A methodology for estimating localization of apurinic (AP) sites in DNA and its application to DNA exposed to ionizing radiations

Akamatsu, Ken; Shikazono, Naoya

It is well-known that DNA lesions induced by ionizing radiation and chemicals can cause mutation and carcinogenesis. In particular, "clustered damage" site, that is a DNA region with multiple lesions within a few helical turns, is believed to hardly be repaired. However, chemical and spatial details of them are not known. We have developed a methodology for estimating localization of AP sites using fluorescence resonance energy transfer (FRET). We have recently found that experimentally-obtained FRET efficiencies for the heat-treated AP-DNA correspond to theoretical ones calculated on the basis of exponential distribution (a Poisson process). Now we are applying the FRET methodology to a plasmid irradiated with radiations such as Co -rays, He, and C ion beam. The results and the prospective will be discussed.