Part:BBa_K4830017

Ll.ltrA RT

Ll.ltrA RT group II intron reverse transcriptase

Usage and Biology

Prime editing is an innovative technology for genome editing that enables the installation of the wide spectrum of gene modifications such as 12 possible base-to-base conversions, small insertions, and deletions, without requiring double-stranded breaks or donor DNA templates. This technology provides high versatility and target specificity, offering the potential to revolutionize medicine by providing novel tools for treating genetic diseases. Prime editing relies on specialized prime editors, which usually consist of reverse transcriptase enzyme fused to nickase Cas9, and prime editing guide RNA containing a spacer that specifies the target site. It also includes a scaffold and 3’ extension containing a primer binding site (PBS) and an RT template encoding the desired edit.

To initiate prime editing, PE creates a single-strand break in the DNA at the target site to allow reverse transcriptase to access the DNA and synthesize a new DNA strand using pegRNA as a template. Then the information from the edited strand is copied to the complementary strand through the cell’s natural repair pathways.

Reverse transcriptases (RTs) are RNA-dependent DNA polymerases isolated from retroviruses, used to generate complementary DNA (cDNA) from an RNA template in process of reverse transcription.

Ll.ltrA reverse transcriptase is one of proteins found in The Lactococcus lactis Ll.LtrB intron, that binds the intron RNA to promote RNA splicing and intron mobility.

Characterization

Reverse Trancriptase fused to nickase Cas9 BBa K4830014, in plasmid form was co-transfected with pegRNA and ngRNA targeting endogeneous genomic loci on HEK293T cells and the editing efficiency was estimated after sanger sequencing. Figure 1 shows the editing efficiency of Ll.ltrA RT along with other the alternative RTs on HEK3 target site.

Fig. 1 Screening of RT variants for prime editing activity at HEK3 target site. Bar graphs show the mean value and error bars indicate S.D. of n = 3, independent biological replicates.

Sequence and Features

Assembly Compatibility:

• 10
  COMPATIBLE WITH RFC[10]
• 12
  COMPATIBLE WITH RFC[12]
• 21
  COMPATIBLE WITH RFC[21]
• 23
  COMPATIBLE WITH RFC[23]
• 25
  COMPATIBLE WITH RFC[25]
• 1000
  COMPATIBLE WITH RFC[1000]