Abstract：
DDX58 encodes RIG-I, a cytosolic RNA sensor that ensures immune surveillance of nonself RNAs. Individuals with RIG-IE510V and RIG-IQ517H mutations have increased susceptibility to Singleton-Merten syndrome (SMS) defects, resulting in tissue-specific (mild) and classic (severe) phenotypes. The coupling between RNA recognition and conformational changes is central to RIG-I RNA proofreading, but the molecular determinants leading to dissociated disease phenotypes remain unknown. Herein, we employed hydrogen/deuterium exchange mass spectrometry (HDX-MS) and single molecule magnetic tweezers (MT) to precisely examine how subtle conformational changes in the helicase insertion domain (HEL2i) promote impaired ATPase and erroneous RNA proofreading activities. We showed that the mutations cause a loosened latch-gate engagement in apo RIG-I, which in turn gradually dampens its self RNA (Cap2 moiety:m7G cap and N1-2-2\'-O-methylation RNA) proofreading ability, leading to increased immunopathy. These results reveal HEL2i as a unique checkpoint directing two specialized functions, i.e. stabilizing the CARD2-HEL2i interface and gating the helicase from incoming self RNAs; thus, these findings add new insights into the role of HEL2i in the control of antiviral innate immunity and autoimmunity diseases.
摘要：
DDX58编码RIG-I,确保非自身RNA免疫监视的胞浆RNA传感器。具有RIG-IE510V和RIG-IQ517H突变的个体对单例-默顿综合征（SMS）缺陷的易感性增加，导致组织特异性（轻度）和经典（严重）表型。RNA识别和构象变化之间的耦合是RIG-IRNA校对的核心，但是导致分离疾病表型的分子决定因素仍然未知。在这里，我们使用氢/氘交换质谱(HDX-MS)和单分子磁镊子(MT)来精确检查解旋酶插入域(HEL2i)的细微构象变化如何促进受损的ATP酶和错误的RNA校对活动。我们发现突变会导致apoRIG-I中的闩锁-门接合松动，这反过来逐渐削弱了其自身RNA（Cap2部分：m7G帽和N1-2-2\'-O-甲基化RNA）的校对能力，导致免疫病增加。这些结果表明HEL2i是一个独特的检查点，指导两个专门的功能，即稳定CARD2-HEL2i界面并从传入的自身RNA中门控解旋酶；因此，这些发现为HEL2i在控制抗病毒先天免疫和自身免疫疾病中的作用增加了新的见解.
