The yjjN of E. Coli Codes for an L-galactonate Dehydrogenase and Can Be Used for Quantification of L-galactonate and L-gulonate

Appl Biochem Biotechnol. 2014 Aug;173(7):1829-35. doi: 10.1007/s12010-014-0969-0. Epub 2014 May 27.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Escherichia coli / enzymology*
  • Escherichia coli / genetics
  • Kinetics
  • Oxidoreductases / genetics
  • Oxidoreductases / metabolism*
  • Sugar Acids / metabolism*


  • Sugar Acids
  • galactonic acid
  • gulonic acid
  • Oxidoreductases