Distinct Structures and Dynamics of Chromatosomes with Different Human Linker Histone Isoforms

By Bing-Rui Zhou, H. Feng, Seyit Kale, T. Fox, H. Khant, Natalia de Val, R. Ghirlando, Anna R. Panchenko, Yawen Bai. 2020

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SUMMARY The repeating structural unit of metazoan chromatin is the chromatosome, a nucleosome bound to a linker histone, H1. There are 11 human H1 isoforms with diverse cellular functions, but how they interact with the nucleosome remains elusive. Here, we determined the cryoelectron microscopy (cryo-EM) structures of chromatosomes containing 197 bp DNA and three different human H1 isoforms, respectively. The globular domains of all three H1 isoforms bound to the nucleosome dyad. However, the flanking/linker DNAs displayed substantial distinct dynamic conformations. Nuclear magnetic resonance (NMR) and H1 tail-swapping cryo-EM experiments revealed that the C-terminal tails of the H1 isoforms mainly controlled the flanking DNA orientations. We also observed partial ordering of the core histone H2A C- and H3 N-tails in the chromatosomes. Our results provide insights into the structures and dynamics of the chromatosomes and have implications for the structure and function of chromatin.

Subfields: Materials Chemistry, Molecular Biology