Parallel homodimer structures of the extracellular domains of the voltage-gated sodium channel β4 subunit explain its role in cell–cell adhesion

Autor: Takaho Terada, Fumitaka Oyama, Haruko Miyazaki, Shun-ichi Sekine, Shisako Shoji, Nobuyuki Nukina, Mikako Shirouzu, Hideaki Shimizu, Yoshiko Ishizuka-Katsura, Shigeyuki Yokoyama, Asako Tosaki, Noboru Ohsawa
Rok vydání: 2017
Předmět:
Models
Molecular

0301 basic medicine
Protein Conformation
Recombinant Fusion Proteins
Dimer
CHO Cells
Crystallography
X-Ray

Biochemistry
Mice
03 medical and health sciences
chemistry.chemical_compound
Cricetulus
0302 clinical medicine
Cell Adhesion
Extracellular
Animals
Humans
membrane protein
Protein Interaction Domains and Motifs
Cysteine
Cell adhesion
Molecular Biology
X-ray crystallography
Voltage-Gated Sodium Channel beta-4 Subunit
Chemistry
Sodium channel
Wild type
Hydrogen Bonding
Cell Biology
Adhesion
dimer
Peptide Fragments
Recombinant Proteins
Transmembrane protein
Cell biology
immunoglobulin-like domain
030104 developmental biology
Membrane protein
Protein Structure and Folding
Cystine
Protein Conformation
beta-Strand

Navβ4
Protein Multimerization
SCN4B
Dimerization
Hydrophobic and Hydrophilic Interactions
030217 neurology & neurosurgery
sodium channel
Zdroj: The Journal of Biological Chemistry
ISSN: 0021-9258
Popis: Voltage-gated sodium channels (VGSCs) are transmembrane proteins required for the generation of action potentials in excitable cells and essential for propagating electrical impulses along nerve cells. VGSCs are complexes of a pore-forming α subunit and auxiliary β subunits, designated as β1/β1B–β4 (encoded by SCN1B–4B, respectively), which also function in cell–cell adhesion. We previously reported the structural basis for the trans homophilic interaction of the β4 subunit, which contributes to its adhesive function. Here, using crystallographic and biochemical analyses, we show that the β4 extracellular domains directly interact with each other in a parallel manner that involves an intermolecular disulfide bond between the unpaired Cys residues (Cys58) in the loop connecting strands B and C and intermolecular hydrophobic and hydrogen-bonding interactions of the N-terminal segments (Ser30-Val35). Under reducing conditions, an N-terminally deleted β4 mutant exhibited decreased cell adhesion compared with the wild type, indicating that the β4 cis dimer contributes to the trans homophilic interaction of β4 in cell–cell adhesion. Furthermore, this mutant exhibited increased association with the α subunit, indicating that the cis dimerization of β4 affects α–β4 complex formation. These observations provide the structural basis for the parallel dimer formation of β4 in VGSCs and reveal its mechanism in cell–cell adhesion.
Databáze: OpenAIRE