title: A minus-end-directed kinesin with plus-end tracking protein activity is involved in spindle morphogenesis.
abstract: Diverse kinesin motor proteins are involved in spindle function; however, the mechanisms by which they are targeted to specific sites within spindles are not well understood. Here, we show that a fusion between yellow fluorescent protein (YFP) and a minus-end-directed Kinesin-14 (C-terminal family) from Arabidopsis, ATK5, localizes to mitotic spindle midzones and regions rich in growing plus-ends within phragmoplasts. Notably, in Arabidopsis interphase cells, YFP::ATK5 localizes to microtubules with a preferential enrichment at growing plus-ends; indicating ATK5 is a plus-end tracking protein (+TIP). This +TIP activity is conferred by regions outside of the C-terminal motor domain, which reveals the presence of independent plus-end tracking and minus-end motor activities within ATK5. Furthermore, mitotic spindles of atk5 null mutant plants are abnormally broadened. Based on these data, we propose a model in which ATK5 uses plus-end tracking to reach spindle midzones, where it then organizes microtubules via minus-end-directed motor activity.
authors.affiliation: Department of Biology, The Pennsylvania State University, University Park, 16802, USA.
authors.forename: J Christian
authors.initials: JC
authors.lastname: Ambrose
authors.forename: Wuxing
authors.initials: W
authors.lastname: Li
authors.forename: Adam
authors.initials: A
authors.lastname: Marcus
authors.forename: Hong
authors.initials: H
authors.lastname: Ma
authors.forename: Richard
authors.initials: R
authors.lastname: Cyr
mesh_terms: D017360:Arabidopsis / Q000166:cytology* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000378:metabolism*; D016547:Kinesins / Q000737:chemistry / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism; D008941:Spindle Apparatus / Q000737:chemistry / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; C502922:ATK5 protein, Arabidopsis; D016547:Kinesins