Center for the Physics of Biological Function, Princeton University, Princeton, United States.
Department of Physics and Astronomy, Johns Hopkins University, Baltimore, United States.
Elife. 2024 Sep 25;12:RP91680. doi: 10.7554/eLife.91680.
A hallmark of biomolecular condensates formed via liquid-liquid phase separation is that they dynamically exchange material with their surroundings, and this process can be crucial to condensate function. Intuitively, the rate of exchange can be limited by the flux from the dilute phase or by the mixing speed in the dense phase. Surprisingly, a recent experiment suggests that exchange can also be limited by the dynamics at the droplet interface, implying the existence of an 'interface resistance'. Here, we first derive an analytical expression for the timescale of condensate material exchange, which clearly conveys the physical factors controlling exchange dynamics. We then utilize sticker-spacer polymer models to show that interface resistance can arise when incident molecules transiently touch the interface without entering the dense phase, i.e., the molecules 'bounce' from the interface. Our work provides insight into condensate exchange dynamics, with implications for both natural and synthetic systems.
液液相分离形成的生物分子凝聚体的一个标志是它们与周围环境动态地交换物质，这一过程对于凝聚体的功能可能至关重要。直观地说，交换速率可能受到来自稀相的通量或密相中的混合速度的限制。令人惊讶的是，最近的一项实验表明，交换也可能受到液滴界面的动力学限制，这意味着存在“界面阻力”。在这里，我们首先推导出凝聚体物质交换的时间尺度的解析表达式，该表达式清楚地传达了控制交换动力学的物理因素。然后，我们利用粘贴间隔聚合物模型表明，当入射分子短暂地接触界面而不进入密相时，即分子“从界面反弹”，会产生界面阻力。我们的工作为凝聚体交换动力学提供了深入的了解，对自然和合成系统都有影响。
