This work was published in the Proceedings of the National Academy of Sciences of the United States of America (PNAS). As one of the authors, I reproduce it here as I am entitled to do according to the PNAS License to Publish.
Proc. Natl. Acad. Sci. USA, 107(21):9620–9625. [full text]
Despite the key role of the linker histone H1 in chromatin structure and dynamics, its location and interactions with nucleosomal DNA have not been elucidated. In this work we have used a combination of electron cryomicroscopy, hydroxyl radical footprinting, and nanoscale modeling to analyze the structure of precisely positioned mono-, di-, and trinucleosomes containing physiologically assembled full-length histone H1 or truncated mutants of this proteins. Single-base resolution •OH footprinting shows that the globular domain of histone H1 (GH1) interacts with the DNA minor groove located at the center of the nucleosome and contacts a 10-bp region of DNA localized symmetrically with respect to the nucleosomal dyad. In addition, GH1 interacts with and organize about one helical turn of DNA in each linker region of the nucleosome. We also find that a seven amino acid residue region (121–127) in the COOH terminus of histone H1 was required for the formation of the stem structure of the linker DNA. A molecular model on the basis of these data and coarse-grain DNA mechanics provides novel insights on how the different domains of H1 interact with the nucleosome and predicts a specific H1-mediated stem structure within linker DNA.
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pnas-107-21-9620.pdf (application/pdf, 2.4M)