Characterization of the lipopolysaccharide of Moraxella catarrhalis

Open Access
Publisher Website
Google Scholar
Abstract
The lipopolysaccharide of Moraxella catarrhalis serotype A (ATCC 25238) was found to consist of a short‐chain oligosaccharide attached to a lipid A moiety. Composition and NMR analyses showed the oligosaccharide component in O‐deacylated LPS to be composed of d‐glucose, d‐galactose, 2‐acetamido‐2‐deoxy‐d‐glucose and 3‐deoxy‐d‐manno‐octulosonic acid in the molar ratio of 5:2:1:2. In addition, the lipid A region contained phosphate, d‐glucosamine, ethanolamine, 3‐hydroxydodecanoic acid, dodecanoic acid and decanoic acid. The lipid A was examined in detail by high‐field NMR spectroscopy and mass spectrometry. It was found to consist of a β‐1,6‐d‐glucosamine disaccharide backbone esterified at C4′ by a phosphomonoester and glycosidically at C1 by diphosphoethanolamine or phosphomonoester. The amide group of the reducing and non‐reducing glucosamine residues were acylated by 3‐dodecanoyloxydodecanoic acid and 3‐decanoyloxydodecanoic acid, respectively. The hydroxyl group at C3 and C3′ were acylated by 3‐decanoyloxydodecanoic acid and 3‐hydroxydodecanoic acid respectively, while the hydroxyl groups at C4 and C6′ were unsubstituted.