Lipopolysaccharide and Bacterial Outer Membrane (LPS)

The bacterial outer membrane is a unique structural feature of Gram-negative bacteria, characterized by an asymmetric bilayer where the outer leaflet is primarily composed of lipopolysaccharide (LPS) (Raetz & Whitfield, 2002, Annual Review of Biochemistry). Lipid A is the highly conserved, hydrophobic anchor of LPS and serves as the primary mediator of endotoxic activity by triggering the TLR4 signaling pathway in host immune cells (Park & Lee, 2013, Experimental & Molecular Medicine). This structure acts as a formidable permeability barrier, protecting the bacterium from environmental stressors and many classes of antibiotics (Nikaido, 2003, Microbiology and Molecular Biology Reviews). Therapeutically, the outer membrane and Lipid A are targeted by polymyxins, which disrupt membrane integrity through electrostatic interactions with negatively charged phosphate groups (Poirel et al., 2017, Clinical Microbiology Reviews). Emerging therapies also focus on inhibiting the transport machinery, such as the Lpt pathway, that assembles LPS at the cell surface (Sperandeo et al., 2019, BBA - Molecular and Cell Biology of Lipids). Targeting this component is critical for treating multidrug-resistant Gram-negative infections, though it carries risks such as nephrotoxicity and the potential for massive endotoxin release during bacterial lysis (Zavascki et al., 2007, Journal of Antimicrobial Chemotherapy).

Other names

Lipid AEndotoxinGram-negative outer membraneLPS

Disruption of outer membrane integrity via displacement of divalent cations from Lipid A phosphate groups; inhibition of LPS transport proteins (e.g., LptD).