Explore the dominant factor in prime editing via a view of DNA processing.

Prime editing is a revolutionary gene-editing method that is capable of introducing insertions, deletions and base substitutions into the genome. However, the editing efficiency of Prime Editor (PE) is limited by the DNA repair process. Here, we show that overexpression of the flap structure-specific endonuclease 1 (FEN1) and the DNA ligase 1 (LIG1) increases the efficiency of prime editing, which is similar to the dominant negative mutL homolog 1 (MLH1dn). In addition, MLH1 is still the dominant factor over FEN1 and LIG1 in prime editing. Our results help to further understand the relationship of proteins involved in prime editing and envisage future directions for the development of PE.