5D9X: Dehydroascorbate Reductase Complexed With Gsh

Dehydroascorbate reductase (DHAR) is a key enzyme involved in the recycling of ascorbate, which catalyses the glutathione (GSH)-dependent reduction of oxidized ascorbate (dehydroascorbate, DHA). As a result, DHAR regenerates a pool of reduced ascorbate and detoxifies reactive oxygen species (ROS). In previous experiments involving transgenic rice, we observed that overexpression of DHAR enhanced grain yield and biomass. Since the structure of DHAR is not available, the enzymatic mechanism is not well-understood and remains poorly characterized. To elucidate the molecular basis of DHAR catalysis, we determined the crystal structures of DHAR from Oryza sativa L. japonica (OsDHAR) in the native, ascorbate-bound, and GSH-bound forms and refined their resolutions to 1.9, 1.7, and 1.7 A, respectively. These complex structures provide the first information regarding the location of the ascorbate and GSH binding sites and their interacting residues. The location of the ascorbate-binding site overlaps with the GSH-binding site, suggesting a ping-pong kinetic mechanism for electron transfer at the common Cys20 active site. Our structural information and mutagenesis data provide useful insights into the reaction mechanism of OsDHAR against ROS-induced oxidative stress in rice.
PDB ID: 5D9XDownload
MMDB ID: 136231
PDB Deposition Date: 2015/8/19
Updated in MMDB: 2016/02
Experimental Method:
x-ray diffraction
Resolution: 1.68  Å
Source Organism:
Similar Structures:
Biological Unit for 5D9X: monomeric; determined by author and by software (PISA)
Molecular Components in 5D9X
Label Count Molecule
Protein (1 molecule)
Dehydroascorbate Reductase
Molecule annotation
Chemicals (2 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB