title: Non-catalytic motor domains enable processive movement and functional diversification of the kinesin-14 Kar3.
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.
authors.affiliation: Research Institute of Molecular Pathology, Vienna, Austria.
authors.forename: Christine
authors.initials: C
authors.lastname: Mieck
authors.affiliation: Research Institute of Molecular Pathology, Vienna, Austria.
authors.forename: Maxim I
authors.initials: MI
authors.lastname: Molodtsov
authors.affiliation: Research Institute of Molecular Pathology, Vienna, Austria.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Drzewicka
authors.affiliation: Research Institute of Molecular Pathology, Vienna, Austria.
authors.forename: Babet
authors.initials: B
authors.lastname: van der Vaart
authors.affiliation: Research Institute of Molecular Pathology, Vienna, Austria.
authors.forename: Gabriele
authors.initials: G
authors.lastname: Litos
authors.affiliation: Research Institute of Molecular Pathology, Vienna, Austria.
authors.forename: Gerald
authors.initials: G
authors.lastname: Schmauss
authors.affiliation: Research Institute of Molecular Pathology, Vienna, Austria.
authors.forename: Alipasha
authors.initials: A
authors.lastname: Vaziri
authors.affiliation: Research Institute of Molecular Pathology, Vienna, Austria.
authors.forename: Stefan
authors.initials: S
authors.lastname: Westermann
mesh_terms: D020134:Catalytic Domain; D019281:Dimerization; D008869:Microtubule-Associated Proteins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000378:metabolism / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D013347:Subcellular Fractions / Q000378:metabolism
chemical_list: C063504:KAR3 protein, S cerevisiae; D008869:Microtubule-Associated Proteins; D029701:Saccharomyces cerevisiae Proteins
keywords: S. cerevisiae; biophysics; cell biology; cytoskeleton; kinesins; microtubules; structural biology