POLB-mediated DNA strand displacement synthesis

DNA polymerase beta (POLB) catalyzes DNA strand displacement synthesis. In this process, 2-10 nucleotides (dNMPs) are incorporated at the 3' end of the single strand break (SSB). Simultaneously, the other broken DNA strand, which contains a 5' oxidatively-damaged AP dideoxyribose phosphate residue (5'ddRP), is displaced as a flap structure. POLB-mediated DNA strand displacement synthesis is facilitated by PARP1 and/or PARP2 dimers, which bind the single strand DNA (ssDNA) ends and FEN1 (flap endonuclease) (Klungland and Lindahl 1997, Prasad et al. 2001, Lavrik et al. 2001, Liu et al. 2005).

DNA多聚酶β（POLB）催化DNA链置换合成。在此过程中，2-10个核苷酸（dNMPs）被纳入单链断裂（SSB）的3'端。同时，另一断裂的DNA链，其中包含5'氧化损伤的AP二脱氧核糖磷酸残基（5'ddRP），作为翘片结构被置换。由POLB介导的DNA链置换合成得到PARP1和/或PARP2二聚体的促进，这些二聚体与单链DNA（ssDNA）末端和FEN1（翘片末端核酸酶）结合（Klungland和Lindahl 1997，Prasad等人2001，Lavrik等人2001，Liu等人2005）。