Academic literature on the topic 'Processivité'
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Journal articles on the topic "Processivité"
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Taylor, Edwin W., and Gary G. Borisy. "Kinesin Processivity." Journal of Cell Biology 151, no. 5 (November 27, 2000): F27—F30. http://dx.doi.org/10.1083/jcb.151.5.f27.
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O'Donnell, Mike. "Processivity factors." Current Biology 9, no. 15 (August 1999): R545. http://dx.doi.org/10.1016/s0960-9822(99)80348-0.
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Moriarty, Tara J., Delphine T. Marie-Egyptienne, and Chantal Autexier. "Functional Organization of Repeat Addition Processivity and DNA Synthesis Determinants in the Human Telomerase Multimer." Molecular and Cellular Biology 24, no. 9 (May 1, 2004): 3720–33. http://dx.doi.org/10.1128/mcb.24.9.3720-3733.2004.
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ABSTRACT Human telomerase is a multimer containing two human telomerase RNAs (hTRs) and most likely two human telomerase reverse transcriptases (hTERTs). Telomerase synthesizes multiple telomeric repeats using a unique repeat addition form of processivity. We investigated hTR and hTERT sequences that were essential for DNA synthesis and processivity using a direct primer extension telomerase assay. We found that hTERT consists of two physically separable functional domains, a polymerase domain containing RNA interaction domain 2 (RID2), reverse transcriptase (RT), and C-terminal sequences, and a major accessory domain, RNA interaction domain 1 (RID1). RID2 mutants defective in high-affinity hTR interactions and an RT catalytic mutant exhibited comparable DNA synthesis defects. The RID2-interacting hTR P6.1 helix was also essential for DNA synthesis. RID1 interacted with the hTR pseudoknot-template domain and hTERT's RT motifs and putative thumb and was essential for processivity, but not DNA synthesis. The hTR pseudoknot was essential for processivity, but not DNA synthesis, and processivity was reduced or abolished in dimerization-defective pseudoknot mutants. trans-acting hTERTs and hTRs complemented the processivity defects of RID1 and pseudoknot mutants, respectively. These data provide novel insight into the catalytic organization of the human telomerase complex and suggest that repeat addition processivity is one of the major catalytic properties conferred by telomerase multimerization.
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Vuong, Thu V., and David B. Wilson. "Processivity, Synergism, and Substrate Specificity of Thermobifida fusca Cel6B." Applied and Environmental Microbiology 75, no. 21 (September 4, 2009): 6655–61. http://dx.doi.org/10.1128/aem.01260-09.
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ABSTRACT A relationship between processivity and synergism has not been reported for cellulases, although both characteristics are very important for hydrolysis of insoluble substrates. Mutation of two residues located in the active site tunnel of Thermobifida fusca exocellulase Cel6B increased processivity on filter paper. Surprisingly, mixtures of the Cel6B mutant enzymes and T. fusca endocellulase Cel5A did not show increased synergism or processivity, and the mutant enzyme which had the highest processivity gave the poorest synergism. This study suggests that improving exocellulase processivity might be not an effective strategy for producing improved cellulase mixtures for biomass conversion. The inverse relationship between the activities of many of the mutant enzymes with bacterial microcrystalline cellulose and their activities with carboxymethyl cellulose indicated that there are differences in the mechanisms of hydrolysis for these substrates, supporting the possibility of engineering Cel6B to target selected substrates.
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LeBrasseur, Nicole. "Profilin for processivity." Journal of Cell Biology 167, no. 4 (November 15, 2004): 581. http://dx.doi.org/10.1083/jcb1674rr5.
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Varrot, A., S. J. Charnock, M. Schülein, H. Driguez, and G. J. Davies. "Cellobiohydrolases and processivity." Acta Crystallographica Section A Foundations of Crystallography 56, s1 (August 25, 2000): s254. http://dx.doi.org/10.1107/s0108767300025460.
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Brenner, Sibylle, Florian Berger, Lu Rao, Matthew P. Nicholas, and Arne Gennerich. "Force production of human cytoplasmic dynein is limited by its processivity." Science Advances 6, no. 15 (April 2020): eaaz4295. http://dx.doi.org/10.1126/sciadv.aaz4295.
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Cytoplasmic dynein is a highly complex motor protein that generates forces toward the minus end of microtubules. Using optical tweezers, we demonstrate that the low processivity (ability to take multiple steps before dissociating) of human dynein limits its force generation due to premature microtubule dissociation. Using a high trap stiffness whereby the motor achieves greater force per step, we reveal that the motor’s true maximal force (“stall force”) is ~2 pN. Furthermore, an average force versus trap stiffness plot yields a hyperbolic curve that plateaus at the stall force. We derive an analytical equation that accurately describes this curve, predicting both stall force and zero-load processivity. This theoretical model describes the behavior of a kinesin motor under low-processivity conditions. Our work clarifies the true stall force and processivity of human dynein and provides a new paradigm for understanding and analyzing molecular motor force generation for weakly processive motors.
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Li, Yongchao, Diana C. Irwin, and David B. Wilson. "Processivity, Substrate Binding, and Mechanism of Cellulose Hydrolysis by Thermobifida fusca Cel9A." Applied and Environmental Microbiology 73, no. 10 (March 16, 2007): 3165–72. http://dx.doi.org/10.1128/aem.02960-06.
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ABSTRACT Thermobifida fusca Cel9A-90 is a processive endoglucanase consisting of a family 9 catalytic domain (CD), a family 3c cellulose binding module (CBM3c), a fibronectin III-like domain, and a family 2 CBM. This enzyme has the highest activity of any individual T. fusca enzyme on crystalline substrates, particularly bacterial cellulose (BC). Mutations were introduced into the CD or the CBM3c of Cel9A-68 using site-directed mutagenesis. The mutant enzymes were expressed in Escherichia coli; purified; and tested for activity on four substrates, ligand binding, and processivity. The results show that H125 and Y206 play an important role in activity by forming a hydrogen bonding network with the catalytic base, D58; another important supporting residue, D55; and Glc(−1) O1. R378, a residue interacting with Glc(+1), plays an important role in processivity. Several enzymes with mutations in the subsites Glc(−2) to Glc(−4) had less than 15% activity on BC and markedly reduced processivity. Mutant enzymes with severalfold-higher activity on carboxymethyl cellulose (CMC) were found in the subsites from Glc(−2) to Glc(−4). The CBM3c mutant enzymes, Y520A, R557A/E559A, and R563A, had decreased activity on BC but had wild-type or improved processivity. Mutation of D513, a conserved residue at the end of the CBM, increased activity on crystalline cellulose. Previous work showed that deletion of the CBM3c abolished crystalline activity and processivity. This study shows that it is residues in the catalytic cleft that control processivity while the CBM3c is important for loose binding of the enzyme to the crystalline cellulose substrate.
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Sharma, Prem L., and Clyde S. Crumpacker. "Decreased Processivity of Human Immunodeficiency Virus Type 1 Reverse Transcriptase (RT) Containing Didanosine-Selected Mutation Leu74Val: a Comparative Analysis of RT Variants Leu74Val and Lamivudine-Selected Met184Val." Journal of Virology 73, no. 10 (October 1, 1999): 8448–56. http://dx.doi.org/10.1128/jvi.73.10.8448-8456.1999.
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ABSTRACT We previously showed that a didanosine-selected mutation in pNL4-3 background conferred a replication disadvantage on human immunodeficiency virus type 1, resulting in a loss of replication fitness. This work has been extended by showing that a recombinant virus with the HXBc2 backbone and reverse transcriptase (RT) fragments from pNL4-3 containing the Leu74Val mutation produce decreasing amounts of p24 antigen over a 3-week period. The HXBc2 recombinant containing the wild-type RT from pNL4-3 replicated efficiently. When the virion-associated RT containing the Leu74Val mutation was used in an RT processivity assay with homopolymer RNA template-primer, poly(A), and oligo(dT), the RT with altered Leu74Val mutation was less processive, generating fewer cDNA products in comparison to wild-type pNL4-3 RT. The replication kinetics and RT processivity of the mutant with the Leu74Val mutation were compared to those of a lamivudine-selected mutant Met184Val. In replication kinetics assays, mutant Leu74Val replicated slower than the mutant Met184Val. In a processivity assay, the mutant RTs from both viruses show comparable decreases in processivity. These observations provide biochemical evidence of decreased processivity to support the decrease in replication fitness observed with the Leu74Val or Met184Val mutations.
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Diatlova, Evgeniia A., Grigory V. Mechetin, Anna V. Yudkina, Vasily D. Zharkov, Natalia A. Torgasheva, Anton V. Endutkin, Olga V. Shulenina, et al. "Correlated Target Search by Vaccinia Virus Uracil–DNA Glycosylase, a DNA Repair Enzyme and a Processivity Factor of Viral Replication Machinery." International Journal of Molecular Sciences 24, no. 11 (May 23, 2023): 9113. http://dx.doi.org/10.3390/ijms24119113.
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The protein encoded by the vaccinia virus D4R gene has base excision repair uracil–DNA N-glycosylase (vvUNG) activity and also acts as a processivity factor in the viral replication complex. The use of a protein unlike PolN/PCNA sliding clamps is a unique feature of orthopoxviral replication, providing an attractive target for drug design. However, the intrinsic processivity of vvUNG has never been estimated, leaving open the question whether it is sufficient to impart processivity to the viral polymerase. Here, we use the correlated cleavage assay to characterize the translocation of vvUNG along DNA between two uracil residues. The salt dependence of the correlated cleavage, together with the similar affinity of vvUNG for damaged and undamaged DNA, support the one-dimensional diffusion mechanism of lesion search. Unlike short gaps, covalent adducts partly block vvUNG translocation. Kinetic experiments show that once a lesion is found it is excised with a probability ~0.76. Varying the distance between two uracils, we use a random walk model to estimate the mean number of steps per association with DNA at ~4200, which is consistent with vvUNG playing a role as a processivity factor. Finally, we show that inhibitors carrying a tetrahydro-2,4,6-trioxopyrimidinylidene moiety can suppress the processivity of vvUNG.
Dissertations / Theses on the topic "Processivité"
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Leroy, Prune. "Erreurs de processivité lors de la synthèse protéique chez Escherichia coli." Paris 6, 2005. http://www.theses.fr/2005PA066324.
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Andraos, Nathalie. "Etudes Structurales et Biochimiques de l'ADN Polymérase du Bactériophage T5." Paris 6, 2004. http://www.theses.fr/2004PA066352.
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Saïfi, Boubekeur. "Caractérisation de cycC, un nouveau gène impliqué dans le programme de réplication d'Escherichia coli." Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-01073566.
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Dans Escherichia coli la Dam Methyl Transferase (DamMT) est responsable du transfert d'un groupement méthyle sur les adénosines situés au cœur du tétranucléotide GATC; il s'agit donc d'une activité post réplicative. Ainsi, après le passage de la fourche de réplication, le brin d'ADN nouvellement synthétisé est non méthylé - l'ADN est dit hémimethylé. L'ADN reste hémimethylé pendent une brève période - de l'ordre de la minute - avant d'être reméthylé par la DamMT. L'hypothèse de l'implication de la méthylation de l'ADN dans le contrôle général du programme de maintenance de l'ADN repose essentiellement sur cette observation, puisque l'ADN hemimethyle - exception faite de l'origine de réplication et de la région promotrice du gène dnaA - est diagnostique du passage récent de la fourche de réplication. Cette hypothèse, et le criblage phylogénomique qui en a découlé a conduit a l'identification de plusieurs gènes dont les produits sont supposes être impliqués dans la maintenance de l'ADN. yjaG est l'un de ces gènes. Il a été renomme cycC en raison des dérèglements de la progression du cycle cellulaire associés a un mutant nul de ce gène. L'étude effectuée au cours de ma thèse s'attachera à expliquer l'état actuel de nos connaissances sur la protéine CycC et de son implication dans le processus de réplication de l'ADN. Nos résultats montrent que la protéine CycC est impliquée dans la processivité de la réplication lorsqu'il y a un dommage au niveau de l'ADN. CycC spécifie une activité qui conduit à freiner les fourches de réplication, afin de prévenir des avortements des réplisomes. La surexpression de CycC bloque l'initiation de la réplication entre l'ouverture de la molécule d'ADN et le chargement de l'hélicase réplicative. Nous proposons que CycC interagisse avec le complexe réplicative et ralentit les fourches de réplication. Ce ralentissement prévient de nouvelles collisions lorsque les cellules sont dans des conditions de stress-qui cause des arrêts de la réplication.
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Kanaan, Joanne. "Étude biochimique et biophysique de l’ARN hélicase UPF1 : un moteur moléculaire hautement régulé." Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLEE008/document.
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UPF1 (Up-Frameshift 1) est une hélicase multifonctionnelle conservée chez tous les eucaryotes. Elle est essentielle à la voie de surveillance du NMD (Nonsense Mediated mRNA Decay), qui dégrade des ARNm portant un codon stop prématuré. UPF1 est l’archétype d’une famille d’hélicases qui partagent des corps similaires mais sont impliquées dans des voies cellulaires variées. Cependant, les relations structure-fonction et les caractéristiques biophysiques intrinsèques de ces moteurs moléculaires restent à ce jour peu connues. In vitro, le coeur hélicase d’UPF1 est hautement processif, il traverse des milliers de bases sur l’ARN ou l’ADN et déroule des doubles brins. Dans ce travail, nous avons cherché les facteurs clés régissant cette remarquable processivité en combinant des techniques de biochimie et de biophysique. En particulier, nous avons utilisé des pinces magnétiques pour étudier en temps réel des hélicases à l’échelle de la molécule unique. Contrairement à UPF1, l’hélicase IGHMBP2 de la famille UPF1-like n’est pas processive ; la processivité n’est donc pas un trait conservé au sein de la famille. Grâce à une étude fine de la structure 3D des deux hélicases, nous avons conçu divers mutants que nous avons utilisés pour identifier les éléments structuraux qui modulent la processivité. Notre approche révèle qu’UPF1 a une prise très ferme sur les acides nucléiques, garantissant de longs temps de résidence et d’action qui dictent sa haute processivité. Grâce à la variété de comportements des mutants, nous avons construit un modèle mécanistique expliquant le lien entre énergie d’interaction et processivité. Nous démontrons aussi que la processivité d’UPF1 est requise pour un processus de NMD efficace in vivo. Nous avons utilisé les mêmes outils biochimiques et biophysiques pour étudier une isoforme naturelle d’UPF1 humaine se déplaçant plus vite que l’isoforme majeure, et pour comparer la régulation d’UPF1 humaine et de levure par leurs domaines flanquants. Nous avons également caractérisé l'interaction d’UPF1 de levure avec de nouveaux partenaires. Nos travaux montrent comment la combinaison d'outils biochimiques, biophysiques, structuraux etin vivo offre des aperçus inattendus quant au mode de fonctionnement des moteurs moléculairesUPF1 (Up-Frameshift 1) is a multifunctional helicase that unwinds nucleic acids and is conserved throughout the eukaryote kingdom. UPF1 is required for the Nonsense Mediated mRNA Decay (NMD) surveillance pathway, which degrades mRNAs carrying premature termination codons, among other substrates. UPF1 is the archetype of a family of 11 helicases sharing similar cores but involved in various cellular pathways. However, the structure-function relationship and intrinsic biophysical properties of these molecular engines remain poorly described. In vitro, the UPF1 helicase core is highly processive, it travels along thousands of RNA or DNA bases and unwinds double-strands. In this work, we looked for key factors governing this remarkable processivity. We combined biochemical and biophysical techniques. In particular, we used magnetic tweezers to study helicases in real time at a single molecule scale. In contrast to UPF1, the related IGHMBP2 is not processive, thus processivity is not a shared family trait. Based on the 3D structures of both proteins, we designed various mutants and used them to identify structural elements that modulate processivity. Our approach reveals that UPF1 has a very firm grip on nucleic acids, guaranteeing long binding lifetimes and action times that dictate its high processivity. Thanks to the variety in mutant behaviors, we built a novel mechanistic model linking binding energy to processivity. Furthermore, we show that UPF1 processivity is required for an efficient NMD in vivo. In addition, we used the same biochemical and biophysical tools to investigate a natural human UPF1 isoform moving faster than the major isoform, and to compare the regulation of human andyeast UPF1 by their flanking domains. We also characterized the interaction of yeast UPF1 with new NMD partners. Our work shows how a combination of biochemical, biophysical, structural and in vivo tools can offer unexpected insights into the operating mode of molecular motors
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Kanaan, Joanne. "Étude biochimique et biophysique de l’ARN hélicase UPF1 : un moteur moléculaire hautement régulé." Electronic Thesis or Diss., Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLEE008.
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UPF1 (Up-Frameshift 1) est une hélicase multifonctionnelle conservée chez tous les eucaryotes. Elle est essentielle à la voie de surveillance du NMD (Nonsense Mediated mRNA Decay), qui dégrade des ARNm portant un codon stop prématuré. UPF1 est l’archétype d’une famille d’hélicases qui partagent des corps similaires mais sont impliquées dans des voies cellulaires variées. Cependant, les relations structure-fonction et les caractéristiques biophysiques intrinsèques de ces moteurs moléculaires restent à ce jour peu connues. In vitro, le coeur hélicase d’UPF1 est hautement processif, il traverse des milliers de bases sur l’ARN ou l’ADN et déroule des doubles brins. Dans ce travail, nous avons cherché les facteurs clés régissant cette remarquable processivité en combinant des techniques de biochimie et de biophysique. En particulier, nous avons utilisé des pinces magnétiques pour étudier en temps réel des hélicases à l’échelle de la molécule unique. Contrairement à UPF1, l’hélicase IGHMBP2 de la famille UPF1-like n’est pas processive ; la processivité n’est donc pas un trait conservé au sein de la famille. Grâce à une étude fine de la structure 3D des deux hélicases, nous avons conçu divers mutants que nous avons utilisés pour identifier les éléments structuraux qui modulent la processivité. Notre approche révèle qu’UPF1 a une prise très ferme sur les acides nucléiques, garantissant de longs temps de résidence et d’action qui dictent sa haute processivité. Grâce à la variété de comportements des mutants, nous avons construit un modèle mécanistique expliquant le lien entre énergie d’interaction et processivité. Nous démontrons aussi que la processivité d’UPF1 est requise pour un processus de NMD efficace in vivo. Nous avons utilisé les mêmes outils biochimiques et biophysiques pour étudier une isoforme naturelle d’UPF1 humaine se déplaçant plus vite que l’isoforme majeure, et pour comparer la régulation d’UPF1 humaine et de levure par leurs domaines flanquants. Nous avons également caractérisé l'interaction d’UPF1 de levure avec de nouveaux partenaires. Nos travaux montrent comment la combinaison d'outils biochimiques, biophysiques, structuraux etin vivo offre des aperçus inattendus quant au mode de fonctionnement des moteurs moléculairesUPF1 (Up-Frameshift 1) is a multifunctional helicase that unwinds nucleic acids and is conserved throughout the eukaryote kingdom. UPF1 is required for the Nonsense Mediated mRNA Decay (NMD) surveillance pathway, which degrades mRNAs carrying premature termination codons, among other substrates. UPF1 is the archetype of a family of 11 helicases sharing similar cores but involved in various cellular pathways. However, the structure-function relationship and intrinsic biophysical properties of these molecular engines remain poorly described. In vitro, the UPF1 helicase core is highly processive, it travels along thousands of RNA or DNA bases and unwinds double-strands. In this work, we looked for key factors governing this remarkable processivity. We combined biochemical and biophysical techniques. In particular, we used magnetic tweezers to study helicases in real time at a single molecule scale. In contrast to UPF1, the related IGHMBP2 is not processive, thus processivity is not a shared family trait. Based on the 3D structures of both proteins, we designed various mutants and used them to identify structural elements that modulate processivity. Our approach reveals that UPF1 has a very firm grip on nucleic acids, guaranteeing long binding lifetimes and action times that dictate its high processivity. Thanks to the variety in mutant behaviors, we built a novel mechanistic model linking binding energy to processivity. Furthermore, we show that UPF1 processivity is required for an efficient NMD in vivo. In addition, we used the same biochemical and biophysical tools to investigate a natural human UPF1 isoform moving faster than the major isoform, and to compare the regulation of human andyeast UPF1 by their flanking domains. We also characterized the interaction of yeast UPF1 with new NMD partners. Our work shows how a combination of biochemical, biophysical, structural and in vivo tools can offer unexpected insights into the operating mode of molecular motors
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Claverie, Marion. "GH70 dextransucases : Insights on the molecular determinants of dextran molar mass control." Thesis, Toulouse, INSA, 2017. http://www.theses.fr/2017ISAT0037/document.
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Les glucane-saccharases (GS) de la famille GH70 sont des enzymes produites par certaines bactéries lactiques. A partir de saccharose, substrat renouvelable et peu coûteux, elles sont capables de catalyser la synthèse d’α-glucanes, homopolysaccharides dont les propriétés diffèrent suivant la spécificité de l’enzyme (taille, type de liaisons α-osidiques, degrés de branchement). Les glucanes contenant une très grande majorité de liaisons α-(1,6), appelés dextranes, présentent de nombreuses applications industrielles qui dépendent principalement de leur taille. Cependant, la synthèse directe de dextranes de taille contrôlée (de 1 à plusieurs millions de kg/mol) avec une faible polydispersité et en utilisant une seule enzyme n’est encore pas envisageable. En effet, les mécanismes moléculaires mis en jeu pour le contrôle de la taille des polymères produits n’ont encore été que peu explorés. Dans ce contexte, deux GSs ont été sélectionnées. La première, DSR-M synthétise uniquement des dextranes de faible masse molaire (MM) (28 kg/mol) exclusivement composés de liaisons α-(1,6). A contrario, le second modèle, DSR-OK produit le plus long dextrane décrit à ce jour (>109 g/mol). La caractérisation biochimique et structurale ainsi que la construction de mutants ont permis l’exploration du mode d’action de ces deux candidats. Plusieurs structures 3D de DSR-M2 (forme tronquée de DSR-M) - sans ou en complexe avec son substrat ou ses produits (isomaltotetraose) - ont été résolues. C’est la première fois que de tels complexes sont décrits et l’une de ces structures présente le domaine V le plus complet décrit à ce jour. L’analyse de ces structures couplée au suivi cinétique de la synthèse du polymère ont montré que la spécificité de DSR-M pour la synthèse de dextranes courts s’explique par un mode d’élongation distributif dû à la faible affinité de deux poches à sucre de son domaine V envers la chaîne en cours de synthèse. Des analyses RMN (15N1H – HSQC) – jamais réalisées auparavant sur une protéine si grosse – ont également étayé l’importance de la présence de résidus aromatiques dans le domaine catalytique pour la synthèse de dextranes supérieurs à 2 kg/mol. En comparaison, la synthèse de dextranes de haute MM par DSR-OK est principalement due au plus grand nombre de poches à sucre de son domaine V, permettant d’assurer une meilleure interaction avec la chaîne en cours d’élongation. L’implication de ces poches dans la détermination de la taille du dextrane a été montrée pour les deux candidats. Leur fonctionnalité est fortement liée à la présence d’un résidu aromatique de stacking, et leur répartition le long du domaine V a aussi une influence. L’ensemble de ces résultats démontre la coopération du domaine V avec le domaine catalytique pour l’élongation des dextranes, tout en offrant de nouvelles perspectives pour approfondir la compréhension de ce mécanisme. Ils offrent également des stratégies prometteuses pour l’ingénierie d’enzyme de la famille des GH70 pour la modulation de la taille des glucanesGlucansucrases (GS) from glycoside hydrolase family 70 (GH70) are -transglucosylases produced by lactic acid bacteria. From sucrose, an economical and abundant agro resource, they catalyze the polymerization of glucosyl residues. Depending on the enzyme specificity, α-glucans vary in terms of size, types of glucosidic bonds and degree of branching and have found multiple industrial applications mainly related to their molar mass (MM). However synthesizing polymers of controlled size with average MM ranging from 1 kg/mol to several millions g/mol and low polydispersity using one single enzyme remains challenging. Indeed, the molecular mechanisms underpinning the control of polymer size have been scarcely explored. To tackle this question, two GSs producing dextran (glucan composed of a majority of α-(1,6) linkages) were selected, and their mode of action explored via biochemical and structural analyses coupled to mutagenesis. The first enzyme selected, called DSR-M synthesizes only low molar mass (LMM) dextran (28 kg/mol) exclusively composed of -(1→6) linkages without any trace of HMM dextran (105 to 108 g/mol). In contrast, DSR-OK (second model), produces the highest MM dextran (>109 g/mol) described to date. Several 3D crystallographic structures of a truncated form of DSR-M (DSR-M2), either free or in complex with its substrate or product (isomaltotetraose) in the domain V or in the active site were solved. Such complexes were never obtained before. Noteworthy, one structure encompassed the most complete domain V reported to date. Analyses of these structures coupled to dextran synthesis monitoring, showed that the LMM dextran specificity of DSR-M2 is explained by a distributive elongation mode due to the weak affinity of its two sugar binding pockets in the domain V which interact with the growing dextran chains and allow the synthesis of dextran longer than 16 kg/mol. 15N1H NMR analyses (HSQC), for the first time performed with such a big protein, further revealed the crucial role of aromatic residues in the catalytic domain for the production of dextran from 2 to 16 kg/mol. In comparison, synthesis of HMM dextran by DSR-OK was shown to be mainly due to the sugar binding pockets of its domain V, ensuring much stronger interactions with growing dextran chains. The role of these pockets was evidenced for both enzymes, their functionality proposed to be linked to the presence of one aromatic stacking residue. Their positioning along domain V relatively to the active site is also important to promote efficient binding. All these findings highlight the cooperation between domain V and the catalytic domain for dextran elongation, offer new perspectives to acquire a deeper knowledge on this interplay and open promising strategies for GH70 enzyme engineering aiming at modulating glucan size
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Lemoine, Maud. "Effets de la conformation et de l'agrégation du kappa-carraghénane sur les modalités de l'hydrolyse enzymatique par la kappa-carraghénase de Pseudoalteromonas carrageenovora." Paris 6, 2009. http://www.theses.fr/2009PA066190.
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Le kappa-carraghénane est un galactane sulfaté formant des gels. L’agrégation des chaînes de polysaccharides implique une transition conformationnelle d’un état désordonné à un état ordonné. La kappa-carraghénase est une glycoside hydrolase qui hydrolyse les liaisons β(1->4) du polymère. Le mode d’action de la kappa-carraghénase a été caractérisé en fonction des différents états conformationnels et de l’état physique du substrat. Des hydrolyses ont été conduites sur le substrat soluble et en phase hétérogène (solide ordonné ou désordonné). Les résultats ont confirmé le mode endo-processif de l’enzyme qui serait modulé par l’état physique du substrat. L’enzyme a permis d’étudier la conformation du polymère. Une baisse de l’activité a été constatée quand le substrat est en conformation hélice en présence d’iode. Des analyses cinétiques, combinées à la caractérisation de la conformation et de l’iode fixé au kappa-carraghénane, ont montré que la diminution d’activité n’est pas causée par la transition conformationnelle mais par la fixation d’iode sur les chaînes qui masquent les liaisons hydrolysables. Le kappa-carraghénane adopterait donc une conformation en simple hélice.
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Pairault, Noël. "Synthèse de [1]rotaxanes par la méthode de reconnaissance active pour le développement d'une polymérase artificielle autonome et adaptative." Thesis, Poitiers, 2016. http://www.theses.fr/2016POIT2321/document.
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Cette thèse est consacrée à la mise au point d'une machine moléculaire artificielle sous la forme d'un [1]rotaxane, capable de synthétiser différents polymères de façon autonome. Au cours de cette étude, nous avons réalisé la première synthèse hautement diastéréosélective de [1]rotaxanes par la méthode de reconnaissance active catalysée au cuivre(I). Nous avons montré qu'un frein moléculaire est nécessaire pour assurer la stabilité de l'architecture entrelacée. De plus, l'utilisation d'un macrocycle avec une chaine latérale courte est indispensable pour favoriser la synthèse de lassos moléculaires. Enfin, le centre asymétrique du frein moléculaire guide la stéréosélectivité de la réaction. Ceci permet de faire la synthèse stéréodivergente de [1]rotaxanes à partir de macrocycles énantiomériquement purs. La seconde partie du projet concerne et de la processivité potentielle de ce type d'architecture moléculaire. Dans ce cadre, nous avons construit un [2]rotaxane présentant un stoppeur labile et une fonction thiol protégée sur la chaine latérale du macrocycle. La libération contrôlée du thiol induit la formation d'un [1]rotaxane piégé in situ par un nucléophile indiquant le potentiel de cette approche pour la conception de machines moléculaires fonctionnant de façon itérativeThis thesis is devoted to the development of an artificial molecular machine in the form of [1]rotaxane, designed to synthesize different kind of polymers autonomously. During this study, we accomplished the first highly diastereoselective synthesis of [1]rotaxanes by the copper(I)-catalysed active template method. We showed that a molecular brake was necessary to ensure the stability of the interlocked architecture. Moreover, the use of a short lateral chain of the macrocycle is essential to promote the synthesis of molecular lassos. Finally, the asymmetric center of the molecular brake induces the stereoselectivity of the reaction. This allows us to accomplish the stereodivergent synthesis of [1]rotaxanes from enantiomerically pure macrocycles. The second part of this project concerns the study of the potential processivity of this kind of molecular architecture. In this context, we built a [2]rotaxane which has a labile stopper and a protected thiol moiety on the lateral chain of the macrocycle. The controlled release of the thiol leads to the formation of a [1]rotaxane trapped in situ by a nucleophile, showing the potential of this approach for the design of molecular machines working processively
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Huard, Sylvain. "Human telomerase determinants of processivity and fidelity." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=85075.
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Telomeres are dynamic nucleoprotein complexes that protect the fragile termini of chromosomes. Without telomeres, chromosome ends are recognized as DNA breaks and inclined to nucleolytic degradation and end-to-end fusions. Telomeres consist of DNA repeats that are synthesized by telomerase, a specialized reverse transcriptase (RT) enzyme minimally composed of a catalytic protein subunit (TERT) and an essential RNA component (TR). Although the functional aspects of telomerase are not well elucidated, this ribonucleoprotein enzyme clearly regulates cellular life-span through its ability to maintain or elongate telomeres. Human TERT (hTERT) has a central region containing conserved (RT)-like motifs, and N- and C-terminal regions that are unique to the TERT family. We analysed the precise role of the C-terminus of hTERT by introducing small deletions and amino acid substitutions throughout the C-terminal region, and demonstrated that the hTERT C-terminal region is essential for enzyme catalysis in vitro. We reported that hTERT multimerization requires the presence of catalytically essential C-terminal amino acid residues and intact RT-like motifs on the same hTERT molecule. We also examined DNA synthesis at nucleotide resolution with a direct primer extension assay, and found that the hTERT C-terminus modulates telomerase processivity. In addition, we reported that human telomerase reconstituted in rabbit reticulocyte lysate (RRL) and partially purified telomerase from human cells catalyze the cleavage of DNA substrates prior to their elongation. Finally, we determined the experimental conditions for human telomerase expression in insect cells in order to obtain an abundant source of catalytically active recombinant telomerase.
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Chiu, Joyce Biotechnology & Biomolecular Sciences Faculty of Science UNSW. "Protein engineering of DNA polymerase I: thioredoxin dependent processivity." Awarded by:University of New South Wales. School of Biotechnology and Biomolecular Sciences, 2005. http://handle.unsw.edu.au/1959.4/23077.
Full textAbstract:
DNA polymerases are found in a diverse range of organisms, prokaryotes, eukaryotes, viruses and bacteriophage. T7 DNA polymerase is a replicative enzyme from E. coli bacteriophage T7. It relies on the thioredoxin binding domain (TBD) of phage gene 5 protein (gp5) and E. coli thioredoxin (Trx) for processive replication of phage DNA. Although T7 DNA polymerase is processive, it is also thermolabile. In order to design a thermostable and processive DNA polymerase, the structural stabilities of the TBD and Trx were studied in respect to their binding affinity and affect on enzyme processivity. An artificial operon was designed for coexpression of subunits of T7 DNA polymerase. By means of a 9??His-tag at the amino terminus of gp5, T7 DNA polymerase complex was purified by one-step nickel-agarose chromatography, with subunits gp5 and Trx co-eluting in a one to one molar ratio. Purified T7 DNA polymerase was assayed for polymerase activity, processivity and residual activity and compared to the commercial T7 DNA polymerase. The two enzymes were not identical with commercial T7 DNA polymerase being less processive at 37??C. Mass spectrometry of the two enzymes identified a mutation of Phe102 to Ser in the Trx subunit (TrxS102) of commercial T7 DNA polymerase. The Ser102 mutation, was found near the carboxyl terminal helix of Trx. TrxS102 was less stable than wild type Trx. In the study of the TBD structural stability, a hybrid polymerase was constructed by inserting the TBD motif into the homologous position in the Stoffel fragment of Taq DNA polymerase. The hybrid enzyme was coexpressed with Trx from an artificial operon; however, the TBD inserted retained a mesophilic binding affinity to Trx. The chimeric polymerase required 100 molar excess of Trx for processive polymerase activity at 60??C. TBD structural deformation at elevated temperatures was hypothesized to be the cause of the change in the subunit stoichiometry. Mutagenesis of TBD would be required to increase its thermostability. An efficient, rapid high throughput mutagenesis method (SLIM) was invented and would be appropriate for further studies.
Books on the topic "Processivité"
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Silva, Laurie Anne. The roles of phosphorylation and the carboxy-terminus in the function of the human cytomegalovirus processivity factor, UL44. 2009.
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Albertus. Liber de Natura Et Origine Animae. Primum Ad Fidem Autographiedidit Bernhardus Geyer. Liber de Principiis Motus Processivi Quaestiones Super de Animalibus. Aschendorff Verlag, 2000.
Find full textBook chapters on the topic "Processivité"
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Gooch, Jan W. "Processivity." In Encyclopedic Dictionary of Polymers, 917. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_14569.
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Wilson, David B., and Maxim Kostylev. "Cellulase Processivity." In Biomass Conversion, 93–99. Totowa, NJ: Humana Press, 2012. http://dx.doi.org/10.1007/978-1-61779-956-3_9.
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Gaudino, R. J., and E. A. Morgan. "The Role of Boxa in Transcription of Ribosomal RNA Operons of Eschericha Coli: Changes in the Processivity of RNA Polymerase." In Post-Transcriptional Control of Gene Expression, 113–23. Berlin, Heidelberg: Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-642-75139-4_12.
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"Processivity." In Encyclopedia of Biophysics, 1954. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-16712-6_100782.
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"Processivity." In Encyclopedia of Genetics, Genomics, Proteomics and Informatics, 1561. Dordrecht: Springer Netherlands, 2008. http://dx.doi.org/10.1007/978-1-4020-6754-9_13470.
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Horn, Svein J., Morten Sørlie, Kjell M. Vårum, Priit Väljamäe, and Vincent G. H. Eijsink. "Measuring Processivity." In Cellulases, 69–95. Elsevier, 2012. http://dx.doi.org/10.1016/b978-0-12-415931-0.00005-7.
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Yao, N. Y., and M. O'Donnell. "Processivity Clamps in DNA Replication." In Encyclopedia of Biological Chemistry, 576–80. Elsevier, 2013. http://dx.doi.org/10.1016/b978-0-12-378630-2.00319-4.
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Bambara, Robert A., Philip J. Fay, and Lisa M. Mallaber. "[21] Methods of analyzing processivity." In Methods in Enzymology, 270–80. Elsevier, 1995. http://dx.doi.org/10.1016/0076-6879(95)62023-0.
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Yao, Nina Y., and Mike O’Donnell. "Processivity Clamps in DNA Replication." In Reference Module in Life Sciences. Elsevier, 2020. http://dx.doi.org/10.1016/b978-0-12-819460-7.00045-1.
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Davey, Megan J., and Mike O'Donnell. "Processivity Clamps in DNA Replication: Clamp Loading." In Encyclopedia of Biological Chemistry, 441–46. Elsevier, 2004. http://dx.doi.org/10.1016/b0-12-443710-9/00181-2.
Full textConference papers on the topic "Processivité"
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Yang, Yang, Jianwei Guo, Sicong Guo, and Shenling Li. "Linear Programming Processivity and Structural Optimisation of Intelligent Systems." In IS4SI Summit 2023. Basel Switzerland: MDPI, 2023. http://dx.doi.org/10.3390/cmsf2023008048.
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