Gram-negative bacterial outer membrane lipid A and anionic phospholipids (Lipid A / Anionic Phospholipids)

Lipid A is the highly conserved, hydrophobic anchor of lipopolysaccharide (LPS) located in the outer leaflet of the Gram-negative bacterial outer membrane. It serves as a critical structural component and a potent endotoxin that triggers the host innate immune response through the TLR4/MD-2 receptor complex. Anionic phospholipids, such as phosphatidylglycerol, further contribute to the overall negative charge of the bacterial surface. These molecules are primary therapeutic targets for polymyxin-class antibiotics, which utilize electrostatic interactions to disrupt membrane stability. Because lipid A is essential for the viability of most Gram-negative pathogens, it remains a focal point for developing novel treatments against multidrug-resistant infections, including those caused by Pseudomonas aeruginosa and Acinetobacter baumannii.

Other names

Lipid AEndotoxin anchorBacterial outer membrane phospholipidsLipopolysaccharide lipid A componentAnionic bacterial membrane lipids

Cationic cyclic peptides bind electrostatically to the negatively charged phosphate groups of lipid A and anionic phospholipids, displacing divalent cations (Ca2+ and Mg2+), which destabilizes the outer membrane and leads to increased permeability, cytoplasmic leakage, and cell death.