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.

基础编辑技术使得在目标DNA上实现可编程的单核苷酸变化成为可能，且不引发双链DNA断裂。腺嘌呤碱基编辑器（ABEs）能够精确地将腺嘌呤（A）转化为鸟嘌呤（G）。然而，优化脱氨酶的有限可用性及其在不同目标序列中效率的差异性，可能限制了ABEs实现有效腺嘌呤编辑的能力。在本研究中，我们探讨了将TurboCas9粘性末端酶应用于ABE中以提高其基因组编辑活性的可能性。所得到的TurboABE在多种腺嘌呤靶位点展现了增强的编辑效率，同时未增加DNA和RNA中的脱靶编辑。TurboABE的一个显著特点是，它能够显著提高通常在目标DNA编辑窗口中编辑效率低下的碱基的编辑频率。改进ABEs的开发为活细胞中基因的精确遗传修饰提供了新的可能性。