title: Control of the AtMAP65-1 interaction with microtubules through the cell cycle.
abstract: Cell division depends on the fine control of both microtubule dynamics and microtubule organisation. The microtubule bundling protein MAP65 is a ;midzone MAP' essential for the integrity of the anaphase spindle and cell division. Arabidopsis thaliana MAP65-1 (AtMAP65-1) binds and bundles microtubules by forming 25 nm cross-bridges. Moreover, as AtMAP65-1 bundles microtubules in interphase, anaphase and telophase but does not bind microtubules in prophase or metaphase, its activity through the cell cycle must be under tight control. Here we show that AtMAP65-1 is hyperphosphorylated during prometaphase and metaphase and that CDK and MAPK are involved in this phosphorylation. This phosphorylation inhibits AtMAP65-1 activity. Expression of non-phosphorylatable AtMAP65-1 has a negative effect on mitotic progression resulting in excessive accumulation of microtubules in the metaphase spindle midzone causing a delay in mitosis. We conclude that normal metaphase spindle organisation and the transition to anaphase is dependent on inactivation of AtMAP65-1.
authors.affiliation: The Integrative Cell Biology Laboratory, School of Biological and Biomedical Sciences, University of Durham, South Road, Durham, DH1 3LE, UK.
authors.forename: Andrei P
authors.initials: AP
authors.lastname: Smertenko
authors.forename: Hsin-Yu
authors.initials: HY
authors.lastname: Chang
authors.forename: Seiji
authors.initials: S
authors.lastname: Sonobe
authors.forename: Stepan I
authors.initials: SI
authors.lastname: Fenyk
authors.forename: Magdalena
authors.initials: M
authors.lastname: Weingartner
authors.forename: Laci
authors.initials: L
authors.lastname: Bögre
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Hussey
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002453:Cell Cycle / Q000502:physiology*; D002478:Cells, Cultured; D018844:Cyclin-Dependent Kinases / Q000378:metabolism; D036681:Fluorescence Recovery After Photobleaching; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism* / Q000648:ultrastructure; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010446:Peptide Fragments / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D008941:Spindle Apparatus / Q000378:metabolism; D014026:Nicotiana / Q000166:cytology
chemical_list: D029681:Arabidopsis Proteins; C492901:MAP65-1 protein, Arabidopsis; D008869:Microtubule-Associated Proteins; D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins; D018844:Cyclin-Dependent Kinases; D020928:Mitogen-Activated Protein Kinases