A CHROMATIN FOLDING MODEL THAT INCORPORATES LINKER VARIABILITY GENERATES FIBERS RESEMBLING THE NATIVE STRUCTURES
A CHROMATIN FOLDING MODEL THAT INCORPORATES LINKER VARIABILITY GENERATES FIBERS RESEMBLING THE NATIVE STRUCTURES
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DOI：
10.1073/pnas.90.19.9021
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发表时间：
1993-10-01
影响因子：
11.1
通讯作者：
WHITAKER, N
中科院分区：
文献类型：
--
作者：
WOODCOCK, CL;GRIGORYEV, SA;WHITAKER, N
在真核生物细胞核中观察到的“30 nm”染色质纤维被认为是 DNA 折叠层次结构中的离散水平。目前，关于核小体和连接DNA如何在染色质纤维内组织存在相当多的争论，并且已经提出了许多模型，其中许多模型基于螺旋对称性并暗示核小体之间的特定接触。然而，当在细胞核中或分离后观察时，染色质纤维显示出相当大的结构不规则性。在本研究中，仅根据核小体-连接单元的已知特性来考虑染色质折叠，同时考虑到 DNA 螺旋扭曲导致的连续核小体之间的相对旋转。基于此前提的模型构建以及连续核小体之间恒定长度的连接DNA，产生了一系列纤维状和带状结构。当核小体之间的连接长度允许变化时，就像自然界中发生的那样，就会产生显示在细胞核和分离的染色质中观察到的不规则类型的纤维。讨论了该模型在确定已知核小体位置的染色质三维组织中的潜在应用。
The ''30-nm'' chromatin fibers, as observed in eukaryotic nuclei, are considered a discrete level in a hierarchy of DNA folding. At present, there is considerable debate as to how the nucleosomes and linker DNA are organized within chromatin fibers, and a number of models have been proposed, many of which are based on helical symmetry and imply specific contacts between nucleosomes. However, when observed in nuclei or after isolation, chromatin fibers show considerable structural irregularity. In the present study, chromatin folding is considered solely in terms of the known properties of the nucleosome-linker unit, taking into account the relative rotation between consecutive nucleosomes that results from the helical twist of DNA. Model building based on this premise, and with a constant length of linker DNA between consecutive nucleosomes, results in a family of fiber- and ribbon-like structures. When the linker length between nucleosomes is allowed to vary, as occurs in nature, fibers showing the types of irregularity observed in nuclei and in isolated chromatin are created. The potential application of the model in determining the three-dimensional organization of chromatin in which nucleosome positions are known is discussed.