Advances in mitochondrial DNA base editing technology

Mitochondria, the energy factories of higher eukaryotes, provide energy (ATP) for life activities through aerobic respiration. They possess their own genome, mitochondrial DNA (mtDNA), which encodes 37 genes. Mutations in mtDNA cause mitochondrial diseases, and more than 100 pathogenic mutations have been identified in human mtDNA, with a total incidence rate of about 1/5000. In recent years, advances in CRISPR-based base editing technology have enabled accurate editing of nuclear genes. However, it remains a challenge to achieve precise base editing on mtDNA due to the difficulty of guide RNA in the CRISPR system passing through the mitochondrial double-membrane. In 2020, David R. Liu's group at Harvard University reported a double-stranded DNA deaminase DddA from Burkholderia cenocepacia, which was fused with the programmable transcription activator-like effector (TALE) and uracil glycosylase inhibitor (UGI) to develop DddA-derived cytosine base editors (DdCBEs). Using DdCBEs, they were able to achieve specific and efficient C?G to T?A conversion on mtDNA for the first time. In this review, we summarize the recent progress of mitochondrial base editing technology based on DddA and prospect its future application prospects. The information presented may facilitate interested researchers to grasp the principles of mitochondrial base editing, to use relevant base editors in their own studies, or to optimize mitochondrial base editors in the future.