Yasuda Ryohei, Masaike Tomoko, Adachi Kengo, Noji Hiroyuki, Itoh Hiroyasu, Kinosita Kazuhiko
Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA.
Proc Natl Acad Sci U S A. 2003 Aug 5;100(16):9314-8. doi: 10.1073/pnas.1637860100. Epub 2003 Jul 22.
F1-ATPase is an ATP-driven rotary motor in which a rod-shaped gamma subunit rotates inside a cylinder made of alpha3beta3 subunits. To elucidate the conformations of rotating F1, we measured fluorescence resonance energy transfer (FRET) between a donor on one of the three betas and an acceptor on gamma in single F1 molecules. The yield of FRET changed stepwise at low ATP concentrations, reflecting the stepwise rotation of gamma. In the ATP-waiting state, the FRET yields indicated a gamma position approximately 40 degrees counterclockwise (= direction of rotation) from that in the crystal structures of mitochondrial F1, suggesting that the crystal structures mimic a metastable state before product release.
F1 - ATP酶是一种由ATP驱动的旋转马达，其中棒状的γ亚基在由α3β3亚基组成的圆柱体内旋转。为了阐明旋转的F1的构象，我们测量了单个F1分子中三个β亚基之一上的供体与γ亚基上的受体之间的荧光共振能量转移（FRET）。在低ATP浓度下，FRET产率呈阶梯式变化，反映了γ亚基的阶梯式旋转。在ATP等待状态下，FRET产率表明γ亚基的位置比线粒体F1晶体结构中的位置逆时针方向大约40度（=旋转方向），这表明晶体结构模拟了产物释放前的亚稳态。
