立陶宛维尔纽斯大学Virginijus Siksnys等研究人员合作发现，TnpB结构揭示Cas12核酸酶家族的最小功能核心。2023年4月5日，《自然》杂志在线发表了这项成果。

研究人员提出了Deinococcus radiodurans TnpB-reRNA（右端转座子元件衍生的RNA）复合物在DNA结合和无DNA形式下的冷冻电镜结构。这些结构揭示了TnpB核酸酶的基本结构以及得到生化实验支持的DNA目标识别和切割的分子机制。总体而言，这些结果表明TnpB代表了Cas12蛋白家族的最小结构和功能核心，并为开发基于TnpB的基因组编辑工具提供了一个框架。

据介绍，IS200/IS605转座子家族中广泛存在的TnpB蛋白最近成为最小的RNA引导的核酸酶，能够在真核细胞中进行靶向基因组编辑。生物信息学分析确定TnpB蛋白可能是Cas12核酸酶的前身，它与Cas9一起被广泛用于基因组定向操作。虽然Cas12家族的核酸酶在生化和结构上都有很好的表征，但TnpB的分子机制仍然未知。

附：英文原文

Title: TnpB structure reveals minimal functional core of Cas12 nuclease family

Author: Sasnauskas, Giedrius, Tamulaitiene, Giedre, Druteika, Gytis, Carabias, Arturo, Silanskas, Arunas, Kazlauskas, Darius, Venclovas, eslovas, Montoya, Guillermo, Karvelis, Tautvydas, Siksnys, Virginijus

Issue&Volume: 2023-04-05

Abstract: The widespread TnpB proteins of IS200/IS605 transposon family have recently emerged as the smallest RNA-guided nucleases capable of targeted genome editing in eukaryotic cells1,2. Bioinformatic analysis identified TnpB proteins as the likely predecessors of Cas12 nucleases3,4,5, which along with Cas9 are widely used for targeted genome manipulation. Whereas Cas12 family nucleases are well characterized both biochemically and structurally6, the molecular mechanism of TnpB remains unknown. Here we present the cryogenic-electron microscopy structures of the Deinococcus radiodurans TnpB–reRNA (right-end transposon element-derived RNA) complex in DNA-bound and -free forms. The structures reveal the basic architecture of TnpB nuclease and the molecular mechanism for DNA target recognition and cleavage that is supported by biochemical experiments. Collectively, these results demonstrate that TnpB represents the minimal structural and functional core of the Cas12 protein family and provide a framework for developing TnpB-based genome editing tools.

DOI: 10.1038/s41586-023-05826-x

Source: https://www.nature.com/articles/s41586-023-05826-x