title: Insight into tubulin regulation from a complex with colchicine and a stathmin-like domain.
abstract: Microtubules are cytoskeletal polymers of tubulin involved in many cellular functions. Their dynamic instability is controlled by numerous compounds and proteins, including colchicine and stathmin family proteins. The way in which microtubule instability is regulated at the molecular level has remained elusive, mainly because of the lack of appropriate structural data. Here, we present the structure, at 3.5 A resolution, of tubulin in complex with colchicine and with the stathmin-like domain (SLD) of RB3. It shows the interaction of RB3-SLD with two tubulin heterodimers in a curved complex capped by the SLD amino-terminal domain, which prevents the incorporation of the complexed tubulin into microtubules. A comparison with the structure of tubulin in protofilaments shows changes in the subunits of tubulin as it switches from its straight conformation to a curved one. These changes correlate with the loss of lateral contacts and provide a rationale for the rapid microtubule depolymerization characteristic of dynamic instability. Moreover, the tubulin-colchicine complex sheds light on the mechanism of colchicine's activity: we show that colchicine binds at a location where it prevents curved tubulin from adopting a straight structure, which inhibits assembly.
authors.affiliation: European Molecular Biology Laboratory (EMBL), Grenoble Outstation, 6 rue Jules Horowitz, BP 181, 38042 Grenoble Cedex 9, France.
authors.forename: Raimond B G
authors.initials: RB
authors.lastname: Ravelli
authors.forename: Benoît
authors.initials: B
authors.lastname: Gigant
authors.forename: Patrick A
authors.initials: PA
authors.lastname: Curmi
authors.forename: Isabelle
authors.initials: I
authors.lastname: Jourdain
authors.forename: Sylvie
authors.initials: S
authors.lastname: Lachkar
authors.forename: André
authors.initials: A
authors.lastname: Sobel
authors.forename: Marcel
authors.initials: M
authors.lastname: Knossow
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D003078:Colchicine / Q000737:chemistry* / Q000378:metabolism* / Q000494:pharmacology; D008868:Microtubule Proteins; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009414:Nerve Growth Factors / Q000737:chemistry* / Q000378:metabolism*; D010750:Phosphoproteins / Q000737:chemistry*; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D021122:Protein Subunits; D050777:Stathmin; D014404:Tubulin / Q000737:chemistry* / Q000378:metabolism*; D050257:Tubulin Modulators
chemical_list: D008868:Microtubule Proteins; D009414:Nerve Growth Factors; D010750:Phosphoproteins; D021122:Protein Subunits; C491795:STMN4 protein, human; D050777:Stathmin; D014404:Tubulin; D050257:Tubulin Modulators; D003078:Colchicine