Functional aspects of 17beta-hydroxysteroid dehydrogenase 1 determined by comparison to a closely related retinol dehydrogenase.
Determining the functional aspects of a gene or protein is a difficult and time-consuming process. De novo analysis is surely the hardest and so it is often quite useful to start with a comparison to functionally or structurally related proteins. Although 17beta-hydroxysteroid dehydrogenase type 1 (17beta-HSD 1) can hardly be called a new protein but rather the best characterized among the family of 17beta-HSDs some aspects of structure-function relationships remain unclear. We have sought new aspects of 17beta-HSD 1 function through a comparison with its closest homolog, a photoreceptor-associated retinol dehydrogenase (prRDH). Overall amino acid identity and size of the proteins are highly conserved, but major differences occur in the C-termini, where prRDH, but not 17beta-HSD 1, harbors motifs indicative of membrane localization. To gain insight into substrate discrimination by prRDH and 17beta-HSD 1, we constructed 3D-structure models of the corresponding zebrafish enzymes. Investigation of the substrate binding site revealed a few identical amino acids, and suggested a role for G143 in zebrafish 17beta-HSD 1 and M146 and M147 in the two zebrafish paralogs prRDH 1 and prRDH 2, respectively, in substrate specificity. Activity measurements of modified proteins in transiently transfected intact HEK 293 cells hint at a putative role of these amino acids in discrimination between steroid and retinoid substrates.
Mindnich
R
R
GSF-National Research Center for Environment and Health, Institute of Experimental Genetics, Genome Analysis Center, Ingolstaedter Landstr. 1, 85764 Neuherberg, Germany.
Adamski
J
J
D015067:17-Hydroxysteroid Dehydrogenases / Q000235:genetics / Q000502:physiology*; D000429:Alcohol Oxidoreductases / Q000235:genetics / Q000502:physiology*; D000595:Amino Acid Sequence; D000818:Animals; D002478:Cells, Cultured; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D012176:Retinoids / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013256:Steroids / Q000378:metabolism; D013379:Substrate Specificity; D014162:Transfection; D015027:Zebrafish / Q000235:genetics
D012176:Retinoids; D013256:Steroids; D015067:17-Hydroxysteroid Dehydrogenases; D000429:Alcohol Oxidoreductases; C022520:retinol dehydrogenase; C044256:3 (or 17)-beta-hydroxysteroid dehydrogenase