Structural highlights
Function
DHAR2_ARATH Displays a dual function. As a soluble protein, exhibits glutathione-dependent thiol transferase and dehydroascorbate (DHA) reductase activities (PubMed:12077129). Exhibits glutathione-dependent thiol transferase and dehydroascorbate (DHA) reductase activities. Key component of the ascorbate recycling system. Involved in the redox homeostasis, especially in scavenging of ROS under oxidative stresses. Plays a role in ozone tolerance.[1] [2]
Publication Abstract from PubMed
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.
Arabidopsis thaliana dehydroascorbate reductase 2: Conformational flexibility during catalysis.,Bodra N, Young D, Astolfi Rosado L, Pallo A, Wahni K, De Proft F, Huang J, Van Breusegem F, Messens J Sci Rep. 2017 Feb 14;7:42494. doi: 10.1038/srep42494. PMID:28195196[3]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Dixon DP, Davis BG, Edwards R. Functional divergence in the glutathione transferase superfamily in plants. Identification of two classes with putative functions in redox homeostasis in Arabidopsis thaliana. J Biol Chem. 2002 Aug 23;277(34):30859-69. Epub 2002 Jun 19. PMID:12077129 doi:http://dx.doi.org/10.1074/jbc.M202919200
- ↑ Yoshida S, Tamaoki M, Shikano T, Nakajima N, Ogawa D, Ioki M, Aono M, Kubo A, Kamada H, Inoue Y, Saji H. Cytosolic dehydroascorbate reductase is important for ozone tolerance in Arabidopsis thaliana. Plant Cell Physiol. 2006 Feb;47(2):304-8. Epub 2005 Dec 16. PMID:16361320 doi:http://dx.doi.org/10.1093/pcp/pci246
- ↑ Bodra N, Young D, Astolfi Rosado L, Pallo A, Wahni K, De Proft F, Huang J, Van Breusegem F, Messens J. Arabidopsis thaliana dehydroascorbate reductase 2: Conformational flexibility during catalysis. Sci Rep. 2017 Feb 14;7:42494. doi: 10.1038/srep42494. PMID:28195196 doi:http://dx.doi.org/10.1038/srep42494
