Laboratory for Soft Matter and Biophysics, KU Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium.
J Chem Phys. 2019 Apr 7;150(13):135101. doi: 10.1063/1.5084950.
By combining analytical results and simulations of various coarse-grained models, we investigate the minimal energy shape of DNA minicircles which are torsionally constrained by an imposed over or undertwist. We show that twist-bend coupling, a cross interaction term discussed in the recent DNA literature, induces minimal energy shapes with a periodic alternation of parts with high and low curvature resembling rounded polygons. We briefly discuss the possible experimental relevance of these findings. We finally show that the twist and bending energies of minicircles are governed by renormalized stiffness constants, rather than the bare ones. This has important consequences for the analysis of experiments involving circular DNA meant to determine DNA elastic constants.
通过结合各种粗粒模型的分析结果和模拟，我们研究了受外加过扭或欠扭约束的 DNA 小环的最小能量形状。我们表明，扭弯耦合，即最近 DNA 文献中讨论的交叉相互作用项，诱导了具有周期性交替的高曲率和低曲率部分的最小能量形状，类似于圆形多边形。我们简要讨论了这些发现的可能实验相关性。最后，我们表明，小环的扭转和弯曲能由重整化的弹性常数而不是原始的弹性常数控制。这对涉及旨在确定 DNA 弹性常数的圆形 DNA 的实验分析有重要影响。
