Thermodynamic origin of cooperativity in actomyosin interactions: the coupling of short-range interactions with actin bending stiffness in an Ising-like model.
Thermodynamic origin of cooperativity in actomyosin interactions: the coupling of short-range interactions with actin bending stiffness in an Ising-like model.
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DOI：
10.1103/physreve.79.041906
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发表时间：
2009-04
期刊：
影响因子：
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通讯作者：
A. Alencar;J. Butler;S. Mijailovich
中科院分区：
文献类型：
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作者：
A. Alencar;J. Butler;S. Mijailovich
我们提出了一个分子运动系统的蒙特卡罗模拟发现几乎所有真核细胞，肌动蛋白运动系统，由一组有机大分子组成。细胞马达被映射成一个类似伊辛的模型，其中相互作用场通过原肌球蛋白聚合物链传递。Ca2+的存在诱导原肌凝蛋白阻断或解除阻断肌凝蛋白运动的结合位点，导致其激活或失活。我们使用Metropolis算法找到了由溶剂、肌动蛋白、原肌球蛋白、肌钙蛋白、Ca2+和肌球蛋白s1组成的肌动蛋白-肌球蛋白系统在给定温度下的瞬态和平衡态，包括原肌球蛋白在肌动蛋白丝表面的空间结构。我们的模型描述了肌动蛋白-肌凝蛋白结合过程中的短期和长期协同性，这种协同性来自于原肌凝蛋白复合物的弯曲刚度。我们只用组分的相互作用能就得到了态间的所有跃迁速率。我们的模型和实验数据之间的一致性也支持了最近的柔性原肌球蛋白理论。
We present Monte Carlo simulations for a molecular motor system found in virtually all eukaryotic cells, the acto-myosin motor system, composed of a group of organic macromolecules. Cell motors were mapped to an Ising-like model, where the interaction field is transmitted through a tropomyosin polymer chain. The presence of Ca2+ induces tropomyosin to block or unblock binding sites of the myosin motor leading to its activation or deactivation. We used the Metropolis algorithm to find the transient and the equilibrium states of the acto-myosin system composed of solvent, actin, tropomyosin, troponin, Ca2+, and myosin-S1 at a given temperature, including the spatial configuration of tropomyosin on the actin filament surface. Our model describes the short- and long-range cooperativity during actin-myosin binding which emerges from the bending stiffness of the tropomyosin complex. We found all transition rates between the states only using the interaction energy of the constituents. The agreement between our model and experimental data also supports the recent theory of flexible tropomyosin.