title: A hint for the function of human Sco1 from different structures.
abstract: The solution structures of apo, Cu(I), and Ni(II) human Sco1 have been determined. The protein passes from an open and conformationally mobile state to a closed and rigid conformation upon metal binding as shown by electrospray ionization MS and NMR data. The metal ligands of Cu(I) are two Cys residues of the CPXXCP motif and a His residue. The latter is suitably located to coordinate the metal anchored by the two Cys residues. The coordination sphere of Ni(II) in solution is completed by another ligand, possibly Asp. Crystals of the Ni(II) derivative were also obtained with the Ni(II) ion bound to the same His residue and to the two oxidized Cys residues of the CPXXCP motif. We propose that the various structures solved here represent the various states of the protein in its functional cycle and that the metal can be bound to the oxidized protein at a certain stage. Although it now seems reasonable that Sco1, which is characterized by a thioredoxin fold, has evolved to bind a metal atom via the di-Cys motif to act as a copper chaperone, the oxidized form of the nickel-bound protein suggests that it may also maintain the thioredoxin function.
authors.affiliation: Magnetic Resonance Center and Department of Chemistry, University of Florence, Via Luigi Sacconi 6, 50019 Florence, Italy.
authors.forename: Lucia
authors.initials: L
authors.lastname: Banci
authors.forename: Ivano
authors.initials: I
authors.lastname: Bertini
authors.forename: Vito
authors.initials: V
authors.lastname: Calderone
authors.forename: Simone
authors.initials: S
authors.lastname: Ciofi-Baffoni
authors.forename: Stefano
authors.initials: S
authors.lastname: Mangani
authors.forename: Manuele
authors.initials: M
authors.lastname: Martinelli
authors.forename: Peep
authors.initials: P
authors.lastname: Palumaa
authors.forename: Shenlin
authors.initials: S
authors.lastname: Wang
mesh_terms: D000595:Amino Acid Sequence; D001059:Apoproteins / Q000737:chemistry; D003300:Copper / Q000737:chemistry; D018360:Crystallography, X-Ray; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism*; D008958:Models, Molecular; D018832:Molecular Chaperones; D008969:Molecular Sequence Data; D009532:Nickel / Q000737:chemistry
chemical_list: D001059:Apoproteins; D008565:Membrane Proteins; D018832:Molecular Chaperones; C489345:SCO1 protein, human; D003300:Copper; D009532:Nickel