title: Mechanism of TRIM25 Catalytic Activation in the Antiviral RIG-I Pathway.
abstract: Antiviral response pathways induce interferon by higher-order assembly of signaling complexes called signalosomes. Assembly of the RIG-I signalosome is regulated by K63-linked polyubiquitin chains, which are synthesized by the E3 ubiquitin ligase, TRIM25. We have previously shown that the TRIM25 coiled-coil domain is a stable, antiparallel dimer that positions two catalytic RING domains on opposite ends of an elongated rod. We now show that the RING domain is a separate self-association motif that engages ubiquitin-conjugated E2 enzymes as a dimer. RING dimerization is required for catalysis, TRIM25-mediated RIG-I ubiquitination, interferon induction, and antiviral activity. We also provide evidence that RING dimerization and E3 ligase activity are promoted by binding of the TRIM25 SPRY domain to the RIG-I effector domain. These results indicate that TRIM25 actively participates in higher-order assembly of the RIG-I signalosome and helps to fine-tune the efficiency of the RIG-I-mediated antiviral response.
authors.affiliation: Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908, USA.
authors.forename: Jacint G
authors.initials: JG
authors.lastname: Sanchez
authors.affiliation: Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA 02115, USA.
authors.forename: Jessica J
authors.initials: JJ
authors.lastname: Chiang
authors.affiliation: Department of Microbiology, University of Chicago, Chicago, IL 60637, USA.
authors.forename: Konstantin M J
authors.initials: KMJ
authors.lastname: Sparrer
authors.affiliation: Department of Biochemistry, University of Utah, Salt Lake City, UT 84112, USA.
authors.forename: Steven L
authors.initials: SL
authors.lastname: Alam
authors.affiliation: Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Chi
authors.affiliation: Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908, USA.
authors.forename: Marcin D
authors.initials: MD
authors.lastname: Roganowicz
authors.affiliation: Molecular Biophysics and Integrated Bioimaging, Berkeley Center for Structural Biology, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
authors.forename: Banumathi
authors.initials: B
authors.lastname: Sankaran
authors.affiliation: Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA 02115, USA; Department of Microbiology, University of Chicago, Chicago, IL 60637, USA. Electronic address: mgack@uchicago.edu.
authors.forename: Michaela U
authors.initials: MU
authors.lastname: Gack
authors.affiliation: Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908, USA. Electronic address: opornillos@virginia.edu.
authors.forename: Owen
authors.initials: O
authors.lastname: Pornillos
mesh_terms: D000998:Antiviral Agents / Q000378:metabolism*; D002384:Catalysis; D002460:Cell Line; D000071457:DEAD Box Protein 58 / Q000378:metabolism*; D019281:Dimerization; D057809:HEK293 Cells; D006801:Humans; D007372:Interferons / Q000378:metabolism; D011485:Protein Binding; D011971:Receptors, Immunologic; D015398:Signal Transduction / Q000502:physiology; D014157:Transcription Factors / Q000378:metabolism*; D000070584:Tripartite Motif Proteins / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*; D054875:Ubiquitination / Q000502:physiology
chemical_list: D000998:Antiviral Agents; D011971:Receptors, Immunologic; D014157:Transcription Factors; D000070584:Tripartite Motif Proteins; D007372:Interferons; C084523:TRIM25 protein, human; D044767:Ubiquitin-Protein Ligases; C452820:RIGI protein, human; D000071457:DEAD Box Protein 58