A motif preferred adenine base editor with minimal bystander and off-targets editing

Abstract

48% of hereditary disease are caused by single C-to-T base conversion, which makes efficient A-to-G base editing tools (ABEs) have great potential in the treatment of these diseases. However, the existing efficient ABE, while catalyzing A-to-G conversion, will bring more A and C bystander editing and off-target events, which poses safety concerns for their clinical application. Here, we developed ABE10 (ABE8e with TadA-8e A48E) for efficient and accurate editing of As in YA motifs with YAY>YAR (Y=T or C, R=A or G) hierarchy through structure-oriented rational design. Compared with ABE3.1, currently the only motif (YAC) preference ABE version, ABE10 exhibited A-to-G editing efficiency improvement with an average up to 3.1-fold in indicated YA motif while maintaining reduced bystander Cs editing and minimized DNA or RNA off-targets. Also, we showed ABE10 corrected pathogenic mutation with high efficiency and precision in human cells. Moreover, by ABE10, we efficiently and precisely generated hypocholes-terolemia and tail-loss mouse models mimicking human associated disease and mouse PCSK9 base editing in vivo for hypercholesterolemia gene therapy, indicating their great potential in broad applications for and disease modeling and gene therapy.