Double-stranded DNA target of CRISPR-Cas12a (dsDNA (Cas12a target))

The target is a specific sequence of double-stranded DNA (dsDNA) within a host or viral genome that is recognized and cleaved by the CRISPR-Cas12a (formerly Cpf1) system. Unlike the Cas9 system which recognizes G-rich protospacer adjacent motifs (PAMs), Cas12a targets sequences adjacent to a T-rich PAM, typically 5'-TTTN-3' or 5'-TTTV-3' (Zetsche et al., 2015). Upon binding of a single CRISPR RNA (crRNA) to the complementary protospacer sequence, the Cas12a enzyme induces a staggered double-strand break with 4-5 nucleotide 5' overhangs. This site-specific cleavage is utilized in therapeutic gene editing to disrupt pathogenic genes or facilitate precise genomic corrections via cellular repair pathways like non-homologous end joining (NHEJ) or homology-directed repair (HDR). Clinical applications include the treatment of hematologic disorders, such as sickle cell disease and beta-thalassemia, by targeting regulatory elements like the HBG1/2 promoter (Editas Medicine, 2023). The specificity of the gRNA-DNA interaction and the presence of the T-rich PAM are the primary determinants of targeting efficiency and safety.

Other names

CRISPR-Cas12a target siteCpf1 target sequenceProtospacer (Cas12a)T-rich PAM-adjacent DNACas12a-programmed DNA target

RNA-guided site-specific staggered double-strand DNA cleavage followed by cellular DNA repair.