SUMO modification of TBK1 at the adaptor-binding C-terminal coiled-coil domain contributes to its antiviral activity

Abstract

The non-canonical IKK kinase TBK1 serves as an important signal transmitter of the antiviral interferon response, but is also involved in the regulation of further processes such as autophagy. The activity of TBK1 is regulated by posttranslational modifications comprising phosphorylation and ubiquitination. This study identifies SUMOylation as a novel posttranslational TBK1 modification. TBK1 kinase activity is required to allow the attachment of SUMO1 or SUMO2/3 proteins. Since TBK1 does not bind to the E2 enzyme Ubc9, this modification most likely proceeds via trans-SUMOylation. Mass spectrometry allowed identifying K694 as the SUMO acceptor site, a residue located in the C-terminal coiled-coil domain which is exclusively responsible for the association with the adaptor proteins NAP1, Sintbad and TANK. SUMO modification at K694 contributes to the antiviral function of TBK1 and accordingly the viral protein Gam1 antagonizes this posttranslational modification.

Methyltransferase Dnmt3a upregulates HDAC9 to deacetylate the kinase TBK1 for activation of antiviral innate immunity

“…Autophosphorylation of TBK1 at Ser172 and K63-linked polyubiquitination of TBK1 are essential for its activation 18,25 . Modification at Lys694 of TBK1 with the small ubiquitin-like modifier SUMO contributes to adaptor binding for the transduction of antiviral signaling 48 . Furthermore, the kinase activity of TBK1 is also regulated through protein interaction, chemical compounds and hormones in a PTM-independent manner 49 .…”

USP7‐TRIM27 axis negatively modulates antiviral type I IFN signaling

“…The phosphorylated state or expression level of TBK1 is precisely modulated by diverse regulators through post-translational modifications, such as phosphorylation, ubiquitination, deubiquitination, and SUMOylation. (28,30,(57)(58)(59)(60)(61)(62). For instance, protein phosphatase, Mg2 + /Mn2 + -dependent 1A and 1B, protein phosphatase 4, Raf kinase inhibitor protein, glycogen synthase kinase-3b, and glucocorticoids have been reported to modulate TBK1 activity through phosphorylation and dephosphorylation (63)(64)(65)(66)(67).…”

“…All data are representative of at least 3 independent experiments. *P , 0.05, **P , 0.01. its activity in innate immune response (59). The methyltransferase DNA (cytosine-5)-methyltransferase 3a upregulates histone deacetylase-9 to maintain the deacetylation status of TBK1 and enhanced its kinase activity (75).…”

The CCR4-NOT complex contributes to repression of Major Histocompatibility Complex class II transcription

“…Raji B cell lymphoma cells were cultured in RPMI medium supplemented with 10% FCS, Glutamine, Penicillin and Streptomycin. Transfection of adherent cells was done using linear polyethylenimine as described 72 . Raji suspension cells were electroporated using a Biorad electroporator.…”