Lipopolysaccharide lipid A (Lipid A)

Lipopolysaccharide lipid A is the highly conserved, hydrophobic anchor of lipopolysaccharide (LPS) located in the outer leaflet of the outer membrane of Gram-negative bacteria. Often referred to as endotoxin, it is the primary bioactive component responsible for the potent inflammatory response associated with Gram-negative infections (Raetz & Whitfield, 2002, Annu Rev Biochem). Lipid A is recognized by the human innate immune system through the Toll-like receptor 4 (TLR4) and myeloid differentiation factor 2 (MD-2) complex, which triggers the release of pro-inflammatory cytokines (Park et al., 2009, Nature). While essential for bacterial viability and membrane stability, Lipid A serves as a critical therapeutic target for cationic antimicrobial peptides like polymyxins, which bind to its phosphate groups to disrupt the bacterial cell wall (Poirel et al., 2017, Clin Microbiol Rev). Furthermore, Lipid A is a focal point in the development of anti-sepsis therapies aimed at neutralizing its activity or blocking its interaction with host receptors to prevent septic shock (Hotchkiss et al., 2016, Nat Rev Dis Primers). Its synthesis and transport from the cytoplasmic membrane to the outer membrane are also targets for novel antibiotic development.

Other names

EndotoxinLipid A component of LPSLipid A moietyLPS Lipid A

Binding to the lipid A moiety of lipopolysaccharide to disrupt the bacterial outer membrane; competitive antagonism of the TLR4/MD-2 receptor complex to prevent endotoxin-induced cytokine release.