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Mol Cell. 2016 May 19;62(4):586-602. doi: 10.1016/j.molcel.2016.04.021.

Structural Analysis of dsRNA Binding to Anti-viral Pattern Recognition Receptors LGP2 and MDA5.

Author information

1
European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France; University Grenoble Alpes, Centre National de la Recherche Scientifique, EMBL Unit of Virus Host-Cell Interactions, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France.
2
CIRI, International Center for Infectiology Research, Université de Lyon, 69007 Lyon, France; Inserm, U1111, 69007 Lyon, France; CNRS, UMR5308, 69007 Lyon, France; Ecole Normale Supérieure de Lyon, 69007 Lyon, France; Université Lyon 1, Centre International de Recherche en Infectiologie, 69007 Lyon, France.
3
European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France; University Grenoble Alpes, Centre National de la Recherche Scientifique, EMBL Unit of Virus Host-Cell Interactions, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France. Electronic address: cusack@embl.fr.

Abstract

RIG-I and MDA5 sense virus-derived short 5'ppp blunt-ended or long dsRNA, respectively, causing interferon production. Non-signaling LGP2 appears to positively and negatively regulate MDA5 and RIG-I signaling, respectively. Co-crystal structures of chicken (ch) LGP2 with dsRNA display a fully or semi-closed conformation depending on the presence or absence of nucleotide. LGP2 caps blunt, 3' or 5' overhang dsRNA ends with 1 bp longer overall footprint than RIG-I. Structures of 1:1 and 2:1 complexes of chMDA5 with short dsRNA reveal head-to-head packing rather than the polar head-to-tail orientation described for long filaments. chLGP2 and chMDA5 make filaments with a similar axial repeat, although less co-operatively for chLGP2. Overall, LGP2 resembles a chimera combining a MDA5-like helicase domain and RIG-I like CTD supporting both stem and end binding. Functionally, RNA binding is required for LGP2-mediated enhancement of MDA5 activation. We propose that LGP2 end-binding may promote nucleation of MDA5 oligomerization on dsRNA.

PMID:
27203181
PMCID:
PMC4885022
DOI:
10.1016/j.molcel.2016.04.021
[Indexed for MEDLINE]
Free PMC Article

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