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Ashraf M, Mao Q, Hong J, Shi L, Ran X, Liaquat F, Uzair M, Liang W, Fernie AR, Shi J. HSP70-16 and VDAC3 jointly inhibit seed germination under cold stress in Arabidopsis. PLANT, CELL & ENVIRONMENT 2021; 44:3616-3627. [PMID: 34173257 DOI: 10.1111/pce.14138] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 06/09/2021] [Accepted: 06/20/2021] [Indexed: 06/13/2023]
Abstract
Abscisic acid (ABA) transport plays a crucial role in seed germination under unfavourable conditions such as cold stress. Both heat shock protein 70 (HSP70) and voltage-dependent anion channel (VDAC) protein are involved in cold stress responses in Arabidopsis. However, their roles in seed germination with regard to ABA signaling remain unknown. Here we demonstrated that Arabidopsis HSP70-16 and VDAC3 jointly suppress seed germination under cold stress conditions. At 4°C, both HSP70-16 and VDAC3 facilitated the efflux of ABA from the endosperm to the embryo and thus inhibited seed germination. HSP70-16 interacted with VDAC3 on the plasma membrane and in the nucleus, and the interplay between HSP70-16 and VDAC3 activated the opening of the VDAC3 ion channel. Our work established a novel function of HSP70-16 in seed germination under cold stress and a possible association of VDAC3 activity with ABA transportation from endosperm to embryo under cold stress conditions. This study reveals that HSP70-16 interacts with VDAC3 and facilitates the opening of the VDAC3 ion channel, which influences ABA efflux from endosperm to embryo, thus negatively regulates seed germination under cold stress.
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Affiliation(s)
- Muhammad Ashraf
- Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Qionglei Mao
- CAS Key Laboratory of Receptor Research, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Jun Hong
- Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Lei Shi
- Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Xiaoruo Ran
- Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Fiza Liaquat
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
| | - Muhammad Uzair
- Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Wanqi Liang
- Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Alisdair R Fernie
- Department of Molecular Physiology, Max-Planck-Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| | - Jianxin Shi
- Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
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2
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Diddi N, Lai L, Brookbank BP, Hussain S, Nambara E, Todd C, Nourimand M, Tar'an B, Song D, Holbrook L, Doshi K, Loewen MC, Luna EK, Shipp J, Leach JE, Robinson SJ, Abrams SR. 3'-(Phenyl alkynyl) analogs of abscisic acid: synthesis and biological activity of potent ABA antagonists. Org Biomol Chem 2021; 19:2978-2985. [PMID: 33729254 DOI: 10.1039/d1ob00166c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report here the synthesis and biological testing of 3'-(phenyl alkynyl) abscisic ABA analogs, a new class of potent ABA antagonists. These ABA analogs incorporate a rigid framework of eight carbon atoms attached at the 3'-carbon atom of ABA that prevents folding of the ABA analog-bound receptor required for ABA signalling. The two-step synthesis is based upon the optimized conversion of natural (S)-ABA to 3'-iodo ABA which can be coupled to phenyl acetylenes using Sonogashira conditions, or to styryl compounds through Suzuki chemistry. The parent 3'-(phenyl alkynyl) ABA analog 7 was obtained in 29% yield, 74% yield based on recovered starting material. In a lentil seed germination assay, compound 7 was found to have more potent activity than other known 3'-substituted ABA antagonists to date. In a structure activity study parasubstituted phenyl alkynyl analogs had comparable activity to the analog 7 while the 3'-styryl ABA 18 was only slightly less active. Analog 7 overcame ABA inhibition of germination and seedling growth in a wide range of mono and dicot plant species, including canola, lentil, soybean, rice, wheat, barley, cannabis and canary seed. 3'-(Phenyl alkynyl) ABA analogs have numerous potential practical agricultural applications including promoting ripening of crops, dormancy breaking of seeds and woody perennials, as well as promoting seed germination, and growth under stress conditions as demonstrated in this report.
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Affiliation(s)
- Naveen Diddi
- Department of Chemistry, University of Saskatchewan, Saskatoon, SK S7N 5C9, Canada.
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Gao F, Yu S, Tao Q, Tan W, Duan L, Li Z, Cui H. Lignosulfonate Improves Photostability and Bioactivity of Abscisic Acid under Ultraviolet Radiation. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2018; 66:6585-6593. [PMID: 28851212 DOI: 10.1021/acs.jafc.7b02002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Abscisic acid (ABA), as a commonly used plant growth regulator, is easy to be degraded and lose its bioactivity under sunshine. To select an eco-friendly and efficient photoprotectant for the improvement of photostability and bioactivity of ABA when exposed to ultraviolet (UV) light, we tested the effects of three biodegradable natural-derived high polymers, sodium lignosulfonates 3A [molecular weight (MW) > 50000, with degree of sulfonation (DS) of 0.48] and NA (20000 < MW < 50000, with DS of 0.7) and calcium lignosulfonate CASA (MW < 20000, with DS of 0.7), on the photodegradation of ABA. Lignosulfonates 3A, NA, and CASA showed significant photostabilizing capability on ABA. Lignosulfonate 3A showed preferable photostabilizing effects on ABA compared to CASA, while NA showed an intermediate effect. That indicated that lignosulfonate with a high MW and low DS had a stronger UV absorption and the hollow aggregate micelles formatted by lignosulfonate protect ABA from UV damage. Approximately 50% more ABA was kept when 280 mg/L ABA aqueous solution was irradiated by UV light for 2 h in the presence of 2000 mg/L lignosulfonate 3A. The bioactivity on wheat (JIMAI 22) seed germination was greatly kept by 3A in comparison to that of ABA alone. The 300 times diluent of 280 mg/L ABA plus 2000 mg/L 3A after 2 h of irradiation showed 20.8, 19.3, and 9.3% more inhibition on shoot growth, root growth, and root numbers of wheat seed, separately, in comparison to ABA diluent alone. We conclude that lignosulfonate 3A was an eco-friendly and efficient agent to keep ABA activity under UV radiation. This research could be used in UV-sensitive and water-soluble agrichemicals and to optimize the application times and dosages of ABA products.
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Affiliation(s)
- Fei Gao
- Institute of Environment and Sustainable Development in Agriculture , Chinese Academy of Agricultural Sciences , Beijing 100081 , People's Republic of China
- State Key Laboratory of Plant Physiology and Biochemistry, Engineering Research Center of Plant Growth Regulators, Ministry of Education, College of Agronomy and Biotechnology , China Agricultural University , Beijing 100193 , People's Republic of China
| | - Sha Yu
- State Key Laboratory of Plant Physiology and Biochemistry, Engineering Research Center of Plant Growth Regulators, Ministry of Education, College of Agronomy and Biotechnology , China Agricultural University , Beijing 100193 , People's Republic of China
| | - Qun Tao
- State Key Laboratory of Plant Physiology and Biochemistry, Engineering Research Center of Plant Growth Regulators, Ministry of Education, College of Agronomy and Biotechnology , China Agricultural University , Beijing 100193 , People's Republic of China
| | - Weiming Tan
- State Key Laboratory of Plant Physiology and Biochemistry, Engineering Research Center of Plant Growth Regulators, Ministry of Education, College of Agronomy and Biotechnology , China Agricultural University , Beijing 100193 , People's Republic of China
| | - Liusheng Duan
- State Key Laboratory of Plant Physiology and Biochemistry, Engineering Research Center of Plant Growth Regulators, Ministry of Education, College of Agronomy and Biotechnology , China Agricultural University , Beijing 100193 , People's Republic of China
| | - Zhaohu Li
- State Key Laboratory of Plant Physiology and Biochemistry, Engineering Research Center of Plant Growth Regulators, Ministry of Education, College of Agronomy and Biotechnology , China Agricultural University , Beijing 100193 , People's Republic of China
| | - Haixin Cui
- Institute of Environment and Sustainable Development in Agriculture , Chinese Academy of Agricultural Sciences , Beijing 100081 , People's Republic of China
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Ramirez L, Negri P, Sturla L, Guida L, Vigliarolo T, Maggi M, Eguaras M, Zocchi E, Lamattina L. Abscisic acid enhances cold tolerance in honeybee larvae. Proc Biol Sci 2018; 284:rspb.2016.2140. [PMID: 28381619 DOI: 10.1098/rspb.2016.2140] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Accepted: 03/08/2017] [Indexed: 12/14/2022] Open
Abstract
The natural composition of nutrients present in food is a key factor determining the immune function and stress responses in the honeybee (Apis mellifera). We previously demonstrated that a supplement of abscisic acid (ABA), a natural component of nectar, pollen, and honey, increases honeybee colony survival overwinter. Here we further explored the role of ABA in in vitro-reared larvae exposed to low temperatures. Four-day-old larvae (L4) exposed to 25°C for 3 days showed lower survival rates and delayed development compared to individuals growing at a standard temperature (34°C). Cold-stressed larvae maintained higher levels of ABA for longer than do larvae reared at 34°C, suggesting a biological significance for ABA. Larvae fed with an ABA-supplemented diet completely prevent the low survival rate due to cold stress and accelerate adult emergence. ABA modulates the expression of genes involved in metabolic adjustments and stress responses: Hexamerin 70b, Insulin Receptor Substrate, Vitellogenin, and Heat Shock Proteins 70. AmLANCL2, the honeybee ABA receptor, is also regulated by cold stress and ABA. These results support a role for ABA increasing the tolerance of honeybee larvae to low temperatures through priming effects.
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Affiliation(s)
- Leonor Ramirez
- Instituto de Investigaciones Biológicas, CONICET - Universidad Nacional de Mar del Plata (UNMdP), CC 1245, 7600 Mar del Plata, Argentina
| | - Pedro Negri
- Centro de Investigación en Abejas Sociales (CIAS), FCEyN, UNMdP, 7600 Mar del Plata, Argentina
| | - Laura Sturla
- DIMES-Sezione Biochimica, Università degli Studi di Genova, Viale Benedetto XV, 116132 Genova, Italia
| | - Lucrezia Guida
- DIMES-Sezione Biochimica, Università degli Studi di Genova, Viale Benedetto XV, 116132 Genova, Italia
| | - Tiziana Vigliarolo
- DIMES-Sezione Biochimica, Università degli Studi di Genova, Viale Benedetto XV, 116132 Genova, Italia
| | - Matías Maggi
- Centro de Investigación en Abejas Sociales (CIAS), FCEyN, UNMdP, 7600 Mar del Plata, Argentina
| | - Martín Eguaras
- Centro de Investigación en Abejas Sociales (CIAS), FCEyN, UNMdP, 7600 Mar del Plata, Argentina
| | - Elena Zocchi
- DIMES-Sezione Biochimica, Università degli Studi di Genova, Viale Benedetto XV, 116132 Genova, Italia
| | - Lorenzo Lamattina
- Instituto de Investigaciones Biológicas, CONICET - Universidad Nacional de Mar del Plata (UNMdP), CC 1245, 7600 Mar del Plata, Argentina
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Malara A, Fresia C, Di Buduo CA, Soprano PM, Moccia F, Balduini C, Zocchi E, De Flora A, Balduini A. The Plant Hormone Abscisic Acid Is a Prosurvival Factor in Human and Murine Megakaryocytes. J Biol Chem 2017; 292:3239-3251. [PMID: 28049729 DOI: 10.1074/jbc.m116.751693] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Revised: 12/23/2016] [Indexed: 11/06/2022] Open
Abstract
Abscisic acid (ABA) is a phytohormone involved in pivotal physiological functions in higher plants. Recently, ABA has been proven to be also secreted and active in mammals, where it stimulates the activity of innate immune cells, mesenchymal and hematopoietic stem cells, and insulin-releasing pancreatic β cells through a signaling pathway involving the second messenger cyclic ADP-ribose (cADPR). In addition to behaving like an animal hormone, ABA also holds promise as a nutraceutical plant-derived compound in humans. Many biological functions of ABA in mammals are mediated by its binding to the LANCL-2 receptor protein. A putative binding of ABA to GRP78, a key regulator of endoplasmic reticulum stress, has also been proposed. Here we investigated the role of exogenous ABA in modulating thrombopoiesis, the process of platelet generation. Our results demonstrate that expression of both LANCL-2 and GRP78 is up-regulated during hematopoietic stem cell differentiation into mature megakaryocytes (Mks). Functional ABA receptors exist in mature Mks because ABA induces an intracellular Ca2+ increase ([Ca2+] i ) through PKA activation and subsequent cADPR generation. In vitro exposure of human or murine hematopoietic progenitor cells to 10 μm ABA does not increase recombinant thrombopoietin (rTpo)-dependent Mk differentiation or platelet release. However, under conditions of cell stress induced by rTpo and serum deprivation, ABA stimulates, in a PKA- and cADPR-dependent fashion, the mitogen-activated kinase ERK 1/2, resulting in the modulation of lymphoma 2 (Bcl-2) family members, increased Mk survival, and higher rates of platelet production. In conclusion, we demonstrate that ABA is a prosurvival factor for Mks in a Tpo-independent manner.
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Affiliation(s)
- Alessandro Malara
- Departments of Molecular Medicine, Laboratories of Biotechnology, IRCCS San Matteo Foundation
| | - Chiara Fresia
- Department of Experimental Medicine, Section of Biochemistry, University of Genova, Genova 16132, Italy
| | | | - Paolo Maria Soprano
- Departments of Molecular Medicine, Laboratories of Biotechnology, IRCCS San Matteo Foundation
| | - Francesco Moccia
- Biology and Biotechnology, University of Pavia, Pavia 27100, Italy
| | - Cesare Balduini
- Biology and Biotechnology, University of Pavia, Pavia 27100, Italy
| | - Elena Zocchi
- Department of Experimental Medicine, Section of Biochemistry, University of Genova, Genova 16132, Italy
| | - Antonio De Flora
- Department of Experimental Medicine, Section of Biochemistry, University of Genova, Genova 16132, Italy
| | - Alessandra Balduini
- Departments of Molecular Medicine, Laboratories of Biotechnology, IRCCS San Matteo Foundation; Department of Biomedical Engineering, Tufts University, Medford, Massachusetts 02155.
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6
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Lievens L, Pollier J, Goossens A, Beyaert R, Staal J. Abscisic Acid as Pathogen Effector and Immune Regulator. FRONTIERS IN PLANT SCIENCE 2017; 8:587. [PMID: 28469630 PMCID: PMC5395610 DOI: 10.3389/fpls.2017.00587] [Citation(s) in RCA: 103] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2017] [Accepted: 03/31/2017] [Indexed: 05/18/2023]
Abstract
Abscisic acid (ABA) is a sesquiterpene signaling molecule produced in all kingdoms of life. To date, the best known functions of ABA are derived from its role as a major phytohormone in plant abiotic stress resistance. Different organisms have developed different biosynthesis and signal transduction pathways related to ABA. Despite this, there are also intriguing common themes where ABA often suppresses host immune responses and is utilized by pathogens as an effector molecule. ABA also seems to play an important role in compatible mutualistic interactions such as mycorrhiza and rhizosphere bacteria with plants, and possibly also the animal gut microbiome. The frequent use of ABA in inter-species communication could be a possible reason for the wide distribution and re-invention of ABA as a signaling molecule in different organisms. In humans and animal models, it has been shown that ABA treatment or nutrient-derived ABA is beneficial in inflammatory diseases like colitis and type 2 diabetes, which confer potential to ABA as an interesting nutraceutical or pharmacognostic drug. The anti-inflammatory activity, cellular metabolic reprogramming, and other beneficial physiological and psychological effects of ABA treatment in humans and animal models has sparked an interest in this molecule and its signaling pathway as a novel pharmacological target. In contrast to plants, however, very little is known about the ABA biosynthesis and signaling in other organisms. Genes, tools and knowledge about ABA from plant sciences and studies of phytopathogenic fungi might benefit biomedical studies on the physiological role of endogenously generated ABA in humans.
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Affiliation(s)
- Laurens Lievens
- Unit of Molecular Signal Transduction in Inflammation, VIB-UGent Center for Inflammation Research, VIBGhent, Belgium
- Department of Biomedical Molecular Biology, Ghent UniversityGhent, Belgium
| | - Jacob Pollier
- VIB-UGent Center for Plant Systems Biology, VIBGhent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent UniversityGhent, Belgium
| | - Alain Goossens
- VIB-UGent Center for Plant Systems Biology, VIBGhent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent UniversityGhent, Belgium
| | - Rudi Beyaert
- Unit of Molecular Signal Transduction in Inflammation, VIB-UGent Center for Inflammation Research, VIBGhent, Belgium
- Department of Biomedical Molecular Biology, Ghent UniversityGhent, Belgium
| | - Jens Staal
- Unit of Molecular Signal Transduction in Inflammation, VIB-UGent Center for Inflammation Research, VIBGhent, Belgium
- Department of Biomedical Molecular Biology, Ghent UniversityGhent, Belgium
- *Correspondence: Jens Staal
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7
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Gordon CS, Rajagopalan N, Risseeuw EP, Surpin M, Ball FJ, Barber CJ, Buhrow LM, Clark SM, Page JE, Todd CD, Abrams SR, Loewen MC. Characterization of Triticum aestivum Abscisic Acid Receptors and a Possible Role for These in Mediating Fusairum Head Blight Susceptibility in Wheat. PLoS One 2016; 11:e0164996. [PMID: 27755583 PMCID: PMC5068739 DOI: 10.1371/journal.pone.0164996] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Accepted: 10/04/2016] [Indexed: 01/31/2023] Open
Abstract
Abscisic acid (ABA) is a well-characterized plant hormone, known to mediate developmental aspects as well as both abiotic and biotic stress responses. Notably, the exogenous application of ABA has recently been shown to increase susceptibility to the fungal pathogen Fusarium graminearum, the causative agent of Fusarium head blight (FHB) in wheat and other cereals. However roles and mechanisms associated with ABA's modulation of pathogen responses remain enigmatic. Here the identification of putative ABA receptors from available genomic databases for Triticum aestivum (bread wheat) and Brachypodium distachyon (a model cereal) are reported. A number of these were cloned for recombinant expression and their functionality as ABA receptors confirmed by in vitro assays against protein phosphatases Type 2Cs. Ligand selectivity profiling of one of the wheat receptors (Ta_PYL2DS_FL) highlighted unique activities compared to Arabidopsis AtPYL5. Mutagenic analysis showed Ta_PYL2DS_FL amino acid D180 as being a critical contributor to this selectivity. Subsequently, a virus induced gene silencing (VIGS) approach was used to knockdown wheat Ta_PYL4AS_A (and similar) in planta, yielding plants with increased early stage resistance to FHB progression and decreased mycotoxin accumulation. Together these results confirm the existence of a family of ABA receptors in wheat and Brachypodium and present insight into factors modulating receptor function at the molecular level. That knockdown of Ta_PYL4AS_A (and similar) leads to early stage FHB resistance highlights novel targets for investigation in the future development of disease resistant crops.
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Affiliation(s)
- Cameron S. Gordon
- Department of Biochemistry, University of Saskatchewan, 107 Wiggins Rd., Saskatoon, SK, S7N 5E5, Canada
- National Research Council of Canada, 110 Gymnasium Place, Saskatoon, SK, S7N 0W9, Canada
| | | | - Eddy P. Risseeuw
- National Research Council of Canada, 110 Gymnasium Place, Saskatoon, SK, S7N 0W9, Canada
| | - Marci Surpin
- Valent BioSciences Corporation, 870 Technology Way, Libertyville, Illinois, 60048, United States of America
| | - Fraser J. Ball
- National Research Council of Canada, 110 Gymnasium Place, Saskatoon, SK, S7N 0W9, Canada
| | - Carla J. Barber
- National Research Council of Canada, 110 Gymnasium Place, Saskatoon, SK, S7N 0W9, Canada
| | - Leann M. Buhrow
- National Research Council of Canada, 110 Gymnasium Place, Saskatoon, SK, S7N 0W9, Canada
| | - Shawn M. Clark
- National Research Council of Canada, 110 Gymnasium Place, Saskatoon, SK, S7N 0W9, Canada
| | - Jonathan E. Page
- National Research Council of Canada, 110 Gymnasium Place, Saskatoon, SK, S7N 0W9, Canada
| | - Chris D. Todd
- Department of Biology, University of Saskatchewan, 112 Science Place, Saskatoon, SK, S7N 5E2, Canada
| | - Suzanne R. Abrams
- National Research Council of Canada, 110 Gymnasium Place, Saskatoon, SK, S7N 0W9, Canada
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, SK, S7N 5C9, Canada
| | - Michele C. Loewen
- Department of Biochemistry, University of Saskatchewan, 107 Wiggins Rd., Saskatoon, SK, S7N 5E5, Canada
- National Research Council of Canada, 110 Gymnasium Place, Saskatoon, SK, S7N 0W9, Canada
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8
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Rajagopalan N, Nelson KM, Douglas AF, Jheengut V, Alarcon IQ, McKenna SA, Surpin M, Loewen MC, Abrams SR. Abscisic Acid Analogues That Act as Universal or Selective Antagonists of Phytohormone Receptors. Biochemistry 2016; 55:5155-64. [DOI: 10.1021/acs.biochem.6b00605] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | - Ken M. Nelson
- National Research Council of Canada, 110 Gymnasium Place, Saskatoon, SK, Canada S7N 0W9
- Department
of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, SK, Canada S7N 5C9
| | - Amy F. Douglas
- National Research Council of Canada, 110 Gymnasium Place, Saskatoon, SK, Canada S7N 0W9
| | - Vishal Jheengut
- National Research Council of Canada, 110 Gymnasium Place, Saskatoon, SK, Canada S7N 0W9
| | - Idralyn Q. Alarcon
- Department
of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, SK, Canada S7N 5C9
| | - Sean A. McKenna
- Department
of Chemistry, University of Manitoba,144 Dysart Road, Winnipeg, MB, Canada R3T 2N2
| | - Marci Surpin
- Valent BioSciences Corporation, 870 Technology Way, Libertyville, Illinois 60048, United States
| | - Michele C. Loewen
- National Research Council of Canada, 100 Sussex Drive, Ottawa, ON, Canada K1N 5A2
- Department
of Biochemistry, University of Saskatchewan, 107 Wiggins Road, Saskatoon, SK, Canada S7N 5E5
| | - Suzanne R. Abrams
- Department
of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, SK, Canada S7N 5C9
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9
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Abstract
Abscisic acid ((+)-ABA) is a phytohormone involved in the modulation of developmental processes and stress responses in plants. A chemical proteomics approach using an ABA mimetic probe was combined with in vitro assays, isothermal titration calorimetry (ITC), x-ray crystallography and in silico modelling to identify putative (+)-ABA binding-proteins in crude extracts of Arabidopsis thaliana. Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) was identified as a putative ABA-binding protein. Radiolabelled-binding assays yielded a Kd of 47 nM for (+)-ABA binding to spinach Rubisco, which was validated by ITC, and found to be similar to reported and experimentally derived values for the native ribulose-1,5-bisphosphate (RuBP) substrate. Functionally, (+)-ABA caused only weak inhibition of Rubisco catalytic activity (Ki of 2.1 mM), but more potent inhibition of Rubisco activation (Ki of ~ 130 μM). Comparative structural analysis of Rubisco in the presence of (+)-ABA with RuBP in the active site revealed only a putative low occupancy (+)-ABA binding site on the surface of the large subunit at a location distal from the active site. However, subtle distortions in electron density in the binding pocket and in silico docking support the possibility of a higher affinity (+)-ABA binding site in the RuBP binding pocket. Overall we conclude that (+)-ABA interacts with Rubisco. While the low occupancy (+)-ABA binding site and weak non-competitive inhibition of catalysis may not be relevant, the high affinity site may allow ABA to act as a negative effector of Rubisco activation.
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10
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Pydi SP, Jaggupilli A, Nelson KM, Abrams SR, Bhullar RP, Loewen MC, Chelikani P. Abscisic Acid Acts as a Blocker of the Bitter Taste G Protein-Coupled Receptor T2R4. Biochemistry 2015; 54:2622-31. [PMID: 25844797 DOI: 10.1021/acs.biochem.5b00265] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Bitter taste receptors (T2Rs) belong to the G protein-coupled receptor superfamily. In humans, 25 T2Rs mediate bitter taste sensation. In addition to the oral cavity, T2Rs are expressed in many extraoral tissues, including the central nervous system, respiratory system, and reproductive system. To understand the mechanistic roles of the T2Rs in oral and extraoral tissues, novel blockers or antagonists are urgently needed. Recently, we elucidated the binding pocket of T2R4 for its agonist quinine, and an antagonist and inhibitory neurotransmitter, γ-aminobutyric acid. This structure-function information about T2R4 led us to screen the plant hormone abscisic acid (ABA), its precursor (xanthoxin), and catabolite phaseic acid for their ability to bind and activate or inhibit T2R4. Molecular docking studies followed by functional assays involving calcium imaging confirmed that ABA is an antagonist with an IC50 value of 34.4 ± 1.1 μM. However, ABA precursor xanthoxin acts as an agonist on T2R4. Interestingly, molecular model-guided site-directed mutagenesis suggests that the T2R4 residues involved in quinine binding are also predominantly involved in binding to the novel antagonist, ABA. The antagonist ability of ABA was tested using another T2R4 agonist, yohimbine. Our results suggest that ABA does not inhibit yohimbine-induced T2R4 activity. The discovery of natural bitter blockers has immense nutraceutical and physiological significance and will help in dissecting the T2R molecular pathways in various tissues.
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Affiliation(s)
- Sai P Pydi
- †Department of Oral Biology, University of Manitoba, Winnipeg, MB R3E 0W4, Canada
| | | | - Ken M Nelson
- ∥Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, SK S7N 5C9, Canada
| | - Suzanne R Abrams
- ∥Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, SK S7N 5C9, Canada
| | - Rajinder P Bhullar
- †Department of Oral Biology, University of Manitoba, Winnipeg, MB R3E 0W4, Canada
| | - Michele C Loewen
- ‡National Research Council of Canada, 110 Gymnasium Place, Saskatoon, SK S7N 0W9, Canada.,§Department of Biochemistry, University of Saskatchewan, 105 Wiggins Road, Saskatoon, SK S7N 5N5, Canada
| | - Prashen Chelikani
- †Department of Oral Biology, University of Manitoba, Winnipeg, MB R3E 0W4, Canada
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