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  • 1
    Publication Date: 2015-02-25
    Description: Single particle electron cryomicroscopy (cryo-EM) has recently made significant progress in high-resolution structure determination of macromolecular complexes due to improvements in electron microscopic instrumentation and computational image analysis. However, cryo-EM structures can be highly non-uniform in local resolution and all structures available to date have been limited to resolutions above 3 A. Here we present the cryo-EM structure of the 70S ribosome from Escherichia coli in complex with elongation factor Tu, aminoacyl-tRNA and the antibiotic kirromycin at 2.65-2.9 A resolution using spherical aberration (Cs)-corrected cryo-EM. Overall, the cryo-EM reconstruction at 2.9 A resolution is comparable to the best-resolved X-ray structure of the E. coli 70S ribosome (2.8 A), but provides more detailed information (2.65 A) at the functionally important ribosomal core. The cryo-EM map elucidates for the first time the structure of all 35 rRNA modifications in the bacterial ribosome, explaining their roles in fine-tuning ribosome structure and function and modulating the action of antibiotics. We also obtained atomic models for flexible parts of the ribosome such as ribosomal proteins L9 and L31. The refined cryo-EM-based model presents the currently most complete high-resolution structure of the E. coli ribosome, which demonstrates the power of cryo-EM in structure determination of large and dynamic macromolecular complexes.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Fischer, Niels -- Neumann, Piotr -- Konevega, Andrey L -- Bock, Lars V -- Ficner, Ralf -- Rodnina, Marina V -- Stark, Holger -- England -- Nature. 2015 Apr 23;520(7548):567-70. doi: 10.1038/nature14275. Epub 2015 Feb 23.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉3D Electron Cryomicroscopy Group, Max-Planck-Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Gottingen, Germany. ; Abteilung Molekulare Strukturbiologie, Institut fur Mikrobiologie und Genetik, GZMB, Georg-August Universitat Gottingen, Justus-von Liebig Weg 11, 37077 Gottingen, Germany. ; 1] Molecular and Radiation Biophysics Department, B.P. Konstantinov Petersburg Nuclear Physics Institute of National Research Centre 'Kurchatov Institute', 188300 Gatchina, Russia [2] St Petersburg Polytechnic University, Polytechnicheskaya, 29, 195251 St Petersburg, Russia [3] Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Gottingen, Germany. ; Department of Theoretical and Computational Biophysics, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Gottingen, Germany. ; Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Gottingen, Germany. ; 1] 3D Electron Cryomicroscopy Group, Max-Planck-Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Gottingen, Germany [2] Department of 3D Electron Cryomicroscopy, Institute of Microbiology and Genetics, Georg-August Universitat, 37077 Gottingen, Germany.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25707802" target="_blank"〉PubMed〈/a〉
    Keywords: Anti-Bacterial Agents/chemistry/metabolism ; *Cryoelectron Microscopy/methods ; Escherichia coli/*chemistry/*ultrastructure ; Ligands ; Models, Molecular ; Peptide Elongation Factor Tu/*chemistry/metabolism/*ultrastructure ; Pyridones/chemistry/metabolism ; RNA, Bacterial/chemistry/metabolism/ultrastructure ; RNA, Ribosomal/chemistry/metabolism/ultrastructure ; RNA, Transfer/chemistry/metabolism/ultrastructure ; Ribosomes/*chemistry/metabolism/*ultrastructure
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2019
    Description: 〈p〉During translation, the ribosome moves along the mRNA one codon at a time with the help of elongation factor G (EF-G). Spontaneous changes in the translational reading frame are extremely rare, yet how the precise triplet-wise step is maintained is not clear. Here, we show that the ribosome is prone to spontaneous frameshifting on mRNA slippery sequences, whereas EF-G restricts frameshifting. EF-G helps to maintain the mRNA reading frame by guiding the A-site transfer RNA during translocation due to specific interactions with the tip of EF-G domain 4. Furthermore, EF-G accelerates ribosome rearrangements that restore the ribosome’s control over the codon-anticodon interaction at the end of the movement. Our data explain how the mRNA reading frame is maintained during translation.〈/p〉
    Electronic ISSN: 2375-2548
    Topics: Natural Sciences in General
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  • 3
    Publication Date: 2015-08-18
    Description: During ribosomal translation, the two ribosomal subunits remain associated through intersubunit bridges, despite rapid large-scale intersubunit rotation. The absence of large barriers hindering rotation is a prerequisite for rapid rotation. Here, we investigate how such a flat free-energy landscape is achieved, in particular considering the large shifts the bridges undergo at the periphery. The dynamics and energetics of the intersubunit contact network are studied using molecular dynamics simulations of the prokaryotic ribosome in intermediate states of spontaneous translocation. Based on observed occupancies of intersubunit contacts, residues were grouped into clusters. In addition to the central contact clusters, peripheral clusters were found to maintain strong steady interactions by changing contacts in the course of rotation. The peripheral B1 bridges are stabilized by a changing contact pattern of charged residues that adapts to the rotational state. In contrast, steady strong interactions of the B4 bridge are ensured by the flexible helix H34 following the movement of protein S15. The tRNAs which span the subunits contribute to the intersubunit binding enthalpy to an almost constant degree, despite their different positions in the ribosome. These mechanisms keep the intersubunit interaction strong and steady during rotation, thereby preventing dissociation and enabling rapid rotation.
    Print ISSN: 0305-1048
    Electronic ISSN: 1362-4962
    Topics: Biology
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