(394h) A split and inducible adenine base editor for precise in vivo base editin

Hongzhi Zeng¹, Qichen Yuan^1†, Fei Peng^2†, Dacheng Ma^1†, Ananya Lingineni³, Kelly Chee⁴, Peretz Gilberd⁴, Emmanuel C. Osikpa¹, Zheng Sun^2,5*, and Xue Gao^1,3,6*

¹Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas 77005, USA

²Department of Medicine, Division of Diabetes, Endocrinology and Metabolism, Baylor College of Medicine, Houston, Texas 77030, USA

³Department of Bioengineering, Rice University, Houston, Texas 77005, USA

⁴Department of Biosciences, Rice University, Houston, Texas 77005, USA

⁵Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030, USA

⁶Department of Chemistry, Rice University, Houston, TX 77005, USA

†These authors contributed equally.

* To whom correspondence should be addressed: xue.gao@rice.edu (X.G.), zheng.sun@bcm.edu (Z.S.)

Abstract Text

DNA base editors use deaminases fused to a programmable DNA-binding protein for targeted nucleotide conversion. However, the most widely used TadA deaminases lack post-translational control in living cells. Here, we present a split adenine base editor (sABE) that utilizes chemically induced dimerization (CID) to control the catalytic activity of the deoxyadenosine deaminase TadA-8e. sABE shows high on-target editing activity comparable to the original ABE with TadA-8e (ABE8e) upon rapamycin induction while maintaining low background activity without induction. Importantly, sABE exhibits a narrower activity window on DNA and higher precision than ABE8e, with an improved single-to-double ratio of adenine editing and reduced genomic and transcriptomic off-target effects. sABE can achieve gene knockout through multiplex splice donor disruption in human cells. Furthermore, when delivered via dual adeno-associated virus vectors, sABE can efficiently convert a single A•T base pair to a G•C base pair on the PCSK9 gene in mouse liver, demonstrating the first in vivo CID-controlled DNA base editing. Thus, sABE enables precise control of base editing, which will have broad implications for basic research and in vivo therapeutic applications.

Keywords

chemically induced dimerization | adenine base editor | gene therapy | protein engineering | inducible gene editing