Non-catalytic motor domains enable processive movement and functional diversification of the kinesin-14 Kar3

Elife. 2015 Jan 27:4:e04489. doi: 10.7554/eLife.04489.

Abstract

Motor proteins of the conserved kinesin-14 family have important roles in mitotic spindle organization and chromosome segregation. Previous studies have indicated that kinesin-14 motors are non-processive enzymes, working in the context of multi-motor ensembles that collectively organize microtubule networks. In this study, we show that the yeast kinesin-14 Kar3 generates processive movement as a heterodimer with the non-motor proteins Cik1 or Vik1. By analyzing the single-molecule properties of engineered motors, we demonstrate that the non-catalytic domain has a key role in the motility mechanism by acting as a 'foothold' that allows Kar3 to bias translocation towards the minus end. This mechanism rivals the speed and run length of conventional motors, can support transport of the Ndc80 complex in vitro and is critical for Kar3 function in vivo. Our findings provide an example for a non-conventional translocation mechanism and can explain how Kar3 substitutes for key functions of Dynein in the yeast nucleus.

Keywords: S. cerevisiae; biophysics; cell biology; cytoskeleton; kinesins; microtubules; structural biology.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Catalytic Domain
  • Dimerization
  • Microtubule-Associated Proteins / chemistry
  • Microtubule-Associated Proteins / metabolism
  • Microtubule-Associated Proteins / physiology*
  • Saccharomyces cerevisiae / metabolism
  • Saccharomyces cerevisiae / physiology
  • Saccharomyces cerevisiae Proteins / chemistry
  • Saccharomyces cerevisiae Proteins / metabolism
  • Saccharomyces cerevisiae Proteins / physiology*
  • Subcellular Fractions / metabolism

Substances

  • KAR3 protein, S cerevisiae
  • Microtubule-Associated Proteins
  • Saccharomyces cerevisiae Proteins

Grants and funding

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.