活细胞的内部微环境是异质的,并且包括具有不同生物化学的多个细胞器。其中包括生物分子缩合物,它们是无膜的,富含系统特异性蛋白质和核酸的相分离区室。细胞的异质性导致化学中存在多个时空梯度,charge,浓度,温度,和压力。这样的热力学梯度可以导致用于生物分子冷凝物的形成和运输的非平衡驱动力。这里,我们报告了离子梯度如何影响生物分子缩合物在中尺度和生物分子在微观尺度上的传输过程。利用微流体平台,我们证明离子浓度梯度的存在可以加速生物分子的运输,包括核酸和蛋白质,通过扩散电泳。这种流体动力学运输过程允许生物分子的局部富集,从而通过相分离促进生物分子缩合物的位置特异性形成。离子梯度进一步赋予冷凝物的定向运动性,允许它们沿着梯度表现出增强的扩散。再加上折返相行为,梯度诱导的增强的运动性导致冷凝物的动态重新分布,最终延长了它们的寿命。一起,我们的结果表明,扩散电泳是一种非平衡热力学力,控制着生物分子缩合物的形成和运输。
The internal microenvironment of a living cell is heterogeneous and comprises a multitude of organelles with distinct biochemistry. Amongst them are biomolecular condensates, which are membrane-less, phase-separated compartments enriched in system-specific proteins and nucleic acids. The heterogeneity of the cell engenders the presence of multiple spatiotemporal gradients in chemistry, charge, concentration, temperature, and pressure. Such thermodynamic gradients can lead to non-equilibrium driving forces for the formation and transport of biomolecular condensates. Here, we report how ion gradients impact the transport processes of biomolecular condensates on the mesoscale and biomolecules on the microscale. Utilizing a microfluidic platform, we demonstrate that the presence of ion concentration gradients can accelerate the transport of biomolecules, including nucleic acids and proteins, via diffusiophoresis. This hydrodynamic transport process allows localized enrichment of biomolecules, thereby promoting the location-specific formation of biomolecular condensates via phase separation. The ion gradients further impart directional motility of condensates, allowing them to exhibit enhanced diffusion along the gradient. Coupled with a reentrant phase behavior, the gradient-induced enhanced motility leads to a dynamical redistribution of condensates that ultimately extends their lifetime. Together, our results demonstrate diffusiophoresis as a non-equilibrium thermodynamic force that governs the formation and transport of biomolecular condensates.