AP endonucleases are required for DNA demethylation in Arabidopsis

AP endonuclease;APE1L;APE2;ARP;DNA demethylation;Arabidopsis;DNA repair;Base excision repair;AP site;complementation test;albino

농업생명과학대학 식물생산과학부(작물생명과학전공) ;

University:서울대학교 대학원

关键词: AP endonuclease;    APE1L;    APE2;    ARP;    DNA demethylation;    Arabidopsis;    DNA repair;    Base excision repair;    AP site;    complementation test;    albino;   

Others  :  http://s-space.snu.ac.kr/bitstream/10371/125627/1/000000008682.pdf

美国|英语

来源: Seoul National University Open Repository

【 摘 要 】

The base excision repair (BER) pathway plays a primary role in removing damaged or mismatched bases from DNA. The BER pathway is important for DNA repair, and notably, also for active DNA demethylation in plants and animals. The BER pathway consists of sequential enzymatic steps and is initiated with excision of abnormal bases by DNA glycosylases. Apurinic/apyrimidinic (AP) endonucleases then take part in to remove 3’ blocking ends which are created during the course of base excision. For DNA demethylation, DEMETER (DME) family DNA glycosylases specifically recognize and excise 5-methylcytosine (5mC), leaving the β/δ-elimination intermediates that need to be removed by AP endonucleases providing 3’-OH for subsequent base incorporation. There exist three putative AP endonucleases APE1L, APE2 and ARP in the Arabidopsis genome. We cloned and purified the three AP endonucleases and tested for their biochemical activity. We demonstrated that both APE1L and ARP were capable of hydrolyzing AP sites after 5mC excision. We also verified that both APE1L and ARP were able to replace the endogenous AP endonuclease activity in E. coli, efficiently processing potentially harmful lesion that resulted from 5mC excision. These findings indicate that AP endonucleases play an essential role at the downstream of 5mC excision to complete DNA demethylation via the BER pathway.