Kinesin-5 is a microtubule polymerase

Nat Commun. 2015 Oct 6;6:8160. doi: 10.1038/ncomms9160.


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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Dimerization
  • Drosophila
  • Drosophila Proteins / metabolism*
  • In Vitro Techniques
  • Kinesin / metabolism*
  • Microtubule-Associated Proteins
  • Microtubules / metabolism*
  • Tubulin / metabolism*
  • Tubulin Modulators / metabolism*
  • Xenopus Proteins / metabolism*
  • Xenopus laevis


  • Drosophila Proteins
  • KIF11 protein, Xenopus
  • Klp61F protein, Drosophila
  • Microtubule-Associated Proteins
  • Tubulin
  • Tubulin Modulators
  • Xenopus Proteins
  • Kinesin