期刊
DNA REPAIR
卷 85, 期 -, 页码 -出版社
ELSEVIER
DOI: 10.1016/j.dnarep.2019.102734
关键词
Archaea; NucS endonuclease; Deamination; DNA repair
资金
- Provincial Natural Science Foundation of Jiangsu [BK20191219]
- Academic Leader of Middle and Young People of Yangzhou University Grant
- State Key Laboratory of Microbial Metabolism, Shanghai JiaoTong University [MMLKF18-05]
- Practice Innovation Training Program for Postgraduate Students in Yangzhou University [XICYCX18072]
Recent studies show that NucS endonucleases participate in mismatch repair in several archaea and bacteria. However, the function of archaeal NucS endonucleases has not been completely clarified. Here, we describe a NucS endonuclease from the hyperthermophilic and radioresistant archaeon Thermococcus garnmatolerans (Tga NucS) that can cleave uracil (U)- and hypoxanthine (I) -containing dsDNA at 80 degrees C. Biochemical evidence shows that the cleavage sites of the enzyme are at the second phosphodiester on the 5'- site of U or I, and at the third phosphodiester on the 5'-site of the opposite base of U or I, creating a double strand break with a 4-nt 5'-overhang. The ends of the cleaved product of Tga NucS are ligatable, possessing 5'-phosphate and 3'-hydroxyl termini, which can be utilized by DNA repair proteins or enzymes. Tga NucS displays a preference for U/G- and I/T-containing dsDNA over other pairs with U or I, suggesting that the enzyme is responsible for repair of U and I in DNA that arise from deamination. Biochemical characterization of cleaving U- and I-containing DNA by Tga NucS was also investigated. The DNA-binding results show that the enzyme exhibits a higher affinity for normal, U- and I-containing dsDNA than for normal, U- and I-containing ssDNA. Therefore, we present an alternative pathway for repair of deaminated bases in DNA triggered by archaeal NucS endonuclease in hyperthermophilic archaea.
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