体内持续表观基因组编辑的IscB进化引导蛋白设计，这一成果由麻省理工学院张锋研究组经过不懈努力而取得。2025年5月7日，国际知名学术期刊《自然—生物技术》发表了这一成果。

本文通过同源筛选、结构引导蛋白结构域设计和RNA工程以及基于深度学习的结构预测相结合，设计了紧凑的专性移动元件引导活性（OMEGA） RNA引导的内切酶IscB及其引导RNA (ωRNA)，以生成改进的变体NovaIscB。该课题组人员发现紧凑的NovaIscB在人类基因组上的indel活性高达40%（比野生型OgeuIscB提高了约100倍），相对于现有的IscB具有更高的特异性。研究团队进一步表明，NovaIscB可以与甲基转移酶进行主题化，以创建一个可编程的转录抑制因子，OMEGAoff，它足够紧凑，可以包装在一个单一的腺相关病毒载体中，用于持续的体内基因抑制。这项研究强调了将自然多样性与蛋白质工程结合起来设计用于分子生物学应用的增强酶的力量。

据了解，天然存在的酶已经适应了各种分子技术，通过对酶的增强或修饰来改善所需的功能；然而，很难在保持特异性的同时设计具有增强活性的变体。

附：英文原文

Title: Evolution-guided protein design of IscB for persistent epigenome editing in vivo

Author: Kannan, Soumya, Altae-Tran, Han, Zhu, Shiyou, Xu, Peiyu, Strebinger, Daniel, Oshiro, Rachel, Faure, Guilhem, Moeller, Lukas, Pham, Julie, Mears, Kepler S., Ni, Heyuan M., Macrae, Rhiannon K., Zhang, Feng

Issue&Volume: 2025-05-07

Abstract: Naturally existing enzymes have been adapted for a variety of molecular technologies, with enhancements or modifications to the enzymes introduced to improve the desired function; however, it is difficult to engineer variants with enhanced activity while maintaining specificity. Here we engineer the compact Obligate Mobile Element Guided Activity (OMEGA) RNA-guided endonuclease IscB and its guiding RNA (ωRNA) by combining ortholog screening, structure-guided protein domain design and RNA engineering, and deep learning-based structure prediction to generate an improved variant, NovaIscB. We show that the compact NovaIscB achieves up to 40% indel activity (~100-fold improvement over wild-type OgeuIscB) on the human genome with improved specificity relative to existing IscBs. We further show that NovaIscB can be fused with a methyltransferase to create a programmable transcriptional repressor, OMEGAoff, that is compact enough to be packaged in a single adeno-associated virus vector for persistent in vivo gene repression. This study highlights the power of combining natural diversity with protein engineering to design enhanced enzymes for molecular biology applications.

DOI: 10.1038/s41587-025-02655-3

Source: https://www.nature.com/articles/s41587-025-02655-3