Improving adenine and dual base editors through introduction of TadA-8e and Rad51DBD.

Base editors, including dual base editors, are innovative techniques for efficient base conversions in genomic DNA. However, the low efficiency of A-to-G base conversion at positions proximal to the protospacer adjacent motif (PAM) and the A/C simultaneous conversion of the dual base editor hinder their broad applications. In this study, through fusion of ABE8e with Rad51 DNA-binding domain, we generate a hyperactive ABE (hyABE) which offers improved A-to-G editing efficiency at the region (A 10 -A 15 ) proximal to the PAM, with 1.2- to 7-fold improvement compared to ABE8e. Similarly, we develop optimized dual base editors (eA&C-BEmax and hyA&C-BEmax) with markedly improved simultaneous A/C conversion efficiency (1.2-fold and 1.5-fold improvement, respectively) compared to A&C-BEmax in human cells. Moreover, these optimized base editors catalyze efficiently nucleotide conversions in zebrafish embryos to mirror human syndrome or in human cells to potentially treat genetic diseases, indicating their great potential in broad applications for disease modeling and gene therapy.