6o8b
Crystal structure of STING CTD in complex with TBK1
Structural highlights
FunctionSTING_HUMAN Facilitator of innate immune signaling that acts as a sensor of cytosolic DNA from bacteria and viruses and promotes the production of type I interferon (IFN-alpha and IFN-beta). Innate immune response is triggered in response to non-CpG double-stranded DNA from viruses and bacteria delivered to the cytoplasm. Acts by recognizing and binding cyclic di-GMP (c-di-GMP), a second messenger produced by bacteria, and cyclic GMP-AMP (cGAMP), a messenger produced in response to DNA virus in the cytosol: upon binding of c-di-GMP or cGAMP, autoinhibition is alleviated and TMEM173/STING is able to activate both NF-kappa-B and IRF3 transcription pathways to induce expression of type I interferon and exert a potent anti-viral state. May be involved in translocon function, the translocon possibly being able to influence the induction of type I interferons. May be involved in transduction of apoptotic signals via its association with the major histocompatibility complex class II (MHC-II). Mediates death signaling via activation of the extracellular signal-regulated kinase (ERK) pathway.[1] [2] [3] [4] [5] [6] [7] Publication Abstract from PubMedNucleic acids from bacteria or viruses induce potent immune responses in infected cells(1-4). The detection of pathogen-derived nucleic acids is a central strategy by which the host senses infection and initiates protective immune responses(5,6). Cyclic GMP-AMP synthase (cGAS) is a double-stranded DNA sensor(7,8). It catalyses the synthesis of cyclic GMP-AMP (cGAMP)(9-12), which stimulates the induction of type I interferons through the STING-TBK1-IRF-3 signalling axis(13-15). STING oligomerizes after binding of cGAMP, leading to the recruitment and activation of the TBK1 kinase(8,16). The IRF-3 transcription factor is then recruited to the signalling complex and activated by TBK1(8,17-20). Phosphorylated IRF-3 translocates to the nucleus and initiates the expression of type I interferons(21). However, the precise mechanisms that govern activation of STING by cGAMP and subsequent activation of TBK1 by STING remain unclear. Here we show that a conserved PLPLRT/SD motif within the C-terminal tail of STING mediates the recruitment and activation of TBK1. Crystal structures of TBK1 bound to STING reveal that the PLPLRT/SD motif binds to the dimer interface of TBK1. Cell-based studies confirm that the direct interaction between TBK1 and STING is essential for induction of IFNbeta after cGAMP stimulation. Moreover, we show that full-length STING oligomerizes after it binds cGAMP, and highlight this as an essential step in the activation of STING-mediated signalling. These findings provide a structural basis for the development of STING agonists and antagonists for the treatment of cancer and autoimmune disorders. A conserved PLPLRT/SD motif of STING mediates the recruitment and activation of TBK1.,Zhao B, Du F, Xu P, Shu C, Sankaran B, Bell SL, Liu M, Lei Y, Gao X, Fu X, Zhu F, Liu Y, Laganowsky A, Zheng X, Ji JY, West AP, Watson RO, Li P Nature. 2019 May;569(7758):718-722. doi: 10.1038/s41586-019-1228-x. Epub 2019 May, 22. PMID:31118511[8] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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