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18 juin 2018: 1 événement

  • Evènements I2BC

    Lundi 18 juin 14:00-15:00 - Scott Blanchard - Department of Physiology & Biophysics, Weill Cornell Medical College, New York, USA

    Single-molecule imaging reveals the rate-determining steps of substrate translocation on the bacterial ribosome

    Résumé : Directional translocation of the ribosome through the mRNA open reading frame is a critical determinant of translational fidelity. This process entails a complex interplay of large-scale conformational changes within the actively translating particle, which together coordinate the movement of tRNA and mRNA substrates with respect to the large and small ribosomal subunits. Using pre–steady state, single-molecule fluorescence resonance energy transfer imaging, we tracked the nature and timing of these conformational events within the Escherichia coli ribosome from five structural perspectives. Our investigations revealed direct evidence of structurally and kinetically distinct late intermediates during substrate movement, whose resolution determines the rate of translocation. These steps involve intramolecular events within the EF-G–GDP–bound ribosome, including exaggerated, reversible fluctuations of the small-subunit head domain, which ultimately facilitate peptidyl-tRNA’s movement into its final post-translocation position.

    Lieu : Auditorium I2BC - Bat. 21, Campus de Gif-sur-Yvette

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