AcrIIA5 unexpectedly improved efficiency while reducing byproduct indels in tested genome-editing settings.
Evidence
Cell-based prime editing experiments showed up to 8.2-fold higher activity across PE2, PE3, PE4, PE5, PE6, multiple edit types, and endogenous loci, with fewer indels.
Caveat
The abstract describes mechanistic and locus-spanning editing tests, but not therapeutic delivery, organism-level editing, or long-term safety.
Simplified
(PE) enables the precise installation of intended base substitutions, small deletions or small insertions into the genome of living cells. While the use of Cas9 nickase can avoid DNA double-strand breaks (DSB), undesired insertions and deletions (indels) often accompany the correct edits, particularly when PE activity increased. Here we show that the (Acr) protein AcrIIA5 can significantly enhance PE activity by up to 8.2-fold while markedly reducing byproduct indels. Further investigation reveals that AcrIIA5 can promote PE across various approaches (PE2, PE3, PE4, PE5, and PE6), edit types (substitutions, insertions and deletions), and endogenous loci. Mechanistically, AcrIIA5 appears to inhibit the re-nicking activity of PE complex rather than enhancing the core editing machinery itself, suggesting a distinct mode of interaction with Cas9. Overall, we demonstrate that a known "inhibitor" Acr protein can unexpectedly acting as an "enhancer" of CRISPR/Cas-based genome editing, providing an effective strategy to optimize PE specificity and activity.
Key numbers
8.2×
Increase in Efficiency
enhances activity for base substitutions.
4.5×
Reduction in
reduces undesired in systems.
Full Text
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CRISPR Gene Editing