研究发现，除了将腺嘌呤转化为鸟嘌呤外，腺嘌呤碱基编辑器还可以在狭窄的编辑窗口（5-7位碱基）和受限的TC * N序列背景下将胞嘧啶转化为鸟嘌呤或胸腺嘧啶。腺嘌呤碱基编辑器引起的胞嘧啶改变不依赖于腺苷转化而发生，其效率高达11.2％，并降低了可用于高特异性碱基编辑合适靶向位点的数量。

研究介绍，腺嘌呤碱基编辑器包含体外进化的腺苷脱氨酶和Cas9 核酸切口酶。

附：

Title: Adenine base editors catalyze cytosine conversions in human cells

Author: Heon Seok Kim, You Kyeong Jeong, Junho K Hur, Jin-Soo Kim, Sangsu Bae

Issue&Volume: 2019-09-23

Abstract: 

Adenine base editors comprise an adenosine deaminase, evolved in vitro, and a Cas9 nickase. Here, we show that in addition to converting adenine to guanine, adenine base editors also convert cytosine to guanine or thymine in a narrow editing window (positions 5–7) and in a confined TC*N sequence context. Adenine base editor–induced cytosine substitutions occur independently of adenosine conversions with an efficiency of up to 11.2% and reduce the number of suitable targeting sites for high-specificity base editing.

DOI: 10.1038/s41587-019-0254-4

Source:https://www.nature.com/articles/s41587-019-0254-4