Geometrical Heterogeneity Dominates Thermal Fluctuations in Facilitating Chromatin Contacts
Geometrical Heterogeneity Dominates Thermal Fluctuations in Facilitating Chromatin Contacts
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DOI：
10.1103/physrevlett.123.208103
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发表时间：
2019-11-15
影响因子：
8.6
通讯作者：
Spakowitz, Andrew J.
中科院分区：
文献类型：
--
作者：
Beltran, Bruno;Kannan, Deepti;Spakowitz, Andrew J.
在活细胞内，无数与DNA结合的蛋白质将不均匀间隔的扭结引入原本半柔性的DNA双螺旋。为了研究异质核小体结合对染色质组织的影响，我们扩展了蠕虫状链模型，包括统计间隔，刚性扭结。在核小体位置固定的时间尺度上，我们发现染色质环形成的概率可以在来自相同分布的两组核小体位置之间变化多达六个数量级。在较长的时间尺度上，我们表明，由于核小体营业额的连续重新随机化的结果在染色质跟踪出一个有效的WLC与显着较小的库恩长度比裸DNA。总之，这些观察结果表明，核小体间距作为主导局部和全局染色质组织的结构异质性的主要来源。
Within a living cell, the myriad of proteins that bind DNA introduce heterogeneously spaced kinks into an otherwise semiflexible DNA double helix. To investigate the effects of heterogeneous nucleosome binding on chromatin organization, we extend the wormlike chain model to include statistically spaced, rigid kinks. On timescales where nucleosome positions are fixed, we find that the probability of chromatin loop formation can vary by up to six orders of magnitude between two sets of nucleosome positions drawn from the same distribution. On longer timescales, we show that continuous rerandomization due to nucleosome turnover results in chromatin tracing out an effective WLC with a dramatically smaller Kuhn length than bare DNA. Together, these observations demonstrate that nucleosome spacing acts as the primary source of the structural heterogeneity that dominates local and global chromatin organization.