Institute for Chemical Reaction Design and Discovery, Hokkaido University, Kita 21 Nishi 10, Kita-ku, Sapporo, Hokkaido 001-0021, Japan.
Soft Matter. 2020 May 21;16(19):4692-4698. doi: 10.1039/c9sm02458a. Epub 2020 May 12.
We here use an extension of the Flory-Huggins theory to predict that phase separation is driven by the production of architectural RNA (arcRNA) at a DNA locus with a constant rate. The arcRNA molecules diffuse in the nucleoplasm and show attractive interactions via proteins that are bound to the arcRNA. Our theory predicts that when the Flory interaction parameter is larger than the value at the critical point, the volume fraction of arcRNA jumps between the two values corresponding to the volume fraction of the two coexisting phases at equilibrium at a distance from the DNA locus due to the local equilibrium condition. The distance defines the radius of the condensate that is assembled by the phase separation. When the interaction parameter is large, the volume of the condensates is proportional to the production rate of arcRNA and inversely proportional to the degradation rate of arcRNA. These results imply that most arcRNA molecules are degraded before they diffuse out from the condensates due to the strong segregation of arcRNA.
我们在这里利用 Flory-Huggins 理论的扩展来预测，通过在 DNA 位置以恒定速率产生结构 RNA (arcRNA) 来驱动相分离。arcRNA 分子在核质中扩散，并通过与 arcRNA 结合的蛋白质显示出吸引力相互作用。我们的理论预测，当 Flory 相互作用参数大于临界点的值时，由于局部平衡条件，arcRNA 的体积分数在两个对应于平衡时两个共存相的体积分数的值之间跳跃，距离 DNA 位置。该距离定义了由相分离组装的凝聚物的半径。当相互作用参数较大时，凝聚物的体积与 arcRNA 的产生速率成正比，与 arcRNA 的降解速率成反比。这些结果表明，由于 arcRNA 的强烈隔离，大多数 arcRNA 分子在从凝聚物中扩散出来之前就被降解了。
