title: Binding of the CYK-4 subunit of the centralspindlin complex induces a large scale conformational change in the kinesin subunit.
abstract: Centralspindlin is a critical regulator of cytokinesis in animal cells. It is a tetramer consisting of ZEN-4/MKLP1, a kinesin-6 motor, and CYK-4/MgcRacGAP, a Rho GTPase-activating protein. At anaphase, centralspindlin localizes to a narrow region of antiparallel microtubule overlap and initiates central spindle assembly. Central spindle assembly requires complex formation between ZEN-4 and CYK-4. However, the structural consequences of CYK-4 binding to ZEN-4 are unclear as are the mechanisms of microtubule bundling. Here we investigate whether CYK-4 binding induces a conformational change in ZEN-4. Characterization of the structure and conformational dynamics of the minimal interacting regions between ZEN-4 and CYK-4 by continuous wave EPR and double electron-electron resonance (DEER) spectroscopy reveals that CYK-4 binding dramatically stabilizes the relative positions of the neck linker regions of ZEN-4. Additionally, our data indicate that each neck linker is similarly structured in the bound and unbound states. CYK-4 binding decreases the rate of ZEN-4-mediated microtubule gliding. These results constrain models for the molecular organization of centralspindlin.
authors.affiliation: Departments of Molecular Genetics and Cell Biology, University of Chicago, Chicago, Illinois 60637, USA.
authors.forename: Erin A
authors.initials: EA
authors.lastname: White
authors.forename: Hariharasundaram
authors.initials: H
authors.lastname: Raghuraman
authors.forename: Eduardo
authors.initials: E
authors.lastname: Perozo
authors.forename: Michael
authors.initials: M
authors.lastname: Glotzer
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy; D016547:Kinesins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008870:Microtubules / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D046912:Multiprotein Complexes / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D008941:Spindle Apparatus / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: C513388:CYK-4 protein, C elegans; D029742:Caenorhabditis elegans Proteins; D046912:Multiprotein Complexes; C114455:ZEN-4 protein, C elegans; D016547:Kinesins
keywords: Cytokinesis; Electron Paramagnetic Resonance (EPR); Kinesin; Microtubules; Molecular Motors