Fig. 1

Genome editing using a structure-guided endonuclease (SGN). SGN-mediated genome editing has two components: a SGN consisting of the FEN-1 enzyme fused with the Fok1 endonuclease and two 20–60-nucleotide target sequences with single, 3′ unpaired bases (3′ Flap). The two guides bind to the complementary sequences and the FEN-1 component of SGN recognizes the 3′ flap structure and guides the Fok1 dimer into position to generate a double-stranded cut, which then repairs by non-homologous end joining after what appears to be an expansion of the deleted region by a currently unknown mechanism