期刊
JOURNAL OF BIOLOGICAL CHEMISTRY
卷 293, 期 50, 页码 19191-19200出版社
AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
DOI: 10.1074/jbc.RA118.005721
关键词
chromatin; chromatin structure; chromatin regulation; histone; histone acetylation; nucleosome; epigenetics; gene regulation; histone H1; linker histone; nucleosome free region
资金
- National Institutes of Health [R01GM052426]
Eukaryotic genomes are packaged into linker-oligonucleosome assemblies, providing compaction of genomic DNA and contributing to gene regulation and genome integrity. To define minimal requirements for initial steps in the transition of compact, closed chromatin to a transcriptionally active, open state, we developed a model in vitro system containing a single, unique, target nucleosome in the center of a 25-nucleosome array and evaluated the accessibility of the linker DNA adjacent to this target nucleosome. We found that condensation of H1-lacking chromatin results in approximate to 60-fold reduction in linker DNA accessibility and that mimics of acetylation within all four core histone tail domains of the target nucleosome synergize to increase accessibility approximate to 3-fold. Notably, stoichiometric binding of histone H1 caused >2 orders of magnitude reduction in accessibility that was marginally diminished by histone acetylation mimics. Remarkably, a nucleosome-free region (NFR) in place of the target nucleosome completely abrogated H1-dependent restriction of linker accessibility in the immediate vicinity of the NFR. Our results suggest that linker DNA is as inaccessible as DNA within the nucleosome core in fully condensed, H1-containing chromatin. They further imply that an unrecognized function of NFRs in gene promoter regions is to locally abrogate the severe restriction of linker DNA accessibility imposed by H1s.
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