TY - JOUR
T1 - Steroid recognition and regulation of hormone action
T2 - Crystal structure of testosterone and NADP+ bound to 3α-hydroxysteroid/dihydrodiol dehydrogenase
AU - Bennett, Melanie J.
AU - Albert, Ross H.
AU - Jez, Joseph M.
AU - Ma, Haiching
AU - Penning, Trevor M.
AU - Lewis, Mitchell
N1 - Funding Information:
We thank D Eisenberg and D Cascio for use of X-ray diffraction facilities while collecting the low temperature data set at the University of California, Los Angeles and DE Vaughn for helpful discussions. We also thank BP Schlegel for sharing unpublished data. This research was supported by the Cancer Research Fund of the Damon Runyon-Walter Winchell Foundation, DRG-1298 and by PHS grants awarded by NIH, DK47015, CA39504 and CA55711.
PY - 1997
Y1 - 1997
N2 - Background: Mammalian 3α-hydroxysteroid dehydrogenases (3α-HSDs) modulate the activities of steroid hormones by reversibly reducing their C3 ketone groups. In steroid target tissues, 3α-HSDs act on 5α-dihydrotestosterone, a potent male sex hormone (androgen) implicated in benign prostate hyperplasia and prostate cancer. Rat liver 3α-HSD belongs to the aldo-keto reductase (AKR) superfamily and provides a model for mammalian 3α-, 17β- and 20α-HSDs, which share >65% sequence identity. The determination of the structure of 3α-HSD in complex with NADP+ and testosterone (a competitive inhibitor) will help to further our understanding of steroid recognition and hormone regulation by mammalian HSDs. Results: We have determined the 2.5 Å resolution crystal structure of recombinant rat liver 3α-HSD complexed with NADP+ and testosterone. The structure provides the first picture of an HSD ternary complex in the AKR superfamily, and is the only structure to date of testosterone bound to a protein. It reveals that the C3 ketone in testosterone, corresponding to the reactive group in a substrate, is poised above the nicotinamide ring which is involved in hydride transfer. In addition, the C3 ketone forms hydrogen bonds with two active-site residues implicated in catalysis (Tyr55 and His 117). Conclusions: The active-site arrangement observed in the 3α-HSD ternary complex structure suggests that each positional-specific and stereospecific reaction catalyzed by an HSD requires a particular substrate orientation, the general features of which can be predicted. 3α-HSDs are likely to bind substrates in a similar manner to the way in which testosterone is bound in the ternary complex, that is with the A ring of the steroid substrate in the active site and the β, face towards the nicotinamide ring to facilitate hydride transfer. In contrast, we predict that 17β-HSDs will bind substrates with the D ring of the steroid in the active site and with the α face towards the nicotinamide ring. The ability to bind substrates in only one or a few orientations could determine the positional-specificity and stereospecificity of each HSD. Residues lining the steroid-binding cavities are highly variable and may select these different orientations.
AB - Background: Mammalian 3α-hydroxysteroid dehydrogenases (3α-HSDs) modulate the activities of steroid hormones by reversibly reducing their C3 ketone groups. In steroid target tissues, 3α-HSDs act on 5α-dihydrotestosterone, a potent male sex hormone (androgen) implicated in benign prostate hyperplasia and prostate cancer. Rat liver 3α-HSD belongs to the aldo-keto reductase (AKR) superfamily and provides a model for mammalian 3α-, 17β- and 20α-HSDs, which share >65% sequence identity. The determination of the structure of 3α-HSD in complex with NADP+ and testosterone (a competitive inhibitor) will help to further our understanding of steroid recognition and hormone regulation by mammalian HSDs. Results: We have determined the 2.5 Å resolution crystal structure of recombinant rat liver 3α-HSD complexed with NADP+ and testosterone. The structure provides the first picture of an HSD ternary complex in the AKR superfamily, and is the only structure to date of testosterone bound to a protein. It reveals that the C3 ketone in testosterone, corresponding to the reactive group in a substrate, is poised above the nicotinamide ring which is involved in hydride transfer. In addition, the C3 ketone forms hydrogen bonds with two active-site residues implicated in catalysis (Tyr55 and His 117). Conclusions: The active-site arrangement observed in the 3α-HSD ternary complex structure suggests that each positional-specific and stereospecific reaction catalyzed by an HSD requires a particular substrate orientation, the general features of which can be predicted. 3α-HSDs are likely to bind substrates in a similar manner to the way in which testosterone is bound in the ternary complex, that is with the A ring of the steroid substrate in the active site and the β, face towards the nicotinamide ring to facilitate hydride transfer. In contrast, we predict that 17β-HSDs will bind substrates with the D ring of the steroid in the active site and with the α face towards the nicotinamide ring. The ability to bind substrates in only one or a few orientations could determine the positional-specificity and stereospecificity of each HSD. Residues lining the steroid-binding cavities are highly variable and may select these different orientations.
KW - 3α-hydroxysteroid/dihydrodiol dehydrogenase
KW - Aldo-keto reductase
KW - Crystal structure
KW - Steroid hormone recognition
KW - Testosterone
UR - http://www.scopus.com/inward/record.url?scp=0031570663&partnerID=8YFLogxK
U2 - 10.1016/S0969-2126(97)00234-7
DO - 10.1016/S0969-2126(97)00234-7
M3 - Article
C2 - 9261071
AN - SCOPUS:0031570663
SN - 0969-2126
VL - 5
SP - 799
EP - 812
JO - Structure
JF - Structure
IS - 6
ER -