Nucleosome Shape Dictates Chromatin Fiber Structure
Nucleosome Shape Dictates Chromatin Fiber Structure
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DOI：
10.1016/j.bpj.2008.09.055
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发表时间：
2009-02-04
影响因子：
3.4
通讯作者：
Schiessel, Helmut
中科院分区：
文献类型：
--
作者：
Depken, Martin;Schiessel, Helmut
除了作为所有进入真核基因组的门户之外，近年来染色质已被鉴定为携带调节转录活性的表观遗传密码。虽然我们对这种编码的生物化学了解很多，但对调节所通过的不同纤维结构却知之甚少。在过去的三十年里，已经提出了许多纤维模型，但没有一个能够预测甚至纤维的基本特性。在这项工作中，我们描述了所有可能的致密纤维，其中包括，但不限于，所有先前提出的结构的集合。为了指导未来的实验工作，我们展示了哪些纤维特性取决于底层结构，而关键是，哪些不取决于底层结构。解决这些模型的预测能力，我们建议一个简单的几何标准的基础上的核小体形状。这使我们能够预测凝聚的染色质纤维的观察到的特征，以及这些特征如何随着核小体重复长度的变化而变化。我们的方法揭示了如何在体内观察到的异质性连接器长度可以容纳在30 nm的纤维，并建议在染色质结构和功能的调节核小体表面相互作用的重要作用。
In addition to being the gateway for all access to the eukaryotic genome, chromatin has in recent years been identified as carrying an epigenetic code regulating transcriptional activity. Though much is known about the biochemistry of this code, little is understood regarding the different fiber structures through which the regulation is mediated. Over the last three decades many fiber models have been suggested, but none are able to predict even the basic characteristics of the fiber. In this work, we characterize the set of all possible dense fibers, which includes, but is not limited to, all previously suggested structures. To guide future experimental efforts, we show which fiber characteristics depend on the underlying structure and, crucially, which do not. Addressing the predictive power of these models, we suggest a simple geometric criterion based on the nucleosome shape alone. This enables us to predict the observed characteristics of the condensed chromatin fiber, and how these change with varying nucleosome repeat length. Our approach sheds light on how the in vivo observed heterogeneity in linker lengths can be accommodated within the 30 nm fiber, and suggest an important role for nucleosome surface interactions in the regulation of chromatin structure and function.