n390054SE Academic Article uri icon

abstract

  • A combination of bioinformatics, steady-state kinetics, and NMR spectroscopy has revealed the catalytic functions of YcjQ, YcjS, and YcjR from the ycj gene cluster in Escherichia coli K-12. YcjS was determined to be a 3-keto-d-glucoside dehydrogenase with a kcat = 22 s-1 and kcat/ Km = 2.3 104 M-1 s-1 for the reduction of methyl -3-keto-d-glucopyranoside at pH 7.0 with NADH. YcjS also exhibited catalytic activity for the NAD+-dependent oxidation of d-glucose, methyl -d-glucopyranoside, and 1,5-anhydro-d-glucitol. YcjQ was determined to be a 3-keto-d-guloside dehydrogenase with kcat = 18 s-1 and kcat/ Km = 2.0 103 M-1 s-1 for the reduction of methyl -3-keto-gulopyranoside. This is the first reported dehydrogenase for the oxidation of d-gulose. YcjQ also exhibited catalytic activity with d-gulose and methyl -d-gulopyranoside. The 3-keto products from both dehydrogenases were found to be extremely labile under alkaline conditions. The function of YcjR was demonstrated to be a C4 epimerase that interconverts 3-keto-d-gulopyranosides to 3-keto-d-glucopyranosides. These three enzymes, YcjQ, YcjR, and YcjS, thus constitute a previously unrecognized metabolic pathway for the transformation of d-gulosides to d-glucosides via the intermediate formation of 3-keto-d-guloside and 3-keto-d-glucoside.

published proceedings

  • Biochemistry

author list (cited authors)

  • Mukherjee, K., Huddleston, J. P., Narindoshvili, T., Nemmara, V. V., & Raushel, F. M.

publication date

  • January 1, 2019 11:11 AM