title: Dissociation of a MAVS/IPS-1/VISA/Cardif-IKKepsilon molecular complex from the mitochondrial outer membrane by hepatitis C virus NS3-4A proteolytic cleavage.
abstract: Intracellular RNA virus infection is detected by the cytoplasmic RNA helicase RIG-I that plays an essential role in signaling to the host antiviral response. Recently, the adapter molecule that links RIG-I sensing of incoming viral RNA to downstream signaling and gene activation events was characterized by four different groups; MAVS/IPS-1-1/VISA/Cardif contains an amino-terminal CARD domain and a carboxyl-terminal mitochondrial transmembrane sequence that localizes to the mitochondrial membrane. Furthermore, the hepatitis C virus NS3-4A protease complex specifically targets MAVS/IPS-1/VISA/Cardif for cleavage as part of its immune evasion strategy. With a novel search program written in python, we also identified an uncharacterized protein, KIAA1271 (K1271), containing a single CARD-like domain at the N terminus and a Leu-Val-rich C terminus that is identical to that of MAVS/IPS-1/VISA/Cardif. Using a combination of biochemical analysis, subcellular fractionation, and confocal microscopy, we now demonstrate that NS3-4A cleavage of MAVS/IPS-1/VISA/Cardif/K1271 results in its dissociation from the mitochondrial membrane and disrupts signaling to the antiviral immune response. Furthermore, virus-induced IKKepsilon kinase, but not TBK1, colocalized strongly with MAVS at the mitochondrial membrane, and the localization of both molecules was disrupted by NS3-4A expression. Mutation of the critical cysteine 508 to alanine was sufficient to maintain mitochondrial localization of MAVS/IPS-1/VISA/Cardif and IKKepsilon in the presence of NS3-4A. These observations provide an outline of the mechanism by which hepatitis C virus evades the interferon antiviral response.
authors.affiliation: Lady Davis Institute for Medical Research, McGill University, Montreal H3T 1E2, Quebec, Canada. rongtuan.lin@mcgill.ca
authors.forename: Rongtuan
authors.initials: R
authors.lastname: Lin
authors.forename: Judith
authors.initials: J
authors.lastname: Lacoste
authors.forename: Peyman
authors.initials: P
authors.lastname: Nakhaei
authors.forename: Qiang
authors.initials: Q
authors.lastname: Sun
authors.forename: Long
authors.initials: L
authors.lastname: Yang
authors.forename: Suzanne
authors.initials: S
authors.lastname: Paz
authors.forename: Peter
authors.initials: P
authors.lastname: Wilkinson
authors.forename: Ilkka
authors.initials: I
authors.lastname: Julkunen
authors.forename: Damien
authors.initials: D
authors.lastname: Vitour
authors.forename: Eliane
authors.initials: E
authors.lastname: Meurs
authors.forename: John
authors.initials: J
authors.lastname: Hiscott
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D016174:Hepacivirus / Q000737:chemistry; D006801:Humans; D051550:I-kappa B Kinase / Q000378:metabolism*; D007425:Intracellular Membranes / Q000378:metabolism; D008928:Mitochondria / Q000648:ultrastructure; D024101:Mitochondrial Proteins / Q000378:metabolism*; D046912:Multiprotein Complexes / Q000378:metabolism*; D010447:Peptide Hydrolases / Q000378:metabolism; D015398:Signal Transduction / Q000276:immunology; D017361:Viral Nonstructural Proteins / Q000378:metabolism*; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D051550:I-kappa B Kinase; D024101:Mitochondrial Proteins; D046912:Multiprotein Complexes; D010447:Peptide Hydrolases; D017361:Viral Nonstructural Proteins; C505371:MAVS protein, human; C084422:NS3 protein, hepatitis C virus; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases