Analyses on interactions of DNA with the novel DNA repairing protein of PprA derived from Deinococcus radiodurans

Adachi, Motoyasu; Tamada, Taro; Sato, Katsuya; Yura, Kei; Narumi, Issei; Kuroki, Ryota

Deinococcus radiodurans exhibits 1000 times higher radiation resistance than human cells. PprA is cloned from the bacteria and the novel DNA repair protein that plays an important role in the resistance. This study is aimed to reveal the structure function relationship of PprA. The recombinant PprA protein was purified from E. coli. The interactions of PprA with DNA were analyzed by gel shift assay and gel filtration. The results showed that (1) at least 280 molecules of PprA can bound to a DNA molecule of pUC19 composed of 2686bp (2) the formation the complex of PprA and DNA depends on Mg, Ca and Sr ions at low concentration (3) the formation the complex of PprA and DNA depends on the concentration of the salt at the range of 0 to 0.4M sodium acetate. In addition, the result indicated that the complexes of PprA and DNA can form larger complex depending on the concentration of PprA molecule, when using linear double stranded DNA. This suggests that PprA may locate two terminals of a DNA molecule damaged by radiation at near distance for DNA repairing.