title: Structural comparison of dimeric Eg5, Neurospora kinesin (Nkin) and Ncd head-Nkin neck chimera with conventional kinesin.
abstract: Cryo-electron microscopy and 3D image reconstruction of microtubules saturated with kinesin dimers has shown one head bound to tubulin, the other free. The free head of rat kinesin sits on the top right of the bound head (with the microtubule oriented plus-end upwards) in the presence of 5'-adenylylimido-diphosphate (AMPPNP) and on the top left in nucleotide-free solutions. To understand the relevance of this movement, we investigated other dimeric plus-end-directed motors: Neurospora kinesin (Nkin); Eg5, a slow non-processive kinesin; and a chimera of Ncd heads attached to Nkin necks. In the AMPPNP (ATP-like) state, all dimers have the free head to the top right. In the absence of nucleotide, the free head of an Nkin dimer appears to occupy alternative positions to either side of the bound head. Despite having the Nkin neck, the free head of the chimera was only seen to the top right of the bound head. Eg5 also has the free head mostly to the top right. We suggest that processive movement may require kinesins to move their heads in alternative ways.
authors.affiliation: National Institute of Advanced Interdisciplinary Research, Tsukuba 305-8562, Institute of Molecular and Cellular Biosciences, University of Tokyo, Tokyo 113, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Hirose
authors.forename: U
authors.initials: U
authors.lastname: Henningsen
authors.forename: M
authors.initials: M
authors.lastname: Schliwa
authors.forename: C
authors.initials: C
authors.lastname: Toyoshima
authors.forename: T
authors.initials: T
authors.lastname: Shimizu
authors.forename: M
authors.initials: M
authors.lastname: Alonso
authors.forename: R A
authors.initials: RA
authors.lastname: Cross
authors.forename: L A
authors.initials: LA
authors.lastname: Amos
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D020285:Cryoelectron Microscopy; D019281:Dimerization; D029721:Drosophila Proteins; D007091:Image Processing, Computer-Assisted; D016547:Kinesins / Q000737:chemistry / Q000648:ultrastructure*; D008870:Microtubules / Q000378:metabolism / Q000648:ultrastructure; D008958:Models, Molecular; D020409:Molecular Motor Proteins / Q000737:chemistry / Q000648:ultrastructure; D008969:Molecular Sequence Data; D009068:Movement; D009491:Neurospora / Q000737:chemistry*; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000648:ultrastructure*; D016415:Sequence Alignment; D029867:Xenopus Proteins
chemical_list: D029721:Drosophila Proteins; C088335:KIF11 protein, Xenopus; D020409:Molecular Motor Proteins; D011993:Recombinant Fusion Proteins; D029867:Xenopus Proteins; C066696:ncd protein, Drosophila; D000255:Adenosine Triphosphate; D016547:Kinesins