3DSO

Crystal structure of Cu(I) bound copper resistance protein CopK

Summary for 3DSO

• Entry DOI: 10.2210/pdb3dso/pdb
• Related: 2K0Q 3DSP
• Descriptor: Putative uncharacterized protein copK, COPPER (I) ION, THIOCYANATE ION, ... (4 entities in total)
• Functional Keywords: copper (i) bound, copper resistance, metal binding protein
• Biological source: Ralstonia metallidurans
• Cellular location: Periplasm : Q58AD3
• Total number of polymer chains: 1
• Total formula weight: 8474.28

Authors

Ash, M.-R.,Maher, M.J. (deposition date: 2008-07-13, release date: 2009-03-10, Last modification date: 2024-03-20)

Primary citation

Chong, L.X.,Ash, M.-R.,Maher, M.J.,Hinds, M.G.,Xiao, Z.,Wedd, A.G.
Unprecedented binding cooperativity between Cu(I) and Cu(II) in the copper resistance protein CopK from Cupriavidus metallidurans CH34: implications from structural studies by NMR spectroscopy and X-ray crystallography
J.Am.Chem.Soc., 131:3549-3564, 2009

PubMed Abstract: The bacterium Cupriavidus metallidurans CH34 is resistant to high environmental concentrations of many metal ions, including copper. This ability arises primarily from the presence of a large plasmid pMOL30 which includes a cluster of 19 cop genes that respond to copper. One of the protein products CopK is induced at high levels and is expressed to the periplasm as a small soluble protein (8.3 kDa). Apo-CopK associates in solution to form a dimer (K(D) approximately 10(-5) M) whose structure was defined by NMR and X-ray crystallography. The individual molecules feature two antiparallel beta-sheets arranged in a sandwich-like structure and interact through C-terminal beta-strands. It binds Cu(II) with low affinity (K(D)(Cu(II)) > 10(-6) M) but Cu(I) with high affinity (K(D)(Cu(I)) = 2 x 10(-11) M). Cu(I)-CopK was also a dimer in the solid state and featured a distorted tetrahedral site Cu(I)(S-Met)(3)(NCS). The isothiocyanato ligand originated from the crystallization solution. Binding of Cu(I) or Ag(I), but not of Cu(II), favored the monomeric form in solution. While Ag(I)-CopK was stable as isolated, Cu(I)-CopK was moderately air-sensitive due to a strong binding cooperativity between Cu(I) and Cu(II). This was documented by determination of the Cu(I) and Cu(II) binding affinities in the presence of the other ion: K(D)(Cu(I)) = 2 x 10(-13) M and K(D)(Cu(II)) = 3 x 10(-12) M, that is, binding of Cu(II) increased the affinity for Cu(I) by a factor of approximately 10(2) and binding of Cu(I) increased the affinity for Cu(II) by a factor of at least 10(6). Stable forms of both Cu(I)Cu(II)-CopK and Ag(I)Cu(II)-CopK were isolated readily. Consistent with this unprecedented copper binding chemistry, NMR spectroscopy detected three distinct forms: apo-CopK, Cu(I)-CopK and Cu(I)Cu(II)-CopK that do not exchange on the NMR time scale. This information provides a valuable guide to the role of CopK in copper resistance.

PubMed: 19236095
DOI: 10.1021/ja807354z

Experimental method

X-RAY DIFFRACTION (1.55 Å)