Characterization of a pentonolactonase involved in D-xylose and L-arabinose catabolism in the haloarchaeon Haloferax volcanii

FEMS Microbiol Lett. 2017 Jul 6;364(13). doi: 10.1093/femsle/fnx140.


Haloferax volcanii degrades the pentoses D-xylose and L-arabinose via an oxidative pathway to α-ketoglutarate as an intermediate. The initial dehydrogenases of the pathway, D-xylose dehydrogenase (XDH) and L-arabinose dehydrogenase (L-AraDH) catalyze the NADP+ dependent D-xylose and L-arabinose oxidation. It is shown here that the pentoses are oxidized to the corresponding lactones, D-xylono-γ-lactone and L-arabino-γ-lactone, rather than to the respective sugar acids. A putative lactonase gene, xacC, located in genomic vicinity of XDH and L-AraDH, was found to be transcriptionally upregulated by both D-xylose and L-arabinose mediated by the pentose-specific regulator XacR. The recombinant lactonase catalyzed the hydrolysis of D-xylono-γ-lactone and L-arabino-γ-lactone. This is the first report of a functional lactonase involved in sugar catabolism in the domain of archaea.

Keywords: Haloferax volcanii; archaea; lactonase; oxidative pentose degradation.

MeSH terms

  • Acyl-Butyrolactones / metabolism
  • Alcohol Oxidoreductases / genetics
  • Alcohol Oxidoreductases / metabolism
  • Arabinose / metabolism*
  • Carbohydrate Dehydrogenases / genetics
  • Carbohydrate Dehydrogenases / metabolism
  • Esterases / genetics
  • Esterases / metabolism*
  • Haloferax volcanii / enzymology*
  • Hydrolysis
  • Ketoglutaric Acids / metabolism
  • Mutation
  • Oxidation-Reduction
  • RNA / genetics
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Up-Regulation
  • Xylose / metabolism*


  • Acyl-Butyrolactones
  • Ketoglutaric Acids
  • Recombinant Proteins
  • RNA
  • Xylose
  • Arabinose
  • Alcohol Oxidoreductases
  • Carbohydrate Dehydrogenases
  • D-xylose dehydrogenase
  • L-arabinose dehydrogenase
  • Esterases