Differential affinity of BsSCO for Cu(II) and Cu(I) suggests a redox role in copper transfer to the Cu-A center of cytochrome c oxidase

作者：Hill Bruce C^*; Andrews Diann

来源：Biochimica et Biophysica Acta-Bioenergetics, 2012, 1817(6): 948-954.

DOI：10.1016/j.bbabio.2011.09.006

• SCO proteins
• BsSCO
• Cu-A assembly
• Cytochrome c oxidase
• Copper binding
• Metal transfer

SCO (synthesis of cytochrome c oxidase) proteins are involved in the assembly of the respiratory chain enzyme cytochrome c oxidase acting to assist in the assembly of the Cu-A center contained within subunit II of the oxidase complex. The Cu-A center receives electrons from the reductive substrate ferrocytochrome c, and passes them on to the cytochrome a center. Cytochrome a feeds electrons to the oxygen reaction site composed of cytochrome 03 and CUB. Cu-A consists of two copper ions positioned within bonding distance and ligated by two histidine side chains, one methionine, a backbone carbonyl and two bridging cysteine residues. The complex structure and redox capacity of Cu-A present a potential assembly challenge. SCO proteins are members of the thioredoxin family which led to the early suggestion of a disulfide exchange function for SCO in Cu-A assembly, whereas the copper binding capacity of the Bacillus subtilis version of SCO (i.e., BsSCO) suggests a direct role for SCO proteins in copper transfer. We have characterized redox and copper exchange properties of apo- and metalated-BsSCO. The release of copper (II) from its complex with BsSCO is best achieved by reducing it to Cu(I). We propose a mechanism involving both disulfide and copper exchange between BsSCO and the apo-Cu-A site. This article is part of a Special Issue entitled: Biogenesis/Assembly of Respiratory Enzyme Complexes.

• 出版日期2012-6