title: Bidirectional power stroke by ncd kinesin.
abstract: Optical trapping experiments reveal details of molecular motor dynamics. In noisy data, temporal structure within the power stroke of motors can be analyzed by ensemble averaging, but this obscures infrequent subcategories of events. We have here developed an analysis method that uses Kalman filtering of measurements, model-based estimation of the power strokes produced by the motor head, and automatic event classification to discriminate between different types of motor events. This method was applied to optical trap measurements of power strokes of the Drosophila kinesin-14 ncd in a three-bead geometry. We found the majority of events to be consistent with the previously discovered minus-end directed power stroke of ncd, occurring with ATP binding. Unexpectedly, 30% of apparent power strokes were plus-directed and 6% of binding events did not terminate in a discernible stroke. Ensemble averaging for each event category revealed that plus- and minus-directed strokes have different size and occur at different instants within the ncd-MT attachment sequence.
authors.affiliation: Department of Chemical Engineering, University of Utah, Salt Lake City, Utah, USA. tony3.1416@gmail.com
authors.forename: Anthony E
authors.initials: AE
authors.lastname: Butterfield
authors.forename: Russell J
authors.initials: RJ
authors.lastname: Stewart
authors.forename: Christoph F
authors.initials: CF
authors.lastname: Schmidt
authors.forename: Mikhail
authors.initials: M
authors.lastname: Skliar
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001696:Biomechanical Phenomena; D003198:Computer Simulation; D029721:Drosophila Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000378:metabolism*; D016547:Kinesins / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism; D008958:Models, Molecular; D015203:Reproducibility of Results
chemical_list: D029721:Drosophila Proteins; C066696:ncd protein, Drosophila; D000255:Adenosine Triphosphate; D016547:Kinesins