Expansion of the mammalian 3 beta-hydroxysteroid dehydrogenase/plant dihydroflavonol reductase superfamily to include a bacterial cholesterol dehydrogenase, a bacterial UDP-galactose-4-epimerase, and open reading frames in vaccinia virus and fish lymphocystis disease virus

FEBS Lett. 1992 Apr 13;301(1):89-93. doi: 10.1016/0014-5793(92)80216-4.


Mammalian 3 beta-hydroxysteroid dehydrogenase and plant dihydroflavonol reductases are descended from a common ancestor. Here we present evidence that Nocardia cholesterol dehydrogenase, E. coli UDP-galactose-4 epimerase, and open reading frames in vaccinia virus and fish lymphocystis disease virus are homologous to 3 beta-hydroxysteroid dehydrogenase and dihydroflavonol reductase. Analysis of a multiple alignment of these sequences indicates that viral ORFs are most closely related to the mammalian 3 beta-hydroxysteroid dehydrogenases. The ancestral protein of this superfamily is likely to be one that metabolized sugar nucleotides. The sequence similarity between 3 beta-hydroxysteroid dehydrogenase and the viral ORFs is sufficient to suggest that these ORFs have an activity that is similar to 3 beta-hydroxysteroid dehydrogenase or cholesterol dehydrogenase, although the putative substrates are not yet known.

MeSH terms

  • 3-Hydroxysteroid Dehydrogenases / genetics*
  • Alcohol Oxidoreductases / genetics*
  • Amino Acid Sequence
  • Biological Evolution*
  • Iridoviridae / genetics
  • Molecular Sequence Data
  • Multigene Family / genetics
  • Nocardia / enzymology
  • Nocardia / genetics
  • Oxidoreductases / genetics*
  • Phylogeny
  • Plants / enzymology
  • Plants / genetics
  • Sequence Homology, Amino Acid
  • UDPglucose 4-Epimerase / genetics*
  • Vaccinia virus / genetics
  • Viral Proteins / genetics*


  • Viral Proteins
  • Oxidoreductases
  • 3-Hydroxysteroid Dehydrogenases
  • Alcohol Oxidoreductases
  • dihydroflavanol 4-reductase
  • cholesterol dehydrogenase
  • UDPglucose 4-Epimerase