title: Lipopolysaccharide and aldoheptose biosynthesis in transketolase mutants of Salmonella typhimurium.
abstract: Genetic and biochemical evidence that sedoheptulose-7-phosphate is an obligatory precursor of the L-glycero-D-mannoheptose residues of the lipopolysaccharide of Salmonella was obtained by isolation and characterization of transketolase-negative mutants of Salmonella typhimurium. These mutants, which are defective in synthesis of sedoheptulose-7-phosphate, were found to produce an incomplete heptose-deficient lipopolysaccharide, and were also sensitive to bile salts, a characteristic property of heptose-deficient mutants. Phenotypic repair of the defect in lipopolysaccharide synthesis was obtained by addition of exogenous sedoheptulose-7-phosphate to growing cultures of the mutant strains. Characterization of revertants isolated either as transketolase-positive or heptose-positive provided further evidence that the heptose deficiency resulted from mutation at the transketolase locus. On the basis of these findings a possible pathway for conversion of sedoheptulose-7-phosphate to L-glycero-D-mannoheptose is proposed.
mesh_terms: D002247:Carbon Isotopes; D002849:Chromatography, Gas; D003470:Culture Media; D004926:Escherichia coli / Q000378:metabolism; D005690:Galactose / Q000378:metabolism; D005947:Glucose / Q000032:analysis; D006539:Heptoses / Q000032:analysis / Q000096:biosynthesis* / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000032:analysis / Q000096:biosynthesis*; D008967:Molecular Biology; D009154:Mutation; D010641:Phenotype; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis; D012486:Salmonella typhimurium / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism*; D014166:Transferases / Q000032:analysis
chemical_list: D002247:Carbon Isotopes; D003470:Culture Media; D006539:Heptoses; D008070:Lipopolysaccharides; D011135:Polysaccharides, Bacterial; D014166:Transferases; D005947:Glucose; D005690:Galactose