The discovery of an anti-CRISPR reveals viral escape from CRISPR immunity Explorations of the evolutionary arms race between bacteria and bacteriophages (viruses that infect bacteria) have unearthed a variety of defense mechanisms that include CRISPR-Cas (CRISPR-associated nuclease) adaptive immune systems (1). Understanding the mechanisms of CRISPR-mediated immunity, involving DNA-encoded, RNA-guided, sequence-specific targeting of invasive nucleic acids (2, 3), has spawned powerful genome engineering platforms based on diverse Cas effectors. Subsequent studies have also revealed anti-CRISPR proteins (4) that have proven valuable as control switches for Cas molecular machines. CRISPR-Cas immune systems encompass diverse families including DNA-targeting effectors such as Cascade-Cas3, Cas9, and Cas12 as well as the recently characterized RNA-targeting Cas13 ribonuclease (RNase) (5). The evolving immune arsenal in bacteria has been matched by diverse anti-CRISPRs that enable viruses to escape Cas nuclease targeting. On page 54 of this issue, Meeske et al. (6) report an anti-CRISPR mechanism that inhibits Cas13a RNase activity, with potential utility as a CRISPR effector control switch.

中文翻译：

---

关闭靶向 RNA 的 CRISPR

抗 CRISPR 的发现揭示了病毒逃避 CRISPR 免疫 对细菌和噬菌体（感染细菌的病毒）之间的进化军备竞赛的探索揭示了多种防御机制，包括 CRISPR-Cas（CRISPR 相关核酸酶）适应性免疫系统(1). 了解 CRISPR 介导的免疫机制，涉及侵入性核酸的 DNA 编码、RNA 引导、序列特异性靶向 (2, 3)，已经产生了基于多种 Cas 效应子的强大基因组工程平台。随后的研究还揭示了抗 CRISPR 蛋白 (4)，这些蛋白已被证明可作为 Cas 分子机器的控制开关。CRISPR-Cas 免疫系统包括多个家族，包括 DNA 靶向效应子，例如 Cascade-Cas3、Cas9、和 Cas12 以及最近表征的靶向 RNA 的 Cas13 核糖核酸酶 (RNase) (5)。细菌中不断进化的免疫武器库与多种抗 CRISPR 相匹配，使病毒能够逃避 Cas 核酸酶靶向。在本期的第 54 页，Meeske 等人。(6) 报告了一种抑制 Cas13a RNase 活性的抗 CRISPR 机制，具有作为 CRISPR 效应器控制开关的潜在效用。