In exponentially growing @entity375 , the @entity1446 enzyme, cytochrome c peroxidase ( @entity39192 ) is targeted to the mitochondrial intermembrane space. When the fermentable source ( @entity413 ) is depleted, cells switch to respiration and mitochondrial @entity274 levels rise. It has long been assumed that CCP activity detoxifies mitochondrial @entity274 because of the efficiency of this activity in vitro. However, we find that a large pool of @entity39192 exits the mitochondria of respiring cells. We detect no extramitochondrial CCP activity because @entity39192 crosses the outer mitochondrial membrane as the @entity1446 -free protein. In parallel with apoCcp1 export, cells exhibit increased activity of catalase A (Cta1), the mitochondrial and peroxisomal catalase isoform in @entity375 . This identifies Cta1 as a likely recipient of @entity39192 @entity1446 , which is supported by low Cta1 activity in @entity39192   cells and the accumulation of holoCcp1 in cta1   mitochondria. We hypothesized that @entity39192 's @entity1446 is labilized by hyperoxidation of the protein during the burst in @entity274 production as cells begin to respire. To test this hypothesis, recombinant @entity39192 was hyperoxidized with excess @entity274 in vitro, which accelerated @entity1446 transfer to apomyoglobin added as a surrogate @entity1446 acceptor. Furthermore, the proximal @entity1446 Fe ligand, His175, was found to be    85% oxidized to oxo-histidine in extramitochondrial @entity39192 isolated from 7-d cells, indicating that @entity1446 labilization results from oxidation of this ligand. We conclude that @entity39192 responds to respiration-derived @entity274 via a previously unidentified mechanism involving @entity274 -activated @entity1446 transfer to apoCta1. Subsequently, the catalase activity of Cta1, not CCP activity, contributes to mitochondrial @entity274 detoxification.

Respiration triggers XXXX transfer from cytochrome c peroxidase to catalase in @entity375 mitochondria.

@entity274 :: ('CHEBI:16240', 'Chemical') :: ['H2O2'] @entity39192 :: ('853940(Tax:4932)', 'Gene') :: ['Ccp1', 'ccp1'] @entity375 :: ('4932', 'Species') :: ['yeast'] @entity413 :: ('MESH:D005947', 'Chemical') :: ['glucose'] @entity1446 :: ('MESH:D006418', 'Chemical') :: ['heme']
@entity1446 :: (MESH:D006418,Chemical) :: ['heme']
