Littérature scientifique sur le sujet « Prolin catabolism »
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Articles de revues sur le sujet "Prolin catabolism"
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Guerrier, Gilles. « Effect of salt-stress on proline metabolism in calli of Lycopersicon esculentum, Lycopersicon pennellii, and their interspecific hybrid ». Canadian Journal of Botany 73, no 12 (1 décembre 1995) : 1939–46. http://dx.doi.org/10.1139/b95-206.
Texte intégralRésumé :
Amino acid pools and enzyme activities of NH3-assimilation (glutamine synthetase, glutamate synthase), proline biosynthesis (pyrroline-5-carboxylate reductase), proline catabolism (proline dehydrogenase, proline oxidase), and ornithine transamination (ornithine transaminase) were determined in control and salinized (140 mM NaCl) calli from tomato roots. Three populations were used: the domestic salt-sensitive Lycopersicon esculentum Mill. cv. P-73, the wild salt-tolerant Lycopersicon pennellii (Correll) D'Arcy, accession PE-47, and their F1 interspecific cross, for which the relative growth rate on salt media was intermediate to those of the parents. Compared with control conditions, proline levels increased with NaCl treatments by twofold, threefold, and sixfold in the wild species, the F1 hybrid, and the domestic species, respectively. This proline accumulation in the F1 and the domestic populations was not modulated by changes in the enzyme activities of proline biosynthesis or catabolism. NaCl tolerance, amino acid (proline, alanine, arginine, asparagine) content, and velocity of enzymes responsible for proline biosynthesis and catabolism are dependent on explant sources (cotyledon, root) from which the F1 calli were derived. The comparison of proline (PRO) responses in the different calli and populations indicated (i) various changes in anabolic or catabolic rates of PRO metabolism for a given range of PRO accumulation and (ii) the presence in the F1 of both wild and sensitive parent characters in growth and PRO responses. Key words: callus culture, Lycopersicon esculentum, Lycopersicon pennellii, F1 tomato, proline synthesis, proline catabolism, salt stress.
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Grantham, Barbara D., et J. Barrett. « Amino acid catabolism in the nematodes Heligmosomoides polygyrus and Panagrellus redivivus 2. Metabolism of the carbon skeleton ». Parasitology 93, no 3 (décembre 1986) : 495–504. http://dx.doi.org/10.1017/s0031182000081208.
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SUMMARYAll of the enzymes of proline catabolism were present in Heligmosomoides polygyrus and Panagrellus redivivus and the activities were, in general, similar to those found in rat liver. Both nematodes were also shown to be able to catabolize the branched-chain amino acids leucine, isoleucine and valine, by pathways similar to those found in mammalian liver. There were no significant differences in amino acid catabolism between the animal-parasitic and free-living species of nematode.
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Phillips, Donald A., Eve S. Sande, J. A. C. Vriezen, Frans J. de Bruijn, Daniel Le Rudulier et Cecillia M. Joseph. « A New Genetic Locus in Sinorhizobium meliloti Is Involved in Stachydrine Utilization ». Applied and Environmental Microbiology 64, no 10 (1 octobre 1998) : 3954–60. http://dx.doi.org/10.1128/aem.64.10.3954-3960.1998.
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ABSTRACT Stachydrine, a betaine released by germinating alfalfa seeds, functions as an inducer of nodulation genes, a catabolite, and an osmoprotectant in Sinorhizobium meliloti. Two stachydrine-inducible genes were found in S. meliloti1021 by mutation with a Tn5-luxAB promoter probe. Both mutant strains (S10 and S11) formed effective alfalfa root nodules, but neither grew on stachydrine as the sole carbon and nitrogen source. When grown in the absence or presence of salt stress, S10 and S11 took up [14C]stachydrine as well as wild-type cells did, but neither used stachydrine effectively as an osmoprotectant. In the absence of salt stress, both S10 and S11 took up less [14C]proline than wild-type cells did. S10 and S11 appeared to colonize alfalfa roots normally in single-strain tests, but when mixed with the wild-type strain, their rhizosphere counts were reduced more than 50% (P ≤ 0.01) relative to the wild type. These results suggest that stachydrine catabolism contributes to root colonization. DNA sequence analysis identified the mutated locus in S11 as putA, and the luxABfusion in that gene was induced by proline as well as stachydrine. DNA that restored the capacity of mutant S10 to catabolize stachydrine contained a new open reading frame, stcD. All data are consistent with the concept that stcD codes for an enzyme that produces proline by demethylation of N-methylproline, a degradation product of stachydrine.
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Diab, Farès, Théophile Bernard, Alexis Bazire, Dominique Haras, Carlos Blanco et Mohamed Jebbar. « Succinate-mediated catabolite repression control on the production of glycine betaine catabolic enzymes in Pseudomonas aeruginosa PAO1 under low and elevated salinities ». Microbiology 152, no 5 (1 mai 2006) : 1395–406. http://dx.doi.org/10.1099/mic.0.28652-0.
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Glycine betaine (GB) and its immediate precursors choline and carnitine, dimethylsulfonioacetate, dimethylsulfoniopropionate, ectoine and proline were effective osmoprotectants for Pseudomonas aeruginosa, but pipecolate, trehalose and sucrose had no osmoprotective effect. GB was accumulated stably or transiently when succinate or glucose, respectively, was used as a carbon and energy source. The catabolite repression mediated by succinate occurred at both low and high salinities, and it did not involve the global regulators Vfr and Crc. A proteomic analysis showed that at least 21 proteins were induced when GB was used as a carbon and energy source, and provided evidence that succinate repressed the synthesis of all these proteins. Many of the proteins induced by GB (sarcosine oxidase, serine hydroxymethyltransferase and serine dehydratase) are involved in GB catabolism. In addition, GB uptake was stimulated at high medium osmolalities but it was insensitive to catabolite repression by succinate. Despite its ability to inhibit betaine catabolism, succinate did not allow any better growth of P. aeruginosa cells under hyperosmotic constraint. Conversely, as observed for cells supplied with glucose, a transient accumulation of GB was sufficient to provide a significant cell osmoprotection.
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Tanner, John J. « Structural biology of proline catabolism ». Amino Acids 35, no 4 (28 mars 2008) : 719–30. http://dx.doi.org/10.1007/s00726-008-0062-5.
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Deutch, Charles E., James M. Hasler, Rochelle M. Houston, Manish Sharma et Valerie J. Stone. « Nonspecific inhibition of proline dehydrogenase synthesis in Escherichia coli during osmotic stress ». Canadian Journal of Microbiology 35, no 8 (1 août 1989) : 779–85. http://dx.doi.org/10.1139/m89-130.
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L-Proline, which is accumulated by Escherichia coli during growth in media of high osmolality, also induces the synthesis of the enzyme degrading it to glutamate. To determine if proline catabolism is inhibited during osmotic stress, proline utilization and the formation of proline dehydrogenase were examined in varying concentrations of NaCl and sucrose. Although the specific growth rate of E. coli with proline as the sole nitrogen source diminished as the solute osmolality increased, a comparable reduction in growth rate occurred with ammonium as the primary nitrogen source. Proline catabolism, as measured in whole cells by the conversion of [14C]proline to [14C]glutamate, was only slightly inhibited by solute osmolalities up to 1.0 osmol/kg; more than 50% of the initial activity was still found at 2.0 osmol/kg. By contrast, the specific activity of proline dehydrogenase in bacteria grown in the presence of added solutes decreased to less than 20% of the control level. This reduction was related to a lower rate of synthesis, but was independent of genes currently known to be involved in osmoregulation or proline metabolism. The specific activities of tryptophanase, β-galactosidase, and histidinol dehydrogenase were also reduced under similar growth conditions. These results indicate that while proline catabolism is not directly inhibited by high solute concentrations, prolonged exposure to osmotic stress leads to its reduction as part of a more general metabolic response.Key words: osmotic stress, proline, proline catabolism, proline dehydrogenase, PutA protein.
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Pallag, Gergely, Sara Nazarian, Dora Ravasz, David Bui, Timea Komlódi, Carolina Doerrier, Erich Gnaiger, Thomas N. Seyfried et Christos Chinopoulos. « Proline Oxidation Supports Mitochondrial ATP Production When Complex I Is Inhibited ». International Journal of Molecular Sciences 23, no 9 (4 mai 2022) : 5111. http://dx.doi.org/10.3390/ijms23095111.
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The oxidation of proline to pyrroline-5-carboxylate (P5C) leads to the transfer of electrons to ubiquinone in mitochondria that express proline dehydrogenase (ProDH). This electron transfer supports Complexes CIII and CIV, thus generating the protonmotive force. Further catabolism of P5C forms glutamate, which fuels the citric acid cycle that yields the reducing equivalents that sustain oxidative phosphorylation. However, P5C and glutamate catabolism depend on CI activity due to NAD+ requirements. NextGen-O2k (Oroboros Instruments) was used to measure proline oxidation in isolated mitochondria of various mouse tissues. Simultaneous measurements of oxygen consumption, membrane potential, NADH, and the ubiquinone redox state were correlated to ProDH activity and F1FO-ATPase directionality. Proline catabolism generated a sufficiently high membrane potential that was able to maintain the F1FO-ATPase operation in the forward mode. This was observed in CI-inhibited mouse liver and kidney mitochondria that exhibited high levels of proline oxidation and ProDH activity. This action was not observed under anoxia or when either CIII or CIV were inhibited. The duroquinone fueling of CIII and CIV partially reproduced the effects of proline. Excess glutamate, however, could not reproduce the proline effect, suggesting that processes upstream of the glutamate conversion from proline were involved. The ProDH inhibitors tetrahydro-2-furoic acid and, to a lesser extent, S-5-oxo-2-tetrahydrofurancarboxylic acid abolished all proline effects. The data show that ProDH-directed proline catabolism could generate sufficient CIII and CIV proton pumping, thus supporting ATP production by the F1FO-ATPase even under CI inhibition.
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Belitsky, Boris R., et Abraham L. Sonenshein. « Modulation of Activity of Bacillus subtilis Regulatory Proteins GltC and TnrA by Glutamate Dehydrogenase ». Journal of Bacteriology 186, no 11 (1 juin 2004) : 3399–407. http://dx.doi.org/10.1128/jb.186.11.3399-3407.2004.
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ABSTRACT The Bacillus subtilis gltAB operon, encoding glutamate synthase, requires a specific positive regulator, GltC, for its expression and is repressed by the global regulatory protein TnrA. The factor that controls TnrA activity, a complex of glutamine synthetase and a feedback inhibitor, such as glutamine, is known, but the signal for modulation of GltC activity has remained elusive. GltC-dependent gltAB expression was drastically reduced when cells were grown in media containing arginine or ornithine or proline, all of which are inducers and substrates of the Roc catabolic pathway. Analysis of gltAB expression in mutants with various defects in the Roc pathway indicated that rocG-encoded glutamate dehydrogenase was required for such repression, suggesting that the substrates or products of this enzyme are the real effectors of GltC. Given that RocG is an enzyme of glutamate catabolism, the main regulatory role of GltC may be prevention of a futile cycle of glutamate synthesis and degradation in the presence of arginine-related amino acids or proline. In addition, high activity of glutamate dehydrogenase was incompatible with activity of TnrA.
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Cruz-Leite, Vanessa Rafaela Milhomem, André Luís Elias Moreira, Lana O’Hara Souza Silva, Moises Morais Inácio, Juliana Alves Parente-Rocha, Orville Hernandez Ruiz, Simone Schneider Weber, Célia Maria de Almeida Soares et Clayton Luiz Borges. « Proteomics of Paracoccidioides lutzii : Overview of Changes Triggered by Nitrogen Catabolite Repression ». Journal of Fungi 9, no 11 (12 novembre 2023) : 1102. http://dx.doi.org/10.3390/jof9111102.
Texte intégralRésumé :
Members of the Paracoccidioides complex are the causative agents of Paracoccidioidomycosis (PCM), a human systemic mycosis endemic in Latin America. Upon initial contact with the host, the pathogen needs to uptake micronutrients. Nitrogen is an essential source for biosynthetic pathways. Adaptation to nutritional stress is a key feature of fungi in host tissues. Fungi utilize nitrogen sources through Nitrogen Catabolite Repression (NCR). NCR ensures the scavenging, uptake and catabolism of alternative nitrogen sources, when preferential ones, such as glutamine or ammonium, are unavailable. The NanoUPLC-MSE proteomic approach was used to investigate the NCR response of Paracoccidioides lutzii after growth on proline or glutamine as a nitrogen source. A total of 338 differentially expressed proteins were identified. P. lutzii demonstrated that gluconeogenesis, β-oxidation, glyoxylate cycle, adhesin-like proteins, stress response and cell wall remodeling were triggered in NCR-proline conditions. In addition, within macrophages, yeast cells trained under NCR-proline conditions showed an increased ability to survive. In general, this study allows a comprehensive understanding of the NCR response employed by the fungus to overcome nutritional starvation, which in the human host is represented by nutritional immunity. In turn, the pathogen requires rapid adaptation to the changing microenvironment induced by macrophages to achieve successful infection.
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Chen, Siyun, Catharine E. White, George C. diCenzo, Ye Zhang, Peter J. Stogios, Alexei Savchenko et Turlough M. Finan. « l-Hydroxyproline and d-Proline Catabolism in Sinorhizobium meliloti ». Journal of Bacteriology 198, no 7 (1 février 2016) : 1171–81. http://dx.doi.org/10.1128/jb.00961-15.
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ABSTRACTSinorhizobium melilotiforms N2-fixing root nodules on alfalfa, and as a free-living bacterium, it can grow on a very broad range of substrates, includingl-proline and several related compounds, such as proline betaine,trans-4-hydroxy-l-proline (trans-4-l-Hyp), andcis-4-hydroxy-d-proline (cis-4-d-Hyp). Fourteenhypgenes are induced upon growth ofS. melilotiontrans-4-l-Hyp, and of those,hypMNPQencodes an ABC-typetrans-4-l-Hyp transporter andhypREencodes an epimerase that convertstrans-4-l-Hyp tocis-4-d-Hyp in the bacterial cytoplasm. Here, we present evidence that the HypO, HypD, and HypH proteins catalyze the remaining steps in whichcis-4-d-Hyp is converted to α-ketoglutarate. The HypO protein functions as ad-amino acid dehydrogenase, convertingcis-4-d-Hyp to Δ1-pyrroline-4-hydroxy-2-carboxylate, which is deaminated by HypD to α-ketoglutarate semialdehyde and then converted to α-ketoglutarate by HypH. The crystal structure of HypD revealed it to be a member of theN-acetylneuraminate lyase subfamily of the (α/β)8protein family and is consistent with the known enzymatic mechanism for other members of the group. It was also shown thatS. melilotican catabolized-proline as both a carbon and a nitrogen source, thatd-proline can complementl-proline auxotrophy, and that the catabolism ofd-proline is dependent on thehypcluster. Transport ofd-proline involves the HypMNPQ transporter, following whichd-proline is converted to Δ1-pyrroline-2-carboxylate (P2C) largely via HypO. The P2C is converted tol-proline through the NADPH-dependent reduction of P2C by the previously uncharacterized HypS protein. Thus, overall, we have now completed detailed genetic and/or biochemical characterization of 9 of the 14hypgenes.IMPORTANCEHydroxyproline is abundant in proteins in animal and plant tissues and serves as a carbon and a nitrogen source for bacteria in diverse environments, including the rhizosphere, compost, and the mammalian gut. While the main biochemical features of bacterial hydroxyproline catabolism were elucidated in the 1960s, the genetic and molecular details have only recently been determined. Elucidating the genetics of hydroxyproline catabolism will aid in the annotation of these genes in other genomes and metagenomic libraries. This will facilitate an improved understanding of the importance of this pathway and may assist in determining the prevalence of hydroxyproline in a particular environment.
Thèses sur le sujet "Prolin catabolism"
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Walters, Nicola Jane. « Arginine and proline catabolism in Schizosaccharomyces pombe ». Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.257192.
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White, Tommi Anna. « Structural and functional studies of proline catabolic enzymes ». Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/4760.
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Thesis (Ph.D.)--University of Missouri-Columbia, 2007.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on March 24, 2009) Vita. Includes bibliographical references.
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Winter, Gudrun [Verfasser]. « Molecular and physiological characterization of arginine and proline catabolism in Arabidopsis / Gudrun Winter ». Konstanz : Bibliothek der Universität Konstanz, 2013. http://d-nb.info/1104844192/34.
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Hull, E. P. « Molecular analysis of the proline catabolism gene cluster of Aspergillus nidulans and sequencing of the regulatory gene ». Thesis, University of Essex, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383551.
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Gomez-Zamorano, Dennis. « Etude de la régulation transcriptionnelle des gènes prn, catabolisme de la proline, chez "Aspergillus nidulans" ». Paris 11, 1999. http://www.theses.fr/1999PA112408.
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Les résultats de ce travail permettent d'établir un modèle global de la régulation transcriptionnelle des gènes "prn". Ces gènes sont soumis à trois niveaux de régulation: la répression catabolique par le carbone, la répression métabolique par l'azote et une induction spécifique. Ces trois niveaux de régulation font intervenir, respectivement, le répresseur CreA, la protéine activatrice AreA et l'activateur spécifique de la voie la protéine PrnA. Les interactions qui s'établissent entre régulateurs à large spectre d'action, CreA et AreA, avec l'activateur spécifique, vont conduire, selon les conditions, à l'expression ou non-expression des différents gènes qui constituent cette voie. En présence de la protéine CreA active, deux fonctions activatrices, celle de la protéine PrnA et de la protéine AreA sont nécessaires pour rétablir l'expression de prnB, qui code pour la perméase de la proline. Cette double action positive s'effectue grâce à deux fonctions activatrices différentes qui peut jouer la protéine PrnA. Toujours en présence d'une protéine CreA active (répression par le glucose), l'inhibition de la protéine AreA (par l'ammonium ou la glutamine) ou l'élimination du site fixé par la protéine PrnA, qui lui permet de jouer un rôle activateur différent de celui qu'elle utilise pour induire la transcription, induit un blocage de l'expression de prnB, entraînant une exclusion de la molécule co-inducteur, nécessaire à l'activation transcriptionnelle des autres gênes. Le mécanisme par lequel les protéines PrnA et Area vont pouvoir contrecarrer l'effet de CreA serait une action synergique des deux activateurs, qui pourrait conduire à l'arrimage de l'appareil transcriptionnel sur le promoteur du gène prnB.
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Faes, Pascal. « Catabolisme de la proline et du GABA chez le colza : incidence de carences azotée et hydrique ». Thesis, Rennes 1, 2014. http://www.theses.fr/2014REN1S173.
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Dans le cadre du changement climatique et de l'évolution de la réglementation concernant les intrants azotés, la culture du colza risque d'être fortement pénalisée dans la mesure où c'est une culture qui nécessite d'importants apports azotés pour atteindre son potentiel de rendement. Par ailleurs, comme chez le colza un déficit hydrique induit l'accumulation de certains composés azotés, il est vraisemblable que cela conduise au détournement d'une quantité importante d'azote vers les organes végétatifs aux dépens des organes reproducteurs et donc du rendement. Chez le colza, la réponse métabolique au déficit hydrique se traduit par une très forte accumulation de proline et dans une moindre mesure une augmentation de la teneur en GABA (acide γ-aminobutyrique), deux acides aminés connus chez la plupart des plantes pour leur réponse à de nombreux stress abiotiques. L'objectif de cette thèse est de déterminer comment le métabolisme de ces deux molécules contribue à l'allocation de l'azote au cours du développement de la plante en situation normale comme en condition de stress hydrique et/ou azoté. Pour répondre à cette question nous avons fait le choix de caractériser deux voies enzymatiques majeures impliquées dans le catabolisme de la proline et du GABA : la proline déshydrogénase (ProDH) et la GABA-transaminase (GABA-T) et d'évaluer l'impact de carences hydriques et/ou azotées sur ces voies. Cette étude nécessitait d'identifier au préalable les gènes codant ces enzymes afin d'aborder une approche fonctionnelle. Les résultats montrent l'existence de multiples copies de gènes ProDH et GABA-T dans le génome du colza. L'analyse de leurs profils d'expression suggère que des processus de sub-fonctionnalisation sont en cours conduisant à l'expression spécifique, de certaines copies en réponse aux stress, et d'autres dans les processus développementaux. La comparaison des profils métaboliques avec les profils spécifiques des transcrits a permis d'élaborer des hypothèses sur le rôle de ces voies dans la gestion de l'azote. L'étude conjointe des métabolismes de la proline et du GABA suggère l'existence de régulations connexes entre les deux. Enfin, l'utilisation de plantules a permis - d'approfondir la régulation des gènes étudiés à des stades précoces de développement - et de mettre en évidence les effets délétères de l'inhibition de la GABA-T par une approche pharmacologique. En conclusion ces résultats apportent des précisions sur la régulation de ces deux enzymes et fournissent des éléments de réponse quant au rôle fonctionnel des catabolismes de la proline et du GABA dans les processus de gestion de l'eau et de l'azote chez le colza. Ces travaux constituent donc une première étape dans une démarche de validation de ces gènes comme candidats pour des programmes d'amélioration du colza visant à sélectionner des génotypes mieux adaptés aux conditions environnementales futuresIn the context of climate change and recent regulation concerning nitrogen inputs, the oilseed rape yields may be severely decreased because its crop requires significant nitrogen supply to reach high yield performance. Moreover, as water deficit induces the accumulation of some nitrogen compounds in oilseed rape, it is likely that this could lead to diversion of significant amounts of nitrogen to the vegetative organs at the expense of the reproductive ones and therefore of the yield. In oilseed rape, the metabolic response to water deficit results in a very high proline accumulation and, to a lesser extent, an increased content of GABA (γ-aminobutyric acid), both these amino acids known for their response to many environmental stresses in most species. The objective of the work presented here was to determine how the metabolism of proline and GABA contributes to the nitrogen allocation during plant development under optimal conditions and under water stress and/or nitrogen depletion. To answer this question, we have chosen to characterize two major enzymatic pathways involved in the catabolism of proline and GABA, proline dehydrogenase (ProDH) and GABA transaminase (GABA-T), and assess the impact of water and/or nitrogen deficiency on these pathways. This study has required to preliminary identify the genes encoding these enzymes in order to initiate a functional approach. The results show the presence of multiple copies of ProDH and GABA-T genes in the oilseed rape genome. Analysis of their expression profiles suggests that sub-functionalization processes are occurring, leading to the specific expression of some copies in response to stress, and some in developmental processes. Comparison of metabolic profiles with specific profiles of transcripts allows us to hypothesize about the role of these pathways in management of nitrogen. The combined study of proline and GABA metabolisms suggests the existence of relationships between them. Finally, the use of seedlings allows - further studying the regulation of genes in the early stages of development - and highlighting the deleterious effects of the inhibition of GABA-T by a pharmacological approach. In conclusion these results supply information on the regulation of these two enzymes and provide answers about the functional roles of proline and GABA catabolisms in the management processes of water and nitrogen in oilseed rape. These works constitute a first step in validation process of these genes as putative candidates for oilseed rape breeding programs to select genotypes better adapted to future environmental conditions
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POKORSKA, ANNA. « Analyse mutationnelle des domaines fonctionnels du regulateur positif prna de la voie du catabolisme de la proline chez aspergillus nidulans ». Paris 11, 1998. http://www.theses.fr/1998PA112094.
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Ce travail porte sur l'analyse de domaines fonctionnels de la proteine prna, indispensable pour l'utilisation de la proline par aspergillus nidulans. C'est un regulateur positif specifique, appartenant a la classe des facteurs a complexe binucleaire a zinc. Le but de ce travail etait d'analyser la fonctionnalite des differents domaines de la proteine, predits par l'analyse de la sequence. Un grand nombre d'alleles de prna ont ete sequences. Je me suis concentree sur l'analyse moleculaire du mutant prna27 situe dans la region centrale. Une mutagenese aleatoire de ce mutant a permis l'identification des suppresseurs intrageniques se situant dans une region encore non caracterisee, appellee region b. La deuxieme partie de cette these presente l'analyse de la sequence d'adressage nucleaire de prna. Une analyse fine de ce nls a permis d'etablir qu'il s'agit d'une sequence tripartite, comprenant trois groupements d'acides amines basiques dont le troisieme fait partie du domaine binucleaire a zinc. J'ai pu faire la distinction entre une localisation nucleaire, dependante de la sequence tripartite et une retention au noyau, necessitant le domaine de dimerisation. Le role de groupements basiques de ce signal tripartite a ete etudie grace a des mutants et des proteines de fusions contenant differents fragments de la proteine prna et la proteine verte fluorescente. La capacite de differentes sequences a induire le transport nucleaire a ete testee par microscopie de fluorescence. Une fusion de prna entiere avec la proteine verte a ete effectuee. Cette proteine de fusion est fonctionnelle et sa localisation ne depend pas de la presence du co-inducteur dans le milieu. La localisation de la proteine entiere est differente de celle de proteines de fusion contenant la partie n-terminale de prna. Sa sous-localisation est coherente avec la coloration au dapi. La derniere partie de ce travail est consacree a l'etude de l'homologue de l'importine alpha chez aspergillus nidulans. La comparaison de cette proteine avec les importines d'eucaryotes superieurs met en evidence une tres grande conservation de la sequence. Je presente ici le sequencage du gene de l'importine potentielle d'aspergillus et l'analyse de sa sequence proteique.
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Demais, Stéphane. « Etude du catabolisme de la proline chez Aspergillus nidulans : analyse fonctionnelle de l'activateur PrnA : caractérisation moléculaire du gène prnX : étude de la régulation transcriptionnelle des gènes du "cluster" prn ». Paris 11, 2006. http://www.theses.fr/2006PA112143.
Texte intégralLivres sur le sujet "Prolin catabolism"
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Turk, Vito. Intracellular Protein Catabolism II. Springer London, Limited, 2012.
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Turk, Vito. Intracellular Protein Catabolism II. Springer, 2012.
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Blaser, Annika Reintam, et Adam M. Deane. Normal physiology of nutrition. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780199600830.003.0201.
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Energy is derived from three major categories of macronutrient—carbohydrate, lipid, and protein. While energy requirements to maintain stable weight can be estimated, it is uncertain if meeting these energy requirements improves outcomes in the critically ill. In health, excess energy is stored via non-oxidative metabolism and during periods of inadequate energy delivery catabolism of storage products occurs. Both storing and using the stores cost energy, each may require up to quarter of energy contained in stored nutrient. Excess carbohydrate stored as glycogen is easily available, albeit in a limited amount. Storage of lipid is the largest energy repository, but requires complex metabolism and is limited by low oxidative capacity. Protein catabolism normally contributes less than 5% of energy requirements, but during periods of inadequate energy delivery or increased catabolism there is a marked increase in endogenous protein breakdown.
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Egreteau, Pierre-Yves, et Jean-Michel Boles. Assessing nutritional status in the ICU. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780199600830.003.0204.
Texte intégralRésumé :
Decreased nutrient intake, increased body requirements, and/or altered nutrient utilization are frequently combined in critically-ill patients. The initial nutritional status and the extent of the disease-related catabolism are the main risk factors for nutrition- related complications. Many complications are related to protein energy malnutrition, which is frequent in the ICU setting. Assessing nutritional status pursues several different goals. Nutritional assessment is required for patients presenting with clinical evidence of malnutrition, with chronic diseases, with acute conditions accompanied by a high catabolic rate, and elderly patients. Recording the patient’s history, nutrient intake, and physical examination, and subjective global assessment allows classification of nutritional status. All the traditional markers of malnutrition, anthropometric measurements and plasma proteins, lose their specificity in the sick adult as each may be affected by a number of non-nutritional factors. Muscle function evaluated by hand-grip strength in cooperative patients and serum albumin provide an objective risk assessment. Several nutritional indices have been validated in specific groups of patients to identify patients at risk of nutritionally-mediated complications and, therefore, the need for nutritional support. A strong suspicion remains the best way of uncovering potentially harmful nutritional deficiencies.
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Casaer, Michael P., et Greet Van den Berghe. Nutrition support in acute cardiac care. Oxford University Press, 2015. http://dx.doi.org/10.1093/med/9780199687039.003.0032.
Texte intégralRésumé :
Malnutrition in cardiac and critical illness is associated with a compromised clinical outcome. The aim of nutrition therapy is to prevent these complications and particularly to attenuate lean tissue wasting and the loss of muscle force and of physical function. During the last decade, several well-powered randomized controlled nutrition trials have been performed. Their results challenge the existing nutrition practices in critically ill patients. Enhancing the nutritional intake and the administration of specialized formulations failed to evoke clinical benefit. Some interventions even provoked an increased mortality or a delayed recovery. These unexpected new findings might be, in part, caused by an important leap forward in the methodological quality in the recent trials. Perhaps reversing early catabolism in the critically ill patient by nutrition or anabolic interventions is impossible or even inappropriate. Nutrients effectively suppress the catabolic intracellular autophagy pathway. But autophagy is crucial for cellular integrity and function during metabolic stress, and consequently its inhibition early in critical illness might be deleterious. Evidence from large nutrition trials, particularly in acute cardiac illness, is scarce. Nutrition therapy is therefore focused on avoiding iatrogenic harm. Some enteral nutrition is administered if possible and eventually temporary hypocaloric feeding is tolerated. Above all, the refeeding syndrome and other nutrition-related complications should be prevented. There is no indication for early parenteral nutrition, increased protein doses, specific amino acids, or modified lipids in critical illness.
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Casaer, Michael P., et Greet Van den Berghe. Nutrition support in acute cardiac care. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780199687039.003.0032_update_001.
Texte intégralRésumé :
Malnutrition in cardiac and critical illness is associated with a compromised clinical outcome. The aim of nutrition therapy is to prevent these complications and particularly to attenuate lean tissue wasting and the loss of muscle force and of physical function. During the last decade, several well-powered randomized controlled nutrition trials have been performed. Their results challenge the existing nutrition practices in critically ill patients. Enhancing the nutritional intake and the administration of specialized formulations failed to evoke clinical benefit. Some interventions even provoked an increased mortality or a delayed recovery. These unexpected new findings might be, in part, caused by an important leap forward in the methodological quality in the recent trials. Perhaps reversing early catabolism in the critically ill patient by nutrition or anabolic interventions is impossible or even inappropriate. Nutrients effectively suppress the catabolic intracellular autophagy pathway. But autophagy is crucial for cellular integrity and function during metabolic stress, and consequently its inhibition early in critical illness might be deleterious. Evidence from large nutrition trials, particularly in acute cardiac illness, is scarce. Nutrition therapy is therefore focused on avoiding iatrogenic harm. Some enteral nutrition is administered if possible and eventually temporary hypocaloric feeding is tolerated. Above all, the refeeding syndrome and other nutrition-related complications should be prevented. There is no indication for early parenteral nutrition, increased protein doses, specific amino acids, or modified lipids in critical illness.
7
Casaer, Michael P., et Greet Van den Berghe. Nutrition support in acute cardiac care. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780199687039.003.0032_update_002.
Texte intégralRésumé :
Malnutrition in cardiac and critical illness is associated with a compromised clinical outcome. The aim of nutrition therapy is to prevent these complications and particularly to attenuate lean tissue wasting and the loss of muscle force and of physical function. During the last decade, several well-powered randomized controlled nutrition trials have been performed. Their results challenge the existing nutrition practices in critically ill patients. Enhancing the nutritional intake and the administration of specialized formulations failed to evoke clinical benefit. Some interventions even provoked an increased mortality or a delayed recovery. These unexpected new findings might be, in part, caused by an important leap forward in the methodological quality in the recent trials. Perhaps reversing early catabolism in the critically ill patient by nutrition or anabolic interventions is impossible or even inappropriate. Nutrients effectively suppress the catabolic intracellular autophagy pathway. But autophagy is crucial for cellular integrity and function during metabolic stress, and consequently its inhibition early in critical illness might be deleterious. Evidence from large nutrition trials, particularly in acute cardiac illness, is scarce. Nutrition therapy is therefore focused on avoiding iatrogenic harm. Some enteral nutrition is administered if possible and eventually temporary hypocaloric feeding is tolerated. Above all, the refeeding syndrome and other nutrition-related complications should be prevented. There is no indication for early parenteral nutrition, increased protein doses, specific amino acids, or modified lipids in critical illness.
8
Rabier, Daniel. Hyperammonemia. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780199972135.003.0078.
Texte intégralRésumé :
Ammonia, an end-product of protein and amino acid catabolism toxic to the brain, must be removed quickly from the circulation. Its removal is achieved in two steps: glutamine synthesis and urea synthesis. Hyperammonemia results from either an excess of production or defective elimination. There are two main etiologies of hyperammonemia: inherited or acquired. Inherited causes are mainly related to defective elimination while acquired ones result either from excess production or deficient detoxification. Good laboratory diagnostic tools are necessary to make the right diagnosis.
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Puthucheary, Zudin, Hugh Montgomery, Nicholas Hart et Stephen Harridge. Skeletal Muscle Mass Regulation in Critical Illness. Oxford University Press, 2014. http://dx.doi.org/10.1093/med/9780199653461.003.0035.
Texte intégralRésumé :
Muscle is a dynamic, plastic, and malleable tissue that is highly sensitive to mechanical and metabolic signals. Muscle mass is regulated by protein homeostasis, with protein being continually turned over, reflecting a balance between synthesis and breakdown. This chapter discusses the effect of critical illness on skeletal muscle mass, protein homeostasis, and the intracellular signalling driving anabolism and catabolism. The focus will be on the unique challenges to which the skeletal muscle are exposed, such as inflammation, sepsis, sedation, and inadequate nutrition, which, in combination with the disuse signals of immobilization and bed rest, engender dramatic changes in muscle structure and function. The mechanisms regulating muscle loss during critical illness are being unravelled, but many questions remain unanswered. Detailed understanding of these mechanisms will help drive strategies to minimize or prevent intensive care-acquired muscle weakness and the long-term consequences experienced by ICU survivors.
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Wise, Matt, et Paul Frost. Nutritional support in the critically ill. Sous la direction de Patrick Davey et David Sprigings. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780199568741.003.0334.
Texte intégralRésumé :
Major injury evokes a constellation of reproducible hormonal, metabolic, and haemodynamic responses which are collectively termed ‘the adaptive stress response’. The purpose of the adaptive stress response is to facilitate tissue repair and restore normal homeostasis. If critical illness is prolonged, the adaptive stress response may become maladaptive, in essence exerting a parasitic effect leaching away structural proteins and impairing host immunity. Primarily therapy should be directed towards the underlying illness, as nutritional support per se will not reverse the stress response and its sequelae. Nonetheless, adequate nutritional support in the early stages of critical illness may attenuate protein catabolism and its adverse effects. This chapter covers nutritional assessment; detection of malnutrition; energy and protein requirements; monitoring the effectiveness of nutritional replacements; nutritional delivery; complications; and refeeding syndrome.
Chapitres de livres sur le sujet "Prolin catabolism"
1
Bode, W., F. Grams, P. Reinemer, F. X. Gomis-Rüth, U. Baumann, D. B. McKay et W. Stöcker. « The Metzincin-Superfamily of Zinc-Peptidases ». Dans Intracellular Protein Catabolism, 1–11. Boston, MA : Springer US, 1996. http://dx.doi.org/10.1007/978-1-4613-0335-0_1.
Texte intégral
2
Järvinen, M., N. Kalkkinen, A. Rinne et V. K. Hopsu-Havu. « The 43 kDa Papain-Inhibiting Protein in Psoriatic Epidermis is Identical to Squamous Cell Carcinoma Antigen (SCC-Antigen) ». Dans Intracellular Protein Catabolism, 87–93. Boston, MA : Springer US, 1996. http://dx.doi.org/10.1007/978-1-4613-0335-0_10.
Texte intégral
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Wang, Kevin K. W., Avigail Posner, Kadee J. Raser, Michelle Buroker-Kilgore, Rathna Nath, Iradj Hajimohammadreza, Albert W. Probert et al. « Alpha-Mercaptoacrylic Acid Derivatives as Novel Selective Calpain Inhibitors ». Dans Intracellular Protein Catabolism, 95–102. Boston, MA : Springer US, 1996. http://dx.doi.org/10.1007/978-1-4613-0335-0_11.
Texte intégral
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Seglen, Per O., Trond Olav Berg, Henrietta Blankson, Monica Fengsrud, Ingunn Holen et Per Eivind Strømhaug. « Structural Aspects of Autophagy ». Dans Intracellular Protein Catabolism, 103–11. Boston, MA : Springer US, 1996. http://dx.doi.org/10.1007/978-1-4613-0335-0_12.
Texte intégral
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Kadowaki, Motoni, Rina Venerando, Giovanni Miotto et Glenn E. Mortimore. « Mechanism of Autophagy in Permeabilized Hepatocytes ». Dans Intracellular Protein Catabolism, 113–19. Boston, MA : Springer US, 1996. http://dx.doi.org/10.1007/978-1-4613-0335-0_13.
Texte intégral
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Ezaki, J., L. S. Wolfe, K. Ishidoh, D. Muno, T. Ueno et E. Kominami. « Lysosomal Proteinosis Based on Decreased Degration of a Specific Protein, Mitochondrial ATP Synthase Subunit C ». Dans Intracellular Protein Catabolism, 121–28. Boston, MA : Springer US, 1996. http://dx.doi.org/10.1007/978-1-4613-0335-0_14.
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Palmer, D. N., et J. M. Hay. « The Neuronal Ceroid Lipofuscinoses (Batten Disease) ». Dans Intracellular Protein Catabolism, 129–36. Boston, MA : Springer US, 1996. http://dx.doi.org/10.1007/978-1-4613-0335-0_15.
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Suzuki, Toshiaki, Kozo Nishiyama, Tsuneyoshi Funai, Keiji Tanaka, Akira Ichihara et Arata Ichiyama. « Energy-Dependent Degration of a Mutant Serine:Pyruvate/Alanin : Glyoxylate Aminotransferase in a Primary Hyperoxaluria Type 1 C ». Dans Intracellular Protein Catabolism, 137–40. Boston, MA : Springer US, 1996. http://dx.doi.org/10.1007/978-1-4613-0335-0_16.
Texte intégral
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Turner, A. J., L. J. Murphy, M. S. Medeiros et K. Barnes. « Endopeptidase-24.11 (Neprilysin) and Relatives ». Dans Intracellular Protein Catabolism, 141–48. Boston, MA : Springer US, 1996. http://dx.doi.org/10.1007/978-1-4613-0335-0_17.
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Hayashi, M., M. Inomata et S. Kawashima. « Function of Calpains ». Dans Intracellular Protein Catabolism, 149–54. Boston, MA : Springer US, 1996. http://dx.doi.org/10.1007/978-1-4613-0335-0_18.
Texte intégralRapports d'organisations sur le sujet "Prolin catabolism"
1
Prusky, Dov, Noel Keen et John Browse. Modulation of the synthesis of the main preformed antifungal compound as abasis for the prevention of postharvest disease of C. gloeosporioides in avocado fruits. United States Department of Agriculture, décembre 2001. http://dx.doi.org/10.32747/2001.7575273.bard.
Texte intégralRésumé :
The most important pathological factor limiting fruit life after harvest in subtropical fruits are quiescent infections of anthracnose caused by Colletotrichum gloeosporioides. Prusky and Keen elucidated the mechanism of resistance in avocado fruits to quiescent infections of C. gloeosporioides and determined that the major biocide involved is the preformed compound,1-acetoxy-2-hydroxy-4-oxo-heneicosa-13, 15 diene. Two possibilities exist for maintaining fungitoxic levels of antifungal compounds in the tissue of ripening fruits: (i). Prevention of catabolism (ii). Induction of synthesis. Previous work has demonstrated that increased fruit susceptibility after fruit harvest occurs through diene catabolism mediated by oxidation of the antifungal compound by the enzyme lipoxygenase. Levels of a non-specific inhibitor, epicatechin, in turn, regulate activity of lipoxygenase, present in the peel of unripe but not ripe fruit. In this proposal, we examined the possibility of exploiting induced synthesis of the antifungal compound for the study of the synthetic pathway. The general objective of the present research was to study the mechanism of biosynthesis of natural antifungal compounds in order to regulate the process of resistance to postharvest diseases in ripening avocado fruits. The specific objectives of the research were: 1. To localize synthesis of the antifungal diene and modulate the process by biotic or a biotic elicitors. 2. To determine the relation between synthesis of the diene and accumulation in the peel and fruit resistance to decay 3. To characterize the biosynthetic pathway and the diene and the genes involved. The analysis of the antifungal compounds in avocado resulted in the detection of a new antifungal compound (E, Z, Z)-1-acetoxy-2-hydroxy-4-oxo- heneicosa-5, 12,15-triene. This new compound was shown to inhibit spore germination of C. gloeosporioides similarly as the antifungal diene. We had localized one of the biosynthetic places of these antifungal compounds in specialized idioblast cells (oil cells) in the mesocarp that can be easily enhanced by elicitors as ethylene. Results have also suggested that the antifungal compounds can be "exported" from the mesocarp to the pericarp where its main activity takes place. The search for the biosynthesis of antifungal compounds and the genes involved took two directions i. direct search for specific genes involved in the synthesis of the diene and ii. Indirect selection of genes using the differential display library. We have cloned , The most important pathological factor limiting fruit life after harvest in subtropical fruits are quiescent infections of anthracnose caused by Colletotrichum gloeosporioides. Prusky and Keen elucidated the mechanism of resistance in avocado fruits to quiescent infections of C. gloeosporioides and determined that the major biocide involved is the preformed compound,1-acetoxy-2-hydroxy-4-oxo-heneicosa-13, 15 diene. Two possibilities exist for maintaining fungitoxic levels of antifungal compounds in the tissue of ripening fruits: (i). Prevention of catabolism (ii). Induction of synthesis. Previous work has demonstrated that increased fruit susceptibility after fruit harvest occurs through diene catabolism mediated by oxidation of the antifungal compound by the enzyme lipoxygenase. Levels of a non-specific inhibitor, epicatechin, in turn, regulate activity of lipoxygenase, present in the peel of unripe but not ripe fruit. In this proposal, we examined the possibility of exploiting induced synthesis of the antifungal compound for the study of the synthetic pathway. The general objective of the present research was to study the mechanism of biosynthesis of natural antifungal compounds in order to regulate the process of resistance to postharvest diseases in ripening avocado fruits. The specific objectives of the research were: 1. To localize synthesis of the antifungal diene and modulate the process by biotic or a biotic elicitors. 2. To determine the relation between synthesis of the diene and accumulation in the peel and fruit resistance to decay 3. To characterize the biosynthetic pathway and the diene and the genes involved. The analysis of the antifungal compounds in avocado resulted in the detection of a new antifungal compound (E, Z, Z)-1-acetoxy-2-hydroxy-4-oxo- heneicosa-5, 12,15-triene. This new compound was shown to inhibit spore germination of C. gloeosporioides similarly as the antifungal diene. We had localized one of the biosynthetic places of these antifungal compounds in specialized idioblast cells (oil cells) in the mesocarp that can be easily enhanced by elicitors as ethylene. Results have also suggested that the antifungal compounds can be "exported" from the mesocarp to the pericarp where its main activity takes place. The search for the biosynthesis of antifungal compounds and the genes involved took two directions i. direct search for specific genes involved in the synthesis of the diene and ii. Indirect selection of genes using the differential display library. We have cloned D9 and D12 desaturase, a protein kinase and a elongase that their transcriptional activation is significantly enhanced during the enhanced synthesis of the antifungal diene. Although we are far away from a complete elucidation of the synthesis of the antifungal compound we have stepped forward determining some of the key steps that might be involved in its synthesis.
2
Wackett, Lawrence, Raphi Mandelbaum et Michael Sadowsky. Bacterial Mineralization of Atrazine as a Model for Herbicide Biodegradation : Molecular and Applied Aspects. United States Department of Agriculture, janvier 1999. http://dx.doi.org/10.32747/1999.7695835.bard.
Texte intégralRésumé :
Atrazine is a broadly used herbicide in agriculture and it was used here as a model to study the biodegradation of herbicides. The bacterium Pseudomonas sp. ADP metabolizes atrazine to carbon dioxide and ammonia and chloride. The genes encoding atrazine catabolism to cyanuric acid were cloned and expressed in Escherichia coli. The genes were designated atzA, atzB and atzC. Each gene was sequenced. The enzyme activities were characterized. AtzA is atrazine chlorohydrolase which takes atrazine to hydroxyatrizine. AtzB is hydroxyatrazine N-ethylaminohydrolase which produces N-isopropylammelide and N-ethylamine. AtzC is N-isopropylammelide N-isopropylaminohydrolase which produces cyanuric acid and N-isopropylamine. Each product was isolated and characterized to confirm their identity by chromatography and mass spectrometry. Sequence analysis indicated that each of the hydrolytic enzymes AtzA, AtzB and AtzC share identity which the aminohydrolase protein superfamily. Atrazine chlorohydrolase was purified to homogeneity. It was shown to have a kcat of 11 s-1 and a KM of 150 uM. It was shown to require a metal ion, either Fe(II), Mn(II) or Co(II), for activity. The atzA, atzB and atzC genes were shown to reside on a broad-host range plasmid in Pseudomonas sp. ADP. Six other recently isolated atrazine-degrading bacteria obtained from Europe and the United States contained homologs to the atz genes identified in Pseudomonas sp. ADP. The identity of the sequences were very high, being greater than 98% in all pairwise comparisons. This indicates that many atrazine-degrading bacteria worldwide metabolize atrazine via a pathway that proceeds through hydroxyatrazine, a metabolite which is non-phytotoxic and non-toxic to mammals. Enzymes were immobilized and used for degradation of atrazine in aqueous phases. The in-depth understanding of the genomics and biochemistry of the atrazine mineralization pathway enabled us to study factors affecting the prevalence of atrazine degradation in various agricultural soils under conservative and new agricultural practices. Moreover, Pseudomonas sp. ADP and/or its enzymes were added to atrazine-contaminated soils, aquifers and industrial wastewater to increase the rate and extent of atrazine biodegradation above that of untreated environments. Our studies enhance the ability to control the fate of regularly introduced pesticides in agriculture, or to reduce the environmental impact of unintentional releases.
3
Blumwald, Eduardo, et Avi Sadka. Citric acid metabolism and mobilization in citrus fruit. United States Department of Agriculture, octobre 2007. http://dx.doi.org/10.32747/2007.7587732.bard.
Texte intégralRésumé :
Accumulation of citric acid is a major determinant of maturity and fruit quality in citrus. Many citrus varieties accumulate citric acid in concentrations that exceed market desires, reducing grower income and consumer satisfaction. Citrate is accumulated in the vacuole of the juice sac cell, a process that requires both metabolic changes and transport across cellular membranes, in particular, the mitochondrial and the vacuolar (tonoplast) membranes. Although the accumulation of citrate in the vacuoles of juice cells has been clearly demonstrated, the mechanisms for vacuolar citrate homeostasis and the components controlling citrate metabolism and transport are still unknown. Previous results in the PIs’ laboratories have indicated that the expression of a large number of a large number of proteins is enhanced during fruit development, and that the regulation of sugar and acid content in fruits is correlated with the differential expression of a large number of proteins that could play significant roles in fruit acid accumulation and/or regulation of acid content. The objectives of this proposal are: i) the characterization of transporters that mediate the transport of citrate and determine their role in uptake/retrieval in juice sac cells; ii) the study of citric acid metabolism, in particular the effect of arsenical compounds affecting citric acid levels and mobilization; and iii) the development of a citrus fruit proteomics platform to identify and characterize key processes associated with fruit development in general and sugar and acid accumulation in particular. The understanding of the cellular processes that determine the citrate content in citrus fruits will contribute to the development of tools aimed at the enhancement of citrus fruit quality. Our efforts resulted in the identification, cloning and characterization of CsCit1 (Citrus sinensis citrate transporter 1) from Navel oranges (Citrus sinesins cv Washington). Higher levels of CsCit1 transcripts were detected at later stages of fruit development that coincided with the decrease in the juice cell citrate concentrations (Shimada et al., 2006). Our functional analysis revealed that CsCit1 mediates the vacuolar efflux of citrate and that the CsCit1 operates as an electroneutral 1CitrateH2-/2H+ symporter. Our results supported the notion that it is the low permeable citrateH2 - the anion that establishes the buffer capacity of the fruit and determines its overall acidity. On the other hand, it is the more permeable form, CitrateH2-, which is being exported into the cytosol during maturation and controls the citrate catabolism in the juice cells. Our Mass-Spectrometry-based proteomics efforts (using MALDI-TOF-TOF and LC2- MS-MS) identified a large number of fruit juice sac cell proteins and established comparisons of protein synthesis patterns during fruit development. So far, we have identified over 1,500 fruit specific proteins that play roles in sugar metabolism, citric acid cycle, signaling, transport, processing, etc., and organized these proteins into 84 known biosynthetic pathways (Katz et al. 2007). This data is now being integrated in a public database and will serve as a valuable tool for the scientific community in general and fruit scientists in particular. Using molecular, biochemical and physiological approaches we have identified factors affecting the activity of aconitase, which catalyze the first step of citrate catabolism (Shlizerman et al., 2007). Iron limitation specifically reduced the activity of the cytosolic, but not the mitochondrial, aconitase, increasing the acid level in the fruit. Citramalate (a natural compound in the juice) also inhibits the activity of aconitase, and it plays a major role in acid accumulation during the first half of fruit development. On the other hand, arsenite induced increased levels of aconitase, decreasing fruit acidity. We have initiated studies aimed at the identification of the citramalate biosynthetic pathway and the role(s) of isopropylmalate synthase in this pathway. These studies, especially those involved aconitase inhibition by citramalate, are aimed at the development of tools to control fruit acidity, particularly in those cases where acid level declines below the desired threshold. Our work has significant implications both scientifically and practically and is directly aimed at the improvement of fruit quality through the improvement of existing pre- and post-harvest fruit treatments.
4
Prusky, Dov, Nancy P. Keller et Amir Sherman. global regulation of mycotoxin accumulation during pathogenicity of Penicillium expansum in postharvest fruits. United States Department of Agriculture, janvier 2014. http://dx.doi.org/10.32747/2014.7600012.bard.
Texte intégralRésumé :
Background to the topic- Penicilliumas a postharvest pathogen and producer of the mycotoxin PAT. Penicilliumspp. are destructive phytopathogens, capable of causing decay in many deciduous fruits, during postharvest handling and storage; and the resulting losses can amount to 10% of the stored produce and the accumulation of large amounts of the mycotoxinpatulin. The overall goal of this proposal is to identify critical host and pathogen factors that modulate P. expansummycotoxin genes and pathways which are required for PAT production and virulence. Our preliminary results indicated that gluconic acid are strongly affecting patulin accumulation during colonization. P. expansumacidifies apple fruit tissue during colonization in part through secretion of gluconic acid (GLA). Several publications suggested that GLA accumulation is an essential factor in P. expansumpathogenicity. Furthermore, down regulation of GOX2 significantly reduced PAT accumulation and pathogenicity. PAT is a polyketide and its biosynthesis pathway includes a 15-gene cluster. LaeA is a global regulator of mycotoxin synthesis. It is now known that patulin synthesis might be subjected to LaeA and sometimes by environmental sensing global regulatory factors including the carbon catabolite repressor CreA as well as the pH regulator factor PacC and nitrogen regulator AreA. The mechanisms by which LaeA regulates patulin synthesis was not fully known and was part of our work. Furthermore, the regulatory system that controls gene expression in accordance with ambient pH was also included in our work. PacC protein is in an inactive conformation and is unable to bind to the promoter sites of the target genes; however, under alkaline growth conditions activated PacC acts as both an activator of alkaline-expressed genes and a repressor of acid-expressed genes. The aims of the project- This project aims to provide new insights on the roles of LaeA and PacC and their signaling pathways that lead to GLA and PAT biosynthesis and pathogenicity on the host. Specifically, our specific aims were: i) To elucidate the mechanism of pH-controlled regulation of GLA and PAT, and their contribution to pathogenesis of P. expansum. We are interested to understanding how pH and/or GLA impact/s under PacC regulation affect PAT production and pathogenesis. ii) To characterize the role of LaeA, the global regulator of mycotoxin production, and its effect on PAT and PacC activity. iii) To identify the signaling pathways leading to GLA and PAT synthesis. Using state- of-the-art RNAseq technologies, we will interrogate the transcriptomes of laeAand pacCmutants, to identify the common signaling pathways regulating synthesis of both GLA and PAT. Major conclusions, solutions, achievements- In our first Aim our results demonstrated that ammonia secreted at the leading edge of the fungal colony induced transcript activation of the global pH modulator PacC and PAT accumulation in the presence of GLA. We assessed these parameters by: (i) direct exogenous treatment of P. expansumgrowing on solid medium; (ii) direct exogenous treatment on colonized apple tissue; (iii) growth under self-ammonia production conditions with limited carbon; and (iv) analysis of the transcriptional response to ammonia of the PAT biosynthesis cluster. Ammonia induced PAT accumulation concurrently with the transcript activation of pacCand PAT biosynthesis cluster genes, indicating the regulatory effect of ammonia on pacCtranscript expression under acidic conditions. Transcriptomic analysis of pH regulated processes showed that important genes and BARD Report - Project 4773 Page 2 of 10 functionalities of P. expansumwere controlled by environmental pH. The differential expression patterns of genes belonging to the same gene family suggest that genes were selectively activated according to their optimal environmental conditions to enable the fungus to cope with varying conditions and to make optimal use of available enzymes. Concerning the second and third Aims, we demonstrated that LaeA regulates several secondary metabolite genes, including the PAT gene cluster and concomitant PAT synthesis invitro. Virulence studies of ΔlaeAmutants of two geographically distant P. expansumisolates (Pe-21 from Israel and Pe-T01 from China) showed differential reduction in disease severity in freshly harvested fruit ranging from no reduction for Ch-Pe-T01 strains in immature fruit to 15–25% reduction for both strains in mature fruit, with the ΔlaeAstrains of Is-Pe-21 always showing a greater loss in virulence. Results suggest the importance of LaeA regulation of PAT and other secondary metabolites on pathogenicity. Our work also characterized for the first time the role of sucrose, a key nutritional factor present in apple fruit, as a negative regulator of laeAexpression and consequent PAT production in vitro. This is the first report of sugar regulation of laeAexpression, suggesting that its expression may be subject to catabolite repression by CreA. Some, but not all of the 54 secondary metabolite backbone genes in the P. expansumgenome, including the PAT polyketide backbone gene, were found to be regulated by LaeA. Together, these findings enable for the first time a straight analysis of a host factor that potentially activates laeAand subsequent PAT synthesis.
5
Lers, Amnon, E. Lomaniec, S. Burd, A. Khalchitski, L. Canetti et Pamela J. Green. Analysis of Senescence Inducible Ribonuclease in Tomato : Gene Regulation and Function. United States Department of Agriculture, février 2000. http://dx.doi.org/10.32747/2000.7570563.bard.
Texte intégralRésumé :
Natural leaf senescence has a negative influence on yield. Postharvest induced senescence contributes to the losses of quality in flowers, foliage, and vegetables. Strategies designed to control the senescence process in crop plants could therefore have great applied significance. Senescence is regulated by differential gene expression yet, functional characterization of the genes specifically induced and study of their expression control, is still in its infancy. Study of senescence-specific genes is required to allow identification of regulatory elements participating in senescence-induced expression and thus provide insights into the genetic regulation of senescence. A main feature of senescence is the hydrolysis of macromolecules by hydrolases of various types such as RNases and proteases. This study was aimed a analysis of senescence-inducible RNases in tomato with the following objectives: Isolation of senescence-inducible RNase cDNA clones; Expression analyses of RNase genes during senescence; Identification of sequences required for senescence-induced gene expression; Functional analyses of senescence-inducible RNases. We narrowed our aims somewhat to focus on the first three objectives because the budget we were awarded was reduced from that requested. We have expanded our research for identification senescence-related RNase/nuclease activities as we thought it will direct us to new RNase/nuclease genes. We have also carried out research in Arabidopsis and parsley, which enabled us to draw mire general conclusions. We completed the first and second objectives and have made considerable progress on the remaining two. We have defined growth conditions suitable for this research and defined the physiological and biochemical parameters characteristic to the advance of leaf senescence. In tomato and arabidopsis we have focused on natural leaf senescence. Parsley was used mainly for study of postharvest senescence in detached leaves. We have identified a 41-kD a tomato nuclease, LeNUCI, specifically induced during senescence which can degrade both RNA and DNA. This activity could be induced by ethylene in young leaves and was subjected to detailed analysis, which enabled its classification as Nuclease I enzyme. LeNUCI may be involved in nucleic acid metabolism during tomato leaf senescence. In parsley senescing leaves we identified 2 main senescence-related nuclease activities of 41 and 39-kDa. These activities were induced in both naturally or artificially senescing leaves, could degrade both DNA and RNA and were very similar in their characteristics to the LeNUCI. Two senescence-induced RNase cDNAs were cloned from tomato. One RNase cDNA was identical to the tomato LX RNase while the second corresponded to the LE RNase. Both were demonstrated before to be induced following phosphate starvation of tomato cell culture but nothing was known about their expression or function in plants. LX gene expression was much more senescence specific and ethylene could activate it in detached young leaves. LE gene expression, which could be transiently induced by wounding, appeared to be activated by abscisic acid. We suggest that the LX RNase has a role in RNA catabolism in the final stage of senescence, and LE may be a defense-related protein. Transgenic plants were generated for altering LX gene expression. No major visible alterations in the phenotype were observed so far. Detailed analysis of senescence in these plants is performed currently. The LX promoter was cloned and its analysis is performed currently for identification of senescence-specific regulatory elements. In Arabidopsis we have identified and characterized a senescence-associated nuclease 1 gene, BFN1, which is highly expressed during leaf and stem senescence. BFN1, is the first example of a senescence- associated gene encoding a nuclease I enzyme as well as the first nuclease I cloned and characterized from Arabidopsis. Our progress should provide excellent tools for the continued analysis of regulation and function of senescence-inducible ribonucleases and nucleases in plants. The cloned genes can be used in reverse genetic approaches, already initiated, which can yield a more direct evidence for the function of these enzymes. Another contribution of this research will be in respect to the molecular mechanism, which controls senescence. We had already initiated in this project and will continue to identify and characterize regulatory elements involved in senescence-specific expression of the genes isolated in this work.
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Aharoni, Asaph, Zhangjun Fei, Efraim Lewinsohn, Arthur Schaffer et Yaakov Tadmor. System Approach to Understanding the Metabolic Diversity in Melon. United States Department of Agriculture, juillet 2013. http://dx.doi.org/10.32747/2013.7593400.bard.
Texte intégralRésumé :
Fruit quality is determined by numerous genetic factors that affect taste, aroma, color, texture, nutritional value and shelf life. To unravel the genetic components involved in the metabolic pathways behind these traits, the major goal of the project was to identify novel genes that are involved in, or that regulate, these pathways using correlation analysis between genotype, metabolite and gene expression data. The original and specific research objectives were: (1) Collection of replicated fruit from a population of 96 RI lines derived from parents distinguished by great diversity in fruit development and quality phenotypes, (2) Phenotypic and metabolic profiling of mature fruit from all 96 RI lines and their parents, (3) 454 pyrosequencing of cDNA representing mRNA of mature fruit from each line to facilitate gene expression analysis based on relative EST abundance, (4) Development of a database modeled after an existing database developed for tomato introgression lines (ILs) to facilitate online data analysis by members of this project and by researchers around the world. The main functions of the database will be to store and present metabolite and gene expression data so that correlations can be drawn between variation in target traits or metabolites across the RI population members and variation in gene expression to identify candidate genes which may impact phenotypic and chemical traits of interest, (5) Selection of RI lines for segregation and/or hybridization (crosses) analysis to ascertain whether or not genes associated with traits through gene expression/metabolite correlation analysis are indeed contributors to said traits. The overall research strategy was to utilize an available recombinant inbred population of melon (Cucumis melo L.) derived from phenotypically diverse parents and for which over 800 molecular markers have been mapped for the association of metabolic trait and gene expression QTLs. Transcriptomic data were obtained by high throughput sequencing using the Illumina platform instead of the originally planned 454 platform. The change was due to the fast advancement and proven advantages of the Illumina platform, as explained in the first annual scientific report. Metabolic data were collected using both targeted (sugars, organic acids, carotenoids) and non-targeted metabolomics analysis methodologies. Genes whose expression patterns were associated with variation of particular metabolites or fruit quality traits represent candidates for the molecular mechanisms that underlie them. Candidate genes that may encode enzymes catalyzingbiosynthetic steps in the production of volatile compounds of interest, downstream catabolic processes of aromatic amino acids and regulatory genes were selected and are in the process of functional analyses. Several of these are genes represent unanticipated effectors of compound accumulation that could not be identified using traditional approaches. According to the original plan, the Cucurbit Genomics Network (http://www.icugi.org/), developed through an earlier BARD project (IS-3333-02), was expanded to serve as a public portal for the extensive metabolomics and transcriptomic data resulting from the current project. Importantly, this database was also expanded to include genomic and metabolomic resources of all the cucurbit crops, including genomes of cucumber and watermelon, EST collections, genetic maps, metabolite data and additional information. In addition, the database provides tools enabling researchers to identify genes, the expression patterns of which correlate with traits of interest. The project has significantly expanded the existing EST resource for melon and provides new molecular tools for marker-assisted selection. This information will be opened to the public by the end of 2013, upon the first publication describing the transcriptomic and metabolomics resources developed through the project. In addition, well-characterized RI lines are available to enable targeted breeding for genes of interest. Segregation of the RI lines for specific metabolites of interest has been shown, demonstrating the utility in these lines and our new molecular and metabolic data as a basis for selection targeting specific flavor, quality, nutritional and/or defensive compounds. To summarize, all the specific goals of the project have been achieved and in many cases exceeded. Large scale trascriptomic and metabolomic resources have been developed for melon and will soon become available to the community. The usefulness of these has been validated. A number of novel genes involved in fruit ripening have been selected and are currently being functionally analyzed. We thus fully addressed our obligations to the project. In our view, however, the potential value of the project outcomes as ultimately manifested may be far greater than originally anticipated. The resources developed and expanded under this project, and the tools created for using them will enable us, and others, to continue to employ resulting data and discoveries in future studies with benefits both in basic and applied agricultural - scientific research.