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AAA+ Ring and Linker Swing Mechanism in the Dynein Motor
Anthony J. Roberts1,Naoki Numata2,Matt L. Walker3,Yusuke S. Kato1,Bara Malkova1,Takahide Kon2,Reiko Ohkura2,Fumio Arisaka4,Peter J. Knight1,Kazuo Sutoh2,,andStan A. Burgess1,,
1 Astbury Centre for Structural Molecular Biology and Institute of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, UK
2 Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Komaba 3-8-1, Tokyo 153-8902, Japan
3 MLW Consulting, 11 Race Hill, Launceston, Cornwall PL15 9BB, UK
4 Graduate School and School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Yokohama 226-8501, Japan
Summary
Dynein ATPases power diverse microtubule-based motilities. Each dynein motor domain comprises a ring-like head containing six AAA+ modules and N- and C-terminal regions, together with a stalk that binds microtubules. How these subdomains are arranged and generate force remains poorly understood. Here, using electron microscopy and image processing of tagged and truncated Dictyostelium cytoplasmic dynein constructs, we show that the heart of the motor is a hexameric ring of AAA+ modules, with the stalk emerging opposite the primary ATPase site (AAA1). The C-terminal region is not an integral part of the ring but spans between AAA6 and near the stalk base. The N-terminal region includes a lever-like linker whose N terminus swings by 17 nm during the ATPase cycle between AAA2 and the stalk base. Together with evidence of stalk tilting, which may communicate changes in microtubule binding affinity, these findings suggest a model for dynein's structure and mechanism.
