Fig. 3

Strategies of non HDR-mediated precise genome-editing. a Cre/loxP system, consisting of Cre recombinase and loxP sites, facilitates DNA recombination through excision (removing a DNA segment between loxP sites in the same orientation), inversion (flipping a segment between loxP sites in opposite orientations), and translocation exchanging segments between two loxP sites in the same orientation on different DNA strands. b Base editing involves the introduction of C•G-to-T•A or C•G-to-G•C point mutations using cytosine base editors (CBEs), which employ Cas9 nickase or dCas9 fused to cytidine deaminase. Additionally, A•T-to-C•G point mutations can be reversed through adenine base editors (ABEs), utilizing a fusion of dCas9 or Cas9 nickase and evolved TadA* deoxyadenosine deaminase. c Prime editors comprise a Cas9 nickase domain fused to a reverse transcriptase domain. A prime editing guide RNA (pegRNA), engineered for specificity, directs the prime editor to its target on genomic DNA, including the desired edit within an extension. Following nicking the PAM-containing strand, the freed genomic DNA 3’ end engages in a primer–template complex with the pegRNA extension. Subsequently, the reverse transcriptase domain copies the template from the pegRNA extension into the genomic DNA directly, facilitating the addition of point mutations, small deletions, or small insertions at the target locus. d CAST combines Cas proteins with transposase-associated components. Transposase proteins (Tns) bind to transposon DNA, while Cas proteins are guided to the target locus in a PAM-dependent, RNA-directed manner. This localization facilitates transposon DNA integration at the target site, with each Cas-transposase complex having a specific guide RNA length and a preferred integration distance 3’ of the PAM. This figure was produced using BioRender.com