Actin filament mechanics in the laser trap
Actin filament mechanics in the laser trap
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DOI：
10.1023/a:1018672631256
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发表时间：
1997-02-01
影响因子：
2.7
通讯作者：
Warshaw, DM
中科院分区：
文献类型：
--
作者：
Dupuis, DE;Guilford, WH;Warshaw, DM
许多生物过程，包括肌肉收缩，都依赖于肌动蛋白细丝的机械特性。一种这样的特性是抗弯(弯曲刚性，Fl)。为了估计F1，我们将荧光标记的肌动蛋白细丝的末端连接到两个在独立激光陷阱中捕获的微球“手柄”上。陷阱的位置被操纵，以通过微球手柄对细丝施加一定范围的张力(0-8pN)。随着纤维张力的增加，微球的位移与刚性的微球-纤维体系不一致。我们坚持认为，这种不一致是由于微球在陷阱中旋转，以及细丝在其附着物附近弯曲以适应这种旋转。将实验数据拟合到这一现象的简单模型中，我们估计肌动蛋白的F1近似于15×10(3)pN nm(2)，这个值在以前报道的结果范围内，尽管使用了新的方法。这些结果既支持肌动蛋白细丝比历史上假设的更顺应性的观点；也表明如果在类似的激光陷阱中没有适当地预拉伸肌动蛋白细丝，单一分子事件(例如肌球蛋白置换)的测量可能被严重低估。
Numerous biological processes, including muscular contraction, depend upon the mechanical properties of actin filaments. One such property is resistance to bending (flexural rigidity, Fl). To estimate Fl, we attached the ends of fluorescently labelled actin filaments to two microsphere 'handles' captured in independent laser traps. The positions of the traps were manipulated to apply a range of tensions (0-8 pN) to the filaments via the microsphere handles. With increasing filament tension, the displacement of the microspheres tvas inconsistent with a microsphere-filament system that is rigid. We maintain that this inconsistency is due to the microspheres rotating in the trap and the filaments bending near their attachments to accommodate this rotation. Fitting the experimental data to a simple model of this phenomena, we estimate actin's Fl to be approximate to 15 x 10(3) pN nm(2), a value within the range of previously reported results, albeit using a novel method. These results both: support the idea that actin filaments are more compliant than historically assumed; and, indicate that without appropriately pretensioning the actin filament in similar laser traps, measurements of unitary molecular events (e.g. myosin displacement) may be significantly underestimated.