Molecular motors pulling cargos in the viscoelastic cytosol: how power strokes beat subdiffusion.
Molecular motors pulling cargos in the viscoelastic cytosol: how power strokes beat subdiffusion.
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DOI：
10.1039/c4cp01234h
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发表时间：
2013-12
期刊：
影响因子：
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通讯作者：
I. Goychuk;V. Kharchenko;R. Metzler
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文献类型：
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作者：
I. Goychuk;V. Kharchenko;R. Metzler
发现较大的生物聚合物和亚微米示踪剂（如活细胞中的内源性颗粒、细胞器或病毒衣壳）的异常扩散归因于细胞质的粘弹性，这引发了一个问题，即这种复杂的环境是否同样影响分子马达（如驱动蛋白）对亚微米货物的主动细胞内转运：自由货物的被动异常扩散是否总是意味着其缓慢的主动运输，即平均运输距离沿微管沿着随时间呈亚线性增长而不是线性增长？在这里，我们分析了这个问题内广泛使用的两个状态的布朗棘轮模型驱动蛋白马达的基础上的连续状态扩散沿着微管驱动的闪光结合电位，其中货物颗粒是弹性连接到电机。根据货物的大小，负载力，结合电位的幅度，分子马达酶的周转频率，和连接器的刚度，我们证明，电机运输可能会变成正常或异常，确实实验测量。我们展示了如何一个高效的正常的主动运输介导的电机可能会出现，尽管被动异常扩散的货物，并研究了复杂的影响的弹性连接器。在不同的，明确规定的条件下，基于微管的马达运输变得非常缓慢，因此效率显着降低。
The discovery of anomalous diffusion of larger biopolymers and submicron tracers such as endogenous granules, organelles, or virus capsids in living cells, attributed to the viscoelastic nature of the cytoplasm, provokes the question whether this complex environment equally impacts the active intracellular transport of submicron cargos by molecular motors such as kinesins: does the passive anomalous diffusion of free cargo always imply its anomalously slow active transport by motors, the mean transport distance along microtubule growing sublinearly rather than linearly in time? Here we analyze this question within the widely used two-state Brownian ratchet model of kinesin motors based on the continuous-state diffusion along microtubules driven by a flashing binding potential, where the cargo particle is elastically attached to the motor. Depending on the cargo size, the loading force, the amplitude of the binding potential, the turnover frequency of the molecular motor enzyme, and the linker stiffness we demonstrate that the motor transport may turn out either normal or anomalous, as indeed measured experimentally. We show how a highly efficient normal active transport mediated by motors may emerge despite the passive anomalous diffusion of the cargo, and study the intricate effects of the elastic linker. Under different, well specified conditions the microtubule-based motor transport becomes anomalously slow and thus significantly less efficient.