Kar3Vik1, a member of the kinesin-14 superfamily, shows a novel kinesin microtubule binding pattern

J Cell Biol. 2012 Jun 25;197(7):957-70. doi: 10.1083/jcb.201201132.

Abstract

Kinesin-14 motors generate microtubule minus-end-directed force used in mitosis and meiosis. These motors are dimeric and operate with a nonprocessive powerstroke mechanism, but the role of the second head in motility has been unclear. In Saccharomyces cerevisiae, the Kinesin-14 Kar3 forms a heterodimer with either Vik1 or Cik1. Vik1 contains a motor homology domain that retains microtubule binding properties but lacks a nucleotide binding site. In this case, both heads are implicated in motility. Here, we show through structural determination of a C-terminal heterodimeric Kar3Vik1, electron microscopy, equilibrium binding, and motility that at the start of the cycle, Kar3Vik1 binds to or occludes two αβ-tubulin subunits on adjacent protofilaments. The cycle begins as Vik1 collides with the microtubule followed by Kar3 microtubule association and ADP release, thereby destabilizing the Vik1-microtubule interaction and positioning the motor for the start of the powerstroke. The results indicate that head-head communication is mediated through the adjoining coiled coil.

Publication types

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

MeSH terms

  • Adenosine Diphosphate / metabolism
  • Cryoelectron Microscopy
  • Fungal Proteins / chemistry
  • Fungal Proteins / metabolism*
  • Fungal Proteins / ultrastructure
  • Kinesins / chemistry
  • Kinesins / metabolism*
  • Kinesins / ultrastructure
  • Microtubule-Associated Proteins / chemistry
  • Microtubule-Associated Proteins / metabolism*
  • Microtubule-Associated Proteins / ultrastructure
  • Microtubules / metabolism*
  • Models, Molecular
  • Protein Binding
  • Protein Structure, Quaternary
  • Protein Structure, Tertiary
  • Saccharomyces cerevisiae / chemistry
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae / ultrastructure
  • Saccharomyces cerevisiae Proteins / chemistry
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Saccharomyces cerevisiae Proteins / ultrastructure

Substances

  • Fungal Proteins
  • KAR3 protein, S cerevisiae
  • Microtubule-Associated Proteins
  • Saccharomyces cerevisiae Proteins
  • VIK1 protein, S cerevisiae
  • Adenosine Diphosphate
  • Kinesins