2N5F
Solution structure of the dehydroascorbate reductase 3A from Populus trichocarpa
Summary for 2N5F
| Entry DOI | 10.2210/pdb2n5f/pdb |
| NMR Information | BMRB: 25712 |
| Descriptor | Dehydroascorbate reductase family protein (1 entity in total) |
| Functional Keywords | gst, dhar, oxidoreductase |
| Biological source | Populus trichocarpa (western balsam poplar) |
| Total number of polymer chains | 1 |
| Total formula weight | 24364.19 |
| Authors | |
| Primary citation | Lallement, P.A.,Roret, T.,Tsan, P.,Gualberto, J.M.,Girardet, J.M.,Didierjean, C.,Rouhier, N.,Hecker, A. Insights into ascorbate regeneration in plants: investigating the redox and structural properties of dehydroascorbate reductases from Populus trichocarpa. Biochem.J., 473:717-731, 2016 Cited by PubMed Abstract: Dehydroascorbate reductases (DHARs), enzymes belonging to the GST superfamily, catalyse the GSH-dependent reduction of dehydroascorbate into ascorbate in plants. By maintaining a reduced ascorbate pool, they notably participate to H2O2 detoxification catalysed by ascorbate peroxidases (APXs). Despite this central role, the catalytic mechanism used by DHARs is still not well understood and there is no supportive 3D structure. In this context, we have performed a thorough biochemical and structural analysis of the three poplar DHARs and coupled this to the analysis of their transcript expression patterns and subcellular localizations. The transcripts for these genes are mainly detected in reproductive and green organs and the corresponding proteins are expressed in plastids, in the cytosol and in the nucleus, but not in mitochondria and peroxisomes where ascorbate regeneration is obviously necessary. Comparing the kinetic properties and the sensitivity to GSSG-mediated oxidation of DHAR2 and DHAR3A, exhibiting 1 or 3 cysteinyl residues respectively, we observed that the presence of additional cysteines in DHAR3A modifies the regeneration mechanism of the catalytic cysteine by forming different redox states. Finally, from the 3D structure of DHAR3A solved by NMR, we were able to map the residues important for the binding of both substrates (GSH and DHA), showing that DHAR active site is very selective for DHA recognition and providing further insights into the catalytic mechanism and the roles of the additional cysteines found in some DHARs. PubMed: 26699905DOI: 10.1042/BJ20151147 PDB entries with the same primary citation |
| Experimental method | SOLUTION NMR |
Structure validation
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