Structural and biochemical studies of RIG-I antiviral signaling.
10.1007/s13238-012-2088-4
- Author:
Miao FENG
1
;
Zhanyu DING
;
Liang XU
;
Liangliang KONG
;
Wenjia WANG
;
Shi JIAO
;
Zhubing SHI
;
Mark I GREENE
;
Yao CONG
;
Zhaocai ZHOU
Author Information
1. State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.
- Publication Type:Journal Article
- MeSH:
Adaptor Proteins, Signal Transducing;
metabolism;
Adenosine Triphosphate;
metabolism;
DEAD Box Protein 58;
DEAD-box RNA Helicases;
chemistry;
genetics;
metabolism;
Dimerization;
Humans;
Mutagenesis, Site-Directed;
Phosphorylation;
Polyubiquitin;
metabolism;
Protein Binding;
Protein Structure, Tertiary;
RNA, Double-Stranded;
metabolism;
Recombinant Proteins;
biosynthesis;
chemistry;
genetics;
Signal Transduction;
Transcription Factors;
metabolism;
Tripartite Motif Proteins;
Ubiquitin-Protein Ligases;
metabolism;
Ubiquitination
- From:
Protein & Cell
2013;4(2):142-154
- CountryChina
- Language:English
-
Abstract:
Retinoic acid-inducible gene I (RIG-I) is an important pattern recognition receptor that detects viral RNA and triggers the production of type-I interferons through the downstream adaptor MAVS (also called IPS-1, CARDIF, or VISA). A series of structural studies have elaborated some of the mechanisms of dsRNA recognition and activation of RIG-I. Recent studies have proposed that K63-linked ubiquitination of, or unanchored K63-linked polyubiquitin binding to RIG-I positively regulates MAVS-mediated antiviral signaling. Conversely phosphorylation of RIG-I appears to play an inhibitory role in controlling RIG-I antiviral signal transduction. Here we performed a combined structural and biochemical study to further define the regulatory features of RIG-I signaling. ATP and dsRNA binding triggered dimerization of RIG-I with conformational rearrangements of the tandem CARD domains. Full length RIG-I appeared to form a complex with dsRNA in a 2:2 molar ratio. Compared with the previously reported crystal structures of RIG-I in inactive state, our electron microscopic structure of full length RIG-I in complex with blunt-ended dsRNA, for the first time, revealed an exposed active conformation of the CARD domains. Moreover, we found that purified recombinant RIG-I proteins could bind to the CARD domain of MAVS independently of dsRNA, while S8E and T170E phosphorylation-mimicking mutants of RIG-I were defective in binding E3 ligase TRIM25, unanchored K63-linked polyubiquitin, and MAVS regardless of dsRNA. These findings suggested that phosphorylation of RIG inhibited downstream signaling by impairing RIG-I binding with polyubiquitin and its interaction with MAVS.
