Host: The Japan Radiation Research Society
Co-host: Asian Association for Radiation Research
7,8-dihydro-8-oxoguanine (8-oxoG) is the most important product of oxidative base damage in DNA, and causes G:C to T:A transversions in bacteria and mammalian cells. 8-oxoG is repaired by MutM in E. coli and 8-oxoG-DNA glycosylase (Ogg1) in yeast and mammalian cells. In the present study, we identified and characterized an ascidian homolog of the human hOgg1 in Ciona intestinalis (CiOgg1). Introduction of the CiOgg1 gene significantly reduced the frequency of spontaneous G:C to T:A transversions in E.coli mutM mutY strain. purified GST-CiOgg1 fusion protein had 8-oxoG DNA glycosylase/AP lyase activity. It formed Schiff base intermediates with 8-oxoG-containing duplex oligonucleotides and removed 8-oxoG preferentially from 8-oxoG/C. The CiOgg1 cleaved 8-oxoG-containing duplex DNA via β-elimination reaction. Furthermore, the expression level of CiOgg1 was compared in various tissues in Ciona intestinalis. The highest expression level was observed in testis.
