Vacuole-type ATPases (VoV1) and FoF1
ATP synthases couple ATP hydrolysis/synthesis in the soluble V1
or F1 portion with proton (or Na+) flow in the
membrane-embedded Vo or Fo portion through
rotation of one common shaft. Here we show at submillisecond
resolutions the ATP-driven rotation of isolated V1 and the
whole VoV1 from Thermus thermophilus, by
attaching a 40-nm gold bead for which viscous drag is almost
negligible. V1 made 120° steps, commensurate with the
presence of three catalytic sites. Dwells between the steps involved at
least two events other than ATP binding, one likely to be ATP
hydrolysis. VoV1 exhibited 12 dwell positions per
revolution, consistent with the 12-fold symmetry of the Vo
rotor in T. thermophilus. Unlike F1 that undergoes
80°–40° substepping, chemo-mechanical checkpoints in isolated V1
are all at the ATP-waiting position, and Vo adds further
bumps through stator–rotor interactions outside and remote from V1.
Affiliations
Department of Physics, Faculty of Science and
Engineering,
Waseda University, Shinjuku-ku, Tokyo 169-8555, Japan.
Department of Physics, Osaka Medical College, Takatsuki,
Osaka
569-8686, Japan.
Chemical Resources Laboratory, Tokyo Institute of
Technology,
4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan.
Institute of Scientific and Industrial Research, Osaka
University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan.
ICORP, ATP Synthesis Regulation Project, Japan Science
and
Technology Agency (JST), National Museum of Emerging Science and
Innovation, 2-41 Aomi, Koto-ku, Tokyo 135-0064, Japan.
Department of Molecular Biosciences, Kyoto Sangyo
University,
Motoyama Kamigamo, Kita-ku, Kyoto 603-8555, Japan.
Present address: Department of Physics, Faculty of
Science,
Gakushuin University, Toshima-ku, Tokyo 171-8588, Japan.