Targeted directional kilobase sequence insertion by combining prime editing with recombinases or integrases

Targeted insertion of exogenous sequences to genomes is useful for therapeutics and biological research. While CRISPR/Cas technologies have been very efficient in gene knockouts by double-strand breaks (DSBs) followed by indel formation through non-homologous end-joining (NHEJ) repair pathway, the precise introduction of new sequences mainly rely on inefficient homology directed repair (HDR) pathways following Cas9-induced DSBs and are restricted to dividing cells. The recent invention of Prime Editing allows short sequences to be precisely inserted at target sites without DSBs. Here, we combine Prime Editing and sequence-specific recombinases and integrases to insert kilobase sequences directionally at target sites. This technique, called PRIMAS for Prime editing, Recombinase, Integrase-mediated Addition of Sequence, will expand our genome editing toolbox for targeted insertion of long sequences up to kilobases and beyond.