The N-terminal and C-terminal halves of histone H2A.Z independently function in nucleosome positioning and stability.

Nucleosome positioning and stability affect gene regulation in eukaryotic chromatin. Histone H2A.Z is an evolutionally conserved histone variant that forms mobile and unstable nucleosomes in vivo and in vitro. In the present study, we reconstituted nucleosomes containing human H2A.Z.1 mutants, in which the N-terminal or C-terminal half of H2A.Z.1 was replaced by the corresponding canonical H2A region. We found that the N-terminal portion of H2A.Z.1 is involved in flexible nucleosome positioning, whereas the C-terminal portion leads to weak H2A.Z.1-H2B association in the nucleosome. These results indicate that the N-terminal and C-terminal portions are independently responsible for the H2A.Z.1 nucleosome characteristics.