One of the grand challenges of bottom-up synthetic biology is the development of minimal machineries for cell division. The mechanical transformation of large-scale compartments, such as Giant Unilamellar Vesicles (GUVs), requires the geometry-specific coordination of active elements, several orders of magnitude larger than the molecular scale. Of all cytoskeletal structures, large-scale actomyosin rings appear to be the most promising cellular elements to accomplish this task. Here, we have adopted advanced encapsulation methods to study bundled actin filaments in GUVs and compare our results with theoretical modeling. By changing few key parameters, actin polymerization can be differentiated to resemble various types of networks in living cells. Importantly, we find membrane binding to be crucial for the robust condensation into a single actin ring in spherical vesicles, as predicted by theoretical considerations. Upon force generation by ATP-driven myosin motors, these ring-like actin structures contract and locally constrict the vesicle, forming furrow-like deformations. On the other hand, cortex-like actin networks are shown to induce and stabilize deformations from spherical shapes.

中文翻译：

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囊泡中收缩性放线菌素环的重构

自下而上的合成生物学的重大挑战之一是开发用于细胞分裂的最小机器。大型隔室（例如巨型单层囊泡（GUV））的机械改造需要活性元素的几何形状特定的配合，比分子尺度大几个数量级。在所有细胞骨架结构中，大规模的肌动球蛋白环似乎是完成这一任务的最有希望的细胞元件。在这里，我们采用了先进的封装方法来研究GUV中捆绑的肌动蛋白丝，并将我们的结果与理论模型进行比较。通过更改几个关键参数，可以区分肌动蛋白聚合反应，使其类似于活细胞中的各种类型的网络。重要的，我们发现，膜结合对于将球形囊泡牢固凝结成单个肌动蛋白环至关重要，这是理论考虑所预测的。在由ATP驱动的肌球蛋白电机产生力时，这些环状肌动蛋白结构收缩并局部收缩囊泡，形成沟状变形。另一方面，显示皮质样肌动蛋白网络可诱导并稳定球形的变形。