Multiscale modeling and simulation of microtubule-motor-protein assemblies.
Multiscale modeling and simulation of microtubule-motor-protein assemblies.
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DOI：
10.1103/physreve.92.062709
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
Shelley MJ
中科院分区：
文献类型：
--
作者：
Gao T;Blackwell R;Glaser MA;Betterton MD;Shelley MJ
微管和马达蛋白自组织成生物上重要的组合，包括有丝分裂纺锤体和中心体微管阵列。在细胞外，微管-马达混合物可以形成新的活性液晶材料，被消耗三磷酸腺苷的马达蛋白驱使失去平衡。微观的马达活动导致马达蛋白和微管之间的极性相关的相互作用，但这些相互作用如何产生更大规模的动力学行为，如复杂的流动和缺陷动力学，还不是很清楚。我们发展了微管-电机系统的多尺度理论，其中利用电机驱动的极性微管的布朗动力学模拟来研究电机介导的微管相互作用所产生的微观组织和应力。我们认为，极性排序和交联系绳松弛是主动不稳定应力的两个特定于极性的来源。然后，我们发展了一个连续介质Doi-Onsager模型，该模型捕获了极性排序和由这些特定于极性的活动应力产生的流体动力学流动。在模拟浸没表面上的主动向列流时，主动应力驱动了湍流动力学和错位缺陷的不断产生和湮灭。动力学由两个不稳定因素引起，考虑到实验的沉浸性，得出了明确的特征长度和时间尺度。当关闭Doi-Onsager模型中的流体动力学时，我们捕获了在布朗动力学模拟中观察到的极线的形成。
Microtubules and motor proteins self-organize into biologically important assemblies including the mitotic spindle and the centrosomal microtubule array. Outside of cells, microtubule-motor mixtures can form novel active liquid-crystalline materials driven out of equilibrium by adenosine triphosphate–consuming motor proteins. Microscopic motor activity causes polarity-dependent interactions between motor proteins and microtubules, but how these interactions yield larger-scale dynamical behavior such as complex flows and defect dynamics is not well understood. We develop a multiscale theory for microtubule-motor systems in which Brownian dynamics simulations of polar microtubules driven by motors are used to study microscopic organization and stresses created by motor-mediated microtubule interactions. We identify polarity-sorting and crosslink tether relaxation as two polar-specific sources of active destabilizing stress. We then develop a continuum Doi-Onsager model that captures polarity sorting and the hydrodynamic flows generated by these polar-specific active stresses. In simulations of active nematic flows on immersed surfaces, the active stresses drive turbulent flow dynamics and continuous generation and annihilation of disclination defects. The dynamics follow from two instabilities, and accounting for the immersed nature of the experiment yields unambiguous characteristic length and time scales. When turning off the hydrodynamics in the Doi-Onsager model, we capture formation of polar lanes as observed in the Brownian dynamics simulation.