title: Utilization of L-ascorbate by Escherichia coli K-12: assignments of functions to products of the yjf-sga and yia-sgb operons.
abstract: 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).
authors.affiliation: Department of Biochemistry, University of Illinois, Urbana, Illinois 61801, USA.
authors.forename: Wen Shan
authors.initials: WS
authors.lastname: Yew
authors.forename: John A
authors.initials: JA
authors.lastname: Gerlt
mesh_terms: D001205:Ascorbic Acid / Q000378:metabolism*; D002238:Carbohydrate Epimerases / Q000235:genetics; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics*; D005285:Fermentation; D005798:Genes, Bacterial; D008954:Models, Biological; D008957:Models, Genetic; D009876:Operon
chemical_list: D002238:Carbohydrate Epimerases; C022553:ribulosephosphate 3-epimerase; C022554:L-ribulosephosphate 4-epimerase; D001205:Ascorbic Acid