title: Direct observation shows superposition and large scale flexibility within cytoplasmic dynein motors moving along microtubules.
abstract: Cytoplasmic dynein is a dimeric AAA(+) motor protein that performs critical roles in eukaryotic cells by moving along microtubules using ATP. Here using cryo-electron microscopy we directly observe the structure of Dictyostelium discoideum dynein dimers on microtubules at near-physiological ATP concentrations. They display remarkable flexibility at a hinge close to the microtubule binding domain (the stalkhead) producing a wide range of head positions. About half the molecules have the two heads separated from one another, with both leading and trailing motors attached to the microtubule. The other half have the two heads and stalks closely superposed in a front-to-back arrangement of the AAA(+) rings, suggesting specific contact between the heads. All stalks point towards the microtubule minus end. Mean stalk angles depend on the separation between their stalkheads, which allows estimation of inter-head tension. These findings provide a structural framework for understanding dynein's directionality and unusual stepping behaviour.
authors.affiliation: School of Molecular and Cellular Biology and Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK.
authors.forename: Hiroshi
authors.identifier: http://orcid.org/0000-0001-8939-2255
authors.initials: H
authors.lastname: Imai
authors.affiliation: Quantitative Biology Center, Riken, 6-2-3 Furuedai, Suita, Osaka 565-0874, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Shima
authors.affiliation: Faculty of Science and Engineering, Waseda University, Takada 1-17-22, Toshima-ku, Tokyo 171-0033, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Sutoh
authors.affiliation: MLW Consulting, 11 Race Hill, Launceston PL15 9BB, Cornwall, UK.
authors.forename: Matthew L
authors.initials: ML
authors.lastname: Walker
authors.affiliation: School of Molecular and Cellular Biology and Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Knight
authors.affiliation: Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, 560-0043 Osaka, Japan.|Japan Science and Technology Agency, Precursory Research for Embryonic Science and Technology, Kawaguchi, 332-0012 Saitama, Japan.
authors.forename: Takahide
authors.identifier: http://orcid.org/0000-0002-1231-7609
authors.initials: T
authors.lastname: Kon
authors.affiliation: School of Molecular and Cellular Biology and Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK.
authors.forename: Stan A
authors.initials: SA
authors.lastname: Burgess
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D020285:Cryoelectron Microscopy; D056445:Cytoplasmic Dyneins / Q000378:metabolism* / Q000648:ultrastructure; D004023:Dictyostelium; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D008870:Microtubules / Q000378:metabolism* / Q000648:ultrastructure; D008958:Models, Molecular; D020409:Molecular Motor Proteins; D013552:Swine; D014404:Tubulin / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D020409:Molecular Motor Proteins; D014404:Tubulin; D000255:Adenosine Triphosphate; D056445:Cytoplasmic Dyneins