Contents
Academic literature on the topic 'Cryo-MET'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Cryo-MET.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Journal articles on the topic "Cryo-MET"
1
Kumar, Anil, Nayanika Sengupta, and Somnath Dutta. "Simplified Approach for Preparing Graphene Oxide TEM Grids for Stained and Vitrified Biomolecules." Nanomaterials 11, no. 3 (March 5, 2021): 643. http://dx.doi.org/10.3390/nano11030643.
Full textAbstract:
In this manuscript, we report the application of graphene oxide (GO) in the preparation of cryo-electron microscopy (cryo-EM) and transmission electron microscopy (TEM) grids. We treated GO with water and organic solvents, such as, methanol, ethanol and isopropanol separately to isolate significantly large GO monolayer flake to fabricate the grids for cryo-EM and TEM study. We implemented a simplified approach to isolate flakes of GO monolayer for constructing the TEM grids, independent of expensive heavy equipment (Langmuir–Blodgett trough, glow-discharge system, carbon-evaporator or plasma-cleaner or peristaltic pumps). We employed confocal microscopy, SEM and TEM to characterize the flake size, stability and transparency of the GO monolayer and atomic force microscopy (AFM) to probe the depth of GO coated grids. Additionally, GO grids are visualized at cryogenic condition for suitability of GO monolayer for cryo-EM study. In addition, GO-Met-H2O grids reduce the effect of preferred orientation of biological macromolecules within the amorphous ice. The power-spectrum and contrast-transfer-function unequivocally suggest that GO-Met-H2O fabricated holey grids have excellent potential for application in high-resolution structural characterization of biomolecules. Furthermore, only 200 movies and ~8000 70S ribosome particles are selected on GO-coated grids for cryo-EM reconstruction to achieve high-resolution structure.
2
Comen, Elizabeth Anne, Yolanda Bryce, David B. Page, Stephen Barnett Solomon, Micaela Rodine, Christina DiLauro Abaya, Elizabeth Anne Morris, et al. "Preoperative checkpoint inhibition (CPI) and cryoablation (Cryo) in women with early-stage breast cancer (ESBC)." Journal of Clinical Oncology 37, no. 15_suppl (May 20, 2019): 592. http://dx.doi.org/10.1200/jco.2019.37.15_suppl.592.
Full textAbstract:
592 Background: Checkpoint inhibition (CPI) combined with local strategies that cause local tumor destruction, such as cryo may augment tumor specific immunity and improve survival. We previously demonstrated in 18 ESBC patients (pts) that pre-operative (pre-op) cryo with ipilimumab (ipi) is not only safe but also generates robust local and systemic immune responses (NCT01502592). Given the added activity of dual CPI in other tumors, we undertook a second pilot study of pre-op ipi/nivolumab (nivo)/cryo to confirm the safety of this combination and the impact on immune biomarkers. Methods: In both pilot studies, eligible pts had operable ≥1.5cm invasive HER2 negative ESBC. CPI was administered 8-15d prior to, and cryo was performed 7-10d prior to, standard-of-care (SOC) surgery. Toxicity evaluation continued for 12wks after drug administration. Blood for immune correlates was obtained at baseline, cryo, surgery and 2-4 weeks thereafter. Tumor samples were obtained at cryo and surgery. Flow-cytometry of peripheral lymphocytes was compared to previously reported ipi/cryo responses. Results: After a median follow-up of 66 months all 18 ESBC ipi/cryo pts, including 3 TNBC pts, are recurrence free. In the ipi/nivo/cryo study, the safety primary endpoint was met when 5 pts underwent SOC surgery without delay. Ipi/nivo/cryo was well tolerated overall. One pt on an aromatase inhibitor had grade 4 liver toxicity 8 weeks after surgery. One pt, 3 weeks after her SOC surgery, developed grade 1 hyperthyroidism, preventing a secondary axillary dissection from proceeding as scheduled. Robust activation of peripheral CD4+ and CD8+ T cells peaked at week 2 post ipi/nivo with the majority of activated CD8+ T cells expressing PD1. Comparing the correlatives of the ipi/nivo/cryo study with the prior ipi/cryo study, we observed higher expression of activation markers (Ki-67, ICOS, CTLA-4, LAG-3) on peripheral T cells and downregulation of suppressor cells. Conclusions: Ipi/cryo-treated pts, including 3 TNBC pts, remain recurrence free after > 5y. Combining cryo with ipi/nivo preop is feasible, safe, and associated with greater T cell activation than ipi/cryo alone. These results informed an ongoing randomized phase 2 study of pre-op ipi/nivo/cryo versus SOC in women with residual TNBC after neoadjuvant chemotherapy (NCT03546686). Clinical trial information: NCT02833233.
3
Ivanov, R. V., N. A. Nikolaeva, U. V. Hompodoeva, and P. P. Borisova. "THE USE OF CRYO-FEED IN THE RATION OF DAIRY COWS AND HERD HORSES OF YAKUTIA." Siberian Herald of Agricultural Science 48, no. 5 (January 9, 2019): 30–37. http://dx.doi.org/10.26898/0370-8799-2018-5-4.
Full textAbstract:
The paper presents testing results of feeding dry cows and horses with cryo-feed, preserved by using natural techniques, at winter grazing (tebenevka). Research into digestibility of nutrition substances of cow ration was carried out on 30 cows of Sirrrmental breed divided into three groups (control and two experimental ones, whose ration included 4 and 1.5 kg of cryo-feed respectively). The introduction of cryo-feed in the ration of cows increased the level of metabolizable energy and had a positive impact on the efficiency of energy metabolism. Cows of the 1 st experimental group, where cryo-feed accounted for 12% of the nutrition ration, showed 5.8% higher protein digestibility than the control group. Feeding cows with cryo-feed in the dry period contributed to the maintenance of reproductive qualities. The percentage of fertilization of cows was 90-100%. It was established that feeding horses on cryo-feed significantly increased their nutritional level at tebenevka in the winter time and fully met the need of animals in feeding elements. This marked a high horse feeding capacity per 1 ha of cryo-feed, which amounted to 129-142 horse days. The advantage in organic matter digestibility at tebenevka on cryo-feed accounted for 11.9%, dry matter - 10.48%, crude protein - 18.3%, crude fiber- 21.9%, crude fat - 13.3%, and nitrogen-free extractive substances - 11.7%. The energy supply of a horse organism per 100 kg of live weight was 32.6 MJ, which exceeded the norm by 14.5%. Better digestibility of nutrients of winter-green mass of oats compared to the grass stand was due to the high content of carotene and provitamin Е in plants preserved on the root by natural cold. During the study it was established that the actual foal crop increased by 12-14% at tebenevka with horses on cryo-feed compared to traditional technology.
4
Solaiman, Kamal A. M., Ashraf Mahrous, Hesham A. Enany, and Ashraf Bor’i. "Drain fluid cryo-explant technique for treatment of superior bullous rhegmatogenous retinal detachment in young adults." Therapeutic Advances in Ophthalmology 13 (January 2021): 251584142098821. http://dx.doi.org/10.1177/2515841420988211.
Full textAbstract:
Purpose: To evaluate the efficacy of the drain fluid cryo-explant (DFCE) technique for the management of uncomplicated superior bullous rhegmatogenous retinal detachment (RRD) in young adults. Patients and methods: A retrospective study that included eyes with uncomplicated superior bullous RRD in patients ⩽40 years old. DFCE technique consists of sequential drainage of subretinal fluid, intravitreal fluid injection, cryotherapy, and placement of a scleral explant(s). The primary outcome measure was anatomical reposition of the retina after a single surgery. Secondary outcome measures included improvement in best corrected visual acuity (BCVA) and any reported complication related to the procedure. Results: The study included 51 eyes which met the study eligibility criteria. The mean duration of detachment was 19.7 ± 6.4 days. A single retinal break was found in 31 eyes (60.8%), and more than one break were found in 20 eyes (39.2%). The mean number of breaks per eye was 1.72 ± 1.04. The mean detached area per eye was 7.21 ± 3.19 clock hours, and the macula was detached in 22 eyes (43.1%). Flattening of the retina and closure of all retinal breaks was achieved in all eyes after a single surgery. Late recurrence of retinal detachment occurred in two eyes (3.9%) due to proliferative vitreoretinopathy (PVR). No complicated cataract or iatrogenic retinal breaks were detected in all eyes. Conclusion: DFCE technique could be effectively used for treatment of uncomplicated superior bullous RRD in adults ⩽40 years. It is safe and provides good visualization during surgery with no iatrogenic retinal breaks or complicated cataract.
5
Francou, Bernard. "Régime thermique des sols et rôle du gel dans la dynamique des versants d’un milieu subéquatorial d’altitude : les Andes centrales du Pérou." Géographie physique et Quaternaire 43, no. 1 (December 18, 2007): 97–112. http://dx.doi.org/10.7202/032757ar.
Full textAbstract:
RÉSUMÉ Le gel et son action sont étudiés ici dans le milieu de la haute montagne subéquatoriale. La fréquence du gel est journalière et son intensité mesurée sous abri à 5 000 m ne descend guère au-delà de - 6° C. Dans le sol, les températures relevées à 10 cm ne dépassent pas - 2° C et le gel est atteint moins de 50 jours par an. L'épaisseur de la couche du sol parcourue par le front de gel est limitée à 10-15 cm. Le gel pénètre mieux dans les sols fins (sables silteux) et bien drainés. Dans les parois rocheuses, le gel est « pelliculaire » et limité à quelques heures jusqu'à 5 200 m. Dans les conditions actuelles, la formation d'un pergélisol dans le sol ou dans la roche n'est pas possible en dessous de 5 200 m. En première hypothèse, on peut mettre en relation les caractéristiques du gel ainsi définies avec la faible efficacité de la gélifraction, si l'on met à part quelques faciès plus gélifs qui fournissent des éléments de petite taille. Dans le sol, à côté de l'action de la glace d'exsudation, on met en évidence le rôle de la cryoreptation dans le déplacement des particules sur les versants. En plus des microformes de tri très répandues dans l'élaboration desquelles les mécanismes cryo-induits et le ruissellement de lavage se combinent étroitement, on insiste sur les particularités que revêtent les éboulis et les lobes à front pierreux dans ce milieu. La principale originalité consiste en la mise en place de dépôts stratifiés. Dans une perspective paléomorphologique, la présence de certaines formes inactives révèle que le cycle de gel-dégel n'a pas toujours eu les mêmes tendances depuis la fin du dernier pléniglaciaire et que les conditions ont dû être réunies dans le passé pour permettre des gels plus intenses et plus durables.
6
Thakur, Anil, Swati Gaikwad, Anil K. Vijjamarri, and Alan G. Hinnebusch. "eIF2α interactions with mRNA control accurate start codon selection by the translation preinitiation complex." Nucleic Acids Research 48, no. 18 (September 21, 2020): 10280–96. http://dx.doi.org/10.1093/nar/gkaa761.
Full textAbstract:
Abstract In translation initiation, AUG recognition triggers rearrangement of the 48S preinitiation complex (PIC) from an open conformation to a closed state with more tightly-bound Met-tRNAi. Cryo-EM structures have revealed interactions unique to the closed complex between arginines R55/R57 of eIF2α with mRNA, including the −3 nucleotide of the ‘Kozak’ context. We found that R55/R57 substitutions reduced recognition of a UUG start codon at HIS4 in Sui− cells (Ssu− phenotype); and in vitro, R55G-R57E accelerated dissociation of the eIF2·GTP·Met-tRNAi ternary complex (TC) from reconstituted PICs with a UUG start codon, indicating destabilization of the closed complex. R55/R57 substitutions also decreased usage of poor-context AUGs in SUI1 and GCN4 mRNAs in vivo. In contrast, eIF2α-R53 interacts with the rRNA backbone only in the open complex, and the R53E substitution enhanced initiation at a UUG codon (Sui− phenotype) and poor-context AUGs, while reducing the rate of TC loading (Gcd− phenotype) in vivo. Consistently, R53E slowed TC binding to the PIC while decreasing TC dissociation at UUG codons in vitro, indicating destabilization of the open complex. Thus, distinct interactions of eIF2α with rRNA or mRNA stabilize first the open, and then closed, conformation of the PIC to influence the accuracy of initiation in vivo.
7
Wells, D. N. "The integration of cloning by nuclear transfer in the conservation of animal genetic resources." BSAP Occasional Publication 30 (2004): 223–41. http://dx.doi.org/10.1017/s0263967x0004204x.
Full textAbstract:
AbstractCloning mammals from somatic cells by nuclear transfer has the potential to assist with the preservation of genetic diversity. An increasing number of species have been successfully cloned by this approach; however, present methods are inefficient with few cloned embryos resulting in healthy offspring. In those livestock species that have already been cloned, it is clearly feasible to use cloning to preserve endangered breeds (e.g. the last surviving Enderby Island cow). The opportunity exists to recover oocytes from these cloned heifers and use frozen Enderby Island sperm from deceased bulls for in vitro fertilisation and thus, expand the genetic diversity of this breed. Where there exists an adequate understanding of the reproductive biology and embryology of the species concerned and adequate sources of females to supply both recipient oocytes and surrogates to gestate the pregnancies, intra-specific nuclear transfer and embryo transfer can be utilised. However, when these requirements cannot be met, as is common for most endangered species, cloning technology invariably involves the use of inter-species nuclear transfer and embryo transfer. Even in intra-specific cloning the source of oocyte for nuclear transfer is an important consideration. Typically, cloned animals are only genomic copies of the founder if they possess mitochondrial DNA which differs from the original animal. Different maternal lineages of oocytes both within and between breeds significantly affect cloning efficiency and livestock production characteristics. Cloning should not distract conservation efforts from encouraging the use of indigenous livestock breeds with traits of adaptation to local environments, the preservation of wildlife habitats or the use of other forms of assisted reproduction. Whilst it is often difficult to justify cloning in animal conservation at present, the appropriate cryo-preservation of tissues and cells from a wide selection of biodiversity is of paramount importance. This provides an insurance against further losses of genetic variation from dwindling populations, disease epidemics or even possible extinction. It would also complement the gene banking of gametes or embryos and can be performed more easily and cheaply. Future cloning from preserved somatic cells can reintroduce lost genes back into the breeding pool. With greater appreciation of the heritable attributes of traditional livestock breeds there is the desire to identify superior animals within these local populations and the genetic loci involved. Through clonal family performance testing, nuclear transfer can aid the selection of desirable genotypes and then the production of larger numbers of embryos or animals for natural breeding to more widely disseminate the desirable traits. With the identification of alleles conferring desirable attributes, transgenesis could be utilised to both improve traditional and industrial livestock breeds. This further emphasizes the importance of preserving global farm animal genetic resources.
8
TALEBIYAN, Reza, Fardin AMIDI, Morteza SAMINI, Pezhman MIRSHOKRAEI, and Saeid HABIBIAN DEHKORDI. "Met-Anandamidin Koç Spermasının Dondurulmasında Hiperaktivasyon, Kryo-Kapasitasyon ve Akrozom Reaksiyonunun Önlenmesi Üzerine Etkisi." Kafkas Universitesi Veteriner Fakultesi Dergisi, 2015. http://dx.doi.org/10.9775/kvfd.2014.12897.
Full text
9
Llácer, Jose Luis, Tanweer Hussain, Adesh K. Saini, Jagpreet Singh Nanda, Sukhvir Kaur, Yuliya Gordiyenko, Rakesh Kumar, Alan G. Hinnebusch, Jon R. Lorsch, and V. Ramakrishnan. "Translational initiation factor eIF5 replaces eIF1 on the 40S ribosomal subunit to promote start-codon recognition." eLife 7 (November 30, 2018). http://dx.doi.org/10.7554/elife.39273.
Full textAbstract:
In eukaryotic translation initiation, AUG recognition of the mRNA requires accommodation of Met-tRNAi in a ‘PIN’ state, which is antagonized by the factor eIF1. eIF5 is a GTPase activating protein (GAP) of eIF2 that additionally promotes stringent AUG selection, but the molecular basis of its dual function was unknown. We present a cryo-electron microscopy (cryo-EM) reconstruction of a yeast 48S pre-initiation complex (PIC), at an overall resolution of 3.0 Å, featuring the N-terminal domain (NTD) of eIF5 bound to the 40S subunit at the location vacated by eIF1. eIF5 interacts with and allows a more accommodated orientation of Met-tRNAi. Substitutions of eIF5 residues involved in the eIF5-NTD/tRNAi interaction influenced initiation at near-cognate UUG codonsin vivo, and the closed/open PIC conformation in vitro, consistent with direct stabilization of the codon:anticodon duplex by the wild-type eIF5-NTD. The present structure reveals the basis for a key role of eIF5 in start-codon selection.
10
Ballesteros, Angela, Cristina Fenollar-Ferrer, and Kenton Jon Swartz. "Structural relationship between the putative hair cell mechanotransduction channel TMC1 and TMEM16 proteins." eLife 7 (July 31, 2018). http://dx.doi.org/10.7554/elife.38433.
Full textAbstract:
The hair cell mechanotransduction (MET) channel complex is essential for hearing, yet it’s molecular identity and structure remain elusive. The transmembrane channel–like 1 (TMC1) protein localizes to the site of the MET channel, interacts with the tip-link responsible for mechanical gating, and genetic alterations in TMC1 alter MET channel properties and cause deafness, supporting the hypothesis that TMC1 forms the MET channel. We generated a model of TMC1 based on X-ray and cryo-EM structures of TMEM16 proteins, revealing the presence of a large cavity near the protein-lipid interface that also harbors the Beethoven mutation, suggesting that it could function as a permeation pathway. We also find that hair cells are permeable to 3 kDa dextrans, and that dextran permeation requires TMC1/2 proteins and functional MET channels, supporting the presence of a large permeation pathway and the hypothesis that TMC1 is a pore forming subunit of the MET channel complex.
Dissertations / Theses on the topic "Cryo-MET"
1
Dallet, Laurence. "Caractérisation et compréhension du mécanisme des nanovecteurs pour la délivrance intracellulaire de macromolécules biologiques." Thesis, Nantes, 2017. http://www.theses.fr/2017NANT1002/document.
Full textAbstract:
L’un des challenges dans la délivrance intracellulaire de macromolécules biologiques est le développement de vecteurs adaptés et efficaces. Des études précédentes ont identifiés les dérivés lipidiques d’aminoglycosides comme étant d’excellents candidats pour la délivrance d’acides nucléiques et récemment de protéines. La délivrance intracellulaire de protéines thérapeutiques représente une approche originale pour le traitement de pathologies car elles ont la capacité d’agir sur des voies de signalisation intracellulaire. Dans cette étude, nous avons identifié les relations entre les caractéristiques physico-chimiques des vecteurs et leur capacité à délivrer efficacement les molécules biologiques au sein des cellules. Pour y parvenir nous avons mis en oeuvre une stratégie originale en étudiant les corrélations existantes par microscopie de fluorescence et électronique. Nous avons ainsi identifié un système micellaire à base d’aminoglycoside permettant la délivrance d’une protéine thérapeutique (anticorps K8-FITC) au sein de cellules vivantes. Les complexes lipide/anticorps sont internalisés par la voie macropinocytose et cavéoledépendant (CvME) dont cette dernière est majoritaire. Ensuite, les complexes concentriques et multilamellaires (25 nm et 1 μm de diamètre) se retrouvent dans des vésicules intracellulaires et sont libérés par un mécanisme de « flipflop ». La formation du couple lipides anioniques/cationiques permet le détachement de l’anticorps et sa libération dans le cytoplasme. Par microscopie corrélative et tomographie, il a été démontré que l’anticorps se distribuait dans l’ensemble de la cellule et restait fonctionnel, attesté par la fixation sur des filaments intermédiaires de cytokératine 8One of the challenges in the intracellular delivery of biological macromolecules is the development of suitable and efficient vectors. Previous studies have identified lipid derivatives of aminoglycosides as excellent candidates to the delivery of nucleic acids and recently proteins. The intracellular delivery of therapeutic proteins represents an original approach for the treatment of pathologies because they have the capacity to act on intracellular signaling pathways. In this study, we identified the relationships between physico-chemical characteristics of vectors and their ability to efficiently deliver biological molecules within cells. To achieve this, we have implemented an original strategy by studying the existing correlations by fluorescence and electron microscopy. We have thus identified an aminoglycoside-based micellar system allowing the delivery of a therapeutic protein (K8- FITC antibody) within living cells. The lipid/antibody complexes are internalized by the macropinocytosis and caveolae-dependent pathway (CvME), of which the latter is the majority. Then, the concentric and multilamellar complexes (25 nm and 1 μm in diameter) are found in intracellular vesicles and are released by a "flip-flop" mechanism. The formation of the anionic/cationic lipid couple allows detachment of the antibody and its release into the cytoplasm. By correlative microscopy and tomography, it was demonstrated that the antibody was distributed throughout the cell and remained functional, ascertained by the fixation on intermediate filaments of cytokeratin 8
2
Guyomar, Charlotte. "Études structurales de la trans-traduction, cible privilégiée pour le développement de nouveaux antibiotiques." Thesis, Rennes 1, 2018. http://www.theses.fr/2018REN1B039.
Full textAbstract:
Le travail retranscrit dans cette thèse porte sur un processus biologique impliqué dans le contrôle qualité de la synthèse protéique bactérienne : la trans-traduction. Ce processus permet de libérer les ribosomes bloqués sur des ARNm défectueux tout en détruisant les peptides et ARNm problématiques impliqués dans le blocage. Il nécessite deux acteurs principaux qui interagissent avec le ribosome: l’ARN transfert-messager (ARNtm) et la protéine SmpB. Dans un premier chapitre, une étude en cryo-microscopie électronique à transmission (cryo-MET) a permis d’obtenir deux structures à l’échelle atomique impliquant le ribosome et différents acteurs de la trans-traduction. La première structure met en évidence l’interaction entre la RNase R, enzyme responsable de la destruction des ARNm défectueux, et le ribosome bactérien. La deuxième structure a mené à la caractérisation des deux premiers états de la trans-traduction à une résolution quasi-atomique. De nouvelles interactions sont notamment observées entre la protéine SmpB et l’hélice H5 de l’ARNtm. Dans un second chapitre, la trans-traduction est exploitée comme cible pour le développement de nouveaux antibiotiques. En effet, cette voie de sauvetage est souvent vitale ou alors indispensable à la virulence bactérienne. Dans l’objectif de découvrir de nouvelles molécules antibiotiques inhibant la trans-traduction, nous avons mis au point un système de détection de la trans-traduction in vitro. Ce système est simple et rapide, basé sur la mesure de la fluorescence d’une GFP tronquée, réassemblée par un ARNtm muté. La validation du système a conduit à la détection de nouveaux composés anti-trans-traductionThis work is focused on a biological process which controls bacterial protein synthesis, trans-translation. This all-in-one process allows the rescuing of ribosomes stalled on defective mRNA, the degradation of the problematic peptides and mRNA. It is driven by two principal actors that interact with the ribosome: transfer-messenger RNA (tmRNA) and Small protein B (SmpB). In a first chapter, by a cryo-electron microscopic (cryo-EM) study, two near-atomic resolution structures, involving the ribosome and various trans-translation actors, were obtained. The first one highlights the interactions between RNase R, an enzyme responsible for mRNA degradation during trans-translation, and the bacterial ribosome. The second one corresponds to the characterization of two early trans-translation states at a near-atomic resolution. New interactions have been observed between SmpB and tmRNA H5 helix. In a second chapter, trans-translation is used as a target for the development of new antibiotic molecules. Indeed, this pathway is often necessary for bacterial survival and pathogenicity. Towards this aim, we designed and set up a new in vitro assay for high-throughput screening assays. This efficient system is based on fluorescence measurements of a GFP reassembled through trans-translation by a mutated tmRNA. This system has been validated and will be used for the discovery of new anti-trans-translation compounds
3
Macé, Kévin. "Le contrôle qualité de la synthèse protéique comme cible pour le développement de nouveaux antibiotiques." Thesis, Rennes 1, 2016. http://www.theses.fr/2016REN1B034/document.
Full textAbstract:
Le travail retranscrit dans cette thèse regroupe l'étude de différents processus biologiques impliqués dans la synthèse protéique bactérienne. Dans un premier chapitre, les origines de la synthèse protéique au temps du monde ARN sont traitées en guise d'introduction. Ce travail théorique se poursuit par la présentation d'une structure à haute résolution du facteur d'élongation G (EF-G) en complexe avec le ribosome par cryo-microscopie électronique à transmission (cryo-MET). Grâce aux avancées techniques de la cryo-MET, nous avons observé pour la première fois EF-G lié au ribosome en l'absence de tout inhibiteur. Cet état particulièr d'EF-G permet de visualiser une flexibilité de son doamine III. Cette étude permet aussi de rationaliser le fonctionnement de l'antibiotique acide fusidique. Nous nous sommes ensuite intéressés aux voies de sauvetage de la synthèse protéique et plus particulièrement de la trans-traduction. Ce mécanisme fascinant permet le recyclage des ribosomes bloqués sur un ARN messager défectueux. Cette voie de sauvetage est généralement vitale ou alors indispensable pour la virulence bactérienne. Nous avons réalisé une étude structurale préliminaire de la dégradation de l'ARNm défectueux durant ce processus. Après une revue traitant du sujet, nous présentons une étude de la trans-traduction comme cible pour le développement de nouveaux antibiotiques. Pour cela, nous avons mis au point un système rapporteur avec contrôle interne de l'activité trans-traductionnelle bactérienne. Après avoir mis au point ce système et validé son utilisation, nous l'avons exploité en testant des molécules ciblant la trans-traductionThe current PhD work brings together various studies linked to bacterial protein synthesis. The first chapter is about the origins of protein synthesis at the time of the RNA world. This theoretical work continues with the presentation of a high-resolution structure of the elongation factor G (EF-G) in complex with the ribosome by cryo-electron transmission microscopy (cryo-TEM). We describe for the first time EF-G bound to the ribosome in the absence of any inhibitor. This particular structure of EF-G displays a yet unseen positioning of its third domain, which becomes very flexible. This study helps to understand the way the antibiotic fusidic acid blocks translation. The work then switches to a study of trans-translation, the main rescuing system of stalled ribosomes in bacteria. Trans-translation is generally vital or at least necessary for bacterial virulence. We conducted a preliminary structural study on the way faulty mRNAs are degraded during this process. This is why we present a study of trans-translation as a target for the development of new antibiotics. For this we developed and validated a reporter system for trans-translation, which is used to screen molecules targeting trans-translation