title: Preferential synthesis of heptaacyl lipopolysaccharide by the ssc permeability mutant of Salmonella typhimurium.
abstract: In Salmonella typhimurium, a chromosomal gene termed ssc has been shown to cause an antibiotic-supersensitive phenotype. We studied the effect of the ssc gene on the chemical composition of the lipopolysaccharide component, using a thermosensitive ssc1 mutant (SH7622) that grows poorly at 42 degrees C. Analysis of the lipopolysaccharide by various techniques including fast-atom-bombardment mass spectrometry of lipid A, and determination of the type of linkage of fatty acids, revealed a profound temperature-dependent effect associated with the ssc1 mutation. At the non-permissive temperature, SH7622 contained hexadecanoic acid in the majority of lipid A molecules, resulting in the exclusive presence of heptaacyl lipopolysaccharide. This effect was largely reversed by the introduction of the cloned wild-type ssc gene to SH7622 and much reduced by growth of SH7622 at 37 degrees C.
authors.affiliation: Department of Bacteriology and Molecular Biology Program, National Public Health Institute, Helsinki, Finland.
authors.forename: I M
authors.initials: IM
authors.lastname: Helander
authors.forename: L
authors.initials: L
authors.lastname: Hirvas
authors.forename: J
authors.initials: J
authors.lastname: Tuominen
authors.forename: M
authors.initials: M
authors.lastname: Vaara
mesh_terms: D002240:Carbohydrate Sequence; D004591:Electrophoresis, Polyacrylamide Gel; D008050:Lipid A / Q000737:chemistry; D008070:Lipopolysaccharides / Q000096:biosynthesis* / Q000737:chemistry; D008969:Molecular Sequence Data; D009154:Mutation; D019308:Palmitic Acid; D010169:Palmitic Acids / Q000737:chemistry; D010641:Phenotype; D012486:Salmonella typhimurium / Q000235:genetics*; D016339:Spectrometry, Mass, Fast Atom Bombardment; D013696:Temperature
chemical_list: D008050:Lipid A; D008070:Lipopolysaccharides; D010169:Palmitic Acids; D019308:Palmitic Acid