Revisit of reconstituted 30-nm nucleosome arrays reveals an ensemble of dynamic structures
By Bing-Rui Zhou, Jiansheng Jiang, R. Ghirlando, D. Norouzi, K. Sathish Yadav, H. Feng, Rui Wang, Ping Zhang, Victor B. Zhurkin, Yawen Bai. 2018
43 citations recorded by the source corpus.
It has long been suggested that chromatin may form a fiber with a diameter of ~30 nm that suppresses transcription. Despite nearly four decades of study, the structural nature of the 30-nm chromatin fiber and conclusive evidence of its existence in vivo remain elusive. The key support for the existence of specific 30 nm chromatin fiber structures is based on the determination of the structures of reconstituted nucleosome arrays using X-ray crystallography and single particle cryo-electron microscopy coupled with glutaraldehyde chemical cross-linking. Here we report the characterization of these nucleosome arrays in solution using analytical ultracentrifugation, nuclear magnetic resonance, and small angle X-ray scattering. We found that the physical properties of these nucleosome arrays in solution are not consistent with formation of just a few discrete structures of nucleosome arrays. In addition, we obtained a crystal of the nucleosome in complex with the globular domain of linker histone H5 that shows a new form of nucleosome packing and suggests a plausible alternative compact conformation for nucleosome arrays. Taken together, our results challenge the key evidence for the existence of a limited number of structures of reconstituted nucleosome arrays in solution by revealing that the reconstituted nucleosome arrays are actually best described as an ensemble of various conformations with a zigzagged arrangement of nucleosomes. Our finding has implications for understanding the structure and function of chromatin in vivo.
Subfields: Molecular Biology
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Citations in the corpus
- Distinct Structures and Dynamics of Chromatosomes with Different Human Linker Histone Isoforms (2020, background): “However, it has been argued that nucleosome arrays condensed by linker histones in the absence of cross-linking are best described with an ensemble of dynamic structures (Zhou and Bai, 2019; Zhou et al., 2018), which is consistent with the observation that nucleosomes can pack in different ways in c”