CprK crystal structures reveal mechanism for transcriptional control of halorespiration

J Biol Chem. 2006 Sep 22;281(38):28318-25. doi: 10.1074/jbc.M602654200. Epub 2006 Jun 27.


Halorespiration is a bacterial respiratory process in which haloorganic compounds act as terminal electron acceptors. This process is controlled at transcriptional level by CprK, a member of the ubiquitous CRP-FNR family. Here we present the crystal structures of oxidized CprK in presence of the ligand ortho-chlorophenolacetic acid and of reduced CprK in absence of this ligand. These structures reveal that highly specific binding of chlorinated, rather than the corresponding non-chlorinated, phenolic compounds in the NH(2)-terminal beta-barrels causes reorientation of these domains with respect to the central alpha-helix at the dimer interface. Unexpectedly, the COOH-terminal DNA-binding domains dimerize in the non-DNA binding state. We postulate the ligand-induced conformational change allows formation of interdomain contacts that disrupt the DNA domain dimer interface and leads to repositioning of the helix-turn-helix motifs. These structures provide a structural framework for further studies on transcriptional control by CRP-FNR homologs in general and of halorespiration regulation by CprK in particular.

Publication types

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

MeSH terms

  • Bacterial Proteins / chemistry*
  • Crystallization
  • Desulfitobacterium / genetics*
  • Desulfitobacterium / metabolism
  • Dimerization
  • Gene Expression Regulation, Bacterial*
  • Phenylacetates / metabolism
  • Protein Structure, Secondary
  • Transcription, Genetic*


  • Bacterial Proteins
  • Phenylacetates
  • 3-chloro-4-hydroxyphenylacetic acid
  • 2-hydroxyphenylacetic acid

Associated data

  • PDB/2H6B
  • PDB/2H6C