Cryo-EM structures of STING reveal its mechanism of activation by cyclic GMP–AMP

Guijun Shang, Conggang Zhang, Zhijian J. Chen, Xiao chen Bai, Xuewu Zhang

Research output: Contribution to journalArticlepeer-review

235 Scopus citations


Infections by pathogens that contain DNA trigger the production of type-I interferons and inflammatory cytokines through cyclic GMP–AMP synthase, which produces 2′3′-cyclic GMP–AMP (cGAMP) that binds to and activates stimulator of interferon genes (STING; also known as TMEM173, MITA, ERIS and MPYS)1–8. STING is an endoplasmic-reticulum membrane protein that contains four transmembrane helices followed by a cytoplasmic ligand-binding and signalling domain9–13. The cytoplasmic domain of STING forms a dimer, which undergoes a conformational change upon binding to cGAMP9,14. However, it remains unclear how this conformational change leads to STING activation. Here we present cryo-electron microscopy structures of full-length STING from human and chicken in the inactive dimeric state (about 80 kDa in size), as well as cGAMP-bound chicken STING in both the dimeric and tetrameric states. The structures show that the transmembrane and cytoplasmic regions interact to form an integrated, domain-swapped dimeric assembly. Closure of the ligand-binding domain, induced by cGAMP, leads to a 180° rotation of the ligand-binding domain relative to the transmembrane domain. This rotation is coupled to a conformational change in a loop on the side of the ligand-binding-domain dimer, which leads to the formation of the STING tetramer and higher-order oligomers through side-by-side packing. This model of STING oligomerization and activation is supported by our structure-based mutational analyses.

Original languageEnglish (US)
Pages (from-to)389-393
Number of pages5
Issue number7748
StatePublished - Mar 21 2019

ASJC Scopus subject areas

  • General


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