Orlandi Javier G, Blanch-Mercader Carles, Brugués Jan, Casademunt Jaume
Departament d'Estructura i Constituents de la Matèria, Facultat de Física, Universitat de Barcelona, Avinguda Diagonal 647, E-08028 Barcelona, Spain.
Phys Rev E Stat Nonlin Soft Matter Phys. 2010 Dec;82(6 Pt 1):061903. doi: 10.1103/PhysRevE.82.061903. Epub 2010 Dec 7.
We study the cooperative dynamics of Brownian motors moving along a one-dimensional track when an external load is applied to the leading motor, mimicking molecular motors pulling on membrane-bound cargoes in intracellular traffic. Due to the asymmetric loading, self-organized motor clusters form spontaneously. We model the motors with a two-state noise-driven ratchet formulation and study analytically and numerically the collective velocity-force and efficiency-force curves resulting from mutual interactions, mostly hard-core repulsion and weak (nonbinding) attraction. We analyze different parameter regimes including the limits of weak noise, mean-field behavior, rigid coupling, and large numbers of motors, for the different interactions. We present a general framework to classify and quantify cooperativity. We show that asymmetric loading leads generically to enhanced cooperativity beyond the simple superposition of the effects of individual motors. For weakly attracting interactions, the cooperativity is mostly enhanced, including highly coordinated motion of motors and complex nonmonotonic velocity-force curves, leading to self-regulated clusters. The dynamical scenario is enriched by resonances associated to commensurability of different length scales. Large clusters exhibit synchronized dynamics and bidirectional motion. Biological implications are discussed.
我们研究了一维轨道上布朗马达的协同动力学，此时外部负载作用于领先的马达，这模拟了细胞内运输中分子马达拉动膜结合货物的过程。由于不对称负载，自组织的马达簇会自发形成。我们用两态噪声驱动棘轮公式对马达进行建模，并通过解析和数值方法研究由相互作用产生的集体速度 - 力曲线和效率 - 力曲线，这些相互作用主要是硬核排斥和弱（非结合）吸引。对于不同的相互作用，我们分析了不同的参数范围，包括弱噪声极限、平均场行为、刚性耦合和大量马达的情况。我们提出了一个对协同性进行分类和量化的通用框架。我们表明，不对称负载通常会导致协同性增强，超出单个马达效应的简单叠加。对于弱吸引相互作用，协同性大多会增强，包括马达的高度协调运动和复杂的非单调速度 - 力曲线，从而导致自我调节的簇。动力学场景因与不同长度尺度的可公度性相关的共振而丰富。大簇表现出同步动力学和双向运动。我们还讨论了其生物学意义。
