Solution structure of variant H2A.Z.1 nucleosome investigated by small-angle X-ray and neutron scatterings

• Outer shape of H2A.Z.1 nucleosome is similar to that of canonical one.
• Histone octamer of H2A.Z.1 nucleosome is smaller than that of canonical one.
• The change of histone octamer might give H2A.Z.1 nucleosome dynamical properties.

Solution structures of nucleosomes containing a human histone variant, H2A.Z.1, were measured by small-angle X-ray and neutron scatterings (SAXS and SANS). SAXS revealed that the outer shape, reflecting the DNA shape, of the H2A.Z.1 nucleosome is almost the same as that of the canonical H2A nucleosome. In contrast, SANS employing a contrast variation technique revealed that the histone octamer of the H2A.Z.1 nucleosome is smaller than that of the canonical nucleosome. The DNA within the H2A.Z.1 nucleosome was more susceptible to micrococcal nuclease than that within the canonical nucleosome. These results suggested that the DNA is loosely wrapped around the histone core in the H2A.Z.1 nucleosome.