...nickase or catalytically inactive “dead” Cas9 (dCas9) to a cytidine deaminase like APOBEC. Base editors...target sequence present in the gRNA. CRISPR was originally employed to knock out target genes in various... gRNA binding that shifts the molecule from an inactive, non-DNA binding conformation into an active DNA-binding... that increase Cas9 proofreading and target discrimination. All three high fidelity enzymes generate less...resulting population of cells will contain some combination of wild type alleles, NHEJ-repaired alleles, ...creating an A to G (or T to C) change. Adenine DNA deaminases do not exist in nature, but have been created... of the Escherichia coli TadA, a tRNA adenine deaminase. Like cytosine base editors, the evolved TadA...