7sii
From Proteopedia
Human STING bound to both cGAMP and 1-[(2-chloro-6-fluorophenyl)methyl]-3,3-dimethyl-2-oxo-N-[(2,4,6-trifluorophenyl)methyl]-2,3-dihydro-1H-indole-6-carboxamide (Compound 53)
Structural highlights
Function[STING_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 PubMedStimulator of interferon genes (STING) is an adaptor protein in innate immunity against DNA viruses or bacteria(1-5). STING-mediated immunity could be exploited in the development of vaccines or cancer immunotherapies. STING is a transmembrane dimeric protein that is located in the endoplasmic reticulum or in the Golgi apparatus. STING is activated by the binding of its cytoplasmic ligand-binding domain to cyclic dinucleotides that are produced by the DNA sensor cyclic GMP-AMP (cGAMP) synthase or by invading bacteria(1,6,7). Cyclic dinucleotides induce a conformational change in the STING ligand-binding domain, which leads to a high-order oligomerization of STING that is essential for triggering the downstream signalling pathways(8,9). However, the cGAMP-induced STING oligomers tend to dissociate in solution and have not been resolved to high resolution, which limits our understanding of the activation mechanism. Here we show that a small-molecule agonist, compound 53 (C53)(10), promotes the oligomerization and activation of human STING through a mechanism orthogonal to that of cGAMP. We determined a cryo-electron microscopy structure of STING bound to both C53 and cGAMP, revealing a stable oligomer that is formed by side-by-side packing and has a curled overall shape. Notably, C53 binds to a cryptic pocket in the STING transmembrane domain, between the two subunits of the STING dimer. This binding triggers outward shifts of transmembrane helices in the dimer, and induces inter-dimer interactions between these helices to mediate the formation of the high-order oligomer. Our functional analyses show that cGAMP and C53 together induce stronger activation of STING than either ligand alone. Activation of STING by targeting a pocket in the transmembrane domain.,Lu D, Shang G, Li J, Lu Y, Bai XC, Zhang X Nature. 2022 Apr 6. pii: 10.1038/s41586-022-04559-7. doi:, 10.1038/s41586-022-04559-7. PMID:35388221[8] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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Categories: Large Structures | Bai, X C | Jie, L | Lu, D | Lu, Y | Shang, G | Zhang, X | Activate conformation | Agonist | Immune system | Oligomer | Sting
