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Evènements I2BC

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  • Lundi 12 juin 14:30-15:30 - Andrew CARTER - MRC, Cambridge

    Transporting cargo over long distances : insight from dynein/dynactin structures

    Résumé : Cells depend on components being moved to the correct place at the correct time. My group is interested in cytoplasmic dynein-1 (dynein), a motor which delivers many different cargos via the microtubule network. When dynein is mutated it leads to neurodegeneration and it is susceptible to hijack by viruses which use it to travel into the cell. In the presence of cargo adaptor proteins, such as BICD, dynein binds a cofactor called dynactin. This generates a transporter complex capable of long distance movement along microtubules. We have used cryo-electron microscopy (cryo-EM) to determine a 4.0Å structure of dynactin that explains how this 23 subunit complex is assembled. We subsequently used cryo-EM, in vitro motility assays and in cell assays to determine why dynein is inhibited when it is on its own and how it is activated by binding dynactin. We are now working to understand how the cargo adaptors specifically recruit dynein to dynactin.
    Invité par Julie Ménétrey, équipe Biochimie Structurale des Microtubules, des Kinésines et de leurs Cargos

    Lieu : Auditorium - Bâtiment 21, campus de gif

  • Lundi 19 juin 11:00-12:00 - Dr Huy Bui - Department of Anatomy and Cell Biology, McGill University, Montreal, Canada

    High-resolution structure of the doublet microtubule reveals new classes of microtubule- associated proteins and insights into its assembly mechanism

    Résumé : Cilia are ubiquitous, hair-like appendages found in eukaryotic cells that carry out functions of cell motility and sensory reception. Cilia contain an intriguing cytoskeletal structure, termed the axoneme, that consists of nine doublet microtubules radially interlinked and longitudinally organized in multiple specific repeat units. Little is known, however, how the axoneme allows cilia to be both actively bendable and sturdy or how it is assembled. To answer these questions, we used cryo-electron microscopy to structurally analyze several of the repeating units of the doublet at subnanometer resolution. This structural detail enables us to unambiguously assign α- and β-tubulins in the doublet microtubule lattice. Our study, for the first time, demonstrates the existence of an inner sheath composed of different kinds of microtubule inner proteins inside the doublet that likely stabilizes the structure and facilitates the specific building of the B-tubule.
    Invité par Anne-Marie Tassin, équipe Biogénese et fonction des structures centriolaires et ciliaires

    Lieu : Auditorium - Bâtiment 21, campus de gif

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