Mesoscale molecular assembly is favored by the active, crowded cytoplasm.
Mesoscale molecular assembly is favored by the active, crowded cytoplasm.
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活跃、拥挤的细胞质有利于中尺度分子组装。
DOI：
10.1101/2023.09.19.558334
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发表时间：
2023
期刊：
影响因子：
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通讯作者：
Holt,LiamJ
中科院分区：
文献类型：
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作者：
Shu,Tong;Mitra,Gaurav;Alberts,Jonathan;Viana,MatheusP;Levy,EmmanuelD;Hocky,GlenM;Holt,LiamJ
分子到无膜生物分子凝聚物的介观组织已经成为细胞内快速和精确时空控制的关键机制。虽然我们对生物分子凝聚物的原理的理解已经通过体外重建研究得到了显着的进步，但认识到细胞内环境比试管环境复杂得多是至关重要的。细胞内环境表现出明显的特征：它们是粘弹性的，在中尺度上高度拥挤，并且由于能量消耗过程的持续作用而远离热力学平衡。为了研究细胞内环境如何影响冷凝物的形成，我们开发了synDrops，一种合成相分离系统。该系统具有三个关键特征，能够进行严格的物理分析：synDrops是可诱导的，生物正交的，并具有明确的几何形状。这种独特的设计使我们能够对synDrop组装进行动力学分析，并对该过程进行计算机模拟。通过对S.酿酒酵母和哺乳动物HeLa细胞，再加上分子动力学模拟，我们的调查揭示了一个多方面的图片。具体而言，我们发现，大分子拥挤在冷凝物形成的动力学中起着双重作用：它通过增加化学键的有效结合亲和力来促进冷凝物的成核，同时通过降低介观冷凝物扩散系数来抑制液滴通过聚结的生长。值得注意的是，ATP依赖性细胞活动通过促进长距离细胞结构重排来帮助克服液滴生长的挫折。特别是，肌动球蛋白动力学通过减少哺乳动物细胞质中的弹性限制来增强液滴生长，从而使synDrop粗化。我们的研究结果表明，中尺度分子组装有利于拥挤和活性物质在细胞质中的综合作用。这些结果有助于更好地预测体内冷凝物的形成。
The mesoscale organization of molecules into membraneless biomolecular condensates has emerged as a key mechanism for rapid and precise spatiotemporal control within cells. While our understanding of the principles governing biomolecular condensates has been significantly advanced through in vitro reconstitution studies, it is crucial to recognize that intracellular environments are much more complex than test-tube environments. The intracellular environments exhibit distinct characteristics: they are viscoelastic, highly crowded at the mesoscale, and are far from thermodynamic equilibrium due to the constant action of energy consuming processes. To investigate how the intracellular environment affects condensate formation, we developed synDrops, a synthetic phase separation system. This system possesses three key features that enable rigorous physical analysis: synDrops are inducible, bioorthogonal, and have well-defined geometry. This unique design allowed us to perform kinetic analyses of synDrop assembly and enable computational simulations of the process. Through a comprehensive comparison of experimental data obtained from both S. cerevisiae yeast and mammalian HeLa cells, coupled with molecular dynamics simulations, our investigation unveiled a multifaceted picture. Specifically, we found that macromolecular crowding plays a dual role in the dynamics of condensate formation: it promotes the nucleation of condensates by increasing effective binding affinity of chemical bonds, while simultaneously inhibiting droplet growth through coalescence by reducing mesoscale condensate diffusivity. Notably, ATP-dependent cellular activities help overcome the frustration of droplet growth by promoting long-range cellular structural rearrangements. In particular, actomyosin dynamics potentiate droplet growth by reducing elastic confinement in the mammalian cytoplasm, thereby enabling synDrop coarsening. Our results demonstrate that mesoscale molecular assembly is favored by the combined effects of crowding and active matter in the cytoplasm. These results move toward a better predictive understanding of condensate formation in vivo.