X-ray structure of the metal-sensor CnrX in both the apo- and copper-bound forms
Guillaume Pompidor1, Antoine P Maillard, Eric Girard
1Laboratoire des Protéines Membranaires, Institut de Biologie Structurale - Jean-Pierre Ebel, UMR 5075 CNRS-CEA-UJF, 41, rue Jules Horowitz, 38027 Grenoble Cedex, France.
Abstract:
Both the X-ray structures of the apo- and the copper-bound forms of the metal-sensor domain (residues 31-148) of CnrX from Cupriavidus metallidurans CH34 were obtained at 1.74A resolution from a selenomethionine derivative. This four-helix hooked-hairpin is the first structure of a metal-sensor in an ECF-type signaling pathway. The copper ion is bound in a type 2-like center with a 3N1O coordination in the equatorial plane and shows an unprecedented remote fifth axial ligand with Met93 contributing a weak S-Cu bond. The signal onset cannot be explained by conformational changes associated with CnrX metallation.
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