A PDI-catalyzed thiol-disulfide switch regulates the production of hydrogen peroxide by human Ero1

Thomas Ramming, Masaki Okumura, Shingo Kanemura, Sefer Baday, Julia Birk, Suzette Moes, Martin Spiess, Paul Jenö, Simon Bernèche, Kenji Inaba, Christian Appenzeller-Herzog

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54 Citations (Scopus)


Oxidative folding in the endoplasmic reticulum (ER) involves ER oxidoreductin 1 (Ero1)-mediated disulfide formation in protein disulfide isomerase (PDI). In this process, Ero1 consumes oxygen (O2) and releases hydrogen peroxide (H2O2), but none of the published Ero1 crystal structures reveal any potential pathway for entry and exit of these reactants. We report that additional mutation of the Cys208-Cys241 disulfide in hyperactive Ero1α (Ero1α-C104A/C131A) potentiates H2O2 production, ER oxidation, and cell toxicity. This disulfide clamps two helices that seal the flavin cofactor where O2 is reduced to H2O2. Through its carboxyterminal active site, PDI unlocks this seal by forming a Cys208/Cys241-dependent mixed-disulfide complex with Ero1α. The H2O2-detoxifying glutathione peroxidase 8 also binds to the Cys208/Cys241 loop region. Supported by O2 diffusion simulations, these data describe the first enzymatically controlled O2 access into a flavoprotein active site, provide molecular-level understanding of Ero1α regulation and H2O2 production/detoxification, and establish the deleterious consequences of constitutive Ero1 activity.

Original languageEnglish
Pages (from-to)361-372
Number of pages12
JournalFree Radical Biology and Medicine
Publication statusPublished - 2015 May 19


  • Disulfide bond formation
  • Endoplasmic reticulum
  • Ero1
  • Hydrogen peroxide
  • Oxidative folding
  • Peroxidase: Free radicals


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