Structure-function analysis of STING activation by c[G(2',5')pA(3',5')p] and targeting by antiviral DMXAA

Cell. 2013 Aug 15;154(4):748-62. doi: 10.1016/j.cell.2013.07.023. Epub 2013 Aug 1.

Abstract

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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antiviral Agents / pharmacology*
  • Crystallography, X-Ray
  • Cyclic GMP / metabolism
  • Humans
  • Interferon Regulatory Factor-3 / metabolism
  • Interferon Type I / metabolism
  • Membrane Proteins / antagonists & inhibitors
  • Membrane Proteins / chemistry*
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Mice
  • Models, Molecular
  • Mutagenesis
  • Nucleotides, Cyclic / metabolism*
  • Protein Conformation
  • Signal Transduction
  • Structure-Activity Relationship
  • Xanthones / pharmacology*

Substances

  • Antiviral Agents
  • Interferon Regulatory Factor-3
  • Interferon Type I
  • MPYS protein, mouse
  • Membrane Proteins
  • Nucleotides, Cyclic
  • STING protein, human
  • Xanthones
  • cyclic guanosine monophosphate-adenosine monophosphate
  • vadimezan
  • Cyclic GMP