Kinesin-5 Kip1 is a bi-directional motor that stabilizes microtubules and tracks their plus-ends in vivo

Vladimir Fridman, Adina Gerson-Gurwitz, Ofer Shapira, Natalia Movshovich, Stefan Lakämper, Christoph F. Schmidt, Larisa Gheber

Research output: Contribution to journalArticlepeer-review

62 Scopus citations

Abstract

In this study, we examined the anaphase functions of the S. cerevisiae kinesin-5 homolog Kip1. We show that Kip1 is attached to the mitotic spindle midzone during late anaphase. This attachment is essential to stabilize interpolar microtubule (iMTs) plus-ends. By detailed examination of iMT dynamics we show that at the end of anaphase, iMTs depolymerize in two stages: during the first stage, one pair of anti-parallel iMTs depolymerizes at a velocity of 7.7 μm/minute; during the second stage, ~90 seconds later, the remaining pair of iMTs depolymerizes at a slower velocity of 5.4 μm/minute. We show that upon the second depolymerization stage, which coincides with spindle breakdown, Kip1 follows the plus-ends of depolymerizing iMTs and translocates toward the spindle poles. This movement is independent of mitotic microtubule motor proteins or the major plus-end binding or tracking proteins. In addition, we show that Kip1 processively tracks the plus-ends of growing and shrinking MTs, both inside and outside the nucleus. The plus-end tracking activity of Kip1 requires its catalytic motor function, because a rigor mutant of Kip1 does not exhibit this activity. Finally, we show that Kip1 is a bi-directional motor: in vitro, at high ionic strength conditions, single Kip1 molecules move processively in the minus-end direction of the MTs, whereas in a multi-motor gliding assay, Kip1 is plus-end directed. The bi-directionality and plus-end tracking activity of Kip1, properties revealed here for the first time, allow Kip1 to perform its multiple functions in mitotic spindle dynamics and to partition the 2-micron plasmid.

Original languageEnglish
Pages (from-to)4147-4159
Number of pages13
JournalJournal of Cell Science
Volume126
Issue number18
DOIs
StatePublished - 18 Oct 2013

Keywords

  • Anaphase B
  • Kinesin-5
  • Kip1
  • Microtubules
  • Mitosis

ASJC Scopus subject areas

  • Cell Biology

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