title: X-ray absorption and NMR spectroscopic studies of CopZ, a copper chaperone in Bacillus subtilis: the coordination properties of the copper ion.
abstract: XAS studies have been performed, under various experimental conditions, on a copper(I)-transporting protein, CopZ, of Bacillus subtilis. The copper(I) ion, reduced with dithiothreitol, is three-coordinate with three sulfur donor atoms, two of which presumably provided by the protein and one by dithiothreitol. If a molar excess of acetate (15 mM; 5:1 respect to CopZ) or citrate (6 mM; 2:1 respect to CopZ) is present in solution, the EXAFS spectra suggest the presence of a dimeric form involving a close contact between Cu(I) ions from two molecules, where Cu is still three-coordinate. (1)H and (15)N NMR data provide further structural details. If copper reduction is accomplished with ascorbate, the data indicate that one oxygen of ascorbate enters in the first-coordination sphere of copper, together with two sulfur atoms, in a dimeric form of the protein. These results are instructive and have been discussed with respect to the molecular basis of copper trafficking.
authors.affiliation: Centro di Risonanze Magnetiche and Department of Chemistry, University of Florence, Via Luigi Sacconi 6, 50019, Sesto Fiorentino, Italy.
authors.forename: Lucia
authors.initials: L
authors.lastname: Banci
authors.forename: Ivano
authors.initials: I
authors.lastname: Bertini
authors.forename: Rebecca
authors.initials: R
authors.lastname: Del Conte
authors.forename: Stefano
authors.initials: S
authors.lastname: Mangani
authors.forename: Wolfram
authors.initials: W
authors.lastname: Meyer-Klaucke
mesh_terms: D001412:Bacillus subtilis / Q000737:chemistry*; D001426:Bacterial Proteins / Q000737:chemistry*; D001665:Binding Sites; D002414:Cations, Monovalent / Q000737:chemistry; D002951:Citrates / Q000737:chemistry; D003300:Copper / Q000737:chemistry*; D019281:Dimerization; D004229:Dithiothreitol / Q000737:chemistry; D018832:Molecular Chaperones / Q000737:chemistry*; D009587:Nitrogen Isotopes; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods; D021381:Protein Transport; D019163:Reducing Agents / Q000737:chemistry; D012492:Salts; D019346:Sodium Acetate / Q000737:chemistry; D000077559:Sodium Citrate; D012996:Solutions; D013057:Spectrum Analysis / Q000379:methods; D015534:Trans-Activators / Q000737:chemistry*; D014965:X-Rays
chemical_list: D001426:Bacterial Proteins; D002414:Cations, Monovalent; D002951:Citrates; C092379:CopZ protein, Enterococcus hirae; D018832:Molecular Chaperones; D009587:Nitrogen Isotopes; D019163:Reducing Agents; D012492:Salts; D012996:Solutions; D015534:Trans-Activators; C042514:cuprous ion; D000077559:Sodium Citrate; D019346:Sodium Acetate; D003300:Copper; D004229:Dithiothreitol