Picometer-scale dynamical observations of individual membrane proteins: The case of bacteriorhodopsin
Picometer-scale dynamical observations of individual membrane proteins: The case of bacteriorhodopsin
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DOI：
10.1103/physreve.70.021917
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发表时间：
2004-08-01
影响因子：
2.4
通讯作者：
Sasaki, YC
中科院分区：
文献类型：
--
作者：
Okumura, Y;Oka, T;Sasaki, YC
在体内测量单个生物分子在功能条件下的动态构象变化对分子和细胞生物学产生了巨大的影响。然而，即使是单分子荧光共振能量转移，由于监测精度的不足，也不能很容易地监测细胞系统的分子内动力学。在这里，我们报告了使用衍射x射线跟踪的单膜蛋白[细菌视紫红质（BR）]的不可逆分子内构象变化的动态观察。光驱动质子泵BR是表征最好的膜蛋白。BR的第35个氨基酸位于离视网膜最远的位置，由于其功能的表达，出现了0.73+/-0.48埃的瞬时位置跳变。在此之后，我们观察到布朗运动，而衍射斑没有回到它们的初始位置。这种跳跃的平均宽度大约是热布朗运动的14倍，与已知x射线晶体学数据估计的运动一致。这一结果是实现在体内观察膜蛋白单分子构象变化的重要一步。
In vivo measurements of dynamical conformational changes in single biomolecules under functional conditions have had a tremendous impact on molecular and cell biology. However, even single-molecule fluorescent resonance energy transfer cannot easily monitor the intramolecular dynamics in cell systems due to shortcomings in monitoring precision. Here, we report dynamical observations of irreversible intramolecular conformational changes in a single-membrane protein [bacteriorhodopsin (BR)] using diffracted x-ray tracking. The light-driven proton pump BR is the best-characterized membrane protein. The position of BR's 35th amino acid, which is located farthest from retinal, exhibits a momentary positional jump of 0.73+/-0.48 Angstrom due to the expression of its function. Following that, we observed Brownian motion without the diffracted spots returning to their initial positions. The average width of this jump is about 14 times larger than that of thermal Brownian motion and agrees with estimated movements from known x-ray crystallography data. This result is an important step toward realizing in vivo observations of single-molecular conformational changes in membrane proteins.