title: The Arabidopsis CLASP gene encodes a microtubule-associated protein involved in cell expansion and division.
abstract: Controlling microtubule dynamics and spatial organization is a fundamental requirement of eukaryotic cell function. Members of the ORBIT/MAST/CLASP family of microtubule-associated proteins associate with the plus ends of microtubules, where they promote the addition of tubulin subunits into attached kinetochore fibers during mitosis and stabilize microtubules in the vicinity of the plasma membrane during interphase. To date, nothing is known about their function in plants. Here, we show that the Arabidopsis thaliana CLASP protein is a microtubule-associated protein that is involved in both cell division and cell expansion. Green fluorescent protein-CLASP localizes along the full length of microtubules and shows enrichment at growing plus ends. Our analysis suggests that CLASP promotes microtubule stability. clasp-1 T-DNA insertion mutants are hypersensitive to microtubule-destabilizing drugs and exhibit more sparsely populated, yet well ordered, root cortical microtubule arrays. Overexpression of CLASP promotes microtubule bundles that are resistant to depolymerization with oryzalin. Furthermore, clasp-1 mutants have aberrant microtubule preprophase bands, mitotic spindles, and phragmoplasts, indicating a role for At CLASP in stabilizing mitotic arrays. clasp-1 plants are dwarf, have significantly reduced cell numbers in the root division zone, and have defects in directional cell expansion. We discuss possible mechanisms of CLASP function in higher plants.
authors.affiliation: University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: J Christian
authors.initials: JC
authors.lastname: Ambrose
authors.forename: Tsubasa
authors.initials: T
authors.lastname: Shoji
authors.forename: Amanda M
authors.initials: AM
authors.lastname: Kotzer
authors.forename: Jamie A
authors.initials: JA
authors.lastname: Pighin
authors.forename: Geoffrey O
authors.initials: GO
authors.lastname: Wasteneys
mesh_terms: D017360:Arabidopsis / Q000166:cytology* / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics*; D002455:Cell Division / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D048429:Cell Size / Q000187:drug effects; D048749:Cytokinesis / Q000187:drug effects; D004136:Dinitrobenzenes / Q000494:pharmacology; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D049452:Green Fluorescent Proteins / Q000378:metabolism; D007399:Interphase / Q000187:drug effects; D008869:Microtubule-Associated Proteins / Q000737:chemistry / Q000235:genetics*; D008870:Microtubules / Q000187:drug effects / Q000378:metabolism; D008938:Mitosis / Q000187:drug effects; D009154:Mutation / Q000235:genetics; D010802:Phylogeny; D019441:Plant Epidermis / Q000166:cytology / Q000187:drug effects / Q000648:ultrastructure; D018515:Plant Leaves / Q000166:cytology / Q000187:drug effects / Q000648:ultrastructure; D018517:Plant Roots / Q000166:cytology / Q000187:drug effects / Q000254:growth & development; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013424:Sulfanilamides / Q000494:pharmacology
chemical_list: D029681:Arabidopsis Proteins; D004136:Dinitrobenzenes; D008869:Microtubule-Associated Proteins; D011993:Recombinant Fusion Proteins; D013424:Sulfanilamides; D049452:Green Fluorescent Proteins; C012465:oryzalin