IscB proteins are putative nucleases encoded in a distinct family of IS200/IS605 transposons and are likely ancestors of the RNA-guided endonuclease Cas9, but the functions of IscB and its interactions with any RNA remain uncharacterized. Using evolutionary analysis, RNA-seq, and biochemical experiments, we reconstruct the evolution of CRISPR-Cas9 systems from IS200/IS605 transposons. We show that IscB utilizes a single non-coding RNA for RNA-guided cleavage of double-stranded DNA and can be harnessed for genome editing in human cells. We also demonstrate the RNA-guided nuclease activity of TnpB, another IS200/605 transposon-encoded protein and the likely ancestor of Cas12 endonucleases. This work reveals a widespread class of transposon-encoded RNA-guided nucleases, which we name OMEGA (Obligate Mobile Element Guided Activity), with strong potential for developing as biotechnologies.

中文翻译：

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广泛分布的 IS200/605 转座子家族编码多种可编程 RNA 引导的核酸内切酶


IscB 蛋白是在 IS200/IS605 转座子的独特家族中编码的假定核酸酶，并且可能是 RNA 引导的核酸内切酶 Cas9 的祖先，但 IscB 的功能及其与任何 RNA 的相互作用仍然未知。利用进化分析、RNA-seq 和生化实验，我们从 IS200/IS605 转座子重建了 CRISPR-Cas9 系统的进化。我们证明 IscB 利用单个非编码 RNA 进行 RNA 引导的双链 DNA 切割，并可用于人类细胞中的基因组编辑。我们还证明了 TnpB 的 RNA 引导核酸酶活性，TnpB 是另一种 IS200/605 转座子编码蛋白，也是 Cas12 核酸内切酶的可能祖先。这项工作揭示了一类广泛存在的转座子编码的 RNA 引导核酸酶，我们将其命名为 OMEGA（专性移动元件引导活性），具有作为生物技术发展的强大潜力。