Bidirectional cooperative motion of molecular motors
Bidirectional cooperative motion of molecular motors
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DOI：
10.1073/pnas.102692399
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发表时间：
2002-05-14
影响因子：
11.1
通讯作者：
Prost, J
中科院分区：
文献类型：
--
作者：
Badoual, M;Jülicher, F;Prost, J
最近，在一组漂亮的实验中，已经表明在其个体运动中缺乏方向性的Ncd突变体NK 11能够在运动性测定中表现出一种新的定向运动（Endow，S. A. & Higuchi，H.（2000）Nature（伦敦）406，913-916）：细丝保持给定的速度一段时间，然后突然以相似的速度沿相反的方向移动。我们表明，这些观察很好地说明了概念的动态转换在电机集合中介绍了前面的情况下，一个无限数量的电机。我们调查实验相关的情况下，有限数量的电机时，方向性是存在的（驱动蛋白，肌球蛋白，NCD）和缺席（NK 11）。使用一个对称的两态模型，我们证明了双向运动是一个动态的过渡，结果从集体行为的许多电机作用在同一灯丝的签名。对于单独表现出方向性偏差的电机，不对称两态模型是合适的。在这种情况下，在存在外力的情况下，运动集合存在动态转变。我们预测ATP浓度，外力，和参与的电机的数量的运动的依赖性。特别是，我们表明，反转时间与每灯丝的电机数量呈指数增长。
Recently, in a beautiful set of experiments, it has been shown that a Ncd mutant, NK11, which lacks directionality in its individual motion, was able to exhibit a new kind of directed motion in motility assays (Endow, S. A. & Higuchi, H. (2000) Nature (London) 406, 913-916): the filaments keep a given velocity for a while and then suddenly move in the opposite direction with similar velocity. We show that these observations nicely illustrate the concept of dynamic transitions in motor collections introduced earlier in the case of an infinite number of motors. We investigate the experimentally relevant case of a finite number of motors both when directionality is present (kinesins, myosins, Ncd) and absent (NK11). Using a symmetric two-state model, we demonstrate that bidirectional motion is the signature of a dynamic transition that results from the collective behavior of many motors acting on the same filament. For motors exhibiting directional bias individually, an asymmetric two-state model is appropriate. In that case, dynamic transitions exist for motor collections in the presence of an external force. We give predictions for the dependence of motion on ATP concentration, external forces, and the number of motors involved. In particular, we show that the reversal time grows exponentially with the number of motors per filament.