Increase base editing efficiency and product variety through fusion of Cas9 nickase to cytosine and adenosine deaminases

Base editors, which are created through fusion of Cas9 nickase to either cytidine or adenine deaminase, efficiently catalyze site-specific nucleotide conversions with minimal indel rates[1, 2] (Ref). However, cytidine base editor (CBE) or adenine base editor (ABE) is able to only generate base conversion on single nucleotide type which limits the product multiplicity. Here we show that through fusion of cytidine and adenine deaminases with Cas9n, a novel cytidine-adenine base editor (ACBE) was developed. ACBE is able to generate C>T and A>G conversions in the same allele.