title: Single-particle EM reveals the higher-order domain architecture of soluble guanylate cyclase.
abstract: 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.
authors: Department of Integrative Structural and Computational Biology, National Resource for Automated Molecular Microscopy, and Department of Chemistry, The Scripps Research Institute, La Jolla, CA, 92037.
authors: Melody G
authors: MG
authors: Campbell
authors: Eric S
authors: ES
authors: Underbakke
authors: Clinton S
authors: CS
authors: Potter
authors: Bridget
authors: B
authors: Carragher
authors: Michael A
authors: MA
authors: Marletta
mesh_terms: D000818:Animals; D003001:Cloning, Molecular; D020536:Enzyme Activators / Q000378:metabolism; D006162:Guanylate Cyclase / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure*; D007091:Image Processing, Computer-Assisted; D046529:Microscopy, Electron, Transmission; D008958:Models, Molecular; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D051381:Rats; D018160:Receptors, Cytoplasmic and Nuclear / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure*; D000071756:Soluble Guanylyl Cyclase
chemical_list: D020536:Enzyme Activators; D018160:Receptors, Cytoplasmic and Nuclear; D006162:Guanylate Cyclase; D000071756:Soluble Guanylyl Cyclase