Ion counting demonstrates a high electrostatic field generated by the nucleosome
Ion counting demonstrates a high electrostatic field generated by the nucleosome
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DOI：
10.7554/elife.44993
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发表时间：
2019-06-11
期刊：
影响因子：
7.7
通讯作者：
Herschlag, Dan
中科院分区：
文献类型：
--
作者：
Gebala, Magdalena;Johnson, Stephanie L.;Herschlag, Dan
在真核生物中，核DNA压缩过程的第一步是核小体的形成，核小体由带负电荷的DNA包裹在带正电荷的组蛋白八聚体周围组成。通常，假设DNA与核小体的复合完全减弱了DNA电荷，从而减弱了分子产生的静电场。相反，理论和计算研究表明，核小体保留了一个强大的，负的静电场。尽管它们对染色质的组织和功能有着根本的影响，但这些关于核小体静电的对立观点还没有经过实验检验。在这里，我们直接测量核小体静电，发现虽然核小体形成减少了一半的复合电荷，但核小体仍然保持着强大的负静电场。我们的研究强调了考虑核小体的生物学性质及其对从因子结合到DNA压缩过程的影响的重要性。
In eukaryotes, a first step towards the nuclear DNA compaction process is the formation of a nucleosome, which is comprised of negatively charged DNA wrapped around a positively charged histone protein octamer. Often, it is assumed that the complexation of the DNA into the nucleosome completely attenuates the DNA charge and hence the electrostatic field generated by the molecule. In contrast, theoretical and computational studies suggest that the nucleosome retains a strong, negative electrostatic field. Despite their fundamental implications for chromatin organization and function, these opposing views of nucleosome electrostatics have not been experimentally tested. Herein, we directly measure nucleosome electrostatics and find that while nucleosome formation reduces the complex charge by half, the nucleosome nevertheless maintains a strong negative electrostatic field. Our studies highlight the importance of considering the polyelectrolyte nature of the nucleosome and its impact on processes ranging from factor binding to DNA compaction.