Structure of the connexin-43 gap junction channel in a putative closed state

• Published in: eLife Vol. 12
• Main Authors: Qi, Chao, Acosta Gutierrez, Silvia, Lavriha, Pia, Othman, Alaa, Lopez-Pigozzi, Diego, Bayraktar, Erva, Schuster, Dina, Picotti, Paola, Zamboni, Nicola, Bortolozzi, Mario, Gervasio, Francesco Luigi, Korkhov, Volodymyr M
• Format: Journal Article
• Language: English
• Published: England eLife Science Publications, Ltd 03-08-2023; eLife Sciences Publications Ltd; eLife Sciences Publications, Ltd
• Subjects: Analysis; Biochemistry and Chemical Biology; Cell Communication - physiology; Cells; Chromatography; Conformation; Connexin 43; Connexin 43 - metabolism; cryo-EM; Data collection; gap junction channel; Gap Junctions - metabolism; hemichannel; Humans; Ion Channels - physiology; membrane protein; Metabolism; Metabolites; Microscopy; Molecular dynamics; Proteins; Scientific equipment and supplies industry; Somatotropin; Structural Biology and Molecular Biophysics; structure; United States; chemical biology; hemichannel; biochemistry; membrane protein; structural biology; gap junction channel; molecular biophysics; cryo-EM; human; structure; connexin-43
• ISSN: 2050-084X; 2050-084X
• DOI: 10.7554/eLife.87616

Gap junction channels (GJCs) mediate intercellular communication by connecting two neighbouring cells and enabling direct exchange of ions and small molecules. Cell coupling via connexin-43 (Cx43) GJCs is important in a wide range of cellular processes in health and disease (Churko and Laird, 2013; Liang et al., 2020; Poelzing and Rosenbaum, 2004), yet the structural basis of Cx43 function and regulation has not been determined until now. Here, we describe the structure of a human Cx43 GJC solved by cryo-EM and single particle analysis at 2.26 Å resolution. The pore region of Cx43 GJC features several lipid-like densities per Cx43 monomer, located close to a putative lateral access site at the monomer boundary. We found a previously undescribed conformation on the cytosolic side of the pore, formed by the N-terminal domain and the transmembrane helix 2 of Cx43 and stabilized by a small molecule. Structures of the Cx43 GJC and hemichannels (HCs) in nanodiscs reveal a similar gate arrangement. The features of the Cx43 GJC and HC cryo-EM maps and the channel properties revealed by molecular dynamics simulations suggest that the captured states of Cx43 are consistent with a closed state.