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Palumbo, V., Pellacani, C., Heesom, K.J., Rogala, K.B., Deane, C.M., Mottier-Pavie, V., Gatti, M., Bonaccorsi, S., Wakefield, J.G. (2015). Misato Controls Mitotic Microtubule Generation by Stabilizing the Tubulin Chaperone Protein-1 Complex.  Curr. Biol. 25(13): 1777--1783.
FlyBase ID
FBrf0228871
Publication Type
Research paper
Abstract

Mitotic spindles are primarily composed of microtubules (MTs), generated by polymerization of α- and β-Tubulin hetero-dimers <up>1, 2</up>. Tubulins undergo a series of protein folding and post-translational modifications in order to fulfill their functions <up>3, 4</up>. Defects in Tubulin polymerization dramatically affect spindle formation and disrupt chromosome segregation. We recently described a role for the product of the conserved misato (mst) gene in regulating mitotic MT generation in flies 5, but the molecular function of Mst remains unknown. Here, we use affinity purification mass spectrometry (AP-MS) to identify interacting partners of Mst in the Drosophila embryo. We demonstrate that Mst associates stoichiometrically with the hetero-octameric Tubulin Chaperone Protein-1 (TCP-1) complex, with the hetero-hexameric Tubulin Prefoldin complex, and with proteins having conserved roles in generating MT-competent Tubulin. We show that RNAi-mediated in vivo depletion of any TCP-1 subunit phenocopies the effects of mutations in mst or the Prefoldin-encoding gene merry-go-round (mgr), leading to monopolar and disorganized mitotic spindles containing few MTs. Crucially, we demonstrate that Mst, but not Mgr, is required for TCP-1 complex stability and that both the efficiency of Tubulin polymerization and Tubulin stability are drastically compromised in mst mutants. Moreover, our structural bioinformatic analyses indicate that Mst resembles the three-dimensional structure of Tubulin monomers and might therefore occupy the TCP-1 complex central cavity. Collectively, our results suggest that Mst acts as a co-factor of the TCP-1 complex, playing an essential role in the Tubulin-folding processes required for proper assembly of spindle MTs.

PubMed ID
PubMed Central ID
PMC4510148 (PMC) (EuropePMC)
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    Language of Publication
    English
    Additional Languages of Abstract
    Parent Publication
    Publication Type
    Journal
    Abbreviation
    Curr. Biol.
    Title
    Current Biology
    Publication Year
    1991-
    ISBN/ISSN
    0960-9822
    Data From Reference