Dynamic polymorphism of single actin molecules in the actin filament
Dynamic polymorphism of single actin molecules in the actin filament
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DOI：
10.1038/nchembio763
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发表时间：
2006-02-01
影响因子：
14.8
通讯作者：
Yanagida, T
中科院分区：
文献类型：
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作者：
Kozuka, J;Yokota, H;Yanagida, T
肌动蛋白丝动力学对细胞运动至关重要（1,2）。肌动蛋白丝的结构可以自发改变，也可以受到肌动蛋白结合蛋白的调节，从而使肌动蛋白容易响应外部刺激发挥作用(1)。与运动蛋白肌球蛋白的相互作用改变了肌动蛋白丝的动态特性（3,4）。然而，肌动蛋白丝动态过程的分子基础尚不清楚。在这里，我们利用全内反射荧光显微镜（TIRFM）的单分子荧光共振能量转移（FRET）（5-7）成像技术监测肌动蛋白细丝中的单个分子，观察了兔骨骼肌肌动蛋白构象的动力学(8)。FRET的时间轨迹表明肌动蛋白在低和高FRET效率状态之间切换的时间尺度为秒。如果肌动蛋白丝是化学交联的，一种抑制肌凝蛋白运动的状态(9)，平衡转移到低FRET构象，而当肌动蛋白丝与肌凝蛋白相互作用时，高FRET构象是有利的。这种动态平衡表明肌动蛋白可以根据外部信号在活性和非活性构象之间切换。
Actin filament dynamics are critical in cell motility(1,2). The structure of actin filament changes spontaneously and can also be regulated by actin-binding proteins, allowing actin to readily function in response to external stimuli(1). The interaction with the motor protein myosin changes the dynamic nature of actin filaments(3,4). However, the molecular bases for the dynamic processes of actin filaments are not well understood. Here, we observed the dynamics of rabbit skeletal-muscle actin conformation by monitoring individual molecules in the actin filaments using single-molecule fluorescence resonance energy transfer (FRET)(5-7) imaging with total internal reflection fluorescence microscopy ( TIRFM)(8). The time trajectories of FRET show that actin switches between low- and high-FRET efficiency states on a timescale of seconds. If actin filaments are chemically cross-linked, a state that inhibits myosin motility(9), the equilibrium shifts to the low- FRET conformation, whereas when the actin filament is interacting with myosin, the high-FRET conformation is favored. This dynamic equilibrium suggests that actin can switch between active and inactive conformations in response to external signals.