title: Lysine 63-linked TANK-binding kinase 1 ubiquitination by mindbomb E3 ubiquitin protein ligase 2 is mediated by the mitochondrial antiviral signaling protein.
abstract: Beta interferon (IFN-β) is involved in a wide range of cellular functions, and its secretion must be tightly controlled to inhibit viral spreading while minimizing cellular damage. Intracellular viral replication triggers cellular signaling cascades leading to the activation of the transcription factors NF-κB and interferon regulatory factor 3 (IRF3) and IRF7 (IRF3/7), which synergistically bind to the IFN-β gene promoter to induce its expression. The mitochondrial antiviral signaling protein (MAVS) is a governing adaptor protein that mediates signaling communications between virus-sensing proteins and transcription factors. The activity of MAVS in the regulation of IFN-β secretion is affected by many cellular factors. However, the mechanism of MAVS-mediated IRF3/7 activation is not completely understood. Here, we identified a highly conserved DLAIS motif at amino acid positions 438 to 442 of MAVS that is indispensable for IRF3/7 activation. Specifically, the L439S and A440R mutations suppress IRF3/7 activation. Pulldown experiments using wild-type and mutant MAVS showed that mindbomb E3 ubiquitin protein ligase 2 (MIB2) binds to the DLAIS motif. Furthermore, the DLAIS motif was found to be critical for MIB2 binding, the ligation of K63-linked ubiquitin to TANK-binding kinase 1, and phosphorylation-mediated IRF3/7 activation. Our results suggest that MIB2 plays a putative role in MAVS-mediated interferon signaling.
  
  
  OBJECTIVE
  Mitochondrial antiviral signaling protein (MAVS) mediates signaling from virus-sensing proteins to transcription factors for the induction of beta interferon. However, the mechanism underlying activation of MAVS-mediated interferon regulatory factors 3 and 7 (IRF3/7) is not completely understood. We found a highly conserved DLAIS motif in MAVS that is indispensable for IRF3/7 activation through TANK-binding kinase 1 (TBK1) and identified it as the binding site for mindbomb E3 ubiquitin protein ligase 2 (MIB2). The mutations that targeted the DLAIS motif abolished MIB2 binding, attenuated the K63-linked ubiquitination of TBK1, and decreased the phosphorylation-mediated activation of IRF3/7.
authors.affiliation: Department of Microbiology, Cell Dysfunction Research Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
authors.forename: Jung Sook
authors.initials: JS
authors.lastname: Ye
authors.affiliation: Department of Microbiology, Cell Dysfunction Research Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
authors.forename: Nari
authors.initials: N
authors.lastname: Kim
authors.affiliation: Department of Microbiology, Cell Dysfunction Research Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
authors.forename: Kyoung Jin
authors.initials: KJ
authors.lastname: Lee
authors.affiliation: Department of Microbiology, Cell Dysfunction Research Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
authors.forename: Young Ran
authors.initials: YR
authors.lastname: Nam
authors.affiliation: Department of Microbiology, Cell Dysfunction Research Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
authors.forename: Uk
authors.initials: U
authors.lastname: Lee
authors.affiliation: Department of Microbiology, Cell Dysfunction Research Center, University of Ulsan College of Medicine, Seoul, Republic of Korea chjoo@amc.seoul.kr.
authors.forename: Chul Hyun
authors.initials: CH
authors.lastname: Joo
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D020816:Amino Acid Motifs; D001665:Binding Sites; D002460:Cell Line; D002498:Centrifugation; D004252:DNA Mutational Analysis; D006801:Humans; D050838:Interferon Regulatory Factor-3 / Q000378:metabolism; D050839:Interferon Regulatory Factor-7 / Q000378:metabolism; D016899:Interferon-beta / Q000378:metabolism; D008239:Lysine / Q000378:metabolism; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D029082:Sendai virus / Q000276:immunology*; D015398:Signal Transduction; D025801:Ubiquitin / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*; D054875:Ubiquitination
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C494232:IRF3 protein, human; C494234:IRF7 protein, human; D050838:Interferon Regulatory Factor-3; D050839:Interferon Regulatory Factor-7; C505371:MAVS protein, human; D025801:Ubiquitin; D016899:Interferon-beta; C478156:MIB2 protein, human; D044767:Ubiquitin-Protein Ligases; D017346:Protein Serine-Threonine Kinases; C403191:TBK1 protein, human; D008239:Lysine