标题： 活性细胞骨架螺旋的尺寸和频率缩放的物理原理 显示英文标题

标题： Physical Principles of Size and Frequency Scaling of Active Cytoskeletal Spirals

摘要： 细胞骨架丝被表面固定的分子马达运输，一端固定在表面上，在肌球蛋白驱动的肌动蛋白“滑动测定”中观察到它们会螺旋运动。 螺旋的半径与马达密度成指数为-1/3的比例关系，而频率理论上预测与马达密度成指数为4/3的比例关系。 虽然螺旋半径和频率都依赖于马达密度，但理论假设了丝长度的独立性，并且尚未在除了肌动蛋白-肌球蛋白以外的细胞骨架系统中进行验证。 在此，我们重建了驱动微管螺旋运动的动力蛋白并将其实验结果与理论和数值模拟进行比较。 我们表征了螺旋微管的标度定律，并发现半径与力密度的关系与之前的结果一致。 另一方面，频率与力密度成指数约为1/3的比例关系，这与之前的预测相反。 我们还预测螺旋半径与丝长度成正比，频率与丝长度成反比，两者的指数均为约1/3。 一个可变持久长度模型最能解释实验中观察到的长度依赖性。 我们的研究结果将理论、模拟和实验协调起来，提高了我们对细胞骨架丝弹性作用、微管屈曲力学和马达运输以及活性丝物理原理的理解。 显示英文摘要

摘要： Cytoskeletal filaments transported by surface immobilized molecular motors with one end pinned to the surface have been observed to spiral in a myosin-driven actin 'gliding assay'. The radius of the spiral was shown to scale with motor density with an exponent of -1/3, while the frequency was theoretically predicted to scale with an exponent of 4/3. While both the spiraling radius and frequency depend on motor density, the theory assumed independence of filament length, and remained to be tested on cytoskeletal systems other than actin-myosin. Here, we reconstitute dynein-driven microtubule spiraling and compare experiments to theory and numerical simulations. We characterize the scaling laws of spiraling MTs and find the radius dependence on force density to be consistent with previous results. Frequency on the other hand scales with force density with an exponent of ~1/3, contrary to previous predictions. We also predict that the spiral radius scales proportionally and the frequency scales inversely with filament length, both with an exponent of ~1/3. A model of variable persistence length best explains the length dependence observed in experiments. Our findings that reconcile theory, simulations, and experiments improve our understanding of the role of cytoskeletal filament elasticity, mechanics of microtubule buckling and motor transport and the physical principles of active filaments.