Structure of bacterial 3beta/17beta-hydroxysteroid dehydrogenase at 1.2 A resolution: a model for multiple steroid recognition

Biochemistry. 2002 Dec 17;41(50):14659-68. doi: 10.1021/bi0203684.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 17-Hydroxysteroid Dehydrogenases / chemistry*
  • 17-Hydroxysteroid Dehydrogenases / genetics
  • Androgens / chemistry
  • Apoenzymes / chemistry
  • Apoenzymes / genetics
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / genetics
  • Bile Acids and Salts / chemistry
  • Binding Sites / genetics
  • Comamonas testosteroni / enzymology*
  • Comamonas testosteroni / genetics
  • Crystallography, X-Ray
  • Estrogens / chemistry
  • Models, Molecular*
  • Point Mutation
  • Protein Folding
  • Protein Structure, Tertiary / genetics
  • Stereoisomerism
  • Substrate Specificity / genetics

Substances

  • Androgens
  • Apoenzymes
  • Bacterial Proteins
  • Bile Acids and Salts
  • Estrogens
  • 17-Hydroxysteroid Dehydrogenases
  • 3 (or 17)-beta-hydroxysteroid dehydrogenase

Associated data

  • PDB/1HXH