Department of Mechanical Engineering, Faculty of Engineering, The University of Hong Kong, Hong Kong (SAR), Hong Kong, China.
School of Biomedical Sciences, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong (SAR), Hong Kong, China.
Nat Commun. 2021 May 27;12(1):3194. doi: 10.1038/s41467-021-23410-7.
The synthetic pathways of life's building blocks are envisaged to be through a series of complex prebiotic reactions and processes. However, the strategy to compartmentalize and concentrate biopolymers under prebiotic conditions remains elusive. Liquid-liquid phase separation is a mechanism by which membraneless organelles form inside cells, and has been hypothesized as a potential mechanism for prebiotic compartmentalization. Associative phase separation of oppositely charged species has been shown to partition RNA, but the strongly negative charge exhibited by RNA suggests that RNA-polycation interactions could inhibit RNA folding and its functioning inside the coacervates. Here, we present a prebiotically plausible pathway for non-associative phase separation within an evaporating all-aqueous sessile droplet. We quantitatively investigate the kinetic pathway of phase separation triggered by the non-uniform evaporation rate, together with the Marangoni flow-driven hydrodynamics inside the sessile droplet. With the ability to undergo liquid-liquid phase separation, the drying droplets provide a robust mechanism for formation of prebiotic membraneless compartments, as demonstrated by localization and storage of nucleic acids, in vitro transcription, as well as a three-fold enhancement of ribozyme activity. The compartmentalization mechanism illustrated in this model system is feasible on wet organophilic silica-rich surfaces during early molecular evolution.
生命基石的合成途径被设想为通过一系列复杂的前生物反应和过程。然而，在原始条件下分隔和浓缩生物聚合物的策略仍然难以捉摸。液-液相分离是无膜细胞器在细胞内形成的一种机制，并被假设为原始分隔的潜在机制。相反电荷物质的缔合相分离已被证明可以分配 RNA，但 RNA 表现出的强烈负电荷表明，RNA-聚阳离子相互作用可能会抑制 RNA 折叠及其在凝聚体中的功能。在这里，我们提出了一种在蒸发的全水固着液滴内进行非缔合相分离的原始合理途径。我们定量研究了由不均匀蒸发率触发的相分离的动力学途径，以及固着液滴内的 Marangoni 流驱动的流体动力学。通过进行液-液相分离，干燥液滴提供了一种用于形成原始无膜隔室的强大机制，这可以通过核酸的定位和储存、体外转录以及核酶活性提高三倍来证明。在早期分子进化过程中，在湿润的亲有机硅丰富的表面上，这种模型系统中的分隔机制是可行的。
