The healthy growth and maintenance of a biological system depends on the precise spatial organization of molecules within the cell through the dissipation of energy. Reaction–diffusion mechanisms can facilitate this organization, as can directional cargo transport orchestrated by motor proteins, by relying on specific protein interactions. However, transport of material through the cell can also be achieved by active processes based on non-specific, purely physical mechanisms, a phenomenon that remains poorly explored. Here, using a combined experimental and theoretical approach, we discover and describe a hidden function of the Escherichia coli MinDE protein system: in addition to forming dynamic patterns, this system accomplishes the directional active transport of functionally unrelated cargo on membranes. Remarkably, this mechanism enables the sorting of diffusive objects according to their effective size, as evidenced using modular DNA origami–streptavidin nanostructures. We show that the diffusive fluxes of MinDE and non-specific cargo couple via density-dependent friction. This non-specific process constitutes a diffusiophoretic mechanism, as yet unknown in a cell biology setting. This nonlinear coupling between diffusive fluxes could represent a generic physical mechanism for establishing intracellular organization.

生物系统的健康生长和维持取决于细胞内分子通过能量耗散进行的精确空间组织。反应-扩散机制可以促进这种组织，就像由运动蛋白协调的定向货物运输一样，依靠特定的蛋白质相互作用。然而，物质通过细胞的运输也可以通过基于非特异性、纯物理机制的主动过程来实现，这种现象仍然很少被探索。在这里，我们使用实验和理论相结合的方法，发现并描述了大肠杆菌的隐藏功能MinDE蛋白系统：除了形成动态模式外，该系统还完成了功能无关货物在膜上的定向主动运输。值得注意的是，这种机制能够根据扩散物体的有效尺寸对其进行分类，正如使用模块化 DNA 折纸-链霉抗生物素纳米结构所证明的那样。我们表明，MinDE 和非特定货物的扩散通量通过与密度相关的摩擦耦合。这种非特异性过程构成了扩散泳动机制，但在细胞生物学环境中尚不清楚。扩散通量之间的这种非线性耦合可以代表建立细胞内组织的通用物理机制。