title: Molecular architecture of inner dynein arms in situ in Chlamydomonas reinhardtii flagella.
abstract: The inner dynein arm regulates axonemal bending motion in eukaryotes. We used cryo-electron tomography to reconstruct the three-dimensional structure of inner dynein arms from Chlamydomonas reinhardtii. All the eight different heavy chains were identified in one 96-nm periodic repeat, as expected from previous biochemical studies. Based on mutants, we identified the positions of the AAA rings and the N-terminal tails of all the eight heavy chains. The dynein f dimer is located close to the surface of the A-microtubule, whereas the other six heavy chain rings are roughly colinear at a larger distance to form three dyads. Each dyad consists of two heavy chains and has a corresponding radial spoke or a similar feature. In each of the six heavy chains (dynein a, b, c, d, e, and g), the N-terminal tail extends from the distal side of the ring. To interact with the B-microtubule through stalks, the inner-arm dyneins must have either different handedness or, more probably, the opposite orientation of the AAA rings compared with the outer-arm dyneins.
authors.affiliation: Department of Biology, Eidgenössische Technische Hochschule Zürich, CH8093 Zurich, Switzerland.
authors.forename: Khanh Huy
authors.initials: KH
authors.lastname: Bui
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Sakakibara
authors.forename: Tandis
authors.initials: T
authors.lastname: Movassagh
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Oiwa
authors.forename: Takashi
authors.initials: T
authors.lastname: Ishikawa
mesh_terms: D000818:Animals; D016825:Chlamydomonas reinhardtii / Q000201:enzymology* / Q000235:genetics / Q000648:ultrastructure; D020285:Cryoelectron Microscopy; D004398:Dyneins / Q000737:chemistry* / Q000235:genetics; D055032:Electron Microscope Tomography; D005407:Flagella / Q000201:enzymology* / Q000648:ultrastructure; D008870:Microtubules / Q000737:chemistry; D008958:Models, Molecular; D009154:Mutation; D011487:Protein Conformation; D055503:Protein Multimerization; D017434:Protein Structure, Tertiary
chemical_list: D004398:Dyneins