Single-particle EM reveals the higher-order domain architecture of soluble guanylate cyclase

Proc Natl Acad Sci U S A. 2014 Feb 25;111(8):2960-5. doi: 10.1073/pnas.1400711111. Epub 2014 Feb 10.


Soluble guanylate cyclase (sGC) is the primary nitric oxide (NO) receptor in mammals and a central component of the NO-signaling pathway. The NO-signaling pathways mediate diverse physiological processes, including vasodilation, neurotransmission, and myocardial functions. sGC is a heterodimer assembled from two homologous subunits, each comprised of four domains. Although crystal structures of isolated domains have been reported, no structure is available for full-length sGC. We used single-particle electron microscopy to obtain the structure of the complete sGC heterodimer and determine its higher-order domain architecture. Overall, the protein is formed of two rigid modules: the catalytic dimer and the clustered Per/Art/Sim and heme-NO/O2-binding domains, connected by a parallel coiled coil at two hinge points. The quaternary assembly demonstrates a very high degree of flexibility. We captured hundreds of individual conformational snapshots of free sGC, NO-bound sGC, and guanosine-5'-[(α,β)-methylene]triphosphate-bound sGC. The molecular architecture and pronounced flexibility observed provides a significant step forward in understanding the mechanism of NO signaling.

Publication types

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

MeSH terms

  • Animals
  • Cloning, Molecular
  • Enzyme Activators / metabolism
  • Guanylate Cyclase / chemistry*
  • Guanylate Cyclase / metabolism
  • Guanylate Cyclase / ultrastructure*
  • Image Processing, Computer-Assisted
  • Microscopy, Electron, Transmission
  • Models, Molecular*
  • Protein Binding
  • Protein Conformation*
  • Protein Structure, Tertiary
  • Rats
  • Receptors, Cytoplasmic and Nuclear / chemistry*
  • Receptors, Cytoplasmic and Nuclear / metabolism
  • Receptors, Cytoplasmic and Nuclear / ultrastructure*
  • Soluble Guanylyl Cyclase


  • Enzyme Activators
  • Receptors, Cytoplasmic and Nuclear
  • Guanylate Cyclase
  • Soluble Guanylyl Cyclase