Molecular architecture of inner dynein arms in situ in Chlamydomonas reinhardtii flagella |
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Authors: | Khanh Huy Bui Hitoshi Sakakibara Tandis Movassagh Kazuhiro Oiwa Takashi Ishikawa |
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Affiliation: | 1.Department of Biology, Eidgenössische Technische Hochschule Zürich, CH8093 Zurich, Switzerland;2.Kobe Advanced ICT Research Center, National Institute of Information and Communications Technology, Iwaoka, Kobe 6512492, Japan;3.Graduate School of Life Science, University of Hyogo, Harima Science Park City, Hyogo 6781297, Japan |
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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. |
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