title: Detailed structural and biochemical characterization of the nexin-dynein regulatory complex.
abstract: The nexin-dynein regulatory complex (N-DRC) forms a cross-bridge between the outer doublet microtubules of the axoneme and regulates dynein motor activity in cilia/flagella. Although the molecular composition and the three-dimensional structure of N-DRC have been studied using mutant strains lacking N-DRC subunits, more accurate approaches are necessary to characterize the structure and function of N-DRC. In this study, we precisely localized DRC1, DRC2, and DRC4 using cryo-electron tomography and structural labeling. All three N-DRC subunits had elongated conformations and spanned the length of N-DRC. Furthermore, we purified N-DRC and characterized its microtubule-binding properties. Purified N-DRC bound to the microtubule and partially inhibited microtubule sliding driven by the outer dynein arms (ODAs). Of interest, microtubule sliding was observed even in the presence of fourfold molar excess of N-DRC relative to ODA. These results provide insights into the role of N-DRC in generating the beating motions of cilia/flagella.
authors.affiliation: Department of Cell Biology and Anatomy, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo Bunkyo-ku, Tokyo 113-0033, Japan tooda@m.u-tokyo.ac.jp.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Oda
authors.affiliation: Department of Cell Biology and Anatomy, Graduate School of Medicine, 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, University of Tokyo, 7-3-1 Hongo Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Masahide
authors.initials: M
authors.lastname: Kikkawa
mesh_terms: D000103:Acetyl-CoA Carboxylase / Q000235:genetics / Q000378:metabolism; D020418:Algal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D056444:Axonemal Dyneins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D054468:Axoneme / Q000378:metabolism* / Q000502:physiology / Q000648:ultrastructure; D016825:Chlamydomonas reinhardtii / Q000235:genetics / Q000378:metabolism*; D005407:Flagella / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D015151:Immunoblotting; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D008869:Microtubule-Associated Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism / Q000502:physiology / Q000648:ultrastructure; D008958:Models, Molecular; D008969:Molecular Sequence Data; D046912:Multiprotein Complexes / Q000737:chemistry / Q000378:metabolism; D009154:Mutation; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism
chemical_list: D020418:Algal Proteins; D008869:Microtubule-Associated Proteins; D046912:Multiprotein Complexes; D021122:Protein Subunits; C484652:microtubule nexin; D056444:Axonemal Dyneins; D000103:Acetyl-CoA Carboxylase