Oxidation state governs structural transitions in peroxiredoxin II that correlate with cell cycle arrest and recovery

Inactivation of eukaryotic 2-Cys peroxiredoxins (Prxs) by hyperoxidation has been proposed to promote accumulation of hydrogen peroxide (H₂O₂) for redox-dependent signaling events. We examined the oxidation and oligomeric states of PrxI and -II in epithelial cells during mitogenic signaling and in response to fluxes of H₂O₂. During normal mitogenic signaling, hyperoxidation of PrxI and -II was not detected. In contrast, H₂O₂-dependent cell cycle arrest was correlated with hyperoxidation of PrxII, which resulted in quantitative recruitment of ~66- and ~140-kD PrxII complexes into large filamentous oligomers. Expression of cyclin D1 and cell proliferation did not resume until PrxII-SO₂H was reduced and native PrxII complexes were regenerated. Ectopic expression of PrxI or -II increased Prx-SO₂H levels in response to oxidant exposure and failed to protect cells from arrest. We propose a model in which Prxs function as peroxide dosimeters in subcellular processes that involve redox cycling, with hyperoxidation controlling structural transitions that alert cells of perturbations in peroxide homeostasis.