Gram-negative bacterial lipopolysaccharide lipid A and outer membrane phospholipids (LPS)

Gram-negative bacterial lipopolysaccharide (LPS) and outer membrane phospholipids are essential components of the Gram-negative bacterial cell envelope, providing a robust permeability barrier against environmental threats and antibiotics (Source: Raetz & Whitfield, 2002, Annual Review of Biochemistry). LPS is composed of three distinct domains: the O-antigen, the core oligosaccharide, and Lipid A, which anchors the molecule into the outer membrane and is responsible for its potent endotoxic activity (Source: NIH/NCBI). Therapeutic agents like polymyxins specifically target the Lipid A moiety and adjacent phospholipids by binding to their negatively charged phosphate groups (Source: Trimble et al., 2016). This binding displaces stabilizing divalent cations, such as magnesium and calcium, causing physical disruption of the outer membrane and subsequent cell death (Source: Velkov et al., 2013, Journal of Medicinal Chemistry). In addition to its structural importance, LPS is a major driver of the host's innate immune response, acting as a ligand for the Toll-like receptor 4 (TLR4) complex, which can lead to life-threatening systemic inflammation and sepsis during severe infections (Source: Park & Lee, 2013, Experimental & Molecular Medicine).

Other names

LipopolysaccharideLipid AEndotoxinBacterial outer membrane phospholipidsLPS-Lipid A complex

Drugs target this site by electrostatically interacting with the negatively charged phosphate groups of Lipid A and phospholipids, displacing divalent cations (Mg2+ and Ca2+) that stabilize the membrane. This leads to membrane reorganization, increased permeability, and osmotic lysis of the bacterial cell (Source: Trimble et al., 2016, Cold Spring Harbor Perspectives in Medicine).