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“Molecular mechanism and
robustness of rotary catalysis of F1-ATPase”
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Date: |
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Time: |
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Thursday, 06. Sept. 2018 |
Video-Recording for any system with MP4-support
- Video.mp4 (ca.425 Mb) |
15:15 – 16:25 |
Hiroyuki Noji
(
Abstract :
F1-ATPase is a
rotary motor protein in which the inner subunit rotates against the
surrounding stator
ring upon ATP hydrolysis(1,2). The stator ring is composed of
3 alpha and 3
beta subunits, and the catalytic reaction centers are located on the
3 alpha-beta
interfaces, mainly on the beta subunits. The unique feature of F1-ATPase
that
discriminates it from other molecular motors is the high energy conversion
efficiency
and the
reversibility of the chemomechanical coupling; when the rotation is forcibly
reversed,
F1-ATPase catalyzes ATP synthesis reaction against large free energy of
ATP hydrolysis
(3). The experimental verification that the rotary angle of the rotary shaft
controls the
chemical equilibrium of ATP hydrolysis/synthesis was thought to suggest
that the 3
reaction centers communicate via the atomically fine-tuned molecular
interaction
of the beta
subunits with the rotary shaft subunit. However, recent experiments showed
the rotation
mechanism is far more robust than we though before; even after removing
the rotary shaft,
the remaining stator ring undergoes cooperative power stroke motion among
3 beta subunits
(4). This finding suggests that the allostery is programmed in the stator ring,
pointing the
possibility that an artificial rod-shaped molecule would be rotated in the
stator ring of
F1-ATPase.
We tested this
hypothesis by incorporating a xenogeneic protein in the stator ring.
The artificial
molecule showed unidirectional rotation although the generated torque is
evidently lower
than the wild-type F1-ATPase(5).
1. Noji, H., Yasuda, R., Yoshida, M., and
Kinosita, K., Jr. (1997) Direct observation
of
the rotation of F1-ATPase. Nature 386, 299-302
2. Okuno, D., Iino, R., and Noji, H. (2011)
Rotation and structure of FoF1-ATP synthase.
Journal of biochemistry 149, 655-664
3. Rondelez, Y., Tresset, G., Nakashima, T.,
Kato-Yamada, Y., Fujita, H., Takeuchi, S.,
and
Noji, H. (2005) Highly coupled ATP synthesis by F1-ATPase single molecules.
Nature 433, 773-777
4. Uchihashi, T., Iino, R., Ando, T., and
Noji, H. (2011) High-speed atomic force
microscopy reveals rotary catalysis of
rotorless F(1)-ATPase. Science 333, 755-758
5. Baba, M., Iwamoto, K., Iino, R., Ueno, H.,
Hara, M., Nakanishi, A., Kishikawa, J. I.,
Noji, H., and Yokoyama, K. (2016) Rotation of
artificial rotor axles in rotary molecular
motors. Proceedings of the