Executing gene circuits by cell-free transcription-translation into cell-sized compartments, such as liposomes, is one of the major bottom-up approaches to building minimal cells. The dynamic synthesis and proper self-assembly of macromolecular structures inside liposomes, the cytoskeleton in particular, stands as a central limitation to the development of cell analogs genetically programmed. In this work, we express the Escherichia coli gene mreB inside vesicles with bilayers made of lipid-polyethylene glycol (PEG). We demonstrate that two-dimensional molecular crowding, emulated by the PEG molecules at the lipid bilayer, is enough to promote the polymerization of the protein MreB at the inner membrane into a sturdy cytoskeleton capable of transforming spherical liposomes into elongated shapes, such as rod-like compartments. We quantitatively describe this mechanism with respect to the size of liposomes, lipid composition of the membrane, crowding at the membrane, and strength of MreB synthesis. So far unexplored, molecular crowding at the surface of synthetic cells emerges as an additional development with potential broad applications. The symmetry breaking observed could be an important step toward compartment self-reproduction.

中文翻译：

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膜分子拥挤可增强MreB聚合，从而将合成细胞从球体塑造成棒状。

通过无细胞转录-翻译进入细胞大小的区室（例如脂质体）来执行基因回路，是构建最少细胞的主要自下而上方法之一。脂质体内大分子结构（尤其是细胞骨架）的动态合成和适当的自组装，是遗传程序化细胞类似物开发的主要限制。在这项工作中，我们在囊泡中表达由脂质-聚乙二醇（PEG）制成的双层的大肠杆菌基因mreB。我们证明，脂质双分子层上的PEG分子模拟的二维分子拥挤足以促进内膜MreB的聚合，使其成为能够将球形脂质体转变为细长形状（例如棒状）的坚固的细胞骨架。像车厢。我们定量描述这种机制有关脂质体的大小，膜的脂质组成，拥挤在膜和MreB合成的强度。迄今为止，尚未开发，合成细胞表面的分子拥挤作为具有潜在广泛应用的附加发展而出现。观察到的对称性破坏可能是朝向车厢自我繁殖的重要一步。