DddA homolog search and engineering expand sequence compatibility of mitochondrial base editing

In this study we discover a new dsDNA deaminase from Simiaoe sunii (Ddd_Ss) that show high activity and broad sequence compatibility. Based on this new dsDNA deaminase, we develop highly efficient base editing tools that introduce mutations at multiple mtDNA loci including disease-related mutations in previously inaccessible GC context. Finally, by introducing a single amino acid substitution from Ddd_Ss to Ddd_Bc, we successfully improve the activity and sequence compatibility of DdCBE_Bc.Our study expands mtDNA editing tool boxes and provides resources for further screening and engineering dsDNA base editors for biological and therapeutic applications.