University of Oulu

Saaranen MJ, Alanen HI, Salo KEH, Nji E, Kärkkäinen P, Schmotz C, Ruddock LW. Introduction of a More Glutaredoxin-like Active Site to PDI Results in Competition between Protein Substrate and Glutathione Binding. Antioxidants. 2022; 11(10):1920.

Introduction of a more glutaredoxin-like active site to PDI results in competition between protein substrate and glutathione binding

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Author: Saaranen, Mirva J.1; Alanen, Heli I.1; Salo, Kirsi E. H.2;
Organizations: 1Protein and Structural Biology, Faculty of Biochemistry and Molecular Medicine, University of Oulu, 90220 Oulu, Finland
2Research Unit of Biomedicine, Faculty of Medicine, University of Oulu, 90220 Oulu, Finland
3Centre for Research in Therapeutic Sciences (CREATES), Strathmore University, Nairobi 59857-00200, Kenya
4BioStruct-Africa, Vårby, 14343 Stockholm, Sweden
5Research Program for Clinical and Molecular Metabolism, University of Helsinki, 00290 Helsinki, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 1.4 MB)
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Language: English
Published: Multidisciplinary Digital Publishing Institute, 2022
Publish Date: 2023-06-19


Proteins in the thioredoxin superfamily share a similar fold, contain a -CXXC- active site, and catalyze oxidoreductase reactions by dithiol-disulfide exchange mechanisms. Protein disulfide isomerase (PDI) has two -CGHC- active sites. For in vitro studies, oxidation/reduction of PDI during the catalytic cycle is accomplished with glutathione. Glutathione may act as electron donor/acceptor for PDI also in vivo, but at least for oxidation reactions, GSSG probably is not the major electron acceptor and PDI may not have evolved to react with glutathione with high affinity, but merely having adequate affinity for both glutathione and folding proteins/peptides. Glutaredoxins, on the other hand, have a high affinity for glutathione. They commonly have -CXFC- or -CXYC- active site, where the tyrosine residue forms part of the GSH binding groove. Mutating the active site of PDI to a more glutaredoxin-like motif increased its reactivity with glutathione. All such variants showed an increased rate in GSH-dependent reduction or GSSG-dependent oxidation of the active site, as well as a decreased rate of the native disulfide bond formation, with the magnitude of the effect increasing with glutathione concentration. This suggests that these variants lead to competition in binding between glutathione and folding protein substrates.

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Series: Antioxidants
ISSN: 2076-3921
ISSN-E: 2076-3921
ISSN-L: 2076-3921
Volume: 11
Issue: 10
Article number: 1920
DOI: 10.3390/antiox11101920
Type of Publication: A1 Journal article – refereed
Field of Science: 1182 Biochemistry, cell and molecular biology
Funding: This research was funded by University of Oulu and Academy of Finland.
Copyright information: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (