The nucleosome is the fundamental chromatin unit, containing two copies of histones H2A, H2B, H3, and H4 wrapped by ~ 146 bp of core DNA plus linker DNA; addition of linker histone H1 forms a chromatosome. Tetra-acetylation of the H4 N-terminal tail (H4-4Kac) enhances H3 N-tail acetylation by altering their mutual dynamics, but how H1 influences these dynamics remains unclear. Using cryo-electron microscopy and coarse-grained molecular dynamics simulations, we show that H4-4Kac and unmodified chromatosomes share essentially identical core histone–DNA structures and similar H3 N-tail dynamics. However, nuclear magnetic resonance spectroscopy reveals that in the H4-4Kac chromatosome, the H3 N-tail adopts a dynamically robust DNA-contact state distinct from that in the unmodified chromatosome, resulting in markedly reduced H3 N-tail acetylation. These findings suggest that linker histone H1 suppresses the progression of euchromatin formation.