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Article

  • The EMBO Journal (2008) 27, 2977 - 2987
  • doi:10.1038/emboj.2008.202

Published online: 2 October 2008

A novel disulphide switch mechanism in Ero1alpha balances ER oxidation in human cells

Christian Appenzeller-Herzog1, Jan Riemer1, Brian Christensen2, Esben S Sørensen2 and Lars Ellgaard1

  1. Department of Biology, University of Copenhagen, Copenhagen Ø, Denmark
  2. Department of Molecular Biology, University of Aarhus, Aarhus C, Denmark

Correspondence to:

Lars Ellgaard, Department of Molecular Biology, University of Copenhagen, August Krogh Building, Universitetsparken 13, Copenhagen DK-2100, Denmark. Tel.: +45 3532 1725; Fax: +45 3532 1567; E-mail: lellgaard@bio.ku.dk

Received 17 June 2008; Accepted 12 September 2008

Oxidative maturation of secretory and membrane proteins in the endoplasmic reticulum (ER) is powered by Ero1 oxidases. To prevent cellular hyperoxidation, Ero1 activity can be regulated by intramolecular disulphide switches. Here, we determine the redox-driven shutdown mechanism of Ero1alpha, the housekeeping Ero1 enzyme in human cells. We show that functional silencing of Ero1alpha in cells arises from the formation of a disulphide bond—identified by mass spectrometry—between the active-site Cys94 (connected to Cys99 in the active enzyme) and Cys131. Competition between substrate thiols and Cys131 creates a feedback loop where activation of Ero1alpha is linked to the availability of its substrate, reduced protein disulphide isomerase (PDI). Overexpression of Ero1alpha-Cys131Ala or the isoform Ero1beta, which does not have an equivalent disulphide switch, leads to augmented ER oxidation. These data reveal a novel regulatory feedback system where PDI emerges as a central regulator of ER redox homoeostasis.

  • Keywords:

    • disulphide-bond formation,
    • endoplasmic reticulum,
    • ER oxidoreductin 1,
    • protein disulphide isomerase,
    • redox homoeostasis