Many organisms have evolved specialized immune pattern-recognition receptors, including nucleotide-binding oligomerization domain–like receptors (NLRs) of the STAND superfamily that are ubiquitous in plants, animals, and fungi. Although the roles of NLRs in eukaryotic immunity are well established, it is unknown whether prokaryotes use similar defense mechanisms. Here, we show that antiviral STAND (Avs) homologs in bacteria and archaea detect hallmark viral proteins, triggering Avs tetramerization and the activation of diverse N-terminal effector domains, including DNA endonucleases, to abrogate infection. Cryo–electron microscopy reveals that Avs sensor domains recognize conserved folds, active-site residues, and enzyme ligands, allowing a single Avs receptor to detect a wide variety of viruses. These findings extend the paradigm of pattern recognition of pathogen-specific proteins across all three domains of life.

中文翻译：

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通过保守病毒蛋白的模式识别的原核先天免疫

许多生物已经进化出专门的免疫模式识别受体，包括广泛存在于植物、动物和真菌中的 STAND 超家族的核苷酸结合寡聚化结构域样受体 (NLR)。尽管 NLRs 在真核免疫中的作用已经确定，但原核生物是否使用类似的防御机制尚不清楚。在这里，我们表明细菌和古细菌中的抗病毒 STAND (Avs) 同系物检测标志性病毒蛋白，触发 Avs 四聚化和不同 N 末端效应域（包括 DNA 核酸内切酶）的激活，以消除感染。冷冻电子显微镜显示 Avs 传感器域识别保守折叠、活性位点残基和酶配体，允许单个 Avs 受体检测多种病毒。