Exogenous nucleic acids induce an innate immune response in mammalian host cells through activation of the retinoic acid-inducible gene I (RIG-I). We evaluated RIG-I protein for RNA binding and ATPase stimulation with RNA ligands to investigate the correlation with the extent of immune response through RIG-I activation in cells. RIG-I protein favored blunt-ended, double-stranded RNA (dsRNA) ligands over sticky-ended dsRNA. Moreover, the presence of the 5'-triphosphate (5'-ppp) moiety in dsRNA further enhanced binding affinity to RIG-I. Two structural motifs in RNA, blunt ends in dsRNA and 5'-ppp, stimulated the ATP hydrolysis activity of RIG-I. These structural motifs also strongly induced IFN expression as an innate immune response in cells. Therefore, we suggest that IFN induction through RIG-I activation is mainly determined by structural motifs in dsRNA that increase its affinity for RIG-I protein and stimulate ATPase activity in RIG-I.

中文翻译：

---

RIG-I 核酸结合和 ATP 水解对 I 型干扰素反应激活的依赖性

外源核酸通过激活视黄酸诱导基因 I (RIG-I) 在哺乳动物宿主细胞中诱导先天免疫反应。我们用 RNA 配体评估了 RIG-I 蛋白的 RNA 结合和 ATP 酶刺激，以研究通过细胞中 RIG-I 激活与免疫反应程度的相关性。与粘性末端 dsRNA 相比，RIG-I 蛋白更喜欢平端双链 RNA (dsRNA) 配体。此外，dsRNA 中 5'-三磷酸 (5'-ppp) 部分的存在进一步增强了与 RIG-I 的结合亲和力。RNA 中的两个结构基序，dsRNA 中的平末端和 5'-ppp，刺激了 RIG-I 的 ATP 水解活性。这些结构基序也强烈诱导 IFN 表达作为细胞中的先天免疫反应。所以，