title: The yjjN of E. coli codes for an L-galactonate dehydrogenase and can be used for quantification of L-galactonate and L-gulonate.
abstract: Escherichia coli is able to utilize L-galactonate as a sole carbon source. A metabolic pathway for L-galactonate catabolism is described in E. coli, and it is known to be interconnected with D-galacturonate metabolism. The corresponding gene encoding the first enzyme in the L-galactonate pathway, L-galactonate-5-dehydrogenase, was suggested to be yjjN. However, L-galactonate dehydrogenase activity was never demonstrated with the yjjN gene product. Here, we show that YjjN is indeed an L-galactonate dehydrogenase having activity also for L-gulonate. The K m and k cat for L-galactonate were 19.5±0.6 mM and 0.51±0.03 s(-1), respectively. In addition, YjjN was applied for a quantitative detection of the both of these substances in a coupled assay. The detection limits for L-galactonate and L-gulonate were 1.65 and 10 μM, respectively.
authors.affiliation: VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044 VTT, Espoo, Finland, joosu.kuivanen@vtt.fi.
authors.forename: Joosu
authors.initials: J
authors.lastname: Kuivanen
authors.forename: Peter
authors.initials: P
authors.lastname: Richard
mesh_terms: D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D007700:Kinetics; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D013400:Sugar Acids / Q000378:metabolism*
chemical_list: D013400:Sugar Acids; C012991:galactonic acid; C015252:gulonic acid; D010088:Oxidoreductases