CHAPTER 17: Copper in Mitochondria

Copper is a cofactor in the mitochondrial enzymes cytochrome c oxidase (CcO) and superoxide dismutase. Delivery and insertion of copper to CcO is mediated by a series of metallochaperones localized in the intermembrane space and inner membrane of mitochondria. The soluble protein Cox17 transiently binds copper in the intermembrane space and delivers it to inner membrane-tethered Sco1 and Cox11, which then deliver copper to the appropriate CcO subunits. CcO has two distinct catalytic copper sites, Cu_A and Cu_B, assembled by Sco1 and Cox11, respectively. Metallation of mitochondrial superoxide dismutase 1 is dependent on the copper chaperone for Sod1 in the intermembrane space. CcO and Sod1 account for between 10 and 40% of the total copper present in mitochondria depending on the conditions and organism. The remainder of the copper is found in a labile pool within the matrix. Matrix copper is relocalized to the intermembrane space as a source of copper for the aforementioned copper chaperones. Herein, we discuss the current understanding of storage, binding and utilization of copper in mitochondria and address the major unresolved questions concerning the nature of mitochondrial copper.