Jan 7, 2020
Cryo-EM Structures of Centromeric Tri-nucleosomes Containing a Central CENP-A Nucleosome.
Structure (London, England : 1993)
- Volume
- 28
- Number
- 1
- First page
- 44
- Last page
- 53
- Language
- English
- Publishing type
- DOI
- 10.1016/j.str.2019.10.016
The histone H3 variant CENP-A is a crucial epigenetic marker for centromere specification. CENP-A forms a characteristic nucleosome and dictates the higher-order configuration of centromeric chromatin. However, little is known about how the CENP-A nucleosome affects the architecture of centromeric chromatin. In this study, we reconstituted tri-nucleosomes mimicking a centromeric nucleosome arrangement containing the CENP-A nucleosome, and determined their 3D structures by cryoelectron microscopy. The H3-CENP-A-H3 tri-nucleosomes adopt an untwisted architecture, with an outward-facing linker DNA path between nucleosomes. This is distinct from the H3-H3-H3 tri-nucleosome architecture, with an inward-facing DNA path. Intriguingly, the untwisted architecture may allow the CENP-A nucleosome to be exposed to the solvent in the condensed chromatin model. These results provide a structural basis for understanding the 3D configuration of CENP-A-containing chromatin, and may explain how centromeric proteins can specifically target the CENP-A nucleosomes buried in robust amounts of H3 nucleosomes in centromeres.
- Link information
- ID information
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- DOI : 10.1016/j.str.2019.10.016
- ISSN : 0969-2126
- Pubmed ID : 31711756