Tryptophan scanning analysis of the membrane domain of CTR-copper transporters.
Membrane proteins of the CTR family mediate cellular copper uptake in all eukaryotic cells and have been shown to participate in uptake of platinum-based anticancer drugs. Despite their importance for life and the clinical treatment of malignancies, directed biochemical studies of CTR proteins have been difficult because high-resolution structural information is missing. Building on our recent 7A structure of the human copper transporter hCTR1, we present the results of an extensive tryptophan-scanning analysis of hCTR1 and its distant relative, yeast CTR3. The comparative analysis supports our previous assignment of the transmembrane helices and shows that most functionally and structurally important residues are clustered around the threefold axis of CTR trimers or engage in helix packing interactions. The scan also identified residues that may play roles in interactions between CTR trimers and suggested that the first transmembrane helix serves as an adaptor that allows evolutionarily diverse CTRs to adopt the same overall structure. Together with previous biochemical and biophysical data, the results of the tryptophan scan are consistent with a mechanistic model in which copper transport occurs along the center of the trimer.
Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06510, USA.
Christopher J
CJ
De Feo
Sara
S
Mootien
Vinzenz M
VM
Unger
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D017920:Antiporters / Q000737:chemistry* / Q000235:genetics; D027682:Cation Transport Proteins / Q000737:chemistry* / Q000235:genetics; D003300:Copper / Q000378:metabolism; D000079923:Copper Transporter 1; D006801:Humans; D026901:Membrane Transport Proteins / Q000378:metabolism; D008958:Models, Molecular; D011499:Protein Processing, Post-Translational; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D000080083:SLC31 Proteins; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics; D014364:Tryptophan / Q000737:chemistry* / Q000235:genetics
D017920:Antiporters; C100982:CTR3 protein, S cerevisiae; D027682:Cation Transport Proteins; D000079923:Copper Transporter 1; D026901:Membrane Transport Proteins; D000080083:SLC31 Proteins; C490079:SLC31A1 protein, human; D029701:Saccharomyces cerevisiae Proteins; D003300:Copper; D014364:Tryptophan