title: Nucleotide exchange in dimeric MCAK induces longitudinal and lateral stress at microtubule ends to support depolymerization.
abstract: Members of the kinesin-13 subfamily use motor domains in an unconventional fashion to initiate microtubule (MT) depolymerization at MT ends, suggesting unique conformational transitions for lattice engagement, end adaptation, or both. Using hydrogen-deuterium exchange and electron microscopy, we explored conformational changes in free dimeric mitotic centromere-associated kinesin (MCAK) and when bound to a depolymerization intermediate. ATP hydrolysis relaxes the conformation of the dimer, notably in the neck and N-terminal domain. Exchanging ADP in dimeric MCAK with ATP at the MT plus end induces outward curvature in α/β-tubulin, accompanied by a restructuring of the MCAK neck and N terminus, as it returns to a closed state. Reestablishing a closed dimer induces lateral separation of paired tubulin dimers, which may assist in depolymerization. Thus, full-length ADP-MCAK transitions from an open diffusion-competent configuration to a closed state upon plus end-mediated nucleotide exchange, which is mediated by conformational changes in the N-terminal domains of the dimer.
authors: Department of Biochemistry and Molecular Biology and Southern Alberta Cancer Research Institute, University of Calgary, Calgary AB T2N 4N1, Canada.
authors: Kyle M
authors: KM
authors: Burns
authors: Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle, WA 98195-7290, USA.
authors: Mike
authors: M
authors: Wagenbach
authors: Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle, WA 98195-7290, USA.
authors: Linda
authors: L
authors: Wordeman
authors: Department of Biochemistry and Molecular Biology and Southern Alberta Cancer Research Institute, University of Calgary, Calgary AB T2N 4N1, Canada. Electronic address: dschriem@ucalgary.ca.
authors: David C
authors: DC
authors: Schriemer
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D002460:Cell Line; D002853:Chromatography, Liquid; D019281:Dimerization; D006868:Hydrolysis; D016547:Kinesins / Q000737:chemistry* / Q000378:metabolism* / Q000648:ultrastructure; D013058:Mass Spectrometry; D008854:Microscopy, Electron; D008870:Microtubules / Q000737:chemistry* / Q000378:metabolism* / Q000648:ultrastructure; D008958:Models, Molecular; D009036:Moths; D009391:Nephelometry and Turbidimetry; D058105:Polymerization; D011487:Protein Conformation
chemical_list: D016547:Kinesins