An ungrouped plant kinesin accumulates at the preprophase band in a cell cycle-dependent manner

Authors

  • Jennelle L. Malcos,

    1. Department of Biology, The Pennsylvania State University, 208 Mueller Laboratory, University Park, Pennsylvania
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  • Richard J. Cyr

    Corresponding author
    1. Department of Biology, The Pennsylvania State University, 208 Mueller Laboratory, University Park, Pennsylvania
    • Department of Biology, The Pennsylvania State University, 208 Mueller Laboratory, University Park, Pennsylvania 16802
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  • Monitoring Editor: Roberto Dominguez

Abstract

Past phylogenic studies have identified a plant-specific, ungrouped family of kinesins in which the motor domain does not group to one of the fourteen recognized families. Members of this family contain an N-terminal motor domain, a C-terminal armadillo repeat domain and a conserved destruction box (D-BOX) motif. This domain architecture is unique to plants and to a subset of protists. Further characterization of one representative member from Arabidopsis, Arabidopsisthaliana KINESIN ungrouped clade, gene A (AtKINUa), was completed to ascertain its functional role in plants. Fluorescence confocal microscopy revealed an accumulation of ATKINUA:GFP at the preprophase band (PPB) in a cell cycle-dependent manner in Arabidopsis epidermal cells and tobacco BY-2 cells. Fluorescence accumulation was highest during prophase and decreased after nuclear envelope breakdown. A conserved D-BOX motif was identified through alignment of AtKINU homologous sequences. Mutagenesis work with D-BOX revealed that conserved residues were necessary for the observed degradation pattern of ATKINUA:GFP, as well as the targeted accumulation at the PPB. Overall results suggest that AtKINUa is necessary for normal plant growth and/or development and is likely involved with PPB organization through microtubule association and specific cell cycle regulation. The D-BOX motif may function to bridge microtubule organization with changes that occur during progression through mitosis and may represent a novel regulatory motif in plant microtubule motor proteins. © 2011 Wiley-Liss, Inc.

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