DNA damage response induces structural alterations in histone H3–H4

Synchrotron-radiation circular-dichroism spectroscopy was used to reveal that the DNA damage response induces a decrement of α-helix and an increment of β-strand contents of histone H3–H4 extracted from X-ray–irradiated human HeLa cells. The trend of the structural alteration was qualitatively opposite to that of our previously reported results for histone H2A–H2B. These results strongly suggest that histones share roles in DNA damage responses, particularly in DNA repair processes and chromatin remodeling, via a specific structural alteration of each histone.