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Literatura académica sobre el tema "Maturation ribosomique"
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Artículos de revistas sobre el tema "Maturation ribosomique"
LEROUX, C. y G. TOSSER-KLOPP. "La fonction du gène : les grandes étapes de l’utilisation de l’information génétique". INRAE Productions Animales 13, HS (22 de octubre de 2000): 21–28. http://dx.doi.org/10.20870/productions-animales.2000.13.hs.3807.
Texto completoTesis sobre el tema "Maturation ribosomique"
Soudet, Julien. "Étude de la maturation cytoplasmique de la petite sous-unité ribosomique chez Saccharomyces cerevisiae". Toulouse 3, 2009. http://thesesups.ups-tlse.fr/2286/.
Texto completoRibosomes constitute one of the major actors of the mechanism of translation in any living cell. The synthesis of ribosomes is a complex process beginning with the transcription of a pre-ribosomal RNA (rRNA) containing future mature rRNAs as well as sequences that are eliminated during ribosome biogenesis. In Saccharomyces cerevisiae, no less than 200 factors are implicated in this process. We were more precisely interested in the cytoplasmic step of the small ribosomal subunit maturation consisting of an endonucleolytic cleavage of the 20S pre-rRNA contained in a pre-40S particle and leading to the mature 18S rRNA contained in the 40S ribosomal subunit. The initial model was that 40S ribosomal subunit maturation might be a pre-requisite for translation initiation. Our experiments have led to the observation that a fraction of 20S pre-rRNA co-sediments with 80S complexes and polysomes. This 20S pre-rRNA fraction can be increased in mutants impaired in the cytoplasmic step of 40S ribosomal subunit maturation. By biochemical approaches, we confirmed the occurrence of ribosomes containing pre-40S particles and mRNAs. Thus, our data suggest that pre-40S particles can initiate translation. These aberrant ribosomes are then degraded via the No Go decay pathway involved in the quality control of some cytoplasmic RNAs. No-Go Decay would function as an ultimate quality control mechanism of the 40S ribosomal subunit
Pintard, Lionel. "Spb1p est une méthylase de levure impliquée dans la maturation des ARNr". Montpellier 1, 2000. http://www.theses.fr/2000MON1T019.
Texto completoLouvet, Emilie. "Dynamique et compartimentation de la machinerie de maturation des ARN ribosomiques en cellules vivantes". Paris 5, 2005. http://www.theses.fr/2005PA05S025.
Texto completoThe functional organisation of the nucleus depends on machineries that are distributed in domains named nuclear bodies. To understand how this distribution is regulated we have chosen the nucleolus as example. We have focused our attention on traffic and compartmentation of the rRNA processing machinery during interphase and mitosis. To follow proteins in living cells we have used microscopy technologies such as: FRAP, videomicroscopy and tdFLIM-FRET. A reversible system capable of disconnecting the processing from the transcription machineries during interphase permitted us to show that the processing machinery can be disconnected from the transcription sites and accumulates in nuclear masses originating from the nucleolar granular component. We named these granular masses. This reversible process permitted us to study reformation of the nucleolus. In control cells and in an assay using permeabilized cells set up in the laboratory, we have shown that nucleolar reformation depends on ATP hydrolysis and that CK2 is involved in nucleolar compartmentation. At the exit of mitosis, we have shown that early and late processing machineries pass through the same PNB. The convergence of the machineries in a single site could be at the origin of PNB formation. Furthermore, we have demonstrated that Nop52 and B23 interact in the same PNB. For this reason, we propose that PNB are preassembly platforms for rRNA processing complexes
Bousquet-Antonelli, Cécile. "Caracterisation de partenaires fonctionnels de la proteine garlp de saccharomyces cerevisiae requise pour la maturation du pre-arn ribosomique". Toulouse 3, 1998. http://www.theses.fr/1998TOU30058.
Texto completoBaudin-Baillieu, Agnès. "Contribution a l'etude systematique du genome de la levure saccharomyces cerevisiae et analyse fonctionnelle d'un nouveau gene implique dans la maturation de l'arn ribosomique". Paris 11, 1997. http://www.theses.fr/1997PA112085.
Texto completoRaoelijaona, Raivoniaina. "Compréhension des rôles des complexes Nob1/Pno1 et RPS14/Cinap dans la maturation cytoplasmique de la petite sous-unité ribosomique (pré-40S) chez les eucaryotes". Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0221/document.
Texto completoRibosomes are translational machineries universally responsible of protein synthesis. In eukaryote, ribosome assembly is a complex and highly regulated process that requires coordinated action of more than 200 biogenesis factors. Ribosome assembly is initiated in the nucleolus, continues in the nucleoplasm and terminates in the cytoplasm. The cytoplasmic maturation events of the small ribosomal subunit are associated with sequential release of the late assembly factors and concomitant maturation of the pre-rRNA. During final maturation of the small subunit, the pre-18S rRNA is cleaved off by the endonuclease Nob1, which activity is coordinated by its binding partner Pno1. Detailed information on pre-ribosomal particle architectures have been provided by structural snapshots of maturation events. However, key functional aspects such as the architecture required for pre-rRNA cleavage have remained elusive. In order to better understand these late steps of cytoplasmic pre-40S maturation, we first redefine the domain organization of Nob1, then study its binding mode with Pno1 using different tools such as sequence analysis, structure prediction and biochemical experiments and, we then performed functional assay to elucidate the role played by Pno1 during the pre-18S rRNA maturation.Our results have shown that eukaryotic Nob1 adopts an atypical PIN domain conformation: two fragments (res 1-104 and 230-255) separated by an internal loop, which is essential for Pno1 recognition. We also found out that Pno1 inhibits Nob1 activity likely by masking the cleavage site. Our findings further support the recently published cryo-EM structure of the pre-40S, where Nob1 displays an inactive conformation. Moreover, 18S rRNA 3’-end cleavage has to happen and this implies structural rearrangement or requirement of some accessory proteins such as Cinap, an atypical kinase involved in pre-18S processing. Studying the interplay between proteins localized in the pre-40S platform (RPS14, RPS26, Nob1/Pno1 complex) has shown that Cinap is able to form a trimeric complex with Nob1 and its binding partner Pno1. Furthermore, Cinap can recognize RPS26 in a RPS14-dependent manner, which had already been studied with its yeast counterpart. It is important to note that RPS26 is the ribosomal protein replacing Pno1 in the mature ribosome. Our finding clearly suggests a mechanism where RPS26 recruitment to the ribosome requires Pno1 dissociation. This exchange would be carried out by Cinap. Therefore, we can suggest a simplified model as follow: upon binding with Pno1, the newly formed complex (Cinap/Pno1) will trigger a conformational change, which will allow the endonuclease Nob1 to reach its substrate (D-site) and perform its cleavage resulting in mature 18 rRNA generation
Halladjian, Maral. "Etude de la fonction de l'hélicase Prp43 dans la synthèse des ribosomes et des connexions entre synthèse et maturation du pré-ARN ribosomique chez la levure". Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30156.
Texto completoIn eukaryotic cells, ribosome synthesis begins with the transcription of ribosomal DNA (rDNA) by RNA polymerase I (Pol I). This process generates a primary transcript (pre-rRNA), containing the sequences corresponding to the mature 18S, 5.8S and 25S rRNAs. The fourth rRNA (5S) is transcribed independently by RNA Pol III. The pre-rRNA associates co-transcriptionally with some ribosomal proteins and many maturation factors to generate a large initial pre-ribosomal particle called the 90S particle. This particle undergoes a complex maturation process generating the pre-40S and pre-60S particles that will generate the mature ribosomal subunits. The first part of my thesis work consisted in the study of the Rpf2-Rrs1 heterodimer in yeast. This heterodimer is known to be essential for the maturation of pre-60S particles through the recruitment of the 5S RNP, a module containing the 5S rRNA associated to ribosomal proteins RpL5 and RpL11. We showed that Rpf2 and Rrs1 interact with rDNA chromatin using chromatin immunoprecipitation (ChIP) experiments and that this interaction does not depend on the integrity of the pre-ribosomal particles. Moreover, both Rpf2 and Rrs1 interact with Pol I subunits and with several rDNA chromatin-associated factors in vivo. These data suggest a function of the Rpf2-Rrs1 heterodimer in the regulation of Pol I transcription in addition to its role in the maturation of pre-60S particles. Interestingly, we observed using Miller spread experiments that loss of expression of Rpf2 or Rrs1 is correlated with strong perturbations in the organization of rDNA units. Using the "run-on" experiment, a technique allowing to determine the occupancy of active polymerases on the rDNA units, I further showed that loss of expression of Rpf2 or Rrs1 strongly affects Pol I transcription in yeast cells. Additional experiments suggest that the Rpf2-Rrs1 complex is present on rDNA units in absence of Pol I transcription in vivo and interacts with purified Pol I in vitro. These data strongly suggest that the Rpf2-Rrs1 heterodimer is a prime candidate to plays a crucial role in the functional coupling between rDNA transcription and pre-ribosome assembly in yeast cells. The second part of my thesis work focused on the study of the Prp43 helicase in yeast. Prp43 is a helicase from the DEAH/RHA family required for both the synthesis of ribosomes and the splicing of pre-mRNAs. Prp43 interacts with G-patch domain-containing proteins which activate its enzymatic activity in vitro by an unknown mechanism. During my thesis, we showed that the activation of Prp43 by G-patch proteins seems to be linked to the unique nucleotide binding mode of this helicase family. Previous structural data showed that the base of the ATP molecule is stacked between two residues, R159 of the RecA1 domain and F357 of the RecA2 domain in the active site of Prp43. The in vitro study of a Prp43 mutant bearing a substitution of F357 to an alanine (F357A) showed that the lack of stacking of the nucleotide base to the F357 residue uncouples the NTPase and helicase activities of Prp43 in vitro. In contrast the substitution of R159 to an alanine (R159A) reduced both the ATPase and helicase activities of the enzyme. We observed in addition that the Prp43 R159A mutation induces the same phenotype as the one resulting from the absence of Gno1, one of the G-patch domain-containing partners of Prp43. This result strongly suggests that the processing defects observed in the absence of Gno1 result from a failure to activate the Prp43 helicase. Overall we propose that the stacking of the ATP base between residues R159 and F357 is important for the activity and regulation of this helicase family
Al, Kadri Yasmine. "Étude de la fonction du complexe Bms1p/Rcl1p dans les étapes précoces de la synthèse des ribosomes et des connexions entre synthèse et maturation du pré-ARN ribosomique chez Saccharomyces cerevisiae". Toulouse 3, 2014. http://www.theses.fr/2014TOU30099.
Texto completoIn eukaryotic cells, ribosome synthesis begins with the transcription of ribosomal DNA (rDNA) by RNA polymerase I (Pol. I) in the nucleolus. This transcription generates a primary transcript precursor to the mature 18S, 5. 8S and 25S. This transcript is co-transcriptionally associated with some ribosomal proteins, many assembly and maturation factors and a set of small ribonucleoprotein particles to generate a giant initial pre-ribosomal particle. This particle undergoes a complex maturation process which begins in the nucleolus and ends in the cytoplasm where the formation of mature ribosomal subunits occurs. Ribosome synthesis is one of the most energy-consuming cellular processes; it must be highly regulated and tightly coordinated with other fundamental cellular processes. As previously mentioned, ribosome synthesis involves around 200 dedicated to the assembly and maturation of pre-ribosomal particles. However, the function of the vast majority of them is still unknown and current challenges in the field are to understand their precise molecular role. Part of my thesis work consisted in the study of the structure / function of the Bms1p/Rcl1p complex involved in ribosome synthesis in yeast. Rcl1p and Bms1p are two essential nucleolar proteins that form a complex required for the maturation of the small ribosomal subunit (40S). Bms1p is a GTPase and Rcl1p is an endoribonuclease which catalyzes the cleavage of the pre-rRNA at site A2; the step which separates the two maturation pathways leading to the formation of ribosomal subunits 40S and 60S. The team of our collaborator Sébastien Fribourg (IECB, Bordeaux) has solved the crystal structure of Rcl1p in complex with a fragment of Bms1p and identified residues at the interface between the two proteins. The substitution of some of these amino acids affects the interaction between Rcl1p and Bms1p in vitro and induces defects in the maturation of pre-rRNA in vivo. We have shown that these defects are probably due to a problem in Rcl1p incorporation into pre-ribosomal particles. Indeed, Bms1p and Rcl1p are imported into the nucleus as a complex via the nuclear localization sequence (NLS) of Bms1p. Both proteins are then recruited simultaneously into pre-ribosomes after incorporation of UTP-A and UTP-B modules but independently of Rrp5p incorporation. Our results also suggest that the GTP-binding to Bms1p is not required for the recruitment of the complex. Following A2 cleavage, the two proteins are both released from pre-40S particles before Rio2p incorporation. Therefore, our data indicate that the direct interaction between Bms1p and Rcl1p is crucial for the incorporation of the complex into pre-ribosomes in yeast. Another part of my thesis work focused on the study of Rpf2p protein, a component of the pre-60S ribosomal particles required for the synthesis of the large ribosomal subunit. Various data from the literature suggest that Rpf2p interacts with rDNA chromatin associated factors. We have confirmed some of these interactions and our results suggest that Rpf2p is associated in vivo with rDNA chromatin and more particularly to transcriptionally active copies. These data suggest that Rpf2p could be involved in mechanisms of chromatin modification required for transcription by RNA Pol. I and indeed, nuclear "run-on" experiments indicate that the loss of Rpf2p expression affects transcription by RNA pol. I. These preliminary results suggest that Rpf2p could be involved in the functional coupling between rDNA transcription and maturation of pre-ribosomal particles
Bertrand, Alexis. "Caractérisation fonctionnelle de mutations somatiques compensatrices d'elF6 dans le contexte du syndrome de Shwachman- Diamond". Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASL089.
Texto completoShwachman Diamond syndrome (SDS) is a rare genetic ribosomopathy leading to impaired protein synthesis, which causes numerous symptoms including bone marrow failure and neutropenia that can evolve to myelodysplasia syndrome or acute myeloid leukaemia. Biallelic mutations in the SBDS gene are responsible of above 90% of the SDS cases and we recently identified biallelic EFL1 mutations as a novel cause of SDS. SBDS together with EFL1 remove the anti-association factor elF6 from the pre60S ribosomal subunit, allowing its interaction with the 40S subunit to form the mature ribosome 80S. Natural acquisition of somatic genetic events over time participâtes to age-related diseases and cancer development. However, in Mendelian diseases these events can, in rare case, counteract the deleterious effect of the germline mutation and provide a sélective advantage to the somatically modified cells, a phenomenon dubbed Somatic Genetic Rescue (SGR). We recently showed that several somatic genetic events affecting the expression or function of elF6 are frequently detected in blood clones from SDS patients but not in healthy individuals, suggesting a mechanism of SGR. While most of these somatic mutations induce elF6 destabilization or EIF6 haploinsufficiency, one récurrent mutation (N106S) did not affect the expression of elF6 but rather impact its ability to interact with the 60S subunit. In order to further investigate the functional conséquences of ElF6 haploinsufficiency and N106S mutation in a context of SDS, I introduced via CRISPR/Cas9 these mutations in immortalized fibroblastic cell line from SDS patients and control. These original cellular models hâve made it possible to détermine the impact of the N106S mutation on the localisation and function of elF6 and also to clarify the effects of these mutations on several aspects of cellular fitness, in particular ribosome biogenesis, translation rate and cell prolifération. Overall, the development of these cellular models has helped to characterise how the somatic N106S mutation and elF6 haploinsufficiency confer a sélective advantage in cells déficient in SBDS or EFL1
Rouquette, Jacques. "Export nucléaire des pré-ribosomes". Toulouse 3, 2005. http://www.theses.fr/2005TOU30250.
Texto completoThe ribosome is composed of the 40S subunit (18S rRNA associated with about thirty proteins), and the 60S subunit (5. 8S, 25S/28S and 5S rRNAs and approximatively forty proteins). Different maturation steps take place as pre-ribosomal particles are transported through the nucleus, from the nucleolus to the nucleoplasm, until nucleocytoplasmic translocation. On a first stage, we studied nucleoporins function in pre-40S particle transport using budding yeast mutant strains. This project has given rise to a complete inventory of nucleoporins required in both pre-40S particle and mRNP nucleocytoplasmic trafficking. Translocation of pre-ribosomal particles and mRNPs through the NPC needs distinct nucleoporins complexes, partially overlapping, indicating different export pathways. On a second stage, we extended the study of pre-ribosome transport to mammalian cells. For the first time, we show the existence of a new 18S rRNA precursor, exported to the cytoplasm, like in yeast