title: Measuring Pushing and Braking Forces Generated by Ensembles of Kinesin-5 Crosslinking Two Microtubules.
abstract: The proper organization of the microtubule-based mitotic spindle is proposed to depend on nanometer-sized motor proteins generating forces that scale with a micron-sized geometric feature, such as microtubule overlap length. However, it is unclear whether such regulation can be achieved by any mitotic motor protein. Here, we employ an optical-trap- and total internal reflection fluorescence (TIRF)-based assay to show that ensembles of kinesin-5, a conserved mitotic motor protein, can push apart overlapping antiparallel microtubules to generate a force whose magnitude scales with filament overlap length. We also find that kinesin-5 can produce overlap-length-dependent "brake-like" resistance against relative microtubule sliding in both parallel and antiparallel geometries, an activity that has been suggested by cell biological studies but had not been directly measured. Together, these findings, along with numerical simulations, reveal how a motor protein can function as an analog converter, "reading" simple geometric and dynamic features in cytoskeletal networks to produce regulated force outputs.
authors.affiliation: Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, NY 10065, USA; JST PRESTO, The Rockefeller University, New York, NY 10065, USA.
authors.forename: Yuta
authors.initials: Y
authors.lastname: Shimamoto
authors.affiliation: Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, NY 10065, USA.
authors.forename: Scott
authors.initials: S
authors.lastname: Forth
authors.affiliation: Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, NY 10065, USA. Electronic address: kapoor@rockefeller.edu.
authors.forename: Tarun M
authors.initials: TM
authors.lastname: Kapoor
mesh_terms: D000818:Animals; D003432:Cross-Linking Reagents / Q000378:metabolism*; D016547:Kinesins / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D008870:Microtubules / Q000378:metabolism*; D008941:Spindle Apparatus / Q000502:physiology*; D029867:Xenopus Proteins / Q000378:metabolism*; D014982:Xenopus laevis / Q000254:growth & development* / Q000378:metabolism
chemical_list: D003432:Cross-Linking Reagents; C088335:KIF11 protein, Xenopus; D029867:Xenopus Proteins; D016547:Kinesins