Structure-function analysis of STING activation by c[G(2',5')pA(3',5')p] and targeting by antiviral DMXAA.
Publication Type:Journal Article
Source:Cell, Volume 154, Issue 4, p.748-62 (2013)
Keywords:Animals, Antiviral Agents, Crystallography, X-Ray, Cyclic GMP, Humans, Interferon Regulatory Factor-3, Interferon Type I, Membrane Proteins, Mice, Models, Molecular, Mutagenesis, Nucleotides, Cyclic, Protein Conformation, Signal Transduction, Structure-Activity Relationship, Xanthones
<p>Binding of dsDNA by cyclic GMP-AMP (cGAMP) synthase (cGAS) triggers formation of the metazoan second messenger c[G(2',5')pA(3',5')p], which binds the signaling protein STING with subsequent activation of the interferon (IFN) pathway. We show that human hSTING(H232) adopts a "closed" conformation upon binding c[G(2',5')pA(3',5')p] and its linkage isomer c[G(2',5')pA(2',5')p], as does mouse mSting(R231) on binding c[G(2',5')pA(3',5')p], c[G(3',5')pA(3',5')p] and the antiviral agent DMXAA, leading to similar "closed" conformations. Comparing hSTING to mSting, 2',5'-linkage-containing cGAMP isomers were more specific triggers of the IFN pathway compared to the all-3',5'-linkage isomer. Guided by structural information, we identified a unique point mutation (S162A) placed within the cyclic-dinucleotide-binding site of hSTING that rendered it sensitive to the otherwise mouse-specific drug DMXAA, a conclusion validated by binding studies. Our structural and functional analysis highlights the unexpected versatility of STING in the recognition of natural and synthetic ligands within a small-molecule pocket created by the dimerization of STING.</p>