Role of Coa6 in Coordinating Cox2 and Cytochrome C Maturation in Yeast Mitochondria

Coa6 controls copper delivery into the Cox2 subunit of the mitochondrial respiratory complex IV. Mutations in COA6 lead to Cox2 degradation and cause cardiomyopathy in humans. We show that decreasing the level of the mobile electron transporter cytochrome c improves both Cox2 accumulation and complex IV assembly in the budding yeast coa6-null mutant. As the heme attachment to apo-cytochrome c and the copper delivery to apo-Cox2 both require cysteine reduction, we propose that Coa6 plays a role in coordinating the maturation of Cox2 and Cytc with their cofactors.