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A Rapid and Specific Microplate Assay for the Determination of Intra- and Extracellular Ascorbate in Cultured Cells
Published on: April 11, 2014
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Plant dehydroascorbate reductase moonlights as membrane integrated ion channel
Bhaba Krishna Das1, Wajahat Ali Khan1, Sreeshma Nellootil Sreekumar2
1Membrane Protein Biology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, 110067, India.
Archives of Biochemistry and Biophysics
|April 21, 2023
Summary
Plant dehydroascorbate reductases (DHARs) are antioxidant enzymes. This study reveals DHARs are dimorphic, functioning as both soluble enzymes and membrane-integrated ion channels, particularly under oxidative stress.
Area of Science:
- Plant biology
- Molecular biology
- Biochemistry
Background:
- Plant dehydroascorbate reductases (DHARs) are known soluble enzymes in the ascorbate-glutathione pathway.
- DHARs protect plants from oxidative stress by recycling ascorbate.
- DHARs share structural similarity with human chloride intracellular channels (HsCLICs), which are known to be dimorphic.
Purpose of the Study:
- To investigate the potential for a membrane-integrated form of plant DHAR.
- To determine if Pennisetum glaucum DHAR (PgDHAR) exhibits dimorphism.
- To explore the localization and function of PgDHAR in the plant plasma membrane.
Main Methods:
- Biochemical assays
- Immunofluorescence confocal microscopy
- Bilayer electrophysiology
- Oxidative stress induction
Main Results:
- Pennisetum glaucum DHAR (PgDHAR) was confirmed to be dimorphic.
- PgDHAR localizes to the plant plasma membrane, with increased translocation under oxidative stress.
- Purified soluble PgDHAR demonstrated ion channel activity in lipid bilayers.
- HsCLIC1 also showed increased plasma membrane translocation in human cells under oxidative stress.
Conclusions:
- Plant DHARs exist in a novel membrane-integrated ion channel form, in addition to their known soluble enzymatic role.
- This dimorphism suggests a broader function for DHARs in cellular processes, including ion transport.
- Understanding the DHAR ion channel structure can provide insights into its function across different life forms.
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