Screening And Verification Of NcRNAs Related To Radioresistance In Deinococcus Radiodurans And Their Function Analysis

Deinococcus radiodurans is one of the most radioresistant organsisms, which was believed to have special protection from ionizing radiation and ultraviolet radiation, but later more serious damage can be made by higher dosage of ionizing radiation, and making the whole genome break into 150-200 DNA fragment, 3000 single strand fragments and 1000 damage site. It can be assumbed that Deinococcus radiodurans possessed no the ability of special radiation protection, while the super-high radioresistance may be due to high precise DNA-repairing ability. Therefore, more research on its radioresistance was mainly focusing on its DNA-repairing mechanism. Recently, more and more noncoding RNAs (ncRNAs) have been found in prokaryotic organism. Furthermore, ncRNAs are playing vital regulation role in both prokaryotic and eukaryotic organism. However no documents on the relationship between ncRNA and radioresistance of Deinococcus radiodurans are avavilable.In the present study, 7 canditate ncRNAs selected from predicted ncRNA by bioinformatic software were experimently confirmed by RT-PCR and sequencing verification, and 4 of them performed well. It is composed of 3 ribosiwitch, which had been deposited in Rfam database, and one DicF, which was first discoved in E. coli but not reported in Deinococcus radiodurans. To verify them, Northern blot was conducted and resulted in hybridization signal near the positive control, demonstrating that DicF may be expressed in Deinococcus radiodurans.To learn more about the function of these ncRNAs, Deinococcus radiodurans was treated byγradiation and continued to be cultured under the normal condition. During the course of its DNA repairing, every half an hour sampled once, and differential expression of these ncRNAs were deteced by real time PCR. The results showed FMN riboswitch and SAM riboswitch both have a trend of over-expressed first and low-expressed then, but the detail of change is different. TPP riboswitch showed low-expressed all the time, and its expression is increasing slowly in the first 1.5 h. Due to the limitation of sample amount of irradiated Deinococcus radiodurans, the expression of DicF was measured at 0 h, 1 h, 2 h, and 3 h after treatment, while other ncRNAs was measured at 0 h, 0.5 h, 1 h, 1.5 h, 2 h, 2.5 h and 3 h. The results showed DicF is over-expressed in the first 2 h, and it's expression is lower than that of the control group afterwards. It can be assumbed that DicF inhibit cell division in Deinococcus radiodurans as in Escherichia coli.