Prime editing guide RNA 3′ polyuridylated tail (pegRNA 3′ poly(U) tail)

The Prime editing guide RNA (pegRNA) 3′ polyuridylated tail is a sequence of uridine residues typically added to the 3′ end of a pegRNA during its synthesis via RNA polymerase III transcription (Anzalone et al., 2019). This tail is a consequence of the transcription termination signal in the DNA template, which consists of a string of thymines. In the context of genome engineering, this poly(U) tail is significant because it renders the pegRNA susceptible to degradation by cellular exonucleases, thereby limiting the duration and efficiency of the prime editing process (Nelson et al., 2022). To overcome this limitation, researchers often engineer the 3′ end of the pegRNA with structural motifs, such as the evopreQ1 or tevopreQ1 RNA pseudoknots, which mask or replace the poly(U) tail to enhance RNA stability (Nelson et al., 2022). These modifications prevent the recognition of the 3' end by degradation machinery, leading to significantly higher editing yields across various cell types. Understanding and modifying this tail is a crucial aspect of optimizing prime editing for therapeutic applications, particularly in the treatment of genetic disorders where high efficiency and precision are required.

Other names

pegRNA 3′ poly(U) sequence3′ poly-U tailpegRNA 3′ uridine tail3′ polyuridylated extension

The 3′ polyuridylated tail acts as a degradation signal that recruits endogenous exonucleases, leading to the rapid turnover of the pegRNA and reducing the time available for the prime editor complex to perform genome modifications (Nelson et al., 2022).