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Pavlovic T, Margarit E, Müller GL, Saenz E, Ruzzo AI, Drincovich MF, Borrás L, Saigo M, Wheeler MCG. Differential metabolic reprogramming in developing soybean embryos in response to nutritional conditions and abscisic acid. Plant Mol Biol 2023; 113:89-103. [PMID: 37702897 DOI: 10.1007/s11103-023-01377-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2022] [Accepted: 08/29/2023] [Indexed: 09/14/2023]
Abstract
Seed storage compound deposition is influenced by both maternal and filial tissues. Within this framework, we analyzed strategies that operate during the development and filling of soybean embryos, using in vitro culture systems combined with metabolomics and proteomics approaches. The carbon:nitrogen ratio (C:N) of the maternal supply and the hormone abscisic acid (ABA) are specific and interacting signals inducing differential metabolic reprogrammings linked to changes in the accumulation of storage macromolecules like proteins or oils. Differences in the abundance of sugars, amino acids, enzymes, transporters, transcription factors, and proteins involved in signaling were detected. Embryos adapted to the nutritional status by enhancing the metabolism of both carbon and nitrogen under lower C:N ratio condition or only carbon under higher C:N ratio condition. ABA turned off multiple pathways especially in high availability of amino acids, prioritizing the storage compounds biosynthesis. Common responses induced by ABA involved increased sucrose uptake (to increase the sink force) and oleosin (oil body structural component) accumulation. In turn, ABA differentially promoted protein degradation under lower nitrogen supply in order to sustain the metabolic demands. Further, the operation of a citrate shuttle was suggested by transcript quantification and enzymatic activity measurements. The results obtained are useful to help define biotechnological tools and technological approaches to improve oil and protein yields, with direct impact on human and animal nutrition as well as in green chemistry.
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Affiliation(s)
- Tatiana Pavlovic
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 570, S2000LRJ, Rosario, Santa Fe, Argentina
| | - Ezequiel Margarit
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 570, S2000LRJ, Rosario, Santa Fe, Argentina
| | - Gabriela Leticia Müller
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 570, S2000LRJ, Rosario, Santa Fe, Argentina
| | - Ezequiel Saenz
- Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR-CONICET), Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, Campo Experimental Villarino CC14, S2125ZAA, Zavalla, Santa Fe, Argentina
| | - Andrés Iván Ruzzo
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 570, S2000LRJ, Rosario, Santa Fe, Argentina
| | - María Fabiana Drincovich
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 570, S2000LRJ, Rosario, Santa Fe, Argentina
| | - Lucas Borrás
- Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR-CONICET), Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, Campo Experimental Villarino CC14, S2125ZAA, Zavalla, Santa Fe, Argentina
| | - Mariana Saigo
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 570, S2000LRJ, Rosario, Santa Fe, Argentina.
| | - Mariel Claudia Gerrard Wheeler
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 570, S2000LRJ, Rosario, Santa Fe, Argentina.
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Gerrard Wheeler MC, Arias CL, E Mello JDFR, Cirauqui Diaz N, Rodrigues CR, Drincovich MF, de Souza AMT, Alvarez CE. Structural insights into the allosteric site of Arabidopsis NADP-malic enzyme 2: role of the second sphere residues in the regulatory signal transmission. Plant Mol Biol 2021; 107:37-48. [PMID: 34333694 DOI: 10.1007/s11103-021-01176-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Accepted: 07/22/2021] [Indexed: 06/13/2023]
Abstract
NADP-ME2 from Arabidopsis thaliana exhibits a distinctive and complex regulation by fumarate, acting as an activator or an inhibitor according to substrate and effector concentrations. In this work, we used molecular modeling approach and site-directed mutagenesis to characterized the NADP-ME2 structural determinants necessary for allosteric regulation providing new insights for enzyme optimization. Structure-function studies contribute to deciphering how small modifications in the primary structure could introduce desirable characteristics into enzymes without affecting its overall functioning. Malic enzymes (ME) are ubiquitous and responsible for a wide variety of functions. The availability of a high number of ME crystal structures from different species facilitates comparisons between sequence and structure. Specifically, the structural determinants necessary for fumarate allosteric regulation of ME has been of particular interest. NADP-ME2 from Arabidopsis thaliana exhibits a distinctive and complex regulation by fumarate, acting as an activator or an inhibitor according to substrate and effector concentrations. However, the 3D structure for this enzyme is not yet reported. In this work, we characterized the NADP-ME2 allosteric site by structural modeling, molecular docking, normal mode analysis and mutagenesis. The regulatory site model and its docking analysis suggested that other C4 acids including malate, NADP-ME2 substrate, could also fit into fumarate's pocket. Besides, a non-conserved cluster of hydrophobic residues in the second sphere of the allosteric site was identified. The substitution of one of those residues, L62, by a less flexible residue as tryptophan, resulted in a complete loss of fumarate activation and a reduction of substrate affinities for the active site. In addition, normal mode analysis indicated that conformational changes leading to the activation could originate in the region surrounding L62, extending through the allosteric site till the active site. Finally, the results in this work contribute to the understanding of structural determinants necessary for allosteric regulation providing new insights for enzyme optimization.
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Affiliation(s)
- Mariel Claudia Gerrard Wheeler
- Centro de Estudios Fotosintéticos y Bioquímicos, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (CEFOBI-CONICET-UNR), Suipacha 570, Rosario, Argentina
| | - Cintia Lucía Arias
- Centro de Estudios Fotosintéticos y Bioquímicos, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (CEFOBI-CONICET-UNR), Suipacha 570, Rosario, Argentina
| | - Juliana da Fonseca Rezende E Mello
- Faculdade de Farmácia, Laboratório de Modelagem Molecular & QSAR (ModMolQSAR), Universidade Federal do Rio de Janeiro, Av. Carlos Chagas Filho, 373 bloco L subsolo, Cidade Universitária, Rio de Janeiro, Brazil
| | - Nuria Cirauqui Diaz
- Faculdade de Farmácia, Laboratório de Modelagem Molecular & QSAR (ModMolQSAR), Universidade Federal do Rio de Janeiro, Av. Carlos Chagas Filho, 373 bloco L subsolo, Cidade Universitária, Rio de Janeiro, Brazil
| | - Carlos Rangel Rodrigues
- Faculdade de Farmácia, Laboratório de Modelagem Molecular & QSAR (ModMolQSAR), Universidade Federal do Rio de Janeiro, Av. Carlos Chagas Filho, 373 bloco L subsolo, Cidade Universitária, Rio de Janeiro, Brazil
| | - María Fabiana Drincovich
- Centro de Estudios Fotosintéticos y Bioquímicos, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (CEFOBI-CONICET-UNR), Suipacha 570, Rosario, Argentina
| | - Alessandra Mendonça Teles de Souza
- Faculdade de Farmácia, Laboratório de Modelagem Molecular & QSAR (ModMolQSAR), Universidade Federal do Rio de Janeiro, Av. Carlos Chagas Filho, 373 bloco L subsolo, Cidade Universitária, Rio de Janeiro, Brazil.
| | - Clarisa Ester Alvarez
- Centro de Estudios Fotosintéticos y Bioquímicos, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (CEFOBI-CONICET-UNR), Suipacha 570, Rosario, Argentina.
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Badia MB, Maurino VG, Pavlovic T, Arias CL, Pagani MA, Andreo CS, Saigo M, Drincovich MF, Gerrard Wheeler MC. Loss of function of Arabidopsis NADP-malic enzyme 1 results in enhanced tolerance to aluminum stress. Plant J 2020; 101:653-665. [PMID: 31626366 DOI: 10.1111/tpj.14571] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Revised: 09/10/2019] [Accepted: 09/19/2019] [Indexed: 05/29/2023]
Abstract
In acidic soils, aluminum (Al) toxicity is a significant limitation to crop production worldwide. Given its Al-binding capacity, malate allows internal as well as external detoxification strategies to cope with Al stress, but little is known about the metabolic processes involved in this response. Here, we analyzed the relevance of NADP-dependent malic enzyme (NADP-ME), which catalyzes the oxidative decarboxylation of malate, in Al tolerance. Plants lacking NADP-ME1 (nadp-me1) display reduced inhibition of root elongation along Al treatment compared with the wild type (wt). Moreover, wt roots exposed to Al show a drastic decrease in NADP-ME1 transcript levels. Although malate levels in seedlings and root exudates are similar in nadp-me1 and wt, a significant increase in intracellular malate is observed in roots of nadp-me1 after long exposure to Al. The nadp-me1 plants also show a lower H2 O2 content in root apices treated with Al and no inhibition of root elongation when exposed to glutamate, an amino acid implicated in Al signaling. Proteomic studies showed several differentially expressed proteins involved in signal transduction, primary metabolism and protection against biotic and other abiotic stimuli and redox processes in nadp-me1, which may participate directly or indirectly in Al tolerance. The results indicate that NADP-ME1 is involved in adjusting the malate levels in the root apex, and its loss results in an increased content of this organic acid. Furthermore, the results suggest that NADP-ME1 affects signaling processes, such as the generation of reactive oxygen species and those that involve glutamate, which could lead to inhibition of root growth.
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Affiliation(s)
- Mariana Beatriz Badia
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Suipacha 531, 2000, Rosario, Argentina
| | - Verónica Graciela Maurino
- Institute of Developmental and Molecular Biology of Plants, Plant Molecular Physiology and Biotechnology Group, Heinrich-Heine-Universität, Universitätsstrasse 1, 40225, Düsseldorf, Germany
- Cluster of Excellence on Plant Sciences (CEPLAS), Universitätsstrasse 1, 40225, Düsseldorf, Germany
| | - Tatiana Pavlovic
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Suipacha 531, 2000, Rosario, Argentina
| | - Cintia Lucía Arias
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Suipacha 531, 2000, Rosario, Argentina
| | - María Ayelén Pagani
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Suipacha 531, 2000, Rosario, Argentina
| | - Carlos Santiago Andreo
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Suipacha 531, 2000, Rosario, Argentina
| | - Mariana Saigo
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Suipacha 531, 2000, Rosario, Argentina
| | - María Fabiana Drincovich
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Suipacha 531, 2000, Rosario, Argentina
| | - Mariel Claudia Gerrard Wheeler
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Suipacha 531, 2000, Rosario, Argentina
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Badia MB, Mans R, Lis AV, Tronconi MA, Arias CL, Maurino VG, Andreo CS, Drincovich MF, van Maris AJA, Gerrard Wheeler MC. Specific Arabidopsis thaliana malic enzyme isoforms can provide anaplerotic pyruvate carboxylation function in Saccharomyces cerevisiae. FEBS J 2017; 284:654-665. [PMID: 28075062 DOI: 10.1111/febs.14013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2016] [Revised: 01/04/2017] [Accepted: 01/05/2017] [Indexed: 11/29/2022]
Abstract
NAD(P)-malic enzyme (NAD(P)-ME) catalyzes the reversible oxidative decarboxylation of malate to pyruvate, CO2 , and NAD(P)H and is present as a multigene family in Arabidopsis thaliana. The carboxylation reaction catalyzed by purified recombinant Arabidopsis NADP-ME proteins is faster than those reported for other animal or plant isoforms. In contrast, no carboxylation activity could be detected in vitro for the NAD-dependent counterparts. In order to further investigate their putative carboxylating role in vivo, Arabidopsis NAD(P)-ME isoforms, as well as the NADP-ME2del2 (with a decreased ability to carboxylate pyruvate) and NADP-ME2R115A (lacking fumarate activation) versions, were functionally expressed in the cytosol of pyruvate carboxylase-negative (Pyc- ) Saccharomyces cerevisiae strains. The heterologous expression of NADP-ME1, NADP-ME2 (and its mutant proteins), and NADP-ME3 restored the growth of Pyc- S. cerevisiae on glucose, and this capacity was dependent on the availability of CO2 . On the other hand, NADP-ME4, NAD-ME1, and NAD-ME2 could not rescue the Pyc- strains from C4 auxotrophy. NADP-ME carboxylation activity could be measured in leaf crude extracts of knockout and overexpressing Arabidopsis lines with modified levels of NADP-ME, where this activity was correlated with the amount of NADP-ME2 transcript. These results indicate that specific A. thaliana NADP-ME isoforms are able to play an anaplerotic role in vivo and provide a basis for the study on the carboxylating activity of NADP-ME, which may contribute to the synthesis of C4 compounds and redox shuttling in plant cells.
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Affiliation(s)
- Mariana Beatriz Badia
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI), Universidad Nacional de Rosario, Argentina
| | - Robert Mans
- Department of Biotechnology, Delft University of Technology, The Netherlands
| | - Alicia V Lis
- Department of Biotechnology, Delft University of Technology, The Netherlands.,Biochemical Engineering Institute, Saarland University, Saarbrücken, Germany
| | - Marcos Ariel Tronconi
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI), Universidad Nacional de Rosario, Argentina
| | - Cintia Lucía Arias
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI), Universidad Nacional de Rosario, Argentina
| | - Verónica Graciela Maurino
- Plant Molecular Physiology and Biotechnology Group, Institute of Developmental and Molecular Biology of Plants, Cluster of Excellence on Plant Sciences (CEPLAS), Heinrich-Heine-Universität, Düsseldorf, Germany
| | - Carlos Santiago Andreo
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI), Universidad Nacional de Rosario, Argentina
| | - María Fabiana Drincovich
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI), Universidad Nacional de Rosario, Argentina
| | - Antonius J A van Maris
- Department of Biotechnology, Delft University of Technology, The Netherlands.,Division of Industrial Biotechnology, School of Biotechnology, KTH Royal Institute of Technology, AlbaNova University Center, Stockholm, Sweden
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Gerrard Wheeler MC, Arias CL, Righini S, Badia MB, Andreo CS, Drincovich MF, Saigo M. Differential Contribution of Malic Enzymes during Soybean and Castor Seeds Maturation. PLoS One 2016; 11:e0158040. [PMID: 27347875 PMCID: PMC4922584 DOI: 10.1371/journal.pone.0158040] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Accepted: 06/09/2016] [Indexed: 01/05/2023] Open
Abstract
Malic enzymes (ME) catalyze the decarboxylation of malate generating pyruvate, CO2 and NADH or NADPH. In some organisms it has been established that ME is involved in lipids biosynthesis supplying carbon skeletons and reducing power. In this work we studied the MEs of soybean and castor, metabolically different oilseeds. The comparison of enzymatic activities, transcript profiles and organic acid contents suggest different metabolic strategies operating in soybean embryo and castor endosperm in order to generate precursors for lipid biosynthesis. In castor, the malate accumulation pattern agrees with a central role of this metabolite in the provision of carbon to plastids, where the biosynthesis of fatty acids occurs. In this regard, the genome of castor possesses a single gene encoding a putative plastidic NADP-ME, whose expression level is high when lipid deposition is active. On the other hand, NAD-ME showed an important contribution to the maturation of soybean embryos, perhaps driving the carbon relocation from mitochondria to plastids to support the fatty acids synthesis in the last stages of seed filling. These findings provide new insights into intermediary metabolism in oilseeds and provide new biotechnological targets to improve oil yields.
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Affiliation(s)
- Mariel Claudia Gerrard Wheeler
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario (UNR), Rosario, Santa Fe, Argentina
| | - Cintia Lucía Arias
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario (UNR), Rosario, Santa Fe, Argentina
| | - Silvana Righini
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario (UNR), Rosario, Santa Fe, Argentina
| | - Mariana Beatriz Badia
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario (UNR), Rosario, Santa Fe, Argentina
| | - Carlos Santiago Andreo
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario (UNR), Rosario, Santa Fe, Argentina
| | - María Fabiana Drincovich
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario (UNR), Rosario, Santa Fe, Argentina
| | - Mariana Saigo
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario (UNR), Rosario, Santa Fe, Argentina
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Tronconi MA, Wheeler MCG, Martinatto A, Zubimendi JP, Andreo CS, Drincovich MF. Allosteric substrate inhibition of Arabidopsis NAD-dependent malic enzyme 1 is released by fumarate. Phytochemistry 2015; 111:37-47. [PMID: 25433630 DOI: 10.1016/j.phytochem.2014.11.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Revised: 10/21/2014] [Accepted: 10/23/2014] [Indexed: 05/19/2023]
Abstract
Plant mitochondria can use L-malate and fumarate, which accumulate in large levels, as respiratory substrates. In part, this property is due to the presence of NAD-dependent malic enzymes (NAD-ME) with particular biochemical characteristics. Arabidopsis NAD-ME1 exhibits a non-hyperbolic behavior for the substrate L-malate, and its activity is strongly stimulated by fumarate. Here, the possible structural connection between these properties was explored through mutagenesis, kinetics, and fluorescence studies. The results indicated that NAD-ME1 has a regulatory site for L-malate that can also bind fumarate. L-Malate binding to this site elicits a sigmoidal and low substrate-affinity response, whereas fumarate binding turns NAD-ME1 into a hyperbolic and high substrate affinity enzyme. This effect was also observed when the allosteric site was either removed or altered. Hence, fumarate is not really an activator, but suppresses the inhibitory effect of l-malate. In addition, residues Arg50, Arg80 and Arg84 showed different roles in organic acid binding. These residues form a triad, which is the basis of the homo and heterotrophic effects that characterize NAD-ME1. The binding of L-malate and fumarate at the same allosteric site is herein reported for a malic enzyme and clearly indicates an important role of NAD-ME1 in processes that control flow of C4 organic acids in Arabidopsis mitochondrial metabolism.
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Affiliation(s)
- Marcos Ariel Tronconi
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, 2000 Rosario, Argentina.
| | - Mariel Claudia Gerrard Wheeler
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, 2000 Rosario, Argentina
| | - Andrea Martinatto
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, 2000 Rosario, Argentina
| | - Juan Pablo Zubimendi
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, 2000 Rosario, Argentina
| | - Carlos Santiago Andreo
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, 2000 Rosario, Argentina
| | - María Fabiana Drincovich
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, 2000 Rosario, Argentina
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Arias CL, Andreo CS, Drincovich MF, Gerrard Wheeler MC. Fumarate and cytosolic pH as modulators of the synthesis or consumption of C(4) organic acids through NADP-malic enzyme in Arabidopsis thaliana. Plant Mol Biol 2013; 81:297-307. [PMID: 23242919 DOI: 10.1007/s11103-012-9999-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Accepted: 12/06/2012] [Indexed: 05/13/2023]
Abstract
Arabidopsis thaliana is a plant species that accumulates high levels of organic acids and uses them as carbon, energy and reducing power sources. Among the enzymes that metabolize these compounds, one of the most important ones is malic enzyme (ME). A. thaliana contains four malic enzymes (NADP-ME 1-4) to catalyze the reversible oxidative decarboxylation of malate in the presence of NADP. NADP-ME2 is the only one located in the cell cytosol of all Arabidopsis organs providing most of the total NADP-ME activity. In the present work, the regulation of this key enzyme by fumarate was investigated by kinetic assays, structural analysis and a site-directed mutagenesis approach. The final effect of this metabolite on NADP-ME2 forward activity not only depends on fumarate and substrate concentrations but also on the pH of the reaction medium. Fumarate produced an increase in NADP-ME2 activity by binding to an allosteric site. However at higher concentrations, fumarate caused a competitive inhibition, excluding the substrate malate from binding to the active site. The characterization of ME2-R115A mutant, which is not activated by fumarate, confirms this hypothesis. In addition, the reverse reaction (reductive carboxylation of pyruvate) is also modulated by fumarate, but in a different way. The results indicate pH-dependence of the fumarate modulation with opposite behavior on the two activities analyzed. Thereby, the coordinated action of fumarate over the direct and reverse reactions would allow a precise and specific modulation of the metabolic flux through this enzyme, leading to the synthesis or degradation of C(4) compounds under certain conditions. Thus, the physiological context might be exerting an accurate control of ME activity in planta, through changes in metabolite and substrate concentrations and cytosolic pH.
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Affiliation(s)
- Cintia Lucía Arias
- Centro de Estudios Fotosintéticos y Bioquímicos, Universidad Nacional de Rosario, Suipacha 531, Rosario, Argentina
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