title: Force-dependent detachment of kinesin-2 biases track switching at cytoskeletal filament intersections.
abstract: Intracellular trafficking of organelles often involves cytoskeletal track switching. Organelles such as melanosomes are transported by multiple motors including kinesin-2, dynein, and myosin-V, which drive switching between microtubules and actin filaments during dispersion and aggregation. Here, we used optical trapping to determine the unitary and ensemble forces of kinesin-2, and to reconstitute cargo switching at cytoskeletal intersections in a minimal system with kinesin-2 and myosin-V motors bound to beads. Single kinesin-2 motors exerted forces up to ∼5 pN, similar to kinesin-1. However, kinesin-2 motors were more likely to detach at submaximal forces, and the duration of force maintenance was short as compared to kinesin-1. In multimotor assays, force increased with kinesin-2 density but was not affected by the presence of myosin-V. In crossed filament assays, switching frequencies of motor-bound beads were dependent on the starting track. At equal average forces, beads tended to switch from microtubules onto overlying actin filaments consistent with the relatively faster detachment of kinesin-2 at near-maximal forces. Thus, in addition to relative force, switching probability at filament intersections is determined by the dynamics of motor-filament interaction, such as the quick detachment of kinesin-2 under load. This may enable fine-tuning of filament switching in the cell.
authors: Pennsylvania Muscle Institute and Department of Physiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA.
authors: Harry W
authors: HW
authors: Schroeder
authors: Adam G
authors: AG
authors: Hendricks
authors: Kazuho
authors: K
authors: Ikeda
authors: Henry
authors: H
authors: Shuman
authors: Vladimir
authors: V
authors: Rodionov
authors: Mitsuo
authors: M
authors: Ikebe
authors: Yale E
authors: YE
authors: Goldman
authors: Erika L F
authors: EL
authors: Holzbaur
mesh_terms: D008841:Actin Cytoskeleton / Q000737:chemistry / Q000502:physiology*; D000818:Animals; D016547:Kinesins / Q000737:chemistry / Q000502:physiology*; D008856:Microscopy, Fluorescence; D008870:Microtubules / Q000502:physiology*; D056004:Molecular Dynamics Simulation; D024701:Myosin Type V / Q000737:chemistry / Q000502:physiology; D011487:Protein Conformation; D011817:Rabbits; D014981:Xenopus; D029867:Xenopus Proteins / Q000737:chemistry / Q000502:physiology*
chemical_list: C499376:XKLP3 protein, Xenopus; D029867:Xenopus Proteins; D024701:Myosin Type V; D016547:Kinesins