Bacterial outer membrane lipopolysaccharide and phospholipid (LPS)

The bacterial outer membrane lipopolysaccharide (LPS) and phospholipids are fundamental structural components that define the surface of Gram-negative bacteria. LPS, often referred to as endotoxin, is a complex glycolipid composed of three regions: the hydrophobic Lipid A, a core oligosaccharide, and a distal O-antigen (Raetz & Whitfield, 2002, Annu Rev Biochem). These molecules are essential for maintaining the integrity of the outer membrane, acting as a selective permeability barrier that protects the bacterium from toxic substances, including detergents and many antibiotics (Nikaido, 2003, Microbiol Mol Biol Rev). In clinical settings, LPS is a major driver of the pathophysiology of sepsis; its recognition by the host's Toll-like receptor 4 (TLR4) triggers a massive release of pro-inflammatory cytokines (Park & Lee, 2013, Exp Mol Med). Drugs such as polymyxins (Polymyxin B and Colistin) specifically target this site by binding to the negatively charged phosphate groups of LPS and phospholipids. This binding displaces stabilizing divalent cations (Mg2+ and Ca2+), leading to membrane destabilization, increased permeability, and eventual cell lysis (Velkov et al., 2013, J Med Chem). Despite their efficacy against multi-drug resistant pathogens, targeting these lipids presents challenges, including significant nephrotoxicity and the risk of inducing a systemic inflammatory response due to rapid endotoxin release (Falagas & Kasiakou, 2006, Nephrol Dial Transplant). Understanding the interaction between these lipids and therapeutic agents is crucial for the development of next-generation antibiotics targeting the Gram-negative cell envelope.

Other names

EndotoxinLipoglycanGram-negative outer membrane lipidsLipid ABacterial outer membrane lipopolysaccharides and phospholipids

Disruption of the outer membrane through displacement of divalent cations (Mg2+ and Ca2+), binding to Lipid A to neutralize endotoxin activity, and inhibition of LPS transport proteins (e.g., LptD)