X-ray crystal structure of Escherichia coli taurine/alpha-ketoglutarate dioxygenase complexed to ferrous iron and substrates

Biochemistry. 2002 Apr 23;41(16):5185-92. doi: 10.1021/bi016014e.


Taurine/alpha-ketoglutarate dioxygenase (TauD), a non-heme Fe(II) oxygenase, catalyses the conversion of taurine (2-aminoethanesulfonate) to sulfite and aminoacetaldehyde concurrent with the conversion of alpha-ketoglutarate (alphaKG) to succinate and CO(2). The enzyme allows Escherichia coli to use taurine, widely available in the environment, as an alternative sulfur source. Here we describe the X-ray crystal structure of TauD complexed to Fe(II) and both substrates, alphaKG and taurine. The tertiary structure and fold of TauD are similar to those observed in other enzymes from the broad family of Fe(II)/alphaKG-dependent oxygenases, with closest structural similarity to clavaminate synthase. Using the TauD coordinates, a model was determined for the closely related enzyme 2,4-dichlorophenoxyacetate/alphaKG dioxygenase (TfdA), supporting predictions derived from site-directed mutagenesis and other studies of that biodegradative protein. The TauD structure and TfdA model define the metal ligands and the positions of nearby aromatic residues that undergo post-translational modifications involving self-hydroxylation reactions. The substrate binding residues of TauD were identified and those of TfdA predicted. These results, along with sequence alignment information, reveal how TauD selects a tetrahedral substrate anion in preference to the planar carboxylate selected by TfdA, providing insight into the mechanism of enzyme catalysis.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • 2,4-Dichlorophenoxyacetic Acid / chemistry
  • 2,4-Dichlorophenoxyacetic Acid / metabolism
  • Amino Acid Sequence
  • Binding Sites
  • Catalysis
  • Crystallization
  • Crystallography, X-Ray
  • Dimerization
  • Escherichia coli / enzymology*
  • Ferrous Compounds / chemistry*
  • Ferrous Compounds / metabolism
  • Ketoglutaric Acids / chemistry
  • Ketoglutaric Acids / metabolism
  • Mixed Function Oxygenases / chemistry*
  • Mixed Function Oxygenases / metabolism
  • Models, Molecular
  • Molecular Sequence Data
  • Protein Processing, Post-Translational
  • Protein Structure, Secondary
  • Substrate Specificity
  • Taurine / chemistry*
  • Taurine / metabolism


  • Ferrous Compounds
  • Ketoglutaric Acids
  • Taurine
  • 2,4-Dichlorophenoxyacetic Acid
  • Mixed Function Oxygenases
  • 2,4-dichlorophenoxyacetate-alpha-ketoglutarate dioxygenase
  • taurine-alpha-ketoglutarate dioxygenase

Associated data

  • PDB/1GQW
  • PDB/1GQX