title: The C-terminal variable region specifies the dynamic properties of Arabidopsis microtubule-associated protein MAP65 isotypes.
abstract: The microtubule-associated protein, MAP65, is a member of a family of divergent microtubule-associated proteins from different organisms generally involved in maintaining the integrity of the central spindle in mitosis. The dicotyledon Arabidopsis thaliana and the monocotyledon rice (Oryza sativa) genomes contain 9 and 11 MAP65 genes, respectively. In this work, we show that the majority of these proteins fall into five phylogenetic clades, with the greatest variation between clades being in the C-terminal random coil domain. At least one Arabidopsis and one rice isotype is within each clade, indicating a functional specification for the C terminus. In At MAP65-1, the C-terminal domain is a microtubule binding region (MTB2) harboring the phosphorylation sites that control its activity. The At MAP65 isotypes show differential localization to microtubule arrays and promote microtubule polymerization with variable efficiency in a MTB2-dependent manner. In vivo studies demonstrate that the dynamics of the association and dissociation of different MAP65 isotypes with microtubules can vary up to 10-fold and that this correlates with their ability to promote microtubule polymerization. Our data demonstrate that the C-terminal variable region, MTB2, determines the dynamic properties of individual isotypes and suggest that slower turnover is conditional for more efficient microtubule polymerization.
authors.affiliation: Integrative Cell Biology Laboratory, School of Biological and Biomedical Sciences, University of Durham, Durham DH1 3LE, United Kingdom.
authors.forename: Andrei P
authors.initials: AP
authors.lastname: Smertenko
authors.forename: Despina
authors.initials: D
authors.lastname: Kaloriti
authors.forename: Hsin-Yu
authors.initials: HY
authors.lastname: Chang
authors.forename: Jindriska
authors.initials: J
authors.lastname: Fiserova
authors.forename: Zdenek
authors.initials: Z
authors.lastname: Opatrny
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Hussey
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D015151:Immunoblotting; D018613:Microscopy, Confocal; D008869:Microtubule-Associated Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism*; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding / Q000235:genetics; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; C492901:MAP65-1 protein, Arabidopsis; D008869:Microtubule-Associated Proteins; D010940:Plant Proteins; D020033:Protein Isoforms; D011994:Recombinant Proteins