Department of Physics, Kanazawa University, Kanazawa 920-1192, Japan.
Nat Nanotechnol. 2010 Mar;5(3):208-12. doi: 10.1038/nnano.2010.7. Epub 2010 Feb 14.
Dynamic changes in protein conformation in response to external stimuli are important in biological processes, but it has proved difficult to directly visualize such structural changes under physiological conditions. Here, we show that high-speed atomic force microscopy can be used to visualize dynamic changes in stimulated proteins. High-resolution movies of a light-driven proton pump, bacteriorhodopsin, reveal that, upon illumination, a cytoplasmic portion of each bacteriorhodopsin monomer is brought into contact with adjacent trimers. The bacteriorhodopsin-bacteriorhodopsin interaction in the transiently formed assembly engenders both positive and negative cooperative effects in the decay kinetics as the initial bacteriorhodopsin recovers and, as a consequence, the turnover rate of the photocycle is maintained constant, on average, irrespective of the light intensity. These results confirm that high-resolution visualization is a powerful approach for studying elaborate biomolecular processes under realistic conditions.
在生物过程中，蛋白质构象对外界刺激的动态变化很重要，但在生理条件下直接观察这种结构变化一直很困难。在这里，我们表明，高速原子力显微镜可用于可视化受刺激蛋白质的动态变化。光驱动质子泵菌紫质的高分辨率电影显示，在光照下，每个菌紫质单体的细胞质部分与相邻的三聚体接触。在瞬态形成的组装体中，菌紫质-菌紫质相互作用在衰减动力学中产生正协同和负协同效应，因为初始菌紫质恢复，因此，光循环的周转率平均保持不变，与光强度无关。这些结果证实，高分辨率可视化是研究现实条件下复杂生物分子过程的有力方法。
