Engineering a precise adenine base editor with minimal bystander editing

作者：Chen, Liang; Zhang, Shun; Xue, Niannian; Hong, Mengjia; Zhang, Xiaohui; Zhang, Dan; Yang, Jing; Bai, Sijia; Huang, Yifan; Meng, Haowei; Wu, Hao; Luan, Changming; Zhu, Biyun; Ru, Gaomeng; Gao, Hongyi; Zhong, Liping; Liu, Meizhen; Liu, Mingyao; Cheng, Yiyun; Yi, Chengqi; Wang, Liren; Zhao, Yongxiang^*; Song, Gaojie^*; Li, Dali^*

来源：Nature Chemical Biology, 2023, 19(1): 101-+.

DOI：10.1038/s41589-022-01163-8

• OFF-TARGET
• GENOMIC DNA
• MOUSE

Adenine base editors (ABEs) catalyze A-to-G transitions showing broad applications, but their bystander mutations and off-target editing effects raise safety concerns. Through structure-guided engineering, we found ABE8e with an N108Q mutation reduced both adenine and cytosine bystander editing, and introduction of an additional L145T mutation (ABE9), further refined the editing window to 1-2 nucleotides with eliminated cytosine editing. Importantly, ABE9 induced very minimal RNA and undetectable Cas9-independent DNA off-target effects, which mainly installed desired single A-to-G conversion in mouse and rat embryos to efficiently generate disease models. Moreover, ABE9 accurately edited the A(5) position of the protospacer sequence in pathogenic homopolymeric adenosine sites (up to 342.5-fold precision over ABE8e) and was further confirmed through a library of guide RNA-target sequence pairs. Owing to the minimized editing window, ABE9 could further broaden the targeting scope for precise correction of pathogenic single-nucleotide variants when fused to Cas9 variants with expanded protospacer adjacent motif compatibility. bpNLS, bipartite nuclear localization signals.

• 单位
  北京大学