Utilization of L-ascorbate by Escherichia coli K-12: assignments of functions to products of the yjf-sga and yia-sgb operons

J Bacteriol. 2002 Jan;184(1):302-6. doi: 10.1128/JB.184.1.302-306.2002.


Escherichia coli K-12 can ferment L-ascorbate. The operon encoding catabolic enzymes in the utilization of L-ascorbate (ula) has been identified; this operon of previously unknown function had been designated the yif-sga operon. Three enzymes in the pathway that produce D-xylulose 5-phosphate have been functionally characterized: 3-keto-L-gulonate 6-phosphate decarboxylase (UlaD), L-xylulose 5-phosphate 3-epimerase (UlaE), and L-ribulose 5-phosphate 4-epimerase (UlaF). Several products of the yia-sgb operon were also functionally characterized, although the substrate and physiological function of the operon remain unknown: 2,3-diketo-L-gulonate reductase (YiaK), 3-keto-L-gulonate kinase (LyxK), 3-keto-L-gulonate 6-phosphate decarboxylase (SgbH), and L-ribulose 5-phosphate 4-epimerase (SgbE).

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Ascorbic Acid / metabolism*
  • Carbohydrate Epimerases / genetics
  • Escherichia coli / enzymology*
  • Escherichia coli / genetics*
  • Fermentation
  • Genes, Bacterial
  • Models, Biological
  • Models, Genetic
  • Operon*


  • Carbohydrate Epimerases
  • ribulosephosphate 3-epimerase
  • L-ribulosephosphate 4-epimerase
  • Ascorbic Acid