Z-nucleic acid structures play vital roles in cellular processes and have implications in innate immunity due to their recognition by Zα domains containing proteins (Z-DNA/Z-RNA binding proteins, ZBPs). Although Zα domains have been identified in six proteins, including viral E3L, ORF112, and I73R, as well as, cellular ADAR1, ZBP1, and PKZ, their prevalence across living organisms remains largely unexplored. In this study, we introduce a computational approach to predict Zα domains, leading to the revelation of previously unidentified Zα domain-containing proteins in eukaryotic organisms, including non-metazoan species. Our findings encompass the discovery of new ZBPs in previously unexplored giant viruses, members of the phylum. Through experimental validation, we confirm the Zα functionality of select proteins, establishing their capability to induce the B-to-Z conversion. Additionally, we identify Zα-like domains within bacterial proteins. While these domains share certain features with Zα domains, they lack the ability to bind to Z-nucleic acids or facilitate the B-to-Z DNA conversion. Our findings significantly expand the ZBP family across a wide spectrum of organisms and raise intriguing questions about the evolutionary origins of Zα-containing proteins. Moreover, our study offers fresh perspectives on the functional significance of Zα domains in virus sensing and innate immunity and opens avenues for exploring hitherto undiscovered functions of ZBPs.

中文翻译：

---

巨型病毒中的新型 Z-DNA 结合域


Z-核酸结构在细胞过程中发挥着至关重要的作用，并且由于其被含有 Zα 结构域的蛋白质（Z-DNA/Z-RNA 结合蛋白，ZBP）识别而对先天免疫产生影响。尽管 Zα 结构域已在六种蛋白质中被发现，包括病毒 E3L、ORF112 和 I73R，以及细胞 ADAR1、ZBP1 和 PKZ，但它们在生物体中的普遍性仍然很大程度上未被探索。在这项研究中，我们引入了一种预测 Zα 结构域的计算方法，从而揭示了真核生物（包括非后生动物物种）中先前未识别的含有 Zα 结构域的蛋白质。我们的发现包括在先前未探索过的巨型病毒（该门的成员）中发现新的 ZBP。通过实验验证，我们确认了所选蛋白质的 Zα 功能，确定了它们诱导 B 到 Z 转换的能力。此外，我们还鉴定了细菌蛋白质内的 Zα 样结构域。虽然这些结构域与 Zα 结构域具有某些特征，但它们缺乏与 Z 核酸结合或促进 B 到 Z DNA 转换的能力。我们的研究结果显着地将 ZBP 家族扩展到了广泛的生物体中，并提出了关于含 Zα 的蛋白质的进化起源的有趣问题。此外，我们的研究为 Zα 结构域在病毒感知和先天免疫中的功能意义提供了新的视角，并为探索 ZBP 迄今为止未被发现的功能开辟了途径。