Two microtubule-associated proteins of Arabidopsis MAP65s promote antiparallel microtubule bundling.
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.
Gaillard
Jérémie
J
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.
Neumann
Emmanuelle
E
Van Damme
Daniel
D
Stoppin-Mellet
Virginie
V
Ebel
Christine
C
Barbier
Elodie
E
Geelen
Danny
D
Vantard
Marylin
M
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
D029681:Arabidopsis Proteins; C492901:MAP65-1 protein, Arabidopsis; C533278:MAP65-5 protein, Arabidopsis; D008869:Microtubule-Associated Proteins; D049452:Green Fluorescent Proteins