Jin Xin, Lee Ji-Eun, Schaefer Charley, Luo Xinwei, Wollman Adam J M, Payne-Dwyer Alex L, Tian Tian, Zhang Xiaowei, Chen Xiao, Li Yingxing, McLeish Tom C B, Leake Mark C, Bai Fan
Biomedical Pioneering Innovation Centre (BIOPIC), School of Life Sciences, Peking University, Beijing, China.
Department of Physics, University of York, York, UK.
Sci Adv. 2021 Oct 22;7(43):eabh2929. doi: 10.1126/sciadv.abh2929. Epub 2021 Oct 20.
Liquid-liquid phase separation is emerging as a crucial phenomenon in several fundamental cell processes. A range of eukaryotic systems exhibit liquid condensates. However, their function in bacteria, which, in general, lack membrane-bound compartments, remains less clear. Here, we used high-resolution optical microscopy to observe single bacterial aggresomes, nanostructured intracellular assemblies of proteins, to undercover their role in cell stress. We find that proteins inside aggresomes are mobile and undergo dynamic turnover, consistent with a liquid state. Our observations are in quantitative agreement with phase-separated liquid droplet formation driven by interacting proteins under thermal equilibrium that nucleate following diffusive collisions in the cytoplasm. We have found aggresomes in multiple species of bacteria and show that these emergent, metastable liquid-structured protein assemblies increase bacterial fitness by enabling cells to tolerate environmental stresses.
液-液相分离正在成为几种基本细胞过程中的关键现象。一系列真核系统表现出液体凝聚物。然而，它们在通常缺乏膜结合区室的细菌中的功能仍不太清楚。在这里，我们使用高分辨率光学显微镜观察单个细菌聚集体，即蛋白质的纳米结构细胞内聚集体，以揭示它们在细胞应激中的作用。我们发现聚集体内的蛋白质是可移动的，并经历动态周转，这与液态一致。我们的观察结果与热平衡下相互作用的蛋白质驱动的相分离液滴形成在数量上一致，这些蛋白质在细胞质中扩散碰撞后成核。我们在多种细菌中发现了聚集体，并表明这些新兴的、亚稳态的液体结构蛋白质聚集体通过使细胞能够耐受环境压力来提高细菌的适应性。
