Jing Hairong, Bai Qingwen, Lin Ya'nan, Chang Haojing, Yin Dongxiao, Liang Dehai
Beijing National Laboratory for Molecular Sciences, MOE Key Laboratory of Polymer Chemistry and Physics, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
Langmuir. 2020 Jul 14;36(27):8017-8026. doi: 10.1021/acs.langmuir.0c01864. Epub 2020 Jul 3.
Construction of protocells with hierarchical structures and living functions is still a great challenge. Growing evidence demonstrates that the membraneless organelles, which facilitate many essential cellular processes, are formed by RNA, protein, and other biopolymers via liquid-liquid phase separation (LLPS). The formation of the protocell in the early days of Earth could follow the same principle. In this work, we develop a novel coacervate-based protocell containing membraneless subcompartments via spontaneous liquid-liquid phase separation by simply mixing single-stranded oligonucleotides (ss-oligo), quaternized dextran (Q-dextran), and poly(l-lysine) (PLL) together. The resulting biphasic droplet, with PLL/ss-oligo phase being the internal subcompartments and Q-dextran/ss-oligo phase as the surrounding medium, is capable of sequestering and partitioning biomolecules into distinct regions. When the droplet is exposed to salt or Dextranase, the surrounding Q-dextran/ss-oligo phase will be gradually dissociated, resulting in the chaotic movement and fusion of internal subcompartments. Besides, the external electric field at a lower strength can drive the biphasic droplet to undergo a deviated circulation concomitant with the fusion of localized subcompartments, while a high-strength electric field can polarize the whole droplet, resulting in the release of daughter droplets in a controllable manner. Our study highlights that liquid-liquid phase separation of biopolymers is a powerful strategy to construct hierarchically structured protocells resembling the morphology and functions of living cells and provides a step toward a better understanding of the transition mechanism from nonliving to living matter under prebiotic conditions.
构建具有层次结构和生命功能的原细胞仍然是一项巨大的挑战。越来越多的证据表明，促进许多重要细胞过程的无膜细胞器是由RNA、蛋白质和其他生物聚合物通过液-液相分离（LLPS）形成的。地球早期原细胞的形成可能遵循相同的原理。在这项工作中，我们通过简单地将单链寡核苷酸（ss-oligo）、季铵化葡聚糖（Q-葡聚糖）和聚（L-赖氨酸）（PLL）混合在一起，开发了一种基于凝聚相的新型原细胞，其包含通过自发液-液相分离形成的无膜亚隔室。所得的双相液滴，其中PLL/ss-oligo相作为内部亚隔室，Q-葡聚糖/ss-oligo相作为周围介质，能够将生物分子隔离并分配到不同区域。当液滴暴露于盐或葡聚糖酶时，周围的Q-葡聚糖/ss-oligo相将逐渐解离，导致内部亚隔室的混乱运动和融合。此外，较低强度的外部电场可以驱动双相液滴进行伴随局部亚隔室融合的偏离循环，而高强度电场可以使整个液滴极化，从而以可控方式释放子液滴。我们的研究强调，生物聚合物的液-液相分离是构建类似于活细胞形态和功能的层次结构原细胞的有力策略，并为更好地理解益生元条件下从非生命物质到生命物质的转变机制迈出了一步。
