title: Two microtubule-associated proteins of Arabidopsis MAP65s promote antiparallel microtubule bundling.
abstract: The Arabidopsis MAP65s are a protein family with similarity to the microtubule-associated proteins PRC1/Ase1p that accumulate in the spindle midzone during late anaphase in mammals and yeast, respectively. Here we investigate the molecular and functional properties of AtMAP65-5 and improve our understanding of AtMAP65-1 properties. We demonstrate that, in vitro, both proteins promote the formation of a planar network of antiparallel microtubules. In vivo, we show that AtMAP65-5 selectively binds the preprophase band and the prophase spindle microtubule during prophase, whereas AtMAP65-1-GFP selectively binds the preprophase band but does not accumulate at the prophase spindle microtubules that coexists within the same cell. At later stages of mitosis, AtMAP65-1 and AtMAP65-5 differentially label the late spindle and phragmoplast. We present evidence for a mode of action for both proteins that involves the binding of monomeric units to microtubules that "zipper up" antiparallel arranged microtubules through the homodimerization of the N-terminal halves when adjacent microtubules encounter.
authors.affiliation: Institut de Recherches en Technologies et Sciences pour le Vivant, Unité Mixte de Recherche, Centre National de la Recherche Scientifique, Centre d'Energie Atomique, Université Joseph Fourier, 38054 Grenoble, France.
authors.forename: Jérémie
authors.initials: J
authors.lastname: Gaillard
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Neumann
authors.forename: Daniel
authors.initials: D
authors.lastname: Van Damme
authors.forename: Virginie
authors.initials: V
authors.lastname: Stoppin-Mellet
authors.forename: Christine
authors.initials: C
authors.lastname: Ebel
authors.forename: Elodie
authors.initials: E
authors.lastname: Barbier
authors.forename: Danny
authors.initials: D
authors.lastname: Geelen
authors.forename: Marylin
authors.initials: M
authors.lastname: Vantard
mesh_terms: D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000502:physiology*; D003599:Cytoskeleton / Q000378:metabolism; D019281:Dimerization; D018506:Gene Expression Regulation, Plant; D049452:Green Fluorescent Proteins / Q000378:metabolism; D008856:Microscopy, Fluorescence; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000502:physiology*; D008870:Microtubules / Q000737:chemistry* / Q000378:metabolism; D008938:Mitosis; D008954:Models, Biological; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D008941:Spindle Apparatus / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; C492901:MAP65-1 protein, Arabidopsis; C533278:MAP65-5 protein, Arabidopsis; D008869:Microtubule-Associated Proteins; D049452:Green Fluorescent Proteins