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Maruta T, Tanaka Y, Yamamoto K, Ishida T, Hamada A, Ishikawa T. Evolutionary insights into strategy shifts for the safe and effective accumulation of ascorbate in plants. JOURNAL OF EXPERIMENTAL BOTANY 2024; 75:2664-2681. [PMID: 38452239 DOI: 10.1093/jxb/erae062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Accepted: 03/06/2024] [Indexed: 03/09/2024]
Abstract
Plants accumulate high concentrations of ascorbate, commonly in their leaves, as a redox buffer. While ascorbate levels have increased during plant evolution, the mechanisms behind this phenomenon are unclear. Moreover, has the increase in ascorbate concentration been achieved without imposing any detrimental effects on the plants? In this review, we focus on potential transitions in two regulatory mechanisms related to ascorbate biosynthesis and the availability of cellular dehydroascorbate (DHA) during plant evolution. The first transition might be that the trigger for the transcriptional induction of VTC2, which encodes the rate-limiting enzyme in ascorbate biosynthesis, has shifted from oxidative stress (in green algae) to light/photosynthesis (in land plants), probably enabling the continuous accumulation of ascorbate under illumination. This could serve as a preventive system against the unpredictable occurrence of oxidative stress. The second transition might be that DHA-degrading enzymes, which protect cells from the highly reactive DHA in green algae and mosses, have been lost in ferns or flowering plants. Instead, flowering plants may have increased glutathione concentrations to reinforce the DHA reduction capacity, possibly allowing ascorbate accumulation and avoiding the toxicity of DHA. These potential transitions may have contributed to strategies for plants' safe and effective accumulation of ascorbate.
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Affiliation(s)
- Takanori Maruta
- Graduate School of Natural Science and Technology, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504, Japan
- Bioresource and Life Sciences, The United Graduate School of Agricultural Sciences, Tottori University, 4-101 Koyama-Minami, Tottori, Tottori 680-8553, Japan
- Institute of Agricultural and Life Sciences, Academic Assembly, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504, Japan
| | - Yasuhiro Tanaka
- Graduate School of Natural Science and Technology, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504, Japan
- Bioresource and Life Sciences, The United Graduate School of Agricultural Sciences, Tottori University, 4-101 Koyama-Minami, Tottori, Tottori 680-8553, Japan
| | - Kojiro Yamamoto
- Graduate School of Natural Science and Technology, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504, Japan
| | - Tetsuya Ishida
- Graduate School of Natural Science and Technology, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504, Japan
| | - Akane Hamada
- Graduate School of Natural Science and Technology, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504, Japan
| | - Takahiro Ishikawa
- Graduate School of Natural Science and Technology, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504, Japan
- Bioresource and Life Sciences, The United Graduate School of Agricultural Sciences, Tottori University, 4-101 Koyama-Minami, Tottori, Tottori 680-8553, Japan
- Institute of Agricultural and Life Sciences, Academic Assembly, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504, Japan
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Das BK, Khan WA, Sreekumar SN, Ponraj K, Achary VMM, Reddy ES, Balasubramaniam D, Chandele A, Reddy MK, Arockiasamy A. Plant dehydroascorbate reductase moonlights as membrane integrated ion channel. Arch Biochem Biophys 2023; 741:109603. [PMID: 37084805 DOI: 10.1016/j.abb.2023.109603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 04/03/2023] [Accepted: 04/17/2023] [Indexed: 04/23/2023]
Abstract
Plant dehydroascorbate reductases (DHARs) are only known as soluble antioxidant enzymes of the ascorbate-glutathione pathway. They recycle ascorbate from dehydroascorbate, thereby protecting plants from oxidative stress and the resulting cellular damage. DHARs share structural GST fold with human chloride intracellular channels (HsCLICs) which are dimorphic proteins that exists in soluble enzymatic and membrane integrated ion channel forms. While the soluble form of DHAR has been extensively studied, the existence of a membrane integrated form remains unknown. We demonstrate for the first time using biochemistry, immunofluorescence confocal microscopy, and bilayer electrophysiology that Pennisetum glaucum DHAR (PgDHAR) is dimorphic and is localized to the plant plasma membrane. In addition, membrane translocation increases under induced oxidative stress. Similarly, HsCLIC1 translocates more into peripheral blood mononuclear cells (PBMCs) plasma membrane under induced oxidative stress conditions. Moreover, purified soluble PgDHAR spontaneously inserts and conducts ions in reconstituted lipid bilayers, and the addition of detergent facilitates insertion. In addition to the well-known soluble enzymatic form, our data provides conclusive evidence that plant DHAR also exists in a novel membrane-integrated form. Thus, the structure of DHAR ion channel form will help gain deeper insights into its function across various life forms.
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Affiliation(s)
- Bhaba Krishna Das
- Membrane Protein Biology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, 110067, India
| | - Wajahat Ali Khan
- Membrane Protein Biology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, 110067, India.
| | - Sreeshma Nellootil Sreekumar
- Membrane Protein Biology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, 110067, India; Department of Biotechnology, Jamia Hamdard University, New Delhi, 110062, India
| | - Kannapiran Ponraj
- Membrane Protein Biology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, 110067, India
| | - V Mohan Murali Achary
- Crop Improvement Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, 110067, India
| | - Elluri Seetharami Reddy
- ICGEB-Emory Vaccine Centre, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, 110067, India; Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, New Delhi, 110016, India
| | - D Balasubramaniam
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, 110067, India
| | - Anmol Chandele
- ICGEB-Emory Vaccine Centre, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, 110067, India
| | - Malireddy K Reddy
- Crop Improvement Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, 110067, India
| | - Arulandu Arockiasamy
- Membrane Protein Biology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, 110067, India.
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Meena RP, Ghosh G, Vishwakarma H, Padaria JC. Expression of a Pennisetum glaucum gene DREB2A confers enhanced heat, drought and salinity tolerance in transgenic Arabidopsis. Mol Biol Rep 2022; 49:7347-7358. [PMID: 35666421 DOI: 10.1007/s11033-022-07527-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 04/26/2022] [Indexed: 11/24/2022]
Abstract
BACKGROUND Pearl millet (Pennisetum glaucum) is an essential cereal crop, whose growth and yield are not impacted by abiotic stresses, such as drought, heat, and cold. The DREB transcription factors (TF) are some of the largest groups of TFs in plants and play varied roles in plant stress response and signal transduction. METHODS AND RESULTS In the present study, PgDREB2A gene encoding a DREB transcription factor in pearl millet was functionally characterized in Arabidopsis. DREB2A proteins contain a conserved domain that binds toethylene responsive element binding factors. Three different T1 transgenic lines overexpressing PgDREB2A gene were identified by Southern blot. Quantitative real-time polymerase chain reaction exhibited that PgDREB2A could be induced under drought conditions. As compared with the control, PgDREB2A overexpressing transgenic Arabidopsis showed increased rate of seed germination and root growth in transgenic lines under higher concentrations of mannitol, NaCl, ABA, heat and cold stress. Additionally, PgDREB2A transgenic lines showed enhanced durability after rehydration and tolerance to drought and salt stress was augmented with increased proline and reduced MDA build-up and diminishing water loss. CONCLUSIONS Results from this study suggested that PgDREB2A as a transcription factor may improve endurance to various abiotic stresses and can be employed for developing crops tolerant to abiotic stresses.
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Affiliation(s)
- Rajendra Prasad Meena
- National Institute for Plant Biotechnology, Pusa Campus, New Delhi, India.,PG School, ICAR-Indian Agricultural Research Institute, Pusa Campus, New Delhi, 110012, India
| | - Gourab Ghosh
- National Institute for Plant Biotechnology, Pusa Campus, New Delhi, India
| | | | - Jasdeep Chatrath Padaria
- National Institute for Plant Biotechnology, Pusa Campus, New Delhi, India. .,PG School, ICAR-Indian Agricultural Research Institute, Pusa Campus, New Delhi, 110012, India.
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Comparative kinetic analysis of ascorbate (Vitamin-C) recycling dehydroascorbate reductases from plants and humans. Biochem Biophys Res Commun 2021; 591:110-117. [PMID: 35007834 DOI: 10.1016/j.bbrc.2021.12.103] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2021] [Accepted: 12/26/2021] [Indexed: 11/20/2022]
Abstract
Ascorbate is an important cellular antioxidant that gets readily oxidized to dehydroascorbate (DHA). Recycling of DHA is therefore paramount in the maintenance of cellular homeostasis and preventing oxidative stress. Dehydroascorbate reductases (DHARs), in conjunction with glutathione (GSH), carry out this vital process in eukaryotes, among which plant DHARs have garnered considerable attention. A detailed kinetic analysis of plant DHARs relative to their human counterparts is, however, lacking. Chloride intracellular channels (HsCLICs) are close homologs of plant DHARs, recently demonstrated to share their enzymatic activity. This study reports the highest turnover rate for a plant DHAR from stress adapted Pennisetum glaucum (PgDHAR). In comparison, HsCLICs 1, 3, and 4 reduced DHA at a significantly lower rate. We further show that the catalytic cysteine from both homologs was susceptible to varying degrees of oxidation, validated by crystal structures and mass-spectrometry. Our findings may have broader implications on crop improvement using pearl millet DHAR vis-à-vis discovery of cancer therapeutics targeting Vitamin-C recycling capability of human CLICs.
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Meena RP, Vishwakarma H, Ghosh G, Gaikwad K, Chellapilla TS, Singh MP, Padaria JC. Novel ASR isolated from drought stress responsive SSH library in pearl millet confers multiple abiotic stress tolerance in PgASR3 transgenic Arabidopsis. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2020; 156:7-19. [PMID: 32891968 DOI: 10.1016/j.plaphy.2020.07.031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2020] [Revised: 07/09/2020] [Accepted: 07/15/2020] [Indexed: 05/09/2023]
Abstract
A genomic resource of drought stress responsive genes/ESTs was generated using Suppression Subtractive Hybridization (SSH) approach in a drought stress tolerant Pennisetum glaucum genotype 841B. Fifty five days old plants were subjected to drought stress after withholding water for different time intervals (10 days, 15 days, 20 days and 25 days). A forward subtractive cDNA library was prepared from isolated RNA of leaf tissue. Differential gene expression under drought stress was validated for selected nine contigs by RT-qPCR. A transcript homologous to Setaria italica ASR3 upregulated under drought stress was isolated from genotype 841B and characterized. Heterologous expression of PgASR3 was validated in Arabidopsis and confirmed under multiple abiotic stress conditions. A total of four independent transgenic lines overexpressing gene PgASR3 were analyzed by Southern blot at T1 stage. For drought stress tolerance, three independent lines (T2 stage) were analyzed by biochemical and physiological assays at seedling stage. The growth rate (shoot and root length) of transgenic seedlings improved as compared to WT seedling under differenct abiotic stress conditions. The three transgenic lines were also validated for drought stress tolerance and RT-qPCR analysis, at maturity stage. Under drought stress conditions, the mature transgenic lines showed higher levels of RWC, chlorophyll and proline but lower levels of MDA as compared to WT plants. PgASR3 gene isolated and validated in this study can be utilized for developing abiotic stress tolerant crops.
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Affiliation(s)
| | | | - Gourab Ghosh
- National Institute for Plant Biotechnology, Pusa Campus, New Delhi, India
| | - Kishor Gaikwad
- National Institute for Plant Biotechnology, Pusa Campus, New Delhi, India
| | - Tara Satyavathi Chellapilla
- National Institute for Plant Biotechnology, Pusa Campus, New Delhi, India; Division of Genetics, IARI, Pusa Campus, New Delhi, India
| | - Madan Pal Singh
- Division of Plant Physiology, IARI Pusa Campus, New Delhi, India
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Ding H, Wang B, Han Y, Li S. The pivotal function of dehydroascorbate reductase in glutathione homeostasis in plants. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:3405-3416. [PMID: 32107543 DOI: 10.1093/jxb/eraa107] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Accepted: 02/25/2020] [Indexed: 05/20/2023]
Abstract
Under natural conditions, plants are exposed to various abiotic and biotic stresses that trigger rapid changes in the production and removal of reactive oxygen species (ROS) such as hydrogen peroxide (H2O2). The ascorbate-glutathione pathway has been recognized to be a key player in H2O2 metabolism, in which reduced glutathione (GSH) regenerates ascorbate by reducing dehydroascorbate (DHA), either chemically or via DHA reductase (DHAR), an enzyme belonging to the glutathione S-transferase (GST) superfamily. Thus, DHAR has been considered to be important in maintaining the ascorbate pool and its redox state. Although some GSTs and peroxiredoxins may contribute to GSH oxidation, analysis of Arabidopsis dhar mutants has identified the key role of DHAR in coupling H2O2 to GSH oxidation. The reaction of DHAR has been proposed to proceed by a ping-pong mechanism, in which binding of DHA to the free reduced form of the enzyme is followed by binding of GSH. Information from crystal structures has shed light on the formation of sulfenic acid at the catalytic cysteine of DHAR that occurs with the reduction of DHA. In this review, we discuss the molecular properties of DHAR and its importance in coupling the ascorbate and glutathione pools with H2O2 metabolism, together with its functions in plant defense, growth, and development.
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Affiliation(s)
- Haiyan Ding
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, Wuhan, China
| | - Bipeng Wang
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, Wuhan, China
| | - Yi Han
- School of Food and Biological Engineering, Hefei University of Technology, Hefei, China
- Engineering Research Center of Bio-process, Ministry of Education, Hefei University of Technology, Hefei, China
| | - Shengchun Li
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, Wuhan, China
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Bandyopadhyay T, Muthamilarasan M, Prasad M. Millets for Next Generation Climate-Smart Agriculture. FRONTIERS IN PLANT SCIENCE 2017; 8:1266. [PMID: 28769966 PMCID: PMC5513978 DOI: 10.3389/fpls.2017.01266] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 07/05/2017] [Indexed: 05/04/2023]
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Non-native ligands define the active site of Pennisetum glaucum (L.) R. Br dehydroascorbate reductase. Biochem Biophys Res Commun 2016; 473:1152-1157. [PMID: 27067046 DOI: 10.1016/j.bbrc.2016.04.031] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 04/07/2016] [Indexed: 11/21/2022]
Abstract
Dehydroascorbate reductase (DHAR), a member of the glutathione-S-transferase (GST) family, reduces dehydroascorbate (DHA) to ascorbate (AsA; Vitamin-C) in a glutathione (GSH)-dependent manner and in doing so, replenishes the critical AsA pool of the cell. To understand the enzyme mechanism in detail, we determined the crystal structure of a plant DHAR from Pennisetum glaucum (PgDHAR) using Iodide-Single Anomalous Dispersion (SAD) and Molecular replacement methods, in two different space groups. Here, we show PgDHAR in complex with two non-native ligands, viz. an acetate bound at the G-site, which resembles the γ-carboxyl moiety of GSH, and a glycerol at the H-site, which shares the backbone of AsA. We also show that, in the absence of bound native substrates, these non-native ligands help define the critical 'hook points' in the DHAR enzyme active site. Further, our data suggest that these non-native ligands can act as the logical bootstrapping points for iterative design of inhibitors/analogs for DHARs.
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