DNA damage in radiation-resistant prokaryotes from evolutionary perspectives

Sghaier, H.; Oba, Hirofumi; Sato, Katsuya; Mitomo, Hiroshi*; Narumi, Issei

The order in which DNA of radiation-resistant prokaryotes has been subjected to constant damage through radiation, elevated temperature, dry, or reactive oxygen species during Earth evolution is important to investigate for a better understanding of environment-genome evolutionary relationship. In analyzing model genomes of radioresistant prokaryotes ( and ), this study assesses the evolutionary itinerary of rough-and-tumble route on which their DNA was assaulted. Together with the examined literature, our analyses suggest the following elements. (1) Based on statistics of ORFs (Open Reading Frames) similarity relationships, we support the hypothesis that radiation resistance is a unique molecular reflection of the early Earth resilience and desiccation tolerance is a mark of cells that colonized land during the Archaean epoch. (2) Using unconventional methods, including oligonucleotide frequencies, numerous compelling data evoke the hypothesis that and progenitor(s) adapted, at least once, to the same environmental pressure, most probably ionizing radiation, through the acquisition of foreign genetic elements from one abnegator or compositionally similar abnegators. In conclusion, we present a model that satisfactorily accounts, from evolutionary perspectives, for DNA damage in radiation-resistant prokaryotes.