Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06520, USA.
Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06520, USA; Howard Hughes Medical Institute, Yale University, New Haven, CT 06520, USA.
Cell. 2014 Jan 16;156(1-2):183-94. doi: 10.1016/j.cell.2013.11.028. Epub 2013 Dec 19.
The physical nature of the bacterial cytoplasm is poorly understood even though it determines cytoplasmic dynamics and hence cellular physiology and behavior. Through single-particle tracking of protein filaments, plasmids, storage granules, and foreign particles of different sizes, we find that the bacterial cytoplasm displays properties that are characteristic of glass-forming liquids and changes from liquid-like to solid-like in a component size-dependent fashion. As a result, the motion of cytoplasmic components becomes disproportionally constrained with increasing size. Remarkably, cellular metabolism fluidizes the cytoplasm, allowing larger components to escape their local environment and explore larger regions of the cytoplasm. Consequently, cytoplasmic fluidity and dynamics dramatically change as cells shift between metabolically active and dormant states in response to fluctuating environments. Our findings provide insight into bacterial dormancy and have broad implications to our understanding of bacterial physiology, as the glassy behavior of the cytoplasm impacts all intracellular processes involving large components.
即使细胞质动力学决定了细胞生理学和行为，但人们对细菌细胞质的物理性质仍知之甚少。通过对不同大小的蛋白质纤维、质粒、储存颗粒和外来颗粒进行单颗粒追踪，我们发现细菌细胞质表现出玻璃形成液体的特性，并以成分大小依赖的方式从液态转变为固态。因此，细胞质成分的运动随着尺寸的增加而受到不成比例的限制。值得注意的是，细胞代谢使细胞质流动化，从而允许更大的成分逃脱其局部环境并探索细胞质的更大区域。因此，细胞质的流动性和动力学随着细胞在代谢活跃和休眠状态之间的转变而发生剧烈变化，以适应环境的波动。我们的发现为细菌休眠提供了深入的了解，并对我们理解细菌生理学具有广泛的意义，因为细胞质的玻璃行为影响涉及大成分的所有细胞内过程。
