CRISPR-associated protein 9-reverse transcriptase fusion protein (PE)

The CRISPR-associated protein 9-reverse transcriptase (nCas9-RT) complex, commonly known as a Prime Editor (PE), is an engineered genome-editing tool that enables precise "search-and-replace" modifications of the human genome. It consists of a catalytically impaired Cas9 nickase (nCas9) fused to an engineered reverse transcriptase (RT) enzyme, typically derived from the Moloney Murine Leukemia Virus (M-MLV). Unlike traditional CRISPR-Cas9 which creates double-strand breaks, the PE complex uses a prime editing guide RNA (pegRNA) to specify the target site and template the desired genetic edit, which the RT then polymerizes directly into the DNA. This technology is capable of installing all twelve types of point mutations, as well as small insertions and deletions, with high precision and minimal off-target effects. It is currently being developed as a one-time curative therapy for a wide range of genetic disorders, including chronic granulomatous disease (CGD) and Wilson's disease. The complex's large size presents delivery challenges, often requiring advanced lipid nanoparticle (LNP) or viral vector strategies for therapeutic application.

Other names

Prime editornCas9-RTnCas9-M-MLV RT fusionSearch-and-replace genome editorPE2PE3PEmax

Search-and-replace genome editing: the nCas9 domain nicks the target DNA strand, while the pegRNA hybridizes to the nicked site and provides a template for the reverse transcriptase domain to synthesize and incorporate the desired genetic edit directly into the genome.