Lipopolysaccharide and aldoheptose biosynthesis in transketolase mutants of Salmonella typhimurium.
نویسندگان
چکیده
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.
منابع مشابه
Phosphoheptose isomerase, first enzyme in the biosynthesis of aldoheptose in Salmonella typhimurium.
Radioactive sedoheptulose 7-phosphate was shown to label specifically the L-glycero-D-mannoheptose residues of the lipopolysaccharide of a transketolase-negative mutant of Salmonella typhimurium. Phosphoheptose isomerase, the first enzyme in the proposed pathway of heptose biosynthesis, was shown to catalyze the reaction: sedoheptulose 7-phosphate --+ D-glycero-D-mannoheptose 7-phosphate. This ...
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عنوان ژورنال:
- Proceedings of the National Academy of Sciences of the United States of America
دوره 68 8 شماره
صفحات -
تاریخ انتشار 1971