Structural And Functional Analysis Of CPDase In Deinococcus Radiodurans

Deinococcus radiodurans can survive high doses of radiation,which is about 200-fold higher than other bacteria without loss of viability.Recent researches revealed that D.radiodurans has a high-efficiency DNA repair system.However,the detailed process of RNA metabolism mediated by CPDase is unclear.The homologues of 2?,3?-cyclic phosphodiesterase?CPDase?exist in almost all organisms from bacteria to mammals and could possibly play a role in RNA and nucleotide metabolisms.D.radiodurans contains one gene?dr CPDase?encoding a2?,3?-cyclic phosphodiesterase.?dr CPDase was successfully constructed and exhibited slow growth rate under normal condition.?dr CPDase displayed increased sensitivities to high doses of various DNA-damaging agents including?-ray,MMC,UV and H₂O₂.The transcriptional level of dr CPDase increased under oxidative stress.Additional nucleotide monophosphate partially recovered the phenotype of dr CPDase knockout cells.In addition,we have determined the crystal structure of the CPDase homologue from D.radiodurans at 1.6?resolution.The structure delineates an open active site for substrate binding with a conserved catalytic mechanism.In summary,dr CPDase contributes to the extreme resistance of D.radiodurans and is presumably involved in damaged nucleotide detoxification.These results will aid in future biochemical analyses of CPDase as well as other members of the 2H phosphoesterase superfamily.