Adenine base editors (ABE) mediate A•T-to-G•C base changes (Figure 1), but it can be challenging to make these base changes, especially in primary human cells. Now, scientists at Beam Therapeutics have found a way to improve editing in primary human cells (Gaudelli et al., 2020).
One of the widely used base editing systems, ABE7.10 (and the starting point for a new generation of ABEs), consists of 3 components:
- a deaminase (TadA, originally from E.coli, named TadA7.10 in ABE7.10)
- a catalytically impaired Cas protein (dCas or Cas nickase)
- a guide RNA that targets the complex of TadA and dCas to the genomic DNA of interest