CRISPR-Cas genome editing tools
(A) Cas9-sgRNA complexes bind to DNA targets in the genome, generating DSBs 3 bp upstream of the PAM. (B) Cytosine base editors (CBEs), composed of cytidine deaminase fused to nCas9 (D10A) and UGI, enable direct conversion of targeted C:G base pairs to T:A base pairs. (C) Adenine base editors (ABEs), which consist of adenine deaminase fused to nCas9 (D10A), convert targeted A:T base pairs to G:C base pairs. (D) Prime editors consist of nCas9 (H840A) fused to an engineered Moloney murine leukemia virus reverse transcriptase domain. These editors can generate any desired sequence contained in the associated prime editing guide RNA (pegRNA).