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Crowding-induced interactions of ring polymers
Soft Matter ( IF 2.9 ) Pub Date : 2020-10-30 , DOI: 10.1039/d0sm01847c
Gaurav Chauhan 1 , Michael L Simpson , Steven M Abel
Affiliation  

Macromolecular crowding and the presence of surfaces can significantly impact the spatial organization of biopolymers. While the importance of crowding-induced depletion interactions in biology has been recognized, much remains to be understood about the effect of crowding on biopolymers such as DNA plasmids. A fundamental problem highlighted by recent experiments is to characterize the impact of crowding on polymer–polymer and polymer–surface interactions. Motivated by the need for quantitative insight, we studied flexible ring polymers in crowded environments using Langevin dynamics simulations. The simulations demonstrated that crowding can lead to compaction of isolated ring polymers and enhanced interactions between two otherwise repulsive polymers. Using umbrella sampling, we determined the potential of mean force (PMF) between two ring polymers as a function of their separation distance at different volume fractions of crowding particles, ϕ. An effective attraction emerged at ϕ ≈ 0.4, which is similar to the degree of crowding in cells. Analogous simulations showed that crowding can lead to strong adsorption of a ring polymer to a wall, with an effective attraction to the wall emerging at a smaller volume fraction of crowders (ϕ ≈ 0.2). Our results reveal the magnitude of depletion interactions in a biologically-inspired model and highlight how crowding can be used to tune interactions in both cellular and cell-free systems.

中文翻译:

拥挤诱导的环状聚合物相互作用

大分子拥挤和表面的存在会显着影响生物聚合物的空间组织。尽管已经认识到拥挤引起的耗竭相互作用在生物学中的重要性,但是拥挤对诸如DNA质粒之类的生物聚合物的影响仍有许多待理解。最近的实验强调的一个基本问题是表征拥挤对聚合物-聚合物和聚合物-表面相互作用的影响。出于对定量洞察力的需求,我们使用Langevin动力学模拟研究了拥挤环境中的柔性环聚合物。模拟表明,拥挤可导致孤立的环状聚合物紧实,并增强两种排斥聚合物之间的相互作用。使用总括抽样ϕ。有效吸引出现在ϕ≈0.4,这类似于细胞的拥挤程度。类似模拟表明拥挤可导致环聚合物壁的吸附力强,用有效吸引到壁新兴在沟渠扫污机的一个较小的体积分数(φ听,说:0.2)。我们的结果揭示了生物学启发模型中耗竭相互作用的强度,并强调了拥挤如何可用于调节细胞和无细胞系统中的相互作用。
更新日期:2020-11-06
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