Human Sco1 and Sco2 Function as Copper-binding Proteins
| Autor: | Dennis R. Winge, Paul A. Cobine, Scot C. Leary, Fiona B J Young, Graham N. George, Yih-Chern Horng, Eric A. Shoubridge |
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| Rok vydání: | 2005 |
| Předmět: |
Protein Conformation
Stereochemistry Mutant Biology medicine.disease_cause Biochemistry Cell Line Mitochondrial Proteins COX17 In vivo Yeasts medicine Humans Molecular Biology Ions Aspartic Acid Mutation Binding Sites Membrane Proteins Proteins Cell Biology Yeast Crystallography Cytoplasm Copper ion binding Mutagenesis Site-Directed Carrier Proteins Copper Function (biology) Molecular Chaperones |
| Zdroj: | Journal of Biological Chemistry. 280:34113-34122 |
| ISSN: | 0021-9258 |
| DOI: | 10.1074/jbc.m506801200 |
| Popis: | The function of human Sco1 and Sco2 is shown to be dependent on copper ion binding. Expression of soluble domains of human Sco1 and Sco2 either in bacteria or the yeast cytoplasm resulted in the recovery of copper-containing proteins. The metallation of human Sco1, but not Sco2, when expressed in the yeast cytoplasm is dependent on the co-expression of human Cox17. Two conserved cysteines and a histidyl residue, known to be important for both copper binding and in vivo function in yeast Sco1, are also critical for in vivo function of human Sco1 and Sco2. Human and yeast Sco proteins can bind either a single Cu(I) or Cu(II) ion. The Cu(II) site yields S-Cu(II) charge transfer transitions that are not bleached by weak reductants or chelators. The Cu(I) site exhibits trigonal geometry, whereas the Cu(II) site resembles a type II Cu(II) site with a higher coordination number. To identify additional potential ligands for the Cu(II) site, a series of mutant proteins with substitutions in conserved residues in the vicinity of the Cu(I) site were examined. Mutation of several conserved carboxylates did not alter either in vivo function or the presence of the Cu(II) chromophore. In contrast, replacement of Asp238 in human or yeast Sco1 abrogated the Cu(II) visible transitions and in yeast Sco1 attenuated Cu(II), but not Cu(I), binding. Both the mutant yeast and human proteins were nonfunctional, suggesting the importance of this aspartate for normal function. Taken together, these data suggest that both Cu(I) and Cu(II) binding are critical for normal Sco function. |
| Databáze: | OpenAIRE |
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