Fig. 4

Structure and function of typical mtDNA editing tools. The general architecture of editing tools with programmable nucleases, including mitoREs, mitoARCUS, mtZFN, and mtTALEN (purple background). mitoREs were the first tools used for mtDNA editing, consisting of MTS and endonucleases. mitoARCUS utilizes a significantly modified and simplified I-CreI homing endonuclease. For mitoZFNs and mitoTALENs, the ZFN or TALE domains are utilized to guide the Fok1 restriction endonuclease to target particular gene sequences in mtDNA. mitoCRISPR comprises an sgRNA and a Cas9 endonuclease. The schematic structure of editing tools with base editors, including DdCBEs, TALEDs, and ZFDs (blue background). DdCBEs contain programmable TALE and UGI, enabling the first C–G to T–A conversion. TALEDs utilize adenine deaminase TadA8e and DddA, promoting the conversion of A–G bases in mtDNA. ZFDs consisting of the zinc finger DNA-binding protein DddA and UGI, catalyze C-to-T conversion. AD adenosine deaminase; DdCBEs DddA-derived cytosine base editors; mitoARCUS mitochondrial-targeted meganuclease; mitoCRISPR mitochondrial-targeted clustered regularly interspaced short palindromic repeats; mitoREs mitochondrial-targeted restriction endonucleases; mitoTALENs mitochondrial-targeted transcription activator-like effector nucleases; mitoZFNs mitochondrial-targeted zinc finger nucleases; mtDNA mitochondrial DNA; MTS mitochondrial targeting sequence; PAM protospacer-adjacent motif; sgRNA guide RNA; TALEDs TALE-linked deaminases; UGI uracil glycosylase inhibitor; ZFDs zinc finger deaminases; ZFP zinc finger proteins (Generated by the authors with Adobe Illustrator)