The influence of chromosome flexibility on chromosome transport during anaphase A.
The influence of chromosome flexibility on chromosome transport during anaphase A.
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染色体柔性对后期染色体运输的影响 A.
DOI：
10.1073/pnas.0601215103
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发表时间：
2006
期刊：
影响因子：
--
通讯作者：
Peskin,CharlesS
中科院分区：
文献类型：
--
作者：
Raj,Arjun;Peskin,CharlesS
蛋白质的灵活性在分子马达功能中的作用以前已经通过考虑布朗棘轮马达进行了研究，该马达通过弹性弹簧连接到其货物，结果是马达/货物系统的平均速度通过降低连杆的刚度而增加。在这里，我们将这项研究扩展到后期A期间染色体转运的情况，其中相关的灵活性主要不是在马达/货物连接中，而是在货物本身中，即，在染色体上。我们模型的电机机制作为一个不完美的布朗棘轮与内置的相反的负载和染色体作为一个集合的离散段连接的弹性能量函数，离散的势能的弹性杆。在模型中，热涨落是由随机力产生的，就像布朗动力学一样。表征染色体的所有参数都是已知的，或者可以从实验数据中估计，除了一个电机参数之外，所有电机参数都可以进行调整，以给出正常长度染色体的正确传输速度。用这样确定的参数，我们再现了Nicklas [Nicklas，R. B。（1965）J. Cell Biol.25，119-135]染色体速度本质上独立于染色体长度，尽管我们的模型不包含“速度调节器”。相反，我们发现这种效应是染色体灵活性的结果，因为当考虑比正常染色体更硬时，它就消失了。
The role of protein flexibility in molecular motor function has previously been studied by considering a Brownian ratchet motor that is connected to its cargo by an elastic spring, with the result that the average velocity of the motor/cargo system is increased by reducing the stiffness of the linkage. Here, we extend this investigation to the case of chromosome transport during anaphase A, in which the relevant flexibility is not primarily in the motor/cargo linkage but rather in the cargo itself, i.e., in the chromosome. We model the motor mechanism as an imperfect Brownian ratchet with a built-in opposing load and the chromosome as a collection of discrete segments linked by an elastic energy function that discretizes the potential energy of an elastic rod. Thermal fluctuations are produced in the model by random forces, as in Brownian dynamics. All of the parameters that characterize the chromosome are known or can be estimated from experimental data, as can all but one of the motor parameters, which is adjusted to give the correct transport velocity of normal-length chromosomes. With the parameters so determined, we then reproduce the experimental finding of Nicklas [Nicklas, R. B. (1965)J. Cell Biol.25, 119–135] that chromosome speed is essentially independent of chromosome length, even though our model contains no “velocity governor.” We find instead that this effect is a consequence of chromosome flexibility, as it disappears when stiffer than normal chromosomes are considered.
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