The targeting construct contains from 5' to 3' a CAGG promoter, FRT site, loxP-stop-loxP, a human optimized Cas9 with the H840A mutation fused to a MMLV-RT (Moloney murine leukemia virus reverse transcriptase, GAG-POL), P2A peptide, an mNeonGreen reporter, WPRE, polyA signal, and a PGK-FRT3-NeoR-polyA. The cre-inducible cas9*/ GAG-POL fusion construct is referred to as the primer editor enzyme (PE2). The PE2 enzyme complexes with prime editing guide RNAs that can encode a mutation of interest within a reverse transcriptase template. (J:335562)