Structural transitions in kinesin minus-end directed microtubule motility.

New transition states and structural movements in a model for motor energy transduction and force production: β-sheet twisting stores free energy in the microtubule-bound nucleotide-free (NF) state. A fluctuating power stroke is produced in the ATP state with neck mimic docking in the ADP·Pi state, resembling the kinesin-1 neck linker. This is followed by β-strand-to-loop transitions in the microtubule-bound ADP + free Pi state. Finally, β-sheet refolding drives the recovery stroke for reversion to the ADP state.