Modifications of P. aeruginosa LPS during CF respiratory infections. Modifications of P. aeruginosa LPS during CF respiratory infections. (A) Structures of LPSs from strains recovered from the environment, acute infections, or bronchiectasis. The lipid A, core oligosaccharide, and O-antigen polysaccharide components are indicated. In the lower panel, a more detailed structure of lipid A is shown. The large polygons represent the diglucosamine bisphosphate backbone of lipid A, and the staggered lines represent acyl groups. (The placement of the lipid A acyl chain shown in gray is unclear [177, 179].) (B) During early infection in individuals with CF, the O-antigen polysaccharide is frequently lost. Also, palmitate (shown as a red staggered line) and aminoarabinose (shown as a red hexagon) are added to the lipid A portion of LPS. (C) In patients with advanced CF, a hydroxydecanoate chain (shown as a red staggered line) is retained, likely due to mutations in the pagL gene, which encodes a lipid A deacylase (89, 175). Alan R. Hauser et al. Clin. Microbiol. Rev. 2011; doi:10.1128/CMR.00036-10