title: 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.
abstract: 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.
authors.affiliation: Department of Medicine, University of California, San Diego, La Jolla 92093-0623.
authors.forename: M E
authors.initials: ME
authors.lastname: Baker
authors.forename: R
authors.initials: R
authors.lastname: Blasco
mesh_terms: D015096:3-Hydroxysteroid Dehydrogenases / Q000235:genetics*; D000429:Alcohol Oxidoreductases / Q000235:genetics*; D000595:Amino Acid Sequence; D005075:Biological Evolution; D007497:Iridoviridae / Q000235:genetics; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000235:genetics; D009615:Nocardia / Q000201:enzymology / Q000235:genetics; D010088:Oxidoreductases / Q000235:genetics*; D010802:Phylogeny; D010944:Plants / Q000201:enzymology / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D014534:UDPglucose 4-Epimerase / Q000235:genetics*; D014616:Vaccinia virus / Q000235:genetics; D014764:Viral Proteins / Q000235:genetics*
chemical_list: D014764:Viral Proteins; D010088:Oxidoreductases; D015096:3-Hydroxysteroid Dehydrogenases; D000429:Alcohol Oxidoreductases; C056570:dihydroflavanol 4-reductase; C019884:cholesterol dehydrogenase; D014534:UDPglucose 4-Epimerase