Non-native ligands define the active site of Pennisetum glaucum (L.) R. Br dehydroascorbate reductase

Das, Bhaba Krishna; Kumar, Amit; Maindola, Priyank; Mahanty, Srikrishna; Jain, Swatantra Kumar; Reddy, Mallireddy K.; Arockiasamy, A.

doi:10.1016/j.bbrc.2016.04.031

Cited by 19 publications

(8 citation statements)

References 41 publications

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“…During this process, the active site of Cys is oxidized by DHA and further converted to the sulfenic acid. The reaction requires one molecule of H 2 O. Knockout mutants of Arabidopsis DHAR1 , DHAR2 , and DHAR3 , did not show any significant differences in total AsA content until facing the abiotic stress condition, which confirmed the necessity of DHAR in reducing the DHA during stress [55].…”

Section: Components Of Asa-gsh Pathwaymentioning

confidence: 96%

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Regulation of Ascorbate-Glutathione Pathway in Mitigating Oxidative Damage in Plants under Abiotic Stress

et al. 2019

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Reactive oxygen species (ROS) generation is a usual phenomenon in a plant both under a normal and stressed condition. However, under unfavorable or adverse conditions, ROS production exceeds the capacity of the antioxidant defense system. Both non-enzymatic and enzymatic components of the antioxidant defense system either detoxify or scavenge ROS and mitigate their deleterious effects. The Ascorbate-Glutathione (AsA-GSH) pathway, also known as Asada–Halliwell pathway comprises of AsA, GSH, and four enzymes viz. ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase, and glutathione reductase, play a vital role in detoxifying ROS. Apart from ROS detoxification, they also interact with other defense systems in plants and protect the plants from various abiotic stress-induced damages. Several plant studies revealed that the upregulation or overexpression of AsA-GSH pathway enzymes and the enhancement of the AsA and GSH levels conferred plants better tolerance to abiotic stresses by reducing the ROS. In this review, we summarize the recent progress of the research on AsA-GSH pathway in terms of oxidative stress tolerance in plants. We also focus on the defense mechanisms as well as molecular interactions.

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Section: Components Of Asa-gsh Pathwaymentioning

confidence: 96%

“…The plant GSH-dependent DHAR is a monomeric enzyme, which is a member of the GSH S -transferase superfamily [55]. Arabidopsis possesses three functional DHAR encoding genes, DHAR1 ( At1g19570 ), DHAR2 ( At1g75270 ), and DHAR3 ( At5g16710 ).…”

Section: Components Of Asa-gsh Pathwaymentioning

confidence: 99%

Regulation of Ascorbate-Glutathione Pathway in Mitigating Oxidative Damage in Plants under Abiotic Stress

et al. 2019

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“…From the structure of the AsA-bound OsDHAR1, Lys8, Asp19, and Lys210 are identified as forming H-bonds with AsA 17 . The structure of PgDHAR1 also supports the role of Lys8 and Asp19 in DHA binding, with glycerol as a mimic of the 1,2-dihydroxyethyl arm of AsA 20 . In addition to the charged residues mentioned above, hydrophobic van der Waals interactions from Pro21, Phe104, and Trp207 contribute to the binding of AsA in the crystal structure of the AsA-bound OsDHAR1 18 .…”

Section: Resultsmentioning

confidence: 61%

“…S3 ). As Asp19 is proposed to be a significant residue in the binding and stabilization of DHA for catalytic reduction 18 20 , preclusion of its carboxylate side-chain from the H-site-binding region in AtDHAR2 complicates understanding of its role in DHA reduction.…”

Section: Resultsmentioning

confidence: 99%

“…Plant DHAR enzymes contain a conserved catalytic motif CPFS/C and are largely categorized into four isoforms, DHAR1, DHAR2, DHAR3 and DHAR4 17 . To date, four independent structures of plant DHAR have been deposited in the Protein Data Bank: the crystallographic structures of Oryza sativa (rice) (OsDHAR1; PDB, 5D9T) 18 , Pennisetum glaucum (pearl millet) (PgDHAR1; PDB, 5EV0, 5IQY), the nuclear magnetic resonance solution structure of DHAR3A from Populus trichocarpa (black cottonwood) (PtDHAR3A; PDB, 2N5F) 19 , and the recently deposited crystal structure of Arabidopsis thaliana DHAR1 (AtDHAR1; PDB, 5EL8) 20 . In addition, crystal structures of P. trichocarpa GST Lambda (PtGSTL) 21 and Homo sapiens GST Omega (HsGSTO) 22 with DHAR activity have been determined with GSH bound at the catalytic cysteine.…”

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confidence: 99%

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Arabidopsis thaliana dehydroascorbate reductase 2: Conformational flexibility during catalysis

Bodra

Young

Rosado

et al. 2017

Sci Rep

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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.

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Molecular and Functional Characterization of Monodehydro-ascorbate and Dehydroascorbate Reductases

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2017

Ascorbic Acid in Plant Growth, Development and Stress Tolerance

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Non-native ligands define the active site of Pennisetum glaucum (L.) R. Br dehydroascorbate reductase

Cited by 19 publications

References 41 publications

Regulation of Ascorbate-Glutathione Pathway in Mitigating Oxidative Damage in Plants under Abiotic Stress

Regulation of Ascorbate-Glutathione Pathway in Mitigating Oxidative Damage in Plants under Abiotic Stress

Arabidopsis thaliana dehydroascorbate reductase 2: Conformational flexibility during catalysis

Molecular and Functional Characterization of Monodehydro-ascorbate and Dehydroascorbate Reductases

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