基因编辑之新宠—单碱基基因组编辑系统-生物通.PDF

Hereditas (Beijing) 2017 年 12 月, 39(12): 1115 ―1121 前沿聚焦 基因编辑之“新宠”—单碱基基因组编辑系统 魏瑜，张晓辉，李大力 200241 摘要: 近年发展起来的人工核酸酶可通过引起特定位点的DNA 双链断裂实现对目的片段的有效编辑。为进一 步提高碱基修改的效率和精确度，2016 年研究者们利用CRISPR/Cas9 识别特定DNA 序列的功能，结合胞嘧啶 脱氨酶的生化活性发明了将胞嘧啶高效转换为胸腺嘧啶(CT) 的嘧啶单碱基编辑系统(base editor) 。这一系统虽 然能精准实现嘧啶直接转换，大大提高精确基因编辑效率，但美中不足的是无法对嘌呤进行修改。近期，Nature 报道了将细菌中的tRNA 腺嘌呤脱氨酶定向进化形成具有催化DNA 腺嘌呤底物的脱氨酶，将其与Cas9 系统融 合发明了具有高效催化腺嘌呤转换为鸟嘌呤的新工具—腺嘌呤单碱基编辑系统(ABEs, adenine base editors) 。本 文总结了单碱基编辑工具的发展历程和最新研究进展，着重介绍ABEs 的研发过程，并对单碱基编辑工具今后 的应用方向和研发方向进行展望。 关键词: 单碱基编辑技术；胞嘧啶脱氨酶；腺苷脱氨酶 The “new favorite” of gene editing technology— single base editors Yu Wei, Xiaohui Zhang, Dali Li Shanghai Key Laboratory of Regulatory Biology, School of Life Sciences, East China Normal University, Shanghai 200241, China Abstract: Programmable nucleases are cutting edge genetic technology which edits targeted DNA sequences through generation of site-specific double-strand DNA breaks (DSBs). To improve the efficiency and precision of genetic modifica- tion, scientists have developed a single-base editing system (base editor) through combining of CRISPR/Cas9 system with cytosine deaminase. Compared with Cas9 system, this base editor can convert cytosine to thymine (C T) at specific site more efficiently without inducing DSBs to avoid generation of indels. However, the base editor can only generate tran- sition of pyrimidine but could not modify purines. Recently, Nature published a novel base editing system to convert ade- nine to guanine (ABEs, adenine base editors) through fusion of Cas9 nickase to a modified deaminase which is evolved through screening of random library based on tRNA adenine deaminase from E. coli. Here, we summarize the development of single-base editing tools and the latest research progress, especially the optimization process of ABEs, as well as the pote