Microtubule organization by the antagonistic mitotic motors kinesin-5 and kinesin-14.
During cell division, different molecular motors act synergistically to rearrange microtubules. Minus end-directed motors are thought to have a dual role: focusing microtubule ends to poles and establishing together with plus end-directed motors a balance of force between antiparallel microtubules in the spindle. We study here the competing action of Xenopus laevis kinesin-14 and -5 in vitro in situations in which these motors with opposite directionality cross-link and slide microtubules. We find that full-length kinesin-14 can form microtubule asters without additional factors, whereas kinesin-5 does not, likely reflecting an adaptation to mitotic function. A stable balance of force is not established between two antiparallel microtubules with these motors. Instead, directional instability is generated, promoting efficient motor and microtubule sorting. A nonmotor microtubule cross-linker can suppress directional instability but also impedes microtubule sorting, illustrating a conflict between stability and dynamicity of organization. These results establish the basic organizational properties of these antagonistic mitotic motors and a microtubule bundler.
Hentrich
Christian
C
Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany.
Surrey
Thomas
T
D000818:Animals; D002455:Cell Division; D016547:Kinesins / Q000235:genetics / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D008870:Microtubules / Q000378:metabolism*; D008941:Spindle Apparatus / Q000378:metabolism; D029867:Xenopus Proteins / Q000235:genetics / Q000378:metabolism*; D014982:Xenopus laevis / Q000378:metabolism
C088335:KIF11 protein, Xenopus; D029867:Xenopus Proteins; D016547:Kinesins