VUV-CD measurements of modified histone proteins

Izumi, Yudai; Matsuo, Koichi*; Fujii, Kentaro; Yokoya, Akinari

The conformational change in the chromatin architecture induced by the phosphorylation plays an important role in the DNA damage responses, such as recruiting DNA repair protein machineries to the damaged sites. In an attempt to study conformational change of histone dimer induced by DNA damage, we measured vacuum ultraviolet circular dichroism (VUV-CD) spectra of histone dimer extracted from X-irradiated cells. An apparent spectral difference was observed below 205 nm. The CD intensity of irradiated sample was shifted toward negative side compared with that of unirradiated sample. Comparing with standard VUV-CD spectra of protein secondary structures, namely -helix, -strand, turn, and unordered structure, it is expected that unordered structure relatively increased in this condition. This result shows that the conformational change of histone dimer is induced by X-ray irradiation.