title: A universal pathway for kinesin stepping.
abstract: Kinesin-1 is an ATP-driven, processive motor that transports cargo along microtubules in a tightly regulated stepping cycle. Efficient gating mechanisms ensure that the sequence of kinetic events proceeds in the proper order, generating a large number of successive reaction cycles. To study gating, we created two mutant constructs with extended neck-linkers and measured their properties using single-molecule optical trapping and ensemble fluorescence techniques. Owing to a reduction in the inter-head tension, the constructs access an otherwise rarely populated conformational state in which both motor heads remain bound to the microtubule. ATP-dependent, processive backstepping and futile hydrolysis were observed under moderate hindering loads. On the basis of measurements, we formulated a comprehensive model for kinesin motion that incorporates reaction pathways for both forward and backward stepping. In addition to inter-head tension, we found that neck-linker orientation is also responsible for ensuring gating in kinesin.
authors.affiliation: Department of Biology, Stanford University, Stanford, California, USA.
authors.forename: Bason E
authors.initials: BE
authors.lastname: Clancy
authors.forename: William M
authors.initials: WM
authors.lastname: Behnke-Parks
authors.forename: Johan O L
authors.initials: JO
authors.lastname: Andreasson
authors.forename: Steven S
authors.initials: SS
authors.lastname: Rosenfeld
authors.forename: Steven M
authors.initials: SM
authors.lastname: Block
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D001665:Binding Sites; D001696:Biomechanical Phenomena; D006801:Humans; D006868:Hydrolysis; D016547:Kinesins / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology; D007700:Kinetics; D008870:Microtubules / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D052898:Optical Tweezers
chemical_list: D000255:Adenosine Triphosphate; D016547:Kinesins