Studies On The RNA Ligase From Deinococcus Radiodurans

Polynucleotide ligases are ubiquitous enzymes that are required for a great deal of important cellular processes that included the replication,repair and recombination of DNA,and the repair,splicing,and editing of RNA,by joining 3’OH and5’PO4 termini to form a phosphodiester. The bacterium Deinococcus radiodurans is one of the most powerful resistance to radiation. It is extremely resistant to ionizing radiation, UV radiation, hydrogen peroxide, and desiccation. Recent researches indicate Deinococcus radiodurans has efficient nucleotide repair mechanisms, but the study on RNA ligases articles rarely reported.The current published Deinococcus radiodurans genome encodes only one RNA ligase DR2339. We constructed the knockout mutant strain of targeted gene through recombinant-DNA technology and then investigated the mutant is homozygous and grow slowly. Furthermore, the RNA ligase mutant strain was sensitive to DNA-damaging agents, such as y radiation, UV radiation, and hydrogen peroxide.To better understand the stress resistance phenotype of the mutant strain, we studied the antioxidant activity of mutant strains. The results showed that ΔDR2339 mutant strains had a slight difference when compared with the wild-type strain R1. The mutant strain’s antioxidant activity was little lower than the wild-type strain Rl.With the RT-PCR technology, we found the gene transcription of some antioxidant gene in the mutant is also lower than the wild-type strain R1.It reflected the RNA ligase may play an important role in the nucleotide repair mechanism in Deinococcus radiodurans.Besides, the DR2339 protein was expressed by E. coli expression system and then purified in vitro.Above all, the study demonstrates that the RNA ligases involved in the resistance phenotype of Deinococcus radiodurans, but the accuracy mechanism is still required for study.