Structural and biochemical studies of RIG-I antiviral signaling
Protein & Cell
;
(12): 142-154, 2013.
Article
in English
| WPRIM
| ID: wpr-757834
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 22 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.
Full text:
Available
Index:
WPRIM (Western Pacific)
Main subject:
Phosphorylation
/
Protein Binding
/
Transcription Factors
/
Recombinant Proteins
/
RNA, Double-Stranded
/
Signal Transduction
/
Adenosine Triphosphate
/
Chemistry
/
Mutagenesis, Site-Directed
/
Protein Structure, Tertiary
Limits:
Humans
Language:
English
Journal:
Protein & Cell
Year:
2013
Type:
Article
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