Motile microtubule crosslinkers require distinct dynamic properties for correct functioning during spindle organization in Xenopus egg extract.
The organization of the microtubule cytoskeleton depends crucially on crosslinking motors that arrange microtubules in space. Kinesin-5 is such an essential motile crosslinker. It is unknown whether its organizing capacity during bipolar spindle formation depends on its characteristic kinetic properties, or whether simply crosslinking combined with any plus-end-directed motility is sufficient for its function in a physiological context. To address this question, we replaced the motor domain of Xenopus Kinesin-5 by motor domains of kinesins belonging to other kinesin subfamilies, without changing the overall architecture of the molecule. This generated novel microtubule crosslinkers with altered kinetic properties. The chimeric crosslinkers mislocalized in spindles and consequently caused spindle collapse into tightly bundled microtubule arrays. This demonstrates that plus-end directionality and microtubule crosslinking are not the only characteristics required for proper functioning of Kinesin-5 during spindle assembly in Xenopus egg extract. Instead, its motor domain properties appear to be fine-tuned for the specific function of this kinesin.
European Molecular Biology Laboratory, Cell Biology and Biophysics Unit, Meyerhofstr. 1, 69117 Heidelberg, Germany.
Julie
J
Cahu
Thomas
T
Surrey
D000595:Amino Acid Sequence; D000818:Animals; D003432:Cross-Linking Reagents / Q000378:metabolism*; D003599:Cytoskeleton / Q000378:metabolism; D016547:Kinesins / Q000235:genetics / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism*; D008969:Molecular Sequence Data; D009865:Oocytes / Q000166:cytology / Q000378:metabolism*; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D008941:Spindle Apparatus / Q000378:metabolism*; D029867:Xenopus Proteins / Q000235:genetics / Q000378:metabolism*; D014982:Xenopus laevis
D003432:Cross-Linking Reagents; C088335:KIF11 protein, Xenopus; D020033:Protein Isoforms; D011993:Recombinant Fusion Proteins; D029867:Xenopus Proteins; D016547:Kinesins