| Structural highlights
Function
[TRAF6_HUMAN] E3 ubiquitin ligase that, together with UBE2N and UBE2V1, mediates the synthesis of 'Lys-63'-linked-polyubiquitin chains conjugated to proteins, such as IKBKG, AKT1 and AKT2. Also mediates ubiquitination of free/unanchored polyubiquitin chain that leads to MAP3K7 activation. Leads to the activation of NF-kappa-B and JUN. May be essential for the formation of functional osteoclasts. Seems to also play a role in dendritic cells (DCs) maturation and/or activation. Represses c-Myb-mediated transactivation, in B-lymphocytes. Adapter protein that seems to play a role in signal transduction initiated via TNF receptor, IL-1 receptor and IL-17 receptor. Regulates osteoclast differentiation by mediating the activation of adapter protein complex 1 (AP-1) and NF-kappa-B, in response to RANK-L stimulation.[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [MAVS_HUMAN] Required for innate immune defense against viruses. Acts downstream of DDX58/RIG-I and IFIH1/MDA5, which detect intracellular dsRNA produced during viral replication, to coordinate pathways leading to the activation of NF-kappa-B, IRF3 and IRF7, and to the subsequent induction of antiviral cytokines such as IFN-beta and RANTES (CCL5). Peroxisomal and mitochondrial MAVS act sequentially to create an antiviral cellular state. Upon viral infection, peroxisomal MAVS induces the rapid interferon-independent expression of defense factors that provide short-term protection, whereas mitochondrial MAVS activates an interferon-dependent signaling pathway with delayed kinetics, which amplifies and stabilizes the antiviral response. May activate the same pathways following detection of extracellular dsRNA by TLR3. May protect cells from apoptosis.[11] [12] [13] [14] [15] [16]
Publication Abstract from PubMed
In response to viral infection, cytosolic retinoic acid-inducible gene I-like receptors sense viral RNA and promote oligomerization of mitochondrial antiviral signaling protein (MAVS), which then recruits tumor necrosis factor receptor-associated factor (TRAF) family proteins, including TRAF6, to activate an antiviral response. Currently, the interaction between MAVS and TRAF6 is only partially understood, and atomic details are lacking. Here, we demonstrated that MAVS directly interacts with TRAF6 through its potential TRAF6-binding motif 2 (T6BM2; amino acids 455-460). Further, we solved the crystal structure of MAVS T6BM2 in complex with the TRAF6 TRAF_C domain at 2.95 A resolution. T6BM2 of MAVS binds to the canonical adaptor-binding groove of the TRAF_C domain. Structure-directed mutational analyses in vitro and in cells revealed that MAVS binding to TRAF6 via T6BM2 instead of T6BM1 is essential but not sufficient for an optimal antiviral response. Particularly, a MAVS mutant Y460E retained its TRAF6-binding ability as predicted but showed significantly impaired signaling activity, highlighting the functional importance of this tyrosine. Moreover, these observations were further confirmed in MAVS(-/-) mouse embryonic fibroblast cells. Collectively, our work provides a structural basis for understanding the MAVS-TRAF6 antiviral response.
Structural Insights into Mitochondrial Antiviral Signaling Protein (MAVS)-Tumor Necrosis Factor Receptor-associated Factor 6 (TRAF6) Signaling.,Shi Z, Zhang Z, Zhang Z, Wang Y, Li C, Wang X, He F, Sun L, Jiao S, Shi W, Zhou Z J Biol Chem. 2015 Oct 30;290(44):26811-20. doi: 10.1074/jbc.M115.666578. Epub, 2015 Sep 18. PMID:26385923[17]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
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- ↑ Seth RB, Sun L, Ea CK, Chen ZJ. Identification and characterization of MAVS, a mitochondrial antiviral signaling protein that activates NF-kappaB and IRF 3. Cell. 2005 Sep 9;122(5):669-82. PMID:16125763 doi:10.1016/j.cell.2005.08.012
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- ↑ Kawai T, Takahashi K, Sato S, Coban C, Kumar H, Kato H, Ishii KJ, Takeuchi O, Akira S. IPS-1, an adaptor triggering RIG-I- and Mda5-mediated type I interferon induction. Nat Immunol. 2005 Oct;6(10):981-8. Epub 2005 Aug 28. PMID:16127453 doi:10.1038/ni1243
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- ↑ Dixit E, Boulant S, Zhang Y, Lee AS, Odendall C, Shum B, Hacohen N, Chen ZJ, Whelan SP, Fransen M, Nibert ML, Superti-Furga G, Kagan JC. Peroxisomes are signaling platforms for antiviral innate immunity. Cell. 2010 May 14;141(4):668-81. doi: 10.1016/j.cell.2010.04.018. Epub 2010 May, 6. PMID:20451243 doi:10.1016/j.cell.2010.04.018
- ↑ Shi Z, Zhang Z, Zhang Z, Wang Y, Li C, Wang X, He F, Sun L, Jiao S, Shi W, Zhou Z. Structural Insights into Mitochondrial Antiviral Signaling Protein (MAVS)-Tumor Necrosis Factor Receptor-associated Factor 6 (TRAF6) Signaling. J Biol Chem. 2015 Oct 30;290(44):26811-20. doi: 10.1074/jbc.M115.666578. Epub, 2015 Sep 18. PMID:26385923 doi:http://dx.doi.org/10.1074/jbc.M115.666578
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