Cofactor Hydrogen Bonding onto the Protein Main Chain Is Conserved in the Short Chain Dehydrogenase/Reductase Family and Contributes to Nicotinamide Orientation

• Published in: The Journal of biological chemistry Vol. 279; no. 16; pp. 16778 - 16785
• Main Authors: Shi, Rong, Lin, Sheng-Xiang
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 16.04.2004; American Society for Biochemistry and Molecular Biology
• Subjects: 08 HYDROGEN; 17-Hydroxysteroid Dehydrogenases - antagonists & inhibitors; 17-Hydroxysteroid Dehydrogenases - chemistry; BONDING; CHAINS; Crystallography, X-Ray; Drug Design; Enzyme Inhibitors - chemistry; Humans; HYDROGEN; Hydrogen Bonding; Models, Molecular; national synchrotron light source; Niacinamide - chemistry; NICOTINAMIDE; ORIENTATION; Protein Conformation; PROTEINS; Structure-Activity Relationship
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M313156200

Human estrogenic 17β-hydroxysteroid dehydrogenase (17β-HSD1), a member of the short chain dehydrogenase/reductase (SDR) family, is responsible for the biosynthesis of all active estrogens. The crystal structures of two C19-steroid ternary complexes (17β-HSD1-androstanedione-NADP and 17β-HSD1-androstenedione-NADP) reveal the critical role of Leu149 in regulating the substrate specificity and provide novel insight into the different fates of a conserved glutamate residue in the estrogen-specific proteins upon the binding of the keto and hydroxyl groups of steroids. The whole NADP molecule can be unambiguously defined in the NADP binary complex, whereas both ternary complexes show that the nicotinamide moiety of NADP cannot be located in the density maps. In both ternary complexes, the expected position of carboxamide oxygen of NADP is occupied by a water molecule, which makes a bifurcated hydrogen bond with the O3 of C19-steroid and the main chain nitrogen of Val188. These results demonstrate that the hydrogen bonding interaction between the main chain amide group and the carboxamide group of NAD(P)(H) plays an important role in anchoring the nicotinamide ring to the enzyme. This finding is substantiated by structural analyses of all 33 NAD(P)(H) complexes of different SDR proteins, because 29 structures of 33 show this interaction. This common feature reveals a general mechanism among the SDR family, providing a rational basis for inhibitor design against biologically relevant SDR targets.