Department of Biochemistry and Molecular Biology, Penn State University College of Medicine, Hershey, PA 17033, USA.
Exp Cell Res. 2012 Jul 15;318(12):1448-55. doi: 10.1016/j.yexcr.2012.02.014. Epub 2012 Feb 24.
Despite over 30 years of work, the fundamental structure of eukaryotic chromatin remains controversial. Here, we review the roots of this controversy in disparities between results derived from studies of chromatin in nuclei, chromatin isolated from nuclei, and chromatin reconstituted from defined components. Thanks to recent advances in imaging, modeling, and other approaches, it is now possible to recognize some unifying principles driving chromatin architecture at the level of the ubiquitous '30 nm' chromatin fiber. These suggest that fiber architecture involves both zigzag and bent linker motifs, and that such heteromorphic structures facilitate the observed high packing ratios. Interactions between neighboring fibers in highly compact chromatin lead to extensive interdigitation of nucleosomes and the inability to resolve individual fibers in compact chromatin in situ.
尽管已经过去了 30 多年，但真核染色质的基本结构仍然存在争议。在这里，我们回顾了这一争议的根源，即源自于细胞核中染色质、从细胞核中分离出来的染色质以及由明确成分重新组成的染色质的研究结果之间存在差异。由于最近在成像、建模和其他方法方面的进展，现在有可能认识到一些统一的原则，这些原则在普遍存在的“30nm”染色质纤维水平上驱动着染色质结构。这些原则表明，纤维结构既涉及曲折的连接基序，也涉及弯曲的连接基序，并且这种异质结构有助于观察到的高包装比。在高度紧凑的染色质中相邻纤维之间的相互作用导致核小体的广泛交错，并且无法在原位解析紧凑染色质中的单个纤维。
