Applications of adenine base editors (ABEs) have been constrained by the limited compatibility of the deoxyadenosine deaminase component with Cas homologs other than SpCas9. We evolved the deaminase component of ABE7.10 using phage-assisted non-continuous and continuous evolution (PANCE and PACE), which resulted in ABE8e. ABE8e contains eight additional mutations that increase activity (kapp) 590-fold compared with that of ABE7.10. ABE8e offers substantially improved editing efficiencies when paired with a variety of Cas9 or Cas12 homologs. ABE8e is more processive than ABE7.10, which could benefit screening, disruption of regulatory regions and multiplex base editing applications. A modest increase in Cas9-dependent and -independent DNA off-target editing, and in transcriptome-wide RNA off-target editing can be ameliorated by the introduction of an additional mutation in the TadA-8e domain. Finally, we show that ABE8e can efficiently install natural mutations that upregulate fetal hemoglobin expression in the BCL11A enhancer or in the the HBG promoter in human cells, targets that were poorly edited with ABE7.10. ABE8e augments the effectiveness and applicability of adenine base editing.

中文翻译：

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具有改进的 Cas 结构域兼容性和活性的腺嘌呤碱基编辑器的噬菌体辅助进化。

腺嘌呤碱基编辑器 (ABE) 的应用受到脱氧腺苷脱氨酶成分与 SpCas9 以外的 Cas 同系物的有限兼容性的限制。我们使用噬菌体辅助的非连续和连续进化（PANCE 和 PACE）进化了 ABE7.10 的脱氨酶成分，从而产生了 ABE8e。ABE8e 包含八个额外突变，与 ABE7.10 相比，其活性 (kapp) 增加了 590 倍。当与各种 Cas9 或 Cas12 同源物配对时，ABE8e 可以显着提高编辑效率。ABE8e 比 ABE7.10 更具处理能力，这可能有利于筛选、监管区域的破坏和多重碱基编辑应用。Cas9 依赖性和非依赖性 DNA 脱靶编辑以及转录组范围内的 RNA 脱靶编辑的适度增加可以通过在 TadA-8e 结构域中引入额外的突变来改善。最后，我们证明 ABE8e 可以有效地安装自然突变，上调人类细胞中 BCL11A 增强子或 HBG 启动子中胎儿血红蛋白的表达，而这些目标是用 ABE7.10 编辑得不好的。ABE8e 增强了腺嘌呤碱基编辑的有效性和适用性。