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

Gram-negative bacterial lipopolysaccharide (LPS) lipid A and outer membrane anionic phospholipids constitute the essential structural framework of the Gram-negative bacterial envelope (PubMed, PMID: 11544358). Lipid A, the hydrophobic anchor of LPS, is a highly conserved glycolipid that serves as a potent endotoxin, triggering robust inflammatory responses via the TLR4 pathway in humans (NIH, 2022). Anionic phospholipids, such as phosphatidylglycerol and cardiolipin, further contribute to the negative surface charge and stability of the bacterial membrane. These components are the primary targets for cationic polypeptide antibiotics like polymyxins, which bind to the negatively charged phosphate groups to disrupt membrane stability (StatPearls, 2023). This disruption leads to increased membrane permeability, leakage of cytoplasmic contents, and rapid bactericidal action. Targeting these lipids is a critical strategy for treating multidrug-resistant infections, although it carries risks of toxicity and the emergence of resistance mechanisms that modify the lipid structures (PubMed, PMID: 27335449).

Other names

Lipid AEndotoxinBacterial outer membrane phospholipidsLPSLipopolysaccharide

Cationic drugs bind electrostatically to the negatively charged phosphate groups of lipid A and anionic phospholipids, displacing stabilizing divalent cations (Mg2+ and Ca2+). This interaction disrupts the outer membrane's integrity, increases permeability, and leads to the leakage of intracellular contents and eventual cell death (StatPearls, 2023; PubMed, PMID: 24762931).