Beyond Langmuir: surface-bound macromolecule condensates.
Beyond Langmuir: surface-bound macromolecule condensates.
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DOI：
10.1091/mbc.e20-06-0393
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发表时间：
2020-11-01
影响因子：
3.3
通讯作者：
Mitchison TJ
中科院分区：
文献类型：
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作者：
Mitchison TJ
大分子凝聚物、相分离和无膜室已成为细胞生物学研究的重要领域，新的生物物理概念正在出现。本文讨论了冷凝物通过多层吸附在DNA、微管或脂质双分子层等多价表面上组装的可能性。朗缪尔等温线理论提出了可饱和表面结合的概念，对物理生物化学产生了深远的影响。brunauer - emmet - teller （BET）理论将Langmuir的思想扩展到多层吸附。一个受bet启发的生化模型预测，具有自结合倾向的表面结合蛋白将在结合表面形成多层凝聚体。这些“结合凝析物”预计会在低于液-液相分离的饱和浓度下聚集，因此它们可以从相分离的液滴中竞争亚基，并在热力学上固定在结合表面。Tau蛋白与微管的结合是一个有趣的测试案例。不饱和结合等温线让人想起BET预测，但低浓度富tau结构域的组装需要不同的模型。表面结合凝析油可能有多种生物用途，特别是在凝析油组装受到空间限制的情况下，比如基因调控。
Macromolecule condensates, phase separation, and membraneless compartments have become an important area of cell biology research where new biophysical concepts are emerging. This article discusses the possibility that condensates assemble on multivalent surfaces such as DNA, microtubules, or lipid bilayers by multilayer adsorption. Langmuir isotherm theory conceptualized saturable surface binding and deeply influenced physical biochemistry. Brunauer-Emmett-Teller (BET) theory extended Langmuir’s ideas to multilayer adsorption. A BET-inspired biochemical model predicts that surface-binding proteins with a tendency to self-associate will form multilayered condensates on binding surfaces. These “bound condensates” are expected to assemble well below the saturation concentration for liquid–liquid phase separation, so they can compete subunits away from phase-separated droplets and are thermodynamically pinned to the binding surface. Tau binding to microtubules is an interesting test case. The nonsaturable binding isotherm is reminiscent of BET predictions, but assembly of Tau-rich domains at low concentrations requires a different model. Surface-bound condensates may find multiple biological uses, particularly in situations where it is important that condensate assembly is spatially constrained, such as gene regulation.