Lipid IIUndecaprenyl-pyrophosphate-MurNAc-pentapeptide-GlcNAcBactoprenol-linked peptidoglycan precursorD-alanyl-D-alanine terminus of peptidoglycan precursorPeptidoglycan transglycosylation substrate

Glycopeptide antibiotics bind to the D-alanyl-D-alanine (D-Ala-D-Ala) C-terminus of the Lipid II pentapeptide via a network of hydrogen bonds. This binding event sterically hinders the transglycosylase enzyme from polymerizing the glycan chain and the transpeptidase enzyme from cross-linking the peptide chains, effectively halting cell wall synthesis (StatPearls, 2023; Nature Reviews Microbiology, 2008).