Loop recognition and copper-mediated disulfide reduction underpin metal site assembly of CuA in human cytochrome oxidase.
Maturation of cytochrome oxidases is a complex process requiring assembly of several subunits and adequate uptake of the metal cofactors. Two orthologous Sco proteins (Sco1 and Sco2) are essential for the correct assembly of the dicopper CuA site in the human oxidase, but their function is not fully understood. Here, we report an in vitro biochemical study that shows that Sco1 is a metallochaperone that selectively transfers Cu(I) ions based on loop recognition, whereas Sco2 is a copper-dependent thiol reductase of the cysteine ligands in the oxidase. Copper binding to Sco2 is essential to elicit its redox function and as a guardian of the reduced state of its own cysteine residues in the oxidizing environment of the mitochondrial intermembrane space (IMS). These results provide a detailed molecular mechanism for CuA assembly, suggesting that copper and redox homeostasis are intimately linked in the mitochondrion.
Instituto de Biología Molecular y Celular de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, 2000 Rosario, Argentina;
Marcos N
MN
Morgada
Instituto de Biología Molecular y Celular de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, 2000 Rosario, Argentina;
Luciano A
LA
Abriata
Fondazione Farmacogenomica FiorGen Onlus, 50019 Sesto Fiorentino, Florence, Italy;
Chiara
C
Cefaro
Magnetic Resonance Center, University of Florence, 50019 Sesto Fiorentino, Florence, Italy; Department of Chemistry, University of Florence, 50019 Sesto Fiorentino, Florence, Italy;
Karolina
K
Gajda
Fondazione Farmacogenomica FiorGen Onlus, 50019 Sesto Fiorentino, Florence, Italy; Magnetic Resonance Center, University of Florence, 50019 Sesto Fiorentino, Florence, Italy; Department of Chemistry, University of Florence, 50019 Sesto Fiorentino, Florence, Italy; vila@ibr-conicet.gov.ar banci@cerm.unifi.it.
Lucia
L
Banci
Instituto de Biología Molecular y Celular de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, 2000 Rosario, Argentina; Plataforma Argentina de Biología Estructural y Metabolómica, 2000 Rosario, Argentina vila@ibr-conicet.gov.ar banci@cerm.unifi.it.
Alejandro J
AJ
Vila
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism; D003300:Copper / Q000378:metabolism*; D004220:Disulfides / Q000378:metabolism*; D004579:Electron Transport; D003576:Electron Transport Complex IV / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D018832:Molecular Chaperones; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D015202:Protein Engineering; D017433:Protein Structure, Secondary; D021122:Protein Subunits / Q000737:chemistry; D066244:Proton Magnetic Resonance Spectroscopy; D012995:Solubility; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D002352:Carrier Proteins; D004220:Disulfides; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D018832:Molecular Chaperones; D021122:Protein Subunits; C489345:SCO1 protein, human; C400285:SCO2 protein, human; D003300:Copper; D003576:Electron Transport Complex IV
CuA site; Sco proteins; cytochrome oxidase; metal site assembly; metallochaperones