Chemical composition of a lipopolysaccharide from Legionella pneumophila

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Abstract
Lipopolysaccharide isolated from Legionella pneumophila (Phil. 1) was examined for chemical composition. The polysaccharide split off by mild acid hydrolysis contained rhamnose, mannose, glucose, quinovosamine, glucosamine and 2-keto-3-deoxyoctonate, in molar proportions 1.6:1.8:1.0:1.5:4.1:2.7. Heptoses were absent and glucose was probably mainly phosphorylated. The carbohydrate backbone of the lipid A part consisted of glucosamine, quinovosamine and glycerol, in the molar ratios 3.9:1.0:3.4, with glycerol as a phosphorylated moiety. A complex fatty acid substitution pattern comprising eight O-ester-linked, exclusively nonhydroxylated acids, and nineteen amide-linked, exclusively 3-hydroxylated acids was revealed. Both straight- and branched (iso and anteiso) carbon chains occurred. The major hydroxy fatty acid was 3-hydroxy-12-methyltridecanoic acid and six others were of a chain-length above 20 carbon atoms, with 3-hydroxy-20-methyldocosanoic acid as the longest. Two dihydroxy fatty acids, 2,3-dihydroxy-12-methyltridecanoic and 2,3-dihydroxytetradecanoic acids, were also detected. These results suggest that L. pneumophila contains a rather complex and unusual lipopolysaccharide structure of considerable biological and chemotaxonomic interest.