Ku binds to complex damaged double strand break DNA

Higuchi, Mariko; Pinak, M.

Double strand break (DSB) of DNA is repaired by non-homologous end joining (NHEJ). Repair DSB due to high-LET (linear energy transfer) iron-ion radiation takes longer time than that due to low-LET X rays. DNA damages due to high-LET iron-ion radiation are more condensed than that due to low-LET X rays. Such DSB with other lesions is called complex DSB. The question is why other lesions near DSB cause delay to repair DSB. The first step of NHEJ is considered binding of Ku70/80 to DSB. One reason of delay to repair complex DSB may be inhibition binding of Ku to complex DNA. The aim of this study is clarify if the complex DSB caused inhibition binding of Ku or not. In this study, we present result of molecular dynamics simulation of Ku and DNA including 8oxoG located on interaction region with Ku. The fluctuation of DNA including 8oxoG bound Ku was rather larger than that of native DNA bound Ku. But, binding structural entropy of DNA including 8oxoG was similar as that of native DNA.