Cytochrome
c oxidase is a pivotal enzyme of the mitochondrial respiratory chain, which sustains bioenergetics of eukaryotic cells. Cox12, a peripheral subunit of cytochrome
c oxidase, is required for full activity of the enzyme, but its exact function is unknown. Here, experimental evolution of a
Saccharomyces cerevisiae Δ
cox12 strain for ∼300 generations allowed to restore the activity of cytochrome
c oxidase. In one population, the enhanced bioenergetics was caused by a A375V mutation in the AAA+ disaggregase Hsp104. Deletion or overexpression of
HSP104 also increased respiration of the Δ
cox12 ancestor strain. This beneficial effect of Hsp104 was related to the loss of the [
PSI+] prion, which forms cytosolic amyloid aggregates of the Sup35 protein. Overall, our data demonstrate that cytosolic aggregation of a prion impairs the mitochondrial metabolism of cells defective for Cox12. These findings identify a new functional connection between cytosolic proteostasis and biogenesis of the mitochondrial respiratory chain.
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