Isolation and characterization of Escherichia coli mutants able to utilize the novel pentose L-ribose.
Wild-type strains of Escherichia coli were unable to utilize L-ribose for growth. However, L-ribose-positive mutants could be isolated from strains of E. coli K-12 which contained a ribitol operon. L-ribose-positive strains of E. coli, isolated after 15 to 20 days, had a growth rate of 0.22 generation per h on L-ribose. Growth on L-ribose was found to induce the enzymes of the L-arabinose and ribitol pathways, but only ribitol-negative mutants derived from strains originally L-ribose positive lost the ability to grow on L-ribose, showing that a functional ribitol pathway was required. One of the mutations permitting growth on L-ribose enabled the mutants to produce constitutively an NADPH-linked reductase which converted L-ribose to ribitol. L-ribose is not metabolized by an isomerization to L-ribulose, as would be predicted on the basis of other pentose pathways in enteric bacteria. Instead, L-ribose was metabolized by the reduction of L-ribose to ribitol, followed by the conversion to D-ribulose by enzymes of the ribitol pathway.
Trimbur
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Department of Microbiology, Cornell University, Ithaca, New York 14853.
Mortlock
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D019747:Aldose-Ketose Isomerases; D001089:Arabinose / Q000378:metabolism; D002238:Carbohydrate Epimerases / Q000032:analysis; D002855:Chromatography, Thin Layer; D002874:Chromosome Mapping; D004586:Electrophoresis; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D010770:Phosphotransferases / Q000032:analysis; D017853:Phosphotransferases (Alcohol Group Acceptor); D012266:Ribose / Q000378:metabolism*; D013401:Sugar Alcohol Dehydrogenases / Q000032:analysis; D014161:Transduction, Genetic
D012266:Ribose; D001089:Arabinose; D013401:Sugar Alcohol Dehydrogenases; C068251:L-ribose reductase; C022529:ribitol 2-dehydrogenase; D010770:Phosphotransferases; D017853:Phosphotransferases (Alcohol Group Acceptor); C022390:phosphoribulokinase; D002238:Carbohydrate Epimerases; D019747:Aldose-Ketose Isomerases; C019715:L-arabinose isomerase