title: Interactions of tobacco microtubule-associated protein MAP65-1b with microtubules.
abstract: Tobacco microtubule associated protein (MAP65) (NtMAP65s) constitute a family of microtubule-associated proteins with apparent molecular weight around 65 kDa that collectively induce microtubule bundling and promote microtubule assembly in vitro. They are associated with most of the tobacco microtubule arrays in situ. Recently, three NtMAP65s belonging to the NtMAP65-1 subfamily have been cloned. Here we investigated in vitro the biochemical properties of one member of this family, the tobacco NtMAP65-1b. We demonstrated that recombinant NtMAP65-1b is a microtubule-binding and a microtubule-bundling protein. NtMAP65-1b has no effect on microtubule polymerization rate and binds microtubules with an estimated equilibrium constant of dissociation (K(d)) of 0.57 micro m. Binding of NtMAP65-1b to microtubules occurs through the carboxy-terminus of tubulin, as NtMAP65-1b was no longer able to bind subtilisin-digested tubulin. In vitro, NtMAP65-1b stabilizes microtubules against depolymerization induced by cold, but not against katanin-induced destabilization. The biological implications of these results are discussed.
authors.affiliation: Laboratoire de Physiologie Cellulaire Végétale, Département Réponse et Dynamique Cellulaire, 17 rue des Martyrs, UMR 5168, CNRS/CEA/INRA/Université Joseph Fourier, F-38054 Grenoble Cedex 9, France.
authors.forename: Catherine
authors.initials: C
authors.lastname: Wicker-Planquart
authors.forename: Virginie
authors.initials: V
authors.lastname: Stoppin-Mellet
authors.forename: Laurent
authors.initials: L
authors.lastname: Blanchoin
authors.forename: Marylin
authors.initials: M
authors.lastname: Vantard
mesh_terms: D000251:Adenosine Triphosphatases / Q000494:pharmacology; D000074201:Katanin; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism* / Q000648:ultrastructure; D008970:Molecular Weight; D010940:Plant Proteins / Q000378:metabolism*; D011485:Protein Binding; D011994:Recombinant Proteins / Q000378:metabolism; D013381:Subtilisins / Q000494:pharmacology; D013997:Time Factors; D014026:Nicotiana / Q000235:genetics* / Q000378:metabolism; D014404:Tubulin / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D008869:Microtubule-Associated Proteins; D010940:Plant Proteins; D011994:Recombinant Proteins; D014404:Tubulin; D013381:Subtilisins; D000251:Adenosine Triphosphatases; D000074201:Katanin