Hyperactive Nickase Activity Improves Adenine Base Editing

Base editing technologies enable
programmable single-nucleotide
changes in target DNA without double-stranded DNA breaks. Adenine
base editors (ABEs) allow precise conversion of adenine (A) to guanine
(G). However, limited availability of optimized deaminases as well
as their variable efficiencies across different target sequences can
limit the ability of ABEs to achieve effective adenine editing. Here,
we explored the use of a TurboCas9 nickase in an ABE to improve its
genome editing activity. The resulting TurboABE exhibits amplified
editing efficiency on a variety of adenine target sites without increasing
off-target editing in DNA and RNA. An interesting feature of TurboABE
is its ability to significantly improve the editing frequency at bases
with normally inefficient editing rates in the editing window of each
target DNA. Development of improved ABEs provides new possibilities
for precise genetic modification of genes in living cells.

基础编辑技术允许在不造成双链DNA断裂的情况下，对目标DNA进行可编程的单核苷酸改变。腺嘌呤碱基编辑器（ABEs）能够实现腺嘌呤（A）到鸟嘌呤（G）的精确转换。然而，优化脱氨酶的有限可用性及其在不同目标序列中的效率变化，可能限制了ABEs实现有效腺嘌呤编辑的能力。在此，我们探讨了在ABE中应用TurboCas9缺口酶以提高其基因组编辑活性的可能性。所获得的TurboABE在多种腺嘌呤目标位点上表现出增强的编辑效率，同时并未增加DNA和RNA中的脱靶编辑。TurboABE的一个显著特点是，它能够显著提高在目标DNA编辑窗口中通常编辑效率低下的碱基的编辑频率。改进ABEs的发展为活细胞中基因的精确遗传修饰提供了新的可能性。