Cooperation of PprI and DrRRA in response to extreme ionizing radiation in Deinococcus radiodurans

Deinococcus radiodurans possesses extreme resistance to ionizing radiation, and has been engineered for the remediation of toxic components in radioactive environments. We have previously shown that PprI (also named IrrE) and DrRRA are essential for the DNA protection and repair pathways that respond to ionizing radiation stress in this species. Here, we investigated the combined roles of PprI and DrRRA in resistance to gamma radiation (800 Gy). The double mutant, Delta drRRA Delta pprI, was more sensitive to gamma rays than either Delta drRRA or Delta pprI single mutants, and exhibited an elevated level of intracellular protein carbonylation, an extended delay in genome reconstitution and reduced transcriptional levels of certain DNA protection and repair proteins, such as kat, sod, recA and pprA. Interestingly, the induction of DrRRA by ionizing radiation was partially inhibited by the deletion of pprI. Taken together, these results suggest that DrRRA and PprI might have collaborative roles in the response of D. radiodurans to extreme ionizing radiation.