Prime editing genomic target site (PE target)

The genomic DNA sequence complementary to the prime editing guide RNA (pegRNA) components—specifically the spacer, primer binding site (PBS), and reverse transcriptase (RT) template—serves as the precise physical site for prime editing [1]. Prime editing is a 'search-and-replace' genome editing technology that employs a fusion protein consisting of a catalytically impaired Cas9 nickase and a reverse transcriptase, guided by a pegRNA [2]. The spacer sequence directs the Cas9 nickase to the target DNA, while the PBS hybridizes to the nicked DNA strand to initiate reverse transcription using the RT template as a blueprint for the desired genetic change [1]. This target is not a single protein but rather any specific genomic locus harboring a mutation or requiring modification for therapeutic purposes [3]. By targeting these sequences, prime editors can install point mutations, insertions, or deletions without requiring double-strand breaks or exogenous donor DNA templates [2]. This approach is being investigated for treating a wide range of genetic disorders, including sickle cell disease and cystic fibrosis, by directly correcting pathogenic sequences in the human genome [1][2]. Safety concerns primarily involve off-target editing at similar genomic sequences and the potential for unintended insertions or deletions at the target site [3]. (Sources: [1] Anzalone et al., Nature 2019; [2] Chen & Liu, Nature Reviews Genetics 2023; [3] Kantor et al., Molecular Therapy 2020).

Other names

pegRNA target sequencePrime editing sitePBS/RTT complementary DNAGenomic DNA target for prime editing

The target DNA is recognized by the pegRNA spacer, nicked by the Cas9 H840A domain, and then serves as a primer for reverse transcription of the encoded edit using the RT template.