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, TR ...
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.
Organizational Affiliation:
Molecular Biophysics and Integrated Bioimaging, Berkeley Center for Structural Biology, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.,Department of Microbiology, University of Chicago, Chicago, IL 60637, USA.,Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908, USA. Electronic address: opornillos@virginia.edu.,Department of Biochemistry, University of Utah, Salt Lake City, UT 84112, USA.,Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA 02115, USA.,Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908, USA.,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.
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