Specific genomic double-stranded DNA sequence containing the Cas12n protospacer and PAM (Cas12n target DNA)

The specific genomic double-stranded DNA sequence containing the Cas12n protospacer and PAM is the primary molecular target for Cas12n-mediated genome engineering. Cas12n, a compact Type V-N CRISPR effector often derived from TnpB proteins, is an RNA-guided endonuclease that identifies its target through Watson-Crick base pairing between a guide RNA and the protospacer sequence (Karvelis et al., 2021, Nature). This recognition is strictly dependent on the presence of a Protospacer Adjacent Motif (PAM), which allows the Cas12n protein to destabilize the DNA duplex and initiate strand invasion (Meers et al., 2023, Molecular Cell). In therapeutic applications, this DNA target is utilized to induce site-specific double-strand breaks, enabling gene disruption via non-homologous end joining or gene correction via homology-directed repair (Wu et al., 2022, Nature Communications). Because Cas12n is significantly smaller than Cas9 or Cas12a, it is particularly well-suited for viral delivery in treating genetic disorders and infectious diseases. However, the potential for off-target activity at genomic sites with sequence similarity to the protospacer remains a critical safety concern in the clinical development of these therapies (Zuo et al., 2020, Science).

Other names

ProtospacerPAM-containing DNA sequenceCRISPR-Cas12n target siteGenomic target locusTnpB target sequenceType V-N CRISPR target

Site-specific DNA cleavage or modification guided by RNA-DNA hybridization and Protospacer Adjacent Motif (PAM) recognition