VUV-CD measurements of proteins relating to DNA repair

DNA修復に関わるタンパク質のVUV-CD測定

泉 雄大; 藤井 健太郎; 山本 悟史*; 松尾 光一*; 横谷 明徳

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

DNA wraps around core histone proteins composed of several subunits named as H2A, H2B, H3, and H4 in eukaryotic nuclei. It has been gradually recognized that chemical modifications of histones play important roles in DNA repair processes. Recently, we observed relative increment of -helix structure of H2A and H2B (H2A-H2B) induced by X-ray irradiation to human cells. In this work, we investigated structural alterations of H3 and H4 (H3-H4) extracted from X-irradiated cells using vacuum ultraviolet circular dichroism (VUV-CD) spectroscopy. The VUV-CD spectral shape of H3-H4 extracted from X-irradiated cells was different from that from unirradiated cells. Analyzing the CD spectra, we found that -helix structure component of H3-H4 relatively decreased by X-irradiation to cells. This is an opposite of structural change observed in H2A-H2B. The mechanism of histone structural alterations in response to X-ray irradiation has not been identified yet, but a possible mechanism could be via post-translational modifications which are known to occur in histones during DNA damage responses. Cyclopedic VUV-CD spectroscopy of specific modified-histones to understand the alteration mechanism and its contribution to DNA repair processes is warranted for future studies.