Wang Y, Ludwig J, Schuberth C, Goldeck M, Schlee M, Li H, Juranek S, Sheng G, Micura R, Tuschl T, Hartmann G, Patel DJ. Structural and functional insights into 5'-ppp RNA pattern recognition by the innate immune receptor RIG-I.
Nat Struct Mol Biol 2010;
17:781-7. [PMID:
20581823 PMCID:
PMC3744876 DOI:
10.1038/nsmb.1863]
[Citation(s) in RCA: 199] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2010] [Accepted: 06/07/2010] [Indexed: 12/25/2022]
Abstract
RIG-I is a cytosolic helicase that senses 5'-ppp RNA contained in negative-strand RNA viruses and triggers innate antiviral immune responses. Calorimetric binding studies established that the RIG-I C-terminal regulatory domain (CTD) binds to blunt-end double-stranded 5'-ppp RNA a factor of 17 more tightly than to its single-stranded counterpart. Here we report on the crystal structure of RIG-I CTD bound to both blunt ends of a self-complementary 5'-ppp dsRNA 12-mer, with interactions involving 5'-pp clearly visible in the complex. The structure, supported by mutation studies, defines how a lysine-rich basic cleft within the RIG-I CTD sequesters the observable 5'-pp of the bound RNA, with a stacked phenylalanine capping the terminal base pair. Key intermolecular interactions observed in the crystalline state are retained in the complex of 5'-ppp dsRNA 24-mer and full-length RIG-I under in vivo conditions, as evaluated from the impact of binding pocket RIG-I mutations and 2'-OCH(3) RNA modifications on the interferon response.
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