title: Binary architecture of the Nav1.2-β2 signaling complex.
abstract: To investigate the mechanisms by which β-subunits influence Nav channel function, we solved the crystal structure of the β2 extracellular domain at 1.35Å. We combined these data with known bacterial Nav channel structural insights and novel functional studies to determine the interactions of specific residues in β2 with Nav1.2. We identified a flexible loop formed by (72)Cys and (75)Cys, a unique feature among the four β-subunit isoforms. Moreover, we found that (55)Cys helps to determine the influence of β2 on Nav1.2 toxin susceptibility. Further mutagenesis combined with the use of spider toxins reveals that (55)Cys forms a disulfide bond with (910)Cys in the Nav1.2 domain II pore loop, thereby suggesting a 1:1 stoichiometry. Our results also provide clues as to which disulfide bonds are formed between adjacent Nav1.2 (912/918)Cys residues. The concepts emerging from this work will help to form a model reflecting the β-subunit location in a Nav channel complex.
authors.affiliation: Department of Biochemistry and Molecular Biology, Life Sciences Institute, University of British Columbia, Vancouver, Canada.
authors.forename: Samir
authors.initials: S
authors.lastname: Das
authors.affiliation: Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, United States.
authors.forename: John
authors.initials: J
authors.lastname: Gilchrist
authors.affiliation: Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, United States.|Solomon H Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, United States.
authors.forename: Frank
authors.initials: F
authors.lastname: Bosmans
authors.affiliation: Department of Biochemistry and Molecular Biology, Life Sciences Institute, University of British Columbia, Vancouver, Canada.
authors.forename: Filip
authors.initials: F
authors.lastname: Van Petegem
mesh_terms: D018360:Crystallography, X-Ray; D004252:DNA Mutational Analysis; D006801:Humans; D062551:NAV1.2 Voltage-Gated Sodium Channel / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D025941:Protein Interaction Mapping; D021122:Protein Subunits / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D062551:NAV1.2 Voltage-Gated Sodium Channel; D021122:Protein Subunits
keywords: <i>e. coli</i>; X-ray structure; beta2 subunit; biophysics; disulfide; scn2b; spider toxin; structural biology; voltage-gated sodium channel; xenopus