Molecular Basis of Halorespiration Control by CprK, a CRP-FNR Type Transcriptional Regulator

Mol Microbiol. 2008 Oct;70(1):151-67. doi: 10.1111/j.1365-2958.2008.06399.x. Epub 2008 Aug 20.


Certain bacteria are able to conserve energy via the reductive dehalogenation of halo-organic compounds in a respiration-type metabolism. The transcriptional regulator CprK from Desulfitobacterium spp. induces expression of halorespiratory genes upon binding of o-chlorophenol ligands and is reversibly inactivated by oxygen through disulphide bond formation. We report crystal structures of D. hafniense CprK in the ligand-free (both oxidation states), ligand-bound (reduced) and DNA-bound states, making it the first member of the widespread CRP-FNR superfamily for which a complete structural description of both redox-dependent and allosteric molecular rearrangements is available. In conjunction with kinetic and thermodynamic ligand binding studies, we provide a model for the allosteric mechanisms underpinning transcriptional control. Amino acids that play a key role in this mechanism are not conserved in functionally distinct CRP-FNR members. This suggests that, despite significant structural homology, distinct allosteric mechanisms are used, enabling this protein family to control a very wide range of processes.

MeSH terms

  • Allosteric Regulation
  • Bacterial Proteins / chemistry*
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Cyclic AMP Receptor Protein / chemistry
  • Cyclic AMP Receptor Protein / genetics
  • Cyclic AMP Receptor Protein / metabolism
  • DNA-Binding Proteins / chemistry
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • Desulfitobacterium / chemistry*
  • Desulfitobacterium / genetics
  • Gene Expression Regulation, Bacterial
  • Halogenation*
  • Iron-Sulfur Proteins / chemistry
  • Iron-Sulfur Proteins / genetics
  • Iron-Sulfur Proteins / metabolism
  • Ligands
  • Oxidation-Reduction
  • Protein Binding
  • Protein Structure, Tertiary
  • Thermodynamics
  • Transcription, Genetic


  • Bacterial Proteins
  • Cyclic AMP Receptor Protein
  • DNA-Binding Proteins
  • Iron-Sulfur Proteins
  • Ligands

Associated data

  • PDB/3E5Q
  • PDB/3E5U
  • PDB/3E5X
  • PDB/3E6B
  • PDB/3E6C
  • PDB/3E6D