At5g50600 encodes a member of the short-chain dehydrogenase reductase superfamily with 11beta- and 17beta-hydroxysteroid dehydrogenase activities associated with Arabidopsis thaliana seed oil bodies

Biochimie. 2007 Feb;89(2):222-9. doi: 10.1016/j.biochi.2006.09.013. Epub 2006 Oct 11.


In a previous work, we presented evidence for the presence of a protein encoded by At5g50600 in oil bodies (OBs) from Arabidopsis thaliana [P. Jolivet, E. Roux, S. D'Andrea, M. Davanture, L. Negroni, M. Zivy, T. Chardot, Protein composition of oil bodies in Arabidopsis thaliana ecotype WS, Plant Physiol. Biochem. 42 (2004) 501-509]. Using specific antibodies and proteomic techniques, we presently confirm the existence of this protein, which is a member of the short-chain steroid dehydrogenase reductase superfamily. We have measured its activity toward various steroids (cholesterol, dehydroepiandrosterone, cortisol, corticosterone, estradiol, estrone) and NAD(P)(H), either within purified OBs or as a purified bacterially expressed chimera. Both enzymatic systems (OBs purified from A. thaliana seeds as well as the chimeric enzyme) exhibited hydroxysteroid dehydrogenase (HSD) activity toward estradiol (17beta-hydroxysteroid) with NAD+ or NADP+, NADP+ being the preferred cofactor. Low levels of activity were observed with cortisol or corticosterone (11beta-hydroxysteroids), but neither cholesterol nor DHEA (3beta-hydroxysteroids) were substrates, whatever the cofactor used. Similar activity profiles were found for both enzyme sources. Purified OBs were found to be also able to catalyze estrone reduction (17beta-ketosteroid reductase activity) with NADPH. The enzyme occurring in A. thaliana OBs can be classified as a NADP+-dependent 11beta-,17beta-hydroxysteroid dehydrogenase/17beta-ketosteroid reductase. This enzyme probably corresponds to AtHSD1, which is encoded by At5g50600. However, its physiological role and substrates still remain to be determined.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 17-Hydroxysteroid Dehydrogenases / genetics
  • 17-Hydroxysteroid Dehydrogenases / metabolism
  • Amino Acid Sequence
  • Arabidopsis / enzymology*
  • Arabidopsis / genetics
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Electrophoresis, Polyacrylamide Gel
  • Estradiol / metabolism
  • Fatty Acid Synthases / genetics
  • Fatty Acid Synthases / metabolism*
  • Kinetics
  • Molecular Sequence Data
  • NADH, NADPH Oxidoreductases / genetics
  • NADH, NADPH Oxidoreductases / metabolism*
  • NADP / metabolism
  • Oxidation-Reduction
  • Phylogeny
  • Plant Oils / metabolism*
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Seeds / genetics
  • Seeds / metabolism*
  • Sequence Alignment
  • Substrate Specificity


  • Arabidopsis Proteins
  • Plant Oils
  • Recombinant Proteins
  • Estradiol
  • NADP
  • 17-Hydroxysteroid Dehydrogenases
  • 3 (or 17)-beta-hydroxysteroid dehydrogenase
  • short chain trans-2-enoyl-CoA reductase
  • NADH, NADPH Oxidoreductases
  • Fatty Acid Synthases