Mitochondrial import of Srx requires a disulfide-linked complex formation with HSP90
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Imported Srx is degraded by Lon in a manner dependent on PrxIII hyperoxidation state
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The import and degradation determine the circadian oscillation of mitochondrial Srx
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The mitochondrial Srx levels govern PrxIII activity and thus mitochondrial H2O2 release
Summary
Hydrogen peroxide (H2O2) released from mitochondria regulates various cell signaling pathways. Given that H2O2-eliminating enzymes such as peroxiredoxin III (PrxIII) are abundant in mitochondria, however, it has remained unknown how such release can occur. Active PrxIII-SH undergoes reversible inactivation via hyperoxidation to PrxIII-SO2, which is then reduced by sulfiredoxin. We now show that the amounts of PrxIII-SO2 and sulfiredoxin undergo antiphasic circadian oscillation in the mitochondria of specific tissues of mice maintained under normal conditions. Cytosolic sulfiredoxin was found to be imported into the mitochondria via a mechanism that requires formation of a disulfide-linked complex with heat shock protein 90, which is promoted by H2O2 released from mitochondria. The imported sulfiredoxin is degraded by Lon in a manner dependent on PrxIII hyperoxidation state. The coordinated import and degradation of sulfiredoxin provide the basis for sulfiredoxin oscillation and consequent PrxIII-SO2 oscillation in mitochondria and likely result in an oscillatory H2O2 release.
