PMD Browser
Detalied information of PMD entry
Entry name
A000099
Type
Artificial
Create date
2007-10-12 15:51:16
Mutated sequences
| No | Name | Length (aa) | Mutated Proteins (Name / Length / Disease name(s) / OMIM term(s)) | |||||
| 1 | A000099 | 328 |
|
References
Title
Dehydroepiandrosterone and dihydrotestosterone recognition by human estrogenic 17beta-hydroxysteroid dehydrogenase. C-18/c-19 steroid discrimination and enzyme-induced strain.
Journal name
The Journal of biological chemistry.
Publication date
2000 : (275) 1105 - 1111
Authors
Han Q, Campbell RL, Gangloff A, Huang YW, Lin SX.
Affiliation
Medical Research Council Group in Molecular Endocrinology, CHUL Research Center and Laval University, Ste-Foy, Québec G1V 4G2, Canada.
Abstract
Steroid hormones share a very similar structure, but they behave distinctly. We present structures of human estrogenic 17beta-hydroxysteroid dehydrogenase (17beta-HSD1) complexes with dehydroepiandrosterone (DHEA) and dihydrotestosterone (DHT), providing the first pictures to date of DHEA and DHT bound to a protein. Comparisons of these structures with that of the enzyme complexed with the most potent estrogen, estradiol, revealed the structural basis and general model for sex hormone recognition and discrimination. Although the binding cavity is almost entirely composed of hydrophobic residues that can make only nonspecific interactions, the arrangement of residues is highly complementary to that of the estrogenic substrate. Relatively small changes in the shape of the steroid hormone can significantly affect the binding affinity and specificity. The K(m) of estrone is more than 1000-fold lower than that of DHEA and the K(m) of estradiol is about 10 times lower than that of DHT. The structures suggest that Leu-149 is the primary contributor to the discrimination of C-19 steroids and estrogens by 17beta-HSD1. The critical role of Leu-149 has been well confirmed by site-directed mutagenesis experiments, as the Leu-149 --> Val variant showed a significantly decreased K(m) for C-19 steroids while losing discrimination between estrogens and C-19 steroids. The electron density of DHEA also revealed a distortion of its 17-ketone toward a beta-oriented form, which approaches the transition-state conformation for DHEA reduction.
