title: Arabidopsis thaliana dehydroascorbate reductase 2: Conformational flexibility during catalysis.
abstract: Dehydroascorbate reductase (DHAR) catalyzes the glutathione (GSH)-dependent reduction of dehydroascorbate and plays a direct role in regenerating ascorbic acid, an essential plant antioxidant vital for defense against oxidative stress. DHAR enzymes bear close structural homology to the glutathione transferase (GST) superfamily of enzymes and contain the same active site motif, but most GSTs do not exhibit DHAR activity. The presence of a cysteine at the active site is essential for the catalytic functioning of DHAR, as mutation of this cysteine abolishes the activity. Here we present the crystal structure of DHAR2 from Arabidopsis thaliana with GSH bound to the catalytic cysteine. This structure reveals localized conformational differences around the active site which distinguishes the GSH-bound DHAR2 structure from that of DHAR1. We also unraveled the enzymatic step in which DHAR releases oxidized glutathione (GSSG). To consolidate our structural and kinetic findings, we investigated potential conformational flexibility in DHAR2 by normal mode analysis and found that subdomain mobility could be linked to GSH binding or GSSG release.
authors.affiliation: Center for Structural Biology, VIB, 1050 Brussels, Belgium.|Brussels Center for Redox Biology, 1050 Brussels, Belgium.|Structural Biology Brussels, Vrije Universiteit Brussel, 1050 Brussels, Belgium.|Center for Plant Systems Biology, VIB, 9052 Gent, Belgium.|Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Gent, Belgium.
authors.forename: Nandita
authors.initials: N
authors.lastname: Bodra
authors.affiliation: Center for Structural Biology, VIB, 1050 Brussels, Belgium.|Brussels Center for Redox Biology, 1050 Brussels, Belgium.|Structural Biology Brussels, Vrije Universiteit Brussel, 1050 Brussels, Belgium.
authors.forename: David
authors.initials: D
authors.lastname: Young
authors.affiliation: Center for Structural Biology, VIB, 1050 Brussels, Belgium.|Brussels Center for Redox Biology, 1050 Brussels, Belgium.|Structural Biology Brussels, Vrije Universiteit Brussel, 1050 Brussels, Belgium.
authors.forename: Leonardo
authors.initials: L
authors.lastname: Astolfi Rosado
authors.affiliation: Center for Structural Biology, VIB, 1050 Brussels, Belgium.|Brussels Center for Redox Biology, 1050 Brussels, Belgium.|Structural Biology Brussels, Vrije Universiteit Brussel, 1050 Brussels, Belgium.
authors.forename: Anna
authors.initials: A
authors.lastname: Pallo
authors.affiliation: Center for Structural Biology, VIB, 1050 Brussels, Belgium.|Brussels Center for Redox Biology, 1050 Brussels, Belgium.|Structural Biology Brussels, Vrije Universiteit Brussel, 1050 Brussels, Belgium.
authors.forename: Khadija
authors.initials: K
authors.lastname: Wahni
authors.affiliation: Research Group of General Chemistry, Vrije Universiteit Brussel, 1050 Brussels, Belgium.
authors.forename: Frank
authors.initials: F
authors.lastname: De Proft
authors.affiliation: Center for Structural Biology, VIB, 1050 Brussels, Belgium.|Brussels Center for Redox Biology, 1050 Brussels, Belgium.|Structural Biology Brussels, Vrije Universiteit Brussel, 1050 Brussels, Belgium.|Center for Plant Systems Biology, VIB, 9052 Gent, Belgium.|Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Gent, Belgium.
authors.forename: Jingjing
authors.initials: J
authors.lastname: Huang
authors.affiliation: Center for Plant Systems Biology, VIB, 9052 Gent, Belgium.|Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Gent, Belgium.
authors.forename: Frank
authors.initials: F
authors.lastname: Van Breusegem
authors.affiliation: Center for Structural Biology, VIB, 1050 Brussels, Belgium.|Brussels Center for Redox Biology, 1050 Brussels, Belgium.|Structural Biology Brussels, Vrije Universiteit Brussel, 1050 Brussels, Belgium.
authors.forename: Joris
authors.initials: J
authors.lastname: Messens