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Molecular dissection of the microtubule depolymerizing activity of mitotic centromere-associated kinesin

T Maney1, M Wagenbach, L Wordeman

  • 1Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle, Washington 98195, USA.

The Journal of Biological Chemistry
|July 24, 2001
PubMed

Insights

Mitotic centromere-associated kinesin (MCAK) is crucial for chromosome segregation. A conserved N-terminal domain, not just the motor domain, is essential for MCAK’s microtubule depolymerization activity, independent of dimerization.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Mitotic centromere-associated kinesin (MCAK) is a key microtubule depolymerizer.
  • MCAK plays a vital role in ensuring accurate chromosome segregation during cell division.
  • Understanding MCAK's function is critical for comprehending mitosis.

Purpose of the Study:

  • To investigate the specific domains of MCAK responsible for its microtubule depolymerization activity.
  • To determine the role of MCAK dimerization in its depolymerization function.
  • To identify the minimal sequence requirements for MCAK's motor function in vitro and in cells.

Main Methods:

  • Site-directed mutagenesis to create MCAK deletion constructs.
  • In vitro microtubule depolymerization assays.
  • Cellular assays to assess MCAK function in chromosome segregation.

Main Results:

  • The motor domain of MCAK is necessary but insufficient for microtubule depolymerization.
  • A short N-terminal extension (30 amino acids) to the motor domain restores depolymerization activity.
  • Small functional MCAK deletion constructs exist as monomers, not dimers.

Conclusions:

  • A highly conserved N-terminal domain, adjacent to the motor, is critical for MCAK's microtubule depolymerization.
  • MCAK-mediated microtubule depolymerization does not require MCAK dimerization.
  • These findings refine our understanding of kinesin motor function in mitosis.

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