55 Amino acid linker between helicase and carboxyl terminal domains of RIG-I functions as a critical repression domain and determines inter-domain conformation
55 Amino acid linker between helicase and carboxyl terminal domains of RIG-I functions as a critical repression domain and determines inter-domain conformation
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DOI：
10.1016/j.bbrc.2011.10.015
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发表时间：
2011-11-11
影响因子：
3.1
通讯作者：
Fujita, Takashi
中科院分区：
文献类型：
--
作者：
Kageyama, Maiko;Takahasi, Kiyohiro;Fujita, Takashi
在病毒感染的细胞中，具有非自结构模式的病毒RNA被DExD/Hbox RNA解旋酶rig - 1识别。一旦RIG-I感知到病毒RNA，它就会触发信号级联反应，导致包括I型干扰素在内的基因激活，从而激活抗病毒反应。过表达n端caspase激活和募集域（CARD）足以激活信号传导；然而，全长rig - 1的基础活性是检测不到的。抑制结构域（RD），最初鉴定为a.a 735-925，负责降低基础活性；因此，我们认为rig - 1在未感染的细胞中处于自我抑制状态，当遇到病毒RNA时，这种抑制被逆转。在本报告中，我们进一步将RD划分为a.a.747 -801，它对应于连接解旋酶和c -末端结构域（CTD）的连接子。连接体中保守残基的丙氨酸取代赋予全长rig - 1结构活性。我们发现组成型活性突变体不表现出atp酶活性，这表明atp酶是去抑制所必需的，但不是信号传导本身。此外，重组rig - 1的胰蛋白酶酶切结果显示，野生型而非连接体突变体符合胰蛋白酶抗性结构，包含CARD和解旋酶结构域。该结果强烈表明，连接子负责将rig - 1维持在“封闭”结构中，以最大限度地减少未感染细胞中不必要的干扰素产生。这些发现揭示了RIG-I功能的结构调控。(C) 2011爱思唯尔公司版权所有。
In virus-infected cells, viral RNA with non-self structural pattern is recognized by DExD/Hbox RNA helicase, RIG-I. Once RIG-I senses viral RNA, it triggers a signaling cascade, resulting in the activation of genes including type I interferon, which activates antiviral responses. Overexpression of N-terminal caspase activation and recruitment domain (CARD) is sufficient to activate signaling; however basal activity of full-length RIG-I is undetectable. The repressor domain (RD), initially identified as a.a. 735-925, is responsible for diminished basal activity; therefore, it is suggested that RIG-I is under auto-repression in uninfected cells and the repression is reversed upon its encounter with viral RNA. In this report, we further delimited RD to a.a. 747-801, which corresponds to a linker connecting the helicase and the C-terminal domain (CTD). Alanine substitutions of the conserved residues in the linker conferred constitutive activity to full-length RIG-I. We found that the constitutive active mutants do not exhibit ATPase activity, suggesting that ATPase is required for de-repression but not signaling itself. Furthermore, trypsin digestion of recombinant RIG-I revealed that the wild-type, but not linker mutant conforms to the trypsin-resistant structure, containing CARD and helicase domain. The result strongly suggests that the linker is responsible for maintaining RIG-I in a "closed" structure to minimize unwanted production of interferon in uninfected cells. These findings shed light on the structural regulation of RIG-I function. (C) 2011 Elsevier Inc. All rights reserved.