title: Kinesin-5 is a microtubule polymerase.
abstract: Kinesin-5 slides antiparallel microtubules during spindle assembly, and regulates the branching of growing axons. Besides the mechanical activities enabled by its tetrameric configuration, the specific motor properties of kinesin-5 that underlie its cellular function remain unclear. Here by engineering a stable kinesin-5 dimer and reconstituting microtubule dynamics in vitro, we demonstrate that kinesin-5 promotes microtubule polymerization by increasing the growth rate and decreasing the catastrophe frequency. Strikingly, microtubules growing in the presence of kinesin-5 have curved plus ends, suggesting that the motor stabilizes growing protofilaments. Single-molecule fluorescence experiments reveal that kinesin-5 remains bound to the plus ends of static microtubules for 7 s, and tracks growing microtubule plus ends in a manner dependent on its processivity. We propose that kinesin-5 pauses at microtubule plus ends and enhances polymerization by stabilizing longitudinal tubulin-tubulin interactions, and that these activities underlie the ability kinesin-5 to slide and stabilize microtubule bundles in cells.
authors.affiliation: Department of Biomedical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.|Interdisciplinary Graduate Degree Program in Cell and Developmental Biology, Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
authors.forename: Yalei
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Department of Biomedical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.|Interdisciplinary Graduate Degree Program in Cell and Developmental Biology, Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
authors.forename: William O
authors.initials: WO
authors.lastname: Hancock
mesh_terms: D000818:Animals; D019281:Dimerization; D004330:Drosophila; D029721:Drosophila Proteins / Q000378:metabolism*; D066298:In Vitro Techniques; D016547:Kinesins / Q000378:metabolism*; D008869:Microtubule-Associated Proteins; D008870:Microtubules / Q000378:metabolism*; D014404:Tubulin / Q000378:metabolism*; D050257:Tubulin Modulators / Q000378:metabolism*; D029867:Xenopus Proteins / Q000378:metabolism*; D014982:Xenopus laevis
chemical_list: D029721:Drosophila Proteins; C088335:KIF11 protein, Xenopus; C084034:Klp61F protein, Drosophila; D008869:Microtubule-Associated Proteins; D014404:Tubulin; D050257:Tubulin Modulators; D029867:Xenopus Proteins; D016547:Kinesins