title: Kinesin-8 is a low-force motor protein with a weakly bound slip state.
abstract: During the cell cycle, kinesin-8s control the length of microtubules by interacting with their plus ends. To reach these ends, the motors have to be able to take many steps without dissociating. However, the underlying mechanism for this high processivity and how stepping is affected by force are unclear. Here, we tracked the motion of yeast (Kip3) and human (Kif18A) kinesin-8s with high precision under varying loads using optical tweezers. Surprisingly, both kinesin-8 motors were much weaker compared with other kinesins. Furthermore, we discovered a force-induced stick-slip motion: the motor frequently slipped, recovered from this state, and then resumed normal stepping motility without detaching from the microtubule. The low forces are consistent with kinesin-8s being regulators of microtubule dynamics rather than cargo transporters. The weakly bound slip state, reminiscent of a molecular safety leash, may be an adaptation for high processivity.
authors.affiliation: Nanomechanics Group, Biotechnology Center, TU Dresden, Dresden, Germany.
authors.forename: Anita
authors.initials: A
authors.lastname: Jannasch
authors.forename: Volker
authors.initials: V
authors.lastname: Bormuth
authors.forename: Marko
authors.initials: M
authors.lastname: Storch
authors.forename: Jonathon
authors.initials: J
authors.lastname: Howard
authors.forename: Erik
authors.initials: E
authors.lastname: Schäffer
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D006801:Humans; D016547:Kinesins / Q000378:metabolism*; D007700:Kinetics; D055595:Mechanical Phenomena; D009068:Movement; D052898:Optical Tweezers; D021381:Protein Transport; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*
chemical_list: C108256:KIP3 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D000244:Adenosine Diphosphate; C502735:KIF18A protein, human; D016547:Kinesins