idnO (Escherichia coli K12 MG1655): 5-keto-D-gluconate 5-reductase; Catalyzes the reduction of 5-keto-D-gluconate to D- gluconate, using either NADH or NADPH. Is likely involved in an L- idonate degradation pathway that allows E.coli to utilize L- idonate as the sole carbon and energy source. Is also able to catalyze the reverse reaction in vitro, but the D-gluconate oxidation by the enzyme can only proceed with NAD