1hxh
COMAMONAS TESTOSTERONI 3BETA/17BETA HYDROXYSTEROID DEHYDROGENASE
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OverviewOverview
The enzyme 3beta/17beta-hydroxysteroid dehydrogenase (3beta/17beta-HSD) is a steroid-inducible component of the Gram-negative bacterium Comamonas testosteroni. It catalyzes the reversible reduction/dehydrogenation of the oxo/beta-hydroxy groups at positions 3 and 17 of steroid compounds, including hormones and isobile acids. Crystallographic analysis at 1.2 A resolution reveals the enzyme to have nearly identical subunits that form a tetramer with 222 symmetry. This is one of the largest oligomeric structures refined at this resolution. The subunit consists of a monomer with a single-domain structure built around a seven-stranded beta-sheet flanked by six alpha-helices. The active site contains a Ser-Tyr-Lys triad, typical for short-chain dehydrogenases/reductases (SDR). Despite their highly diverse substrate specificities, SDR members show a close to identical folding pattern architectures and a common catalytic mechanism. In contrast to other SDR apostructures determined, the substrate binding loop is well-defined. Analysis of structure-activity relationships of catalytic cleft residues, docking analysis of substrates and inhibitors, and accessible surface analysis explains how 3beta/17beta-HSD accommodates steroid substrates of different conformations.
About this StructureAbout this Structure
1HXH is a Single protein structure of sequence from Comamonas testosteroni. Active as 3(or 17)-beta-hydroxysteroid dehydrogenase, with EC number 1.1.1.51 Full crystallographic information is available from OCA.
ReferenceReference
Structure of bacterial 3beta/17beta-hydroxysteroid dehydrogenase at 1.2 A resolution: a model for multiple steroid recognition., Benach J, Filling C, Oppermann UC, Roversi P, Bricogne G, Berndt KD, Jornvall H, Ladenstein R, Biochemistry. 2002 Dec 17;41(50):14659-68. PMID:12475215
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