Format

Send to

Choose Destination
Nucleic Acids Res. 2016 Jan 29;44(2):896-909. doi: 10.1093/nar/gkv1299. Epub 2015 Nov 26.

The autoinhibitory CARD2-Hel2i Interface of RIG-I governs RNA selection.

Author information

1
Robert Wood Johnson Medical School, Department of Biochemistry and Molecular Biology, Rutgers University, Piscataway, NJ 08854, USA.
2
Center for Advanced Biotechnology and Medicine, Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ 08854, USA.
3
Center for Advanced Biotechnology and Medicine, Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ 08854, USA jmarco@cabm-new.rutgers.edu.
4
Robert Wood Johnson Medical School, Department of Biochemistry and Molecular Biology, Rutgers University, Piscataway, NJ 08854, USA patelss@rutgers.edu.

Abstract

RIG-I (Retinoic Acid Inducible Gene-I) is a cytosolic innate immune receptor that detects atypical features in viral RNAs as foreign to initiate a Type I interferon signaling response. RIG-I is present in an autoinhibited state in the cytoplasm and activated by blunt-ended double-stranded (ds)RNAs carrying a 5' triphosphate (ppp) moiety. These features found in many pathogenic RNAs are absent in cellular RNAs due to post-transcriptional modifications of RNA ends. Although RIG-I is structurally well characterized, the mechanistic basis for RIG-I's remarkable ability to discriminate between cellular and pathogenic RNAs is not completely understood. We show that RIG-I's selectivity for blunt-ended 5'-ppp dsRNAs is ≈3000 times higher than non-blunt ended dsRNAs commonly found in cellular RNAs. Discrimination occurs at multiple stages and signaling RNAs have high affinity and ATPase turnover rate and thus a high katpase/Kd. We show that RIG-I uses its autoinhibitory CARD2-Hel2i (second CARD-helicase insertion domain) interface as a barrier to select against non-blunt ended dsRNAs. Accordingly, deletion of CARDs or point mutations in the CARD2-Hel2i interface decreases the selectivity from ≈3000 to 150 and 750, respectively. We propose that the CARD2-Hel2i interface is a 'gate' that prevents cellular RNAs from generating productive complexes that can signal.

PMID:
26612866
PMCID:
PMC4737149
DOI:
10.1093/nar/gkv1299
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Silverchair Information Systems Icon for PubMed Central
Loading ...
Support Center