title: The determinants that govern microtubule assembly from the atomic structure of GTP-tubulin.
abstract: Tubulin alternates between a soluble curved structure and a microtubule straight conformation. GTP binding to αβ-tubulin is required for microtubule assembly, but whether this triggers conversion into a straighter structure is still debated. This is due, at least in part, to the lack of structural data for GTP-tubulin before assembly. Here, we report atomic-resolution crystal structures of soluble tubulin in the GDP and GTP nucleotide states in a complex with a stathmin-like domain. The structures differ locally in the neighborhood of the nucleotide. A loop movement in GTP-bound tubulin favors its recruitment to the ends of growing microtubules and facilitates its curved-to-straight transition, but this conversion has not proceeded yet. The data therefore argue for the conformational change toward the straight structure occurring as microtubule-specific contacts are established. They also suggest a model for the way the tubulin structure is modified in relation to microtubule assembly.
authors.affiliation: Laboratoire d'Enzymologie et Biochimie Structurales (LEBS), Centre de Recherche de Gif, CNRS, Bat. 34, 1, avenue de la Terrasse, 91198 Gif sur Yvette, France.
authors.forename: Agata
authors.initials: A
authors.lastname: Nawrotek
authors.forename: Marcel
authors.initials: M
authors.lastname: Knossow
authors.forename: Benoît
authors.initials: B
authors.lastname: Gigant
mesh_terms: D018360:Crystallography, X-Ray; D003599:Cytoskeleton / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism*; D008870:Microtubules / Q000737:chemistry / Q000378:metabolism; D008954:Models, Biological; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D014404:Tubulin / Q000737:chemistry / Q000378:metabolism*
chemical_list: D014404:Tubulin; D006160:Guanosine Triphosphate