title: α- and β-Tubulin Lattice of the Axonemal Microtubule Doublet and Binding Proteins Revealed by Single Particle Cryo-Electron Microscopy and Tomography.
abstract: Microtubule doublet (MTD) is the main skeleton of cilia/flagella. Many proteins, such as dyneins and radial spokes, bind to MTD, and generate or regulate force. While the structure of the reconstituted microtubule has been solved at atomic resolution, nature of the axonemal MTD is still unclear. There are a few hypotheses of the lattice arrangement of its α- and β-tubulins, but it has not been described how dyneins and radial spokes bind to MTD. In this study, we analyzed the three-dimensional structure of Tetrahymena MTD at ∼19 Å resolution by single particle cryo-electron microscopy. To identify α- and β-tubulins, we combined image analysis of MTD with specific kinesin decoration. This work reveals that α- and β-tubulins form a B-lattice arrangement in the entire MTD with a seam at the outer junction. We revealed the unique way in which inner arm dyneins, radial spokes, and proteins inside MTD bind and bridge protofilaments.
authors.affiliation: Biomolecular Research Laboratory, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland; Department of Biology, ETH Zurich, Otto-Stern-Weg 5, 8093 Zurich, Switzerland.
authors.forename: Aditi
authors.initials: A
authors.lastname: Maheshwari
authors.affiliation: Biomolecular Research Laboratory, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland.
authors.forename: Jagan Mohan
authors.initials: JM
authors.lastname: Obbineni
authors.affiliation: Biomolecular Research Laboratory, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland.
authors.forename: Khanh Huy
authors.initials: KH
authors.lastname: Bui
authors.affiliation: Department of Life Science, Graduate School of Arts and Sciences, University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan.
authors.forename: Keitaro
authors.initials: K
authors.lastname: Shibata
authors.affiliation: Department of Life Science, Graduate School of Arts and Sciences, University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan.
authors.forename: Yoko Y
authors.initials: YY
authors.lastname: Toyoshima
authors.affiliation: Biomolecular Research Laboratory, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland. Electronic address: takashi.ishikawa@psi.ch.
authors.forename: Takashi
authors.initials: T
authors.lastname: Ishikawa
mesh_terms: D001665:Binding Sites; D002923:Cilia / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D020285:Cryoelectron Microscopy / Q000379:methods*; D018360:Crystallography, X-Ray; D003598:Cytoskeletal Proteins / Q000737:chemistry* / Q000378:metabolism; D016547:Kinesins / Q000378:metabolism; D008958:Models, Molecular; D011485:Protein Binding; D015800:Protozoan Proteins / Q000737:chemistry* / Q000378:metabolism; D016808:Tetrahymena thermophila / Q000737:chemistry / Q000378:metabolism*; D014404:Tubulin / Q000737:chemistry / Q000378:metabolism
chemical_list: D003598:Cytoskeletal Proteins; D015800:Protozoan Proteins; D014404:Tubulin; D016547:Kinesins