National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)
R01GM113164
United States
Natural Sciences and Engineering Research Council (NSERC, Canada)
RGPIN/356025-2013
Canada
Canadian Institutes of Health Research (CIHR)
MOP-97832
Canada
Citation
Journal: Nat Commun / Year: 2022 Title: Kinesin-8-specific loop-2 controls the dual activities of the motor domain according to tubulin protofilament shape. Authors: Byron Hunter / Matthieu P M H Benoit / Ana B Asenjo / Caitlin Doubleday / Daria Trofimova / Corey Frazer / Irsa Shoukat / Hernando Sosa / John S Allingham / Abstract: Kinesin-8s are dual-activity motor proteins that can move processively on microtubules and depolymerize microtubule plus-ends, but their mechanism of combining these distinct activities remains ...Kinesin-8s are dual-activity motor proteins that can move processively on microtubules and depolymerize microtubule plus-ends, but their mechanism of combining these distinct activities remains unclear. We addressed this by obtaining cryo-EM structures (2.6-3.9 Å) of Candida albicans Kip3 in different catalytic states on the microtubule lattice and on a curved microtubule end mimic. We also determined a crystal structure of microtubule-unbound CaKip3-ADP (2.0 Å) and analyzed the biochemical activity of CaKip3 and kinesin-1 mutants. These data reveal that the microtubule depolymerization activity of kinesin-8 originates from conformational changes of its motor core that are amplified by dynamic contacts between its extended loop-2 and tubulin. On curved microtubule ends, loop-1 inserts into preceding motor domains, forming head-to-tail arrays of kinesin-8s that complement loop-2 contacts with curved tubulin and assist depolymerization. On straight tubulin protofilaments in the microtubule lattice, loop-2-tubulin contacts inhibit conformational changes in the motor core, but in the ADP-Pi state these contacts are relaxed, allowing neck-linker docking for motility. We propose that these tubulin shape-induced alternations between pro-microtubule-depolymerization and pro-motility kinesin states, regulated by loop-2, are the key to the dual activity of kinesin-8 motors.
Applied symmetry - Helical parameters - Δz: 5.56 Å Applied symmetry - Helical parameters - Δ&Phi: 168.089 ° Applied symmetry - Helical parameters - Axial symmetry: C1 (asymmetric) Resolution.type: BY AUTHOR / Resolution: 2.8 Å / Resolution method: FSC 0.143 CUT-OFF / Software - Name: RELION (ver. 3.1) Details: 2 half datasets containing one distinct half of each filament were refined independently. Number of asymmetric units used is reported in "number of segments used", due to the local processing strategy employed. Number images used: 124055
Segment selection
Details: manual picking of filaments
Startup model
Type of model: OTHER
Final angle assignment
Type: NOT APPLICABLE / Software - Name: RELION (ver. 3.1)
FSC plot (resolution estimation)
-
Atomic model buiding 1
Refinement
Space: REAL / Protocol: FLEXIBLE FIT
Output model
PDB-7tqx: CaKip3[2-482] - AMP-PNP in complex with a microtubule
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