CopK from Cupriavidus metallidurans CH34 Binds Cu(I) in a Tetrathioether Site: Characterization by X-ray Absorption and NMR Spectroscopy

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Authors

  • Géraldine Sarret
  • Adrien Favier
  • Jacques Covès
  • Jean-Louis Hazemann
  • Max Mergeay
  • Beate Bersch

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Abstract

Cupriavidus metallidurans CH34 is a bacterium that is resistant to high metal concentrations in the environment. Increased copper resistance is associated with the cop cluster on the large plasmid pMOL30 that is composed of at least 21 genes. The copK gene encodes a 74 residue periplasmic protein whose expression is strongly upregulated in the presence of copper. CopK was previously shown to cooperatively bind Cu(I) and Cu(II) in distinct, specific sites. The solution structure of Cu(I)-CopK and the characterization of the Cu(I) site by X-ray absorption spectroscopy and NMR are reported here. EXAFS spectra are in agreement with a tetrathioether Cu(I) site, providing so far unique spectral information on a 4S-coordinated Cu(I) in a protein. The methionine residues forming the Cu(I) site, M28, M38, M44, and M54, are identified by NMR. We propose the chemical shift of the methionine Cε as a new and sensitive probe for the detection of Cu(I) bound to thioether groups. The solution structure of Cu(I)-CopK demonstrates that Cu(I) binding induces a complete structural modification with the disruption of the second beta-sheet and a rotation of the C-terminal part of nearly 180° around a hinge formed by asparagine 57.

Details

Original languageEnglish
Pages (from-to)3770-3777
JournalJournal of American Chemical Society
Volume132
Issue number11
DOIs
Publication statusPublished - 1 Mar 2010

Keywords

  • CopK from Cupriavidus metallidurans CH34 Binds Cu(I) in a Tetrathioether Site: Characterization by X-ray Absorption and NMR Spectroscopy

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