title: Crystal structure of human copper homeostasis protein CutC reveals a potential copper-binding site.
abstract: Copper is an essential trace element to life and particularly plays a pivotal role in the physiology of aerobic organisms. The Cut protein family is associated with copper homeostasis and involved in uptake, storage, delivery, and efflux of copper. CutC is a member of the Cut family and is suggested to be involved in efflux trafficking of cuprous ion. We report here the biochemical and structural characterization of human CutC (hCutC). hCutC can bind Cu(I) with a stoichiometry of 1:1 and an apparent dissociation constant of 15.5+/-2.8 microM. hCutC assumes a typical TIM-barrel fold and forms a tetramer in both crystal structure and solution which is different from the dimeric architecture of the bacterial CutC. Structure analysis and sequence comparison of CutC proteins from different species reveal two strictly conserved Cys residues on the inner surface of the C-terminal end of the TIM-barrel. Mutations of the two Cys residues can significantly impair the binding ability of hCutC with Cu(I). Our results suggest that hCutC functions as an enzyme with Cu(I) as a cofactor rather than a copper transporter and the potential Cu(I)-binding site consists of the two Cys residues and other conserved residues in the vicinity.
authors.affiliation: State Key Laboratory of Molecular Biology and Research Center for Structural Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yue-Yang Road, Shanghai 200031, China.
authors.forename: Yingjie
authors.initials: Y
authors.lastname: Li
authors.forename: Jiamu
authors.initials: J
authors.lastname: Du
authors.forename: Peng
authors.initials: P
authors.lastname: Zhang
authors.forename: Jianping
authors.initials: J
authors.lastname: Ding
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D027682:Cation Transport Proteins / Q000737:chemistry* / Q000378:metabolism*; D003300:Copper / Q000378:metabolism*; D000079922:Copper Transport Proteins; D006801:Humans; D008969:Molecular Sequence Data; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017386:Sequence Homology, Amino Acid; D014961:X-Ray Diffraction
chemical_list: D027682:Cation Transport Proteins; D003300:Copper; D000079922:Copper Transport Proteins; C505249:CUTC protein, human