Cryo-EM study of the chromatin fiber reveals a double helix twisted by tetranucleosomal units.
basic_science · Level V
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- Record sourced from PubMed, PMID 24763583.
- Also identified by DOI 10.1126/science.1251413.
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Abstract
The hierarchical packaging of eukaryotic chromatin plays a central role in transcriptional regulation and other DNA-related biological processes. Here, we report the 11-angstrom-resolution cryogenic electron microscopy (cryo-EM) structures of 30-nanometer chromatin fibers reconstituted in the presence of linker histone H1 and with different nucleosome repeat lengths. The structures show a histone H1-dependent left-handed twist of the repeating tetranucleosomal structural units, within which the four nucleosomes zigzag back and forth with a straight linker DNA. The asymmetric binding and the location of histone H1 in chromatin play a role in the formation of the 30-nanometer fiber. Our results provide mechanistic insights into how nucleosomes compact into higher-order chromatin fibers.
Medical subject headings
- Chromatin
- DNA
- Histones
- Nucleosomes