Fusion of a rice endogenous N-methylpurine DNA glycosylase to a plant adenine base transition editor ABE8e enables A-to-K base editing in rice plants

This study is led by Professor Lanqin Xia (Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China). The authors isolated a rice endogenous hypoxanthine excision protein N-methylpurine DNA glycosylase (OsMPG) and engineered two plant A-to-K (K=G or T) base editors, rAKBE01 and rAKBE02, for simultaneous adenine transition and transversion base editing in rice by fusing OsMPG or its mutant mOsMPG to a plant adenine transition base editor ABE8e. Furthermore，by coupling either OsMPG or mOsMPG with a transactivation factor VP64 to generate rAKBE03 and rAKBE04, respectively. Testing these four rAKBEs at five endogenous loci in rice protoplasts indicated that rAKBE03 and rAKBE04 enabled higher levels of A-to-G base transitions in compared to ABE8e and ABE8e-VP64. Furthermore, whereas rAKBE01 only enabled A-to-C/T editing at one endogenous locus, in comparison with rAKBE02 and rAKBE03, rAKBE04 could significantly improve the A-to-C/T base transversion efficiencies by up to 6.57- and 1.75-folds in the rice protoplasts, respectively. Moreover, because MPGs are involved in base excision repair (BER) pathway, we observed the occurrences of on-target indels induced by rAKBE03 and rAKBE04 in the rice protoplasts, respectively. Although no stable lines with A-to-C transversion were induced by rAKBE01 and rAKBE04, rAKBE04 could enable simultaneous A-to-G and A-to-T transition and transversion base editing at all the five target loci, with the efficiencies of A-to-G transition and A-to-T transversion editing ranging from 70.97% to 92.31% and 1.67%-4.84% in rice stable lines, respectively. Together, the rAKBEs enables different portfolios of editing products and thus expands the potential of base editing in diverse application scenario for crop improvement.

See the article:

Fusion of a rice endogenous N-methylpurine DNA glycosylase to a plant adenine base transition editor ABE8e enables A-to-K base editing in rice plants

https://link.springer.com/article/10.1007/s42994-024-00138-8