上海辉大基因公司Yingsi Zhou、Hui Yang研究组在研究中取得进展。他们通过改造IscB切口酶研发了微型碱基编辑器。相关论文发表在2023年5月25日出版的《自然—方法学》杂志上。

研究人员优化了OgeuIscB及其相应的ωRNA的设计方法，研发出一种在哺乳动物系统中具有高效编辑效率的IscB系统，命名为enIscB。通过将enIscB与T5核酸外切酶（T5E）相融合，研究人员发现在人类细胞中enIscB-T5E表现出与SpG Cas9相当的编辑效率，同时会产生更少的染色体易位效应。

此外，通过将胞嘧啶或腺苷脱氨酶与enIscB切口酶相融合，研究人员研发了微型IscB衍生的碱基编辑器（miBE），其表现出强大的编辑效率（高达92%）以诱导DNA碱基转换。总体而言，该工作表明enIscB-T5E和miBE是高效的多功能基因组编辑工具。

据悉，作为一种微型RNA引导的核酸内切酶，IscB被认为是Cas9的祖先，并具有与Cas9相似的功能。IscB的大小不到Cas9的一半，因此更适合体内递送。然而，IscB在真核细胞中的编辑效率差限制了其在体内的应用。

附：英文原文

Title: Development of miniature base editors using engineered IscB nickase

Author: Han, Dingyi, Xiao, Qingquan, Wang, Yifan, Zhang, Hainan, Dong, Xue, Li, Guoling, Kong, Xiangfeng, Wang, Shihao, Song, Jinhui, Zhang, Weihong, Zhou, Jingxing, Bi, Lanting, Yuan, Yuan, Shi, Linyu, Zhong, Na, Yang, Hui, Zhou, Yingsi

Issue&Volume: 2023-05-25

Abstract: As a miniature RNA-guided endonuclease, IscB is presumed to be the ancestor of Cas9 and to share similar functions. IscB is less than half the size of Cas9 and thus more suitable for in vivo delivery. However, the poor editing efficiency of IscB in eukaryotic cells limits its in vivo applications. Here we describe the engineering of OgeuIscB and its corresponding ωRNA to develop an IscB system that is highly efficient in mammalian systems, named enIscB. By fusing enIscB with T5 exonuclease (T5E), we found enIscB-T5E exhibited comparable targeting efficiency to SpG Cas9 while showing reduced chromosome translocation effects in human cells. Furthermore, by fusing cytosine or adenosine deaminase with enIscB nickase, we generated miniature IscB-derived base editors (miBEs), exhibiting robust editing efficiency (up to 92%) to induce DNA base conversions. Overall, our work establishes enIscB-T5E and miBEs as versatile tools for genome editing.

DOI: 10.1038/s41592-023-01898-9

Source: https://www.nature.com/articles/s41592-023-01898-9