Lipopolysaccharide

Structure of a lipopolysaccharide

Lipopolysaccharides (LPS), also known as lipoglycans, are large molecules made of a lipid and a polysaccharide joined by a covalent bond.

They occur in the outer membrane of Gram-negative bacteria, and act as triggers for the innate immune system. Their presence is sensed by toll-like receptors on dendritic cells. This causes a strong immune response in animals.

Lipopolysaccharide Media

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  The saccharolipid Kdo2-Lipid A. Kdo residues in red (core), glucosamine residues in blue, acyl chains in black and phosphate groups in green.

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  LPS final assembly: O-antigen subunits are translocated across the inner membrane (by Wzx) where they are polymerized (by Wzy, chain length determined by Wzz) and ligated (by WaaL) on to complete Core-Lipid A molecules (which were translocated by MsbA).

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  LPS transport: Completed LPS molecules are transported across the periplasm and outer membrane by the lipopolysaccharide transport (Lpt) proteins A, B, C, D, E, F, and G.

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  Toll-like receptors of the innate immune system recognize LPS and trigger an immune response.