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Eukaryotic Cell, July 2008, p. 1136-1145, Vol. 7, No. 7
1535-9778/08/$08.00+0 doi:10.1128/EC.00102-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.
Heavy Chain
Hiroko Takazaki,2,
Yuki Nakazawa,1
Miho Sakato,3
Toshiki Yagi,1,4
Takuo Yasunaga,2
Stephen M. King,3 and
Ritsu Kamiya1,5*
Department of Biological Sciences, Graduate School of Science, University of Tokyo, Hongo, Bunkyo-ku, Tokyo,1 Department of Bioscience and Bioinformatics, Kyushu Institute of Technology, Iizuka, Japan,2 Department of Molecular, Microbial and Structural Biology, University of Connecticut Health Center, Farmington, Connecticut,3 Structural Biology, Graduate School of Science, Kyoto University, Kyoto,4 CREST, Japan Science and Technology Corporation, Kawaguchi, Japan5
Received 21 March 2008/ Accepted 6 May 2008
The outer dynein arm of Chlamydomonas flagella contains three heavy chains (
, β, and
), each of which exhibits motor activity. How they assemble and cooperate is of considerable interest. Here we report the isolation of a novel mutant, oda2-t, whose
heavy chain is truncated at about 30% of the sequence. While the previously isolated
chain mutant oda2 lacks the entire outer arm, oda2-t retains outer arms that contain
and β heavy chains, suggesting that the N-terminal sequence (corresponding to the tail region) is necessary and sufficient for stable outer-arm assembly. Thin-section electron microscopy and image analysis localize the
heavy chain to a basal region of the outer-arm image in the axonemal cross section. The motility of oda2-t is lower than that of the wild type and oda11 (lacking the
heavy chain) but higher than that of oda2 and oda4-s7 (lacking the motor domain of the β heavy chain). Thus, the outer-arm dynein lacking the
heavy-chain motor domain is partially functional. The availability of mutants lacking individual heavy chains should greatly facilitate studies on the structure and function of the outer-arm dynein.
Published ahead of print on 16 May 2008.
These authors equally contributed to this study.
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