Axle-Less F1-ATPase Rotates in the Correct
Direction
Shou Furuike,1*Mohammad
Delawar Hossain,1,2* Yasushi
Maki,3 Kengo Adachi,1 Toshiharu
Suzuki,4,5 Ayako Kohori,1
Hiroyasu Itoh,6,7 Masasuke
Yoshida,4,5 Kazuhiko Kinosita, Jr.1†
F1–adenosine triphosphatase (ATPase) is an
ATP-driven rotary molecular motor in which the central γ
subunit rotates inside a cylinder made of three α and three β subunits alternately
arranged. The rotor shaft, an antiparallel α-helical coiled coil of
the amino and carboxyl termini of the γ subunit, deeply penetrates the
central cavity of the stator cylinder. We truncated the shaft
step by step until the remaining rotor head would be outside the
cavity and simply sat on the concave entrance of the stator orifice.
All truncation mutants rotated in the correct direction, implying
torque generation, although the average rotary speeds were
low and short mutants exhibited moments of irregular motion. Neither
a fixed pivot nor a rigid axle was needed for rotation of F1-ATPase.
1 Department of Physics, Faculty
of Science and
Engineering, Waseda University, Shinjuku-ku, Tokyo 169-8555, Japan.
2 Department of Physics, School of Physical Sciences,
Shahjalal University of Science and Technology, Sylhet-3114, Bangladesh.
3 Department of Physics, Osaka Medical College, Osaka
569-8686, Japan.
4 Chemical Resources Laboratory, Tokyo Institute of
Technology, Nagatsuta 4259, Yokohama 226-8503, Japan.
5 ATP-Synthesis Regulation Project, International
Cooperative Research Project (ICORP), Japan Science and Technology
Agency (JST), Aomi 2-41, Tokyo 135-0064, Japan.
6 Tsukuba Research Laboratory, Hamamatsu Photonics KK,
Tokodai, Tsukuba 300-2635, Japan.
7 Core Research for Evolutional Science and Technology
(CREST) "Formation of Soft Nano-Machines" Team 13*, Tokodai, Tsukuba
300-2635, Japan.
* These authors contributed equally to this
work.
†To whom correspondence should be
addressed.