title: Docking-complex-independent alignment of Chlamydomonas outer dynein arms with 24-nm periodicity in vitro.
abstract: The docking complex is a molecular complex necessary for assembly of outer dynein arms (ODAs) on the axonemal doublet microtubules (DMTs) in cilia and flagella. The docking complex is hypothesized to be a 24-nm molecular ruler because ODAs align along the DMTs with 24-nm periodicity. In this study, we rigorously tested this hypothesis using structural and genetic methods. We found that the ODAs can bind to DMTs and porcine microtubules with 24-nm periodicities even in the absence of the docking complexin vitro Using cryo-electron tomography and structural labeling, we observed that the docking complex took an unexpectedly flexible conformation and did not lie along the length of DMTs. In the absence of docking complex, ODAs were released from the DMT at relatively low ionic strength conditions, suggesting that the docking complex strengthens the electrostatic interactions between the ODA and DMT. Based on these results, we conclude that the docking complex serves as a flexible stabilizer of the ODA rather than as a molecular ruler.
authors.affiliation: Department of Cell Biology and Anatomy, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan Department of Anatomy and Structural Biology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, 1110 Shimokatoh, Chuo, Yamanashi 409-3898, Japan toda@yamanashi.ac.jp.
authors.forename: Toshiyuki
authors.identifier: http://orcid.org/0000-0001-8090-2159
authors.initials: T
authors.lastname: Oda
authors.affiliation: Department of Cell Biology and Anatomy, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Tatsuki
authors.initials: T
authors.lastname: Abe
authors.affiliation: Department of Cell Biology and Anatomy, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Haruaki
authors.initials: H
authors.lastname: Yanagisawa
authors.affiliation: Department of Cell Biology and Anatomy, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Masahide
authors.initials: M
authors.lastname: Kikkawa
mesh_terms: D000818:Animals; D056444:Axonemal Dyneins / Q000235:genetics / Q000378:metabolism*; D001921:Brain / Q000378:metabolism; D002696:Chlamydomonas / Q000502:physiology*; D002923:Cilia / Q000378:metabolism*; D020285:Cryoelectron Microscopy; D005407:Flagella / Q000378:metabolism*; D008870:Microtubules / Q000235:genetics* / Q000378:metabolism*; D046912:Multiprotein Complexes / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D055550:Protein Stability; D013329:Structure-Activity Relationship; D013552:Swine
chemical_list: D046912:Multiprotein Complexes; D056444:Axonemal Dyneins
keywords: Axoneme; Cilia; Docking complex; Flagella; Microtubule; Outer dynein arm