Artigos
URI permanente para esta coleçãohttps://locus.ufv.br/handle/123456789/11846
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Item Downregulation of the δ-subunit reduces mitochondrial ATP synthase levels, alters respiration, and restricts growth and gametophyte development in Arabidopsis(The Plant Cell, 2012-07) Nunes-Nesi, Adriano; Geisler, Daniela A.; Päpke, Carola; Obata, Toshihiro; Matthes, Annemarie; Schneitz, Kay; Maximova, Eugenia; Araújo, Wagner L.; Fernie, Alisdair R.; Persson, StaffanThe mitochondrial ATP synthase (F1Fo complex) is an evolutionary conserved multimeric protein complex that synthesizes the main bulk of cytosolic ATP, but the regulatory mechanisms of the subunits are only poorly understood in plants. In yeast, the δ-subunit links the membrane-embedded Fo part to the matrix-facing central stalk of F1. We used genetic interference and an inhibitor to investigate the molecular function and physiological impact of the δ-subunit in Arabidopsis thaliana. Delta mutants displayed both male and female gametophyte defects. RNA interference of delta resulted in growth retardation, reduced ATP synthase amounts, and increased alternative oxidase capacity and led to specific long-term increases in Ala and Gly levels. By contrast, inhibition of the complex using oligomycin triggered broad metabolic changes, affecting glycolysis and the tricarboxylic acid cycle, and led to a successive induction of transcripts for alternative respiratory pathways and for redox and biotic stress-related transcription factors. We conclude that (1) the δ-subunit is essential for male gametophyte development in Arabidopsis, (2) a disturbance of the ATP synthase appears to lead to an early transition phase and a long-term metabolic steady state, and (3) the observed long-term adjustments in mitochondrial metabolism are linked to reduced growth and deficiencies in gametophyte development.Item Data-mining bioinformatics: connecting adenylate transport and metabolic responses to stress(Trends in Plant Science, 2018-11) Fonseca-Pereira, Paula da; Neri-Silva, Roberto; Cavalcanti, João Henrique F.; Brito, Danielle S.; Weber, Andreas P. M.; Araújo, Wagner L.; Nunes-Nesi, AdrianoAdenine nucleotides are essential in countless processes within the cellular metabolism. In plants, ATP is mainly produced in chloroplasts and mitochondria through photophosphorylation and oxidative phosphorylation, respectively. Thus, efficient adenylate transport systems are required for intracellular energy partitioning between the cell organelles. Adenylate carriers present in different subcellular compartments have been previously identified and biochemically characterized in plants. Here, by using data-mining bioinformatics tools, we propose how, and to what extent, these carriers integrate energy metabolism within a plant cell under different environmental conditions. We demonstrate that the expression pattern of the corresponding genes is variable under different environmental conditions, suggesting that specific adenylate carriers have distinct and nonredundant functions in plants.Item Differential root and shoot responses in the metabolism of tomato plants exhibiting reduced levels of gibberellin(Environmental and Experimental Botany, 2019-01) Martins, Auxiliadora O.; Omena-Garcia, Rebeca P.; Oliveira, Franciele S.; Silva, Welder A.; Hajirezaei, Mohammad-Reza; Vallarino, José G.; Ribeiro, Dimas Mendes; Fernie, Alisdair R.; Nunes-Nesi, Adriano; Araújo, Wagner L.The ability to adapt to the environment is crucial for plant survival and thus a refined communication system capable of integrating endogenous and exogenous signals and further relaying this information to different parts of the plant is a key component of such adaptability. Given that they grow in highly distinct environments it is arguably unsurprising that roots and shoots display different responses to a given environmental condition. Accordingly, a higher sensitivity of roots to gibberellins (GAs) allows rapid adjustments in growth and development possibly triggering (a) stress tolerance mechanism(s). Here we investigated the differential metabolic responses between root and shoot following reductions of the endogenous GA content using tomato (Solanum lycopersicum L.) plants deficient in GA biosynthesis (gib3, moderately deficient, gib2, intermediate deficiency and gib1, extremely deficient in GAs). GA depletion impedes shoot growth to a greater extent than root growth in all mutants. Moreover, the greater the reduction in GA content the greater the extent of a disturbance at the metabolic level. Low leaf carbohydrate contents were observed in plants displaying higher root growth, suggesting an enhanced flow of photoassimilate to support root growth. Large increases in amino acids contents of either roots or shoot were observed. The increased amino acid content was coupled to reduced levels of TCA cycle intermediates suggesting that these changes are directly linked to early reactions of nitrogen assimilation. The combined data are discussed in terms of our current understanding of the interaction between GA and primary metabolism and their crosstalk in environmental responses.Item Increased urea availability promotes adjustments in C/N metabolism and lipid content without impacting growth in Chlamydomonas reinhardtii(Metabolomics, 2019-03) Batista, Aline D.; Rosa, Rinamara M.; Machado, Mariana; Magalhães, Alan S.; Shalaguti, Bárbara A.; Gomes, Priscilla F.; Covell, Lidiane; Vaz, Marcelo G. M. V.; Araújo, Wagner L.; Nunes-Nesi, AdrianoThe use of urea as a nitrogen (N) source by Chlorophytes usually enhances biomass and lipid production when compared to ammonium (NH4+). However, the metabolic shifts displayed byChlamydomonas reinhardtii growing with this organic N source are not known. This study aimed: (i) to characterize the metabolism of C. reinhardtii cultivated in media containing only urea as N source as well as combined with different NH4+ ratios; (ii) to understand how metabolism respond to urea availability. Specific quantification of metabolites using 96-well microplates, and high-performance liquid chromatography combined with non-targeted metabolite profiling by gas chromatography (GC)–time-of-flight (TOF)-mass spectrometry (MS) were used in this study. In addition, GC analysis was used to determine fatty acid profiling. The use of urea did not alter the growth rate in comparison with NH4+. Interestingly, the cell number decreased and the cell size increased proportionally with urea availability. Furthermore, chlorophyll, protein and lipid contents increased with the amount of urea. Regarding the fatty acid profile, oleic acid (C18:1 w8) decreased with amount of urea, while linoleic acid (C18:2 w6) doubled in urea-containing medium. These results indicate that urea promotes remarkable adjustments in metabolism, without drastic changes in biomass, promoting changes in carbohydrate and amino acid metabolism, as well as in lipids production and fatty acid profile.Item On the role of plant mitochondrial metabolism and its impact on photosynthesis in both optimal and sub-optimal growth conditions(Photosynthesis Research, 2014-02) Araújo, Wagner L.; Nunes-Nesi, Adriano; Fernie, Alisdair R.Given that the pathways of photosynthesis and respiration catalyze partially opposing processes, it follows that their relative activities must be carefully regulated within plant cells. Recent evidence has shown that the components of the mitochondrial electron transport chain are essential for the proper maintenance of intracellular redox gradients, to allow considerable rates of photorespiration and in turn efficient photosynthesis. Thus considerable advances have been made in understanding the interaction between respiration and photosynthesis during the last decades and the potential mechanisms linking mitochondrial function and photosynthetic efficiency will be reviewed. Despite the fact that manipulation of various steps of mitochondrial metabolism has been demonstrated to alter photosynthesis under optimal growth conditions, it is likely that these changes will, by and large, not be maintained under sub-optimal situations. Therefore producing plants to meet this aim remains a critical challenge. It is clear, however, that although there have been a range of studies analysing changes in respiratory and photosynthetic rates in response to light, temperature and CO2, our knowledge of the environmental impact on these processes and its linkage still remains fragmented. We will also discuss the metabolic changes associated to plant respiration and photosynthesis as important components of the survival strategy as they considerably extend the period that a plant can withstand to a stress situation.Item Antisense inhibition of the 2-oxoglutarate dehydrogenase complex in tomato demonstrates its importance for plant respiration and during leaf senescence and fruit maturation(The Plant Cell, 2012-06) Araújo, Wagner L.; Nunes-Nesi, Adriano; Tohge, Takayuki; Osorio, Sonia; Lohse, Marc; Balbo, Ilse; Krahnert, Ina; Sienkiewicz-Porzucek, Agata; Usadel, Björn; Fernie, Alisdair R.Transgenic tomato (Solanum lycopersicum) plants expressing a fragment of the gene encoding the E1 subunit of the 2-oxoglutarate dehydrogenase complex in the antisense orientation and exhibiting substantial reductions in the activity of this enzyme exhibit a considerably reduced rate of respiration. They were, however, characterized by largely unaltered photosynthetic rates and fruit yields but restricted leaf, stem, and root growth. These lines displayed markedly altered metabolic profiles, including changes in tricarboxylic acid cycle intermediates and in the majority of the amino acids but unaltered pyridine nucleotide content both in leaves and during the progression of fruit ripening. Moreover, they displayed a generally accelerated development exhibiting early flowering, accelerated fruit ripening, and a markedly earlier onset of leaf senescence. In addition, transcript and selective hormone profiling of gibberellins and abscisic acid revealed changes only in the former coupled to changes in transcripts encoding enzymes of gibberellin biosynthesis. The data obtained are discussed in the context of the importance of this enzyme in both photosynthetic and respiratory metabolism as well as in programs of plant development connected to carbon–nitrogen interactions.Item Metabolic control and regulation of the tricarboxylic acid cycle in photosynthetic and heterotrophic plant tissues(Plant, Cell and Environment, 2011-04-08) Nunes-Nesi, Adriano; Araújo, Wagner L.; Nikoloski, Zoran; Sweetlove, Lee J.; Fernie, Alisdair R.The tricarboxylic acid (TCA) cycle is a crucial component of respiratory metabolism in both photosynthetic and heterotrophic plant organs. All of the major genes of the tomato TCA cycle have been cloned recently, allowing the generation of a suite of transgenic plants in which the majority of the enzymes in the pathway are progres- sively decreased. Investigations of these plants have provided an almost complete view of the distribution of control in this important pathway. Our studies suggest that citrate synthase, aconitase, isocitrate dehydrogenase, succi- nyl CoA ligase, succinate dehydrogenase, fumarase and malate dehydrogenase have control coefficients flux for res- piration of -0.4, 0.964, -0.123, 0.0008, 0.289, 0.601 and 1.76, respectively; while 2-oxoglutarate dehydrogenase is esti- mated to have a control coefficient of 0.786 in potato tubers. These results thus indicate that the control of this pathway is distributed among malate dehydrogenase, aconitase, fumarase, succinate dehydrogenase and 2-oxoglutarate dehydrogenase. The unusual distribution of control esti- mated here is consistent with specific non-cyclic flux mode and cytosolic bypasses that operate in illuminated leaves. These observations are discussed in the context of known regulatory properties of the enzymes and some illustrative examples of how the pathway responds to environmental change are given.Item Comprehensive metabolic reprograming in freshwater Nitzschia palea strains undergoing nitrogen starvation is likely associated with its ecological origin(Algal Research, 2016-09) Machado, Mariana; Bromke, Mariusz; Domingues Júnior, Adilson Pereira; Vaz, Marcelo Gomes Marçal Vieira; Rosa, Rinamara Martins; Vinson, Christina C.; Sabir, Jamal S.; Rocha, Diego Ismael; Martins, Marcio Arêdes; Araújo, Wagner L.; Willmitzer, Lothar; Szymanski, Jedrzej; Nunes-Nesi, AdrianoNitrogen deficiency can increase the lipid content in certain microalgae species, including diatoms. However, the molecular and metabolic basis of such changes remains rather unclear. We analyzed strains of freshwater Nitzschia palea collected from a eutrophic pond and from an artificial rock. The habitats, differing in light and nutrient availability, lead to two metabolically distinct strains, BR006 and BR022. Differential accumulation of primary compounds, membrane lipid composition and fatty acid saturation were observed. Metabolic and biophysical analysis demonstrated differential sensitivity to N regimes: depleted, replete and saturated. Whereas N depletion leads to typical stress-related responses in both strains, including reduction of protein and photosynthesis, the response observed in BR006 is far more severe. Our results demonstrated that these strains developed distinct metabolic responses to N conditions. BR022 is able to maintain cellular homeostasis and slows down growth according to N availability. In contrast, BR006 maximizes growth rate even under N limitation, by triggering stress response, relocating carbon pool to lipid compounds and quickly reaching growth arrest after N exhaustion. We identified a relationship between habitat characteristics and metabolic responses, providing a metabolic perspective on ecological plasticity of N. palea, which helps it to survive a wide range of habitats.Item Can stable isotope mass spectrometry replace radiolabelled approaches in metabolic studies?(Plant Science, 2016-05-14) Silva, Willian Batista; Daloso, Danilo M.; Fernie, Alisdair R.; Nunes-Nesi, Adriano; Araújo, Wagner L.Metabolic pathways and the key regulatory points thereof can be deduced using isotopically labelled substrates. One prerequisite is the accurate measurement of the labeling pattern of targeted metabolites. The subsequent estimation of metabolic fluxes following incubation in radiolabelled substrates has been extensively used. Radiolabelling is a sensitive approach and allows determination of total label uptake since the total radiolabel content is easy to detect. However, the incubation of cells, tissues or the whole plant in a stable isotope enriched environment and the use of either mass spectrometry or nuclear magnetic resonance techniques to determine label incorporation within specific metabolites offers the possibility to readily obtain metabolic information with higher resolution. It additionally also offers an important complement to other post-genomic strategies such as metabolite profiling providing insights into the regulation of the metabolic network and thus allowing a more thorough description of plant cellular function. Thus, although safety concerns mean that stable isotope feeding is generally preferred, the techniques are in truth highly complementary and application of both approaches in tandem currently probably provides the best route towards a comprehensive understanding of plant cellular metabolism.Item The complex role of mitochondrial metabolism in plant aluminum resistance(Trends in Plant Science, 2014-01-24) Nunes-Nesi, Adriano; Brito, Danielle Santos; Inostroza-Blancheteau, Claudio; Fernie, Alisdair R.; Araújo, Wagner L.The majority of soils in tropical and subtropical regions are acidic, rendering the soil a major limitation to plant growth and food production in many developing countries. High concentrations of soluble aluminum cations,particularly Al 3+ , are largely responsible for reducing root elongation and disrupting nutrient and water uptake.Two mechanisms, namely, the exclusion mechanism and tolerance mechanism, have been proposed to govern Al 3+ resistance in plants. Both mechanisms are related to mitochondrial activity as well as to mitochondrial metabolism and organic acid transport. Here, we review the considerable progress that has been made towards developing an understanding of the physiological role of mitochondria in the aluminum response and discuss the potential for using this knowledge in next-generation engineering.
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