Structure of the connexin-43 gap junction channel reveals a closed sieve-like molecular gate

Qi, C.; Acosta-Gutierrez, S.; Lavriha, P.; Othman, A.; Lopez-Pigozzi, D.; Bayraktar, E.; Schuster, D.; Picotti, P.; Zamboni, N.; Bortolozzi, M.; Gervasio, F. L.; Korkhov, V. M.

doi:10.1101/2022.03.26.485947

bioRxiv · 10.1101/2022.03.26.485947

Structure of the connexin-43 gap junction channel reveals a closed sieve-like molecular gate

Qi, C.·Acosta-Gutierrez, S.·Lavriha, P.·Othman, A.·Lopez-Pigozzi, D.·Bayraktar, E.·Schuster, D.·Picotti, P.·Zamboni, N.·Bortolozzi, M.·Gervasio, F. L.·Korkhov, V. M.

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Abstract

Gap junction channels (GJCs) mediate intercellular communication by connecting two neighboring 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 1-3, 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 [A] 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 in nanodiscs reveal a similar gate arrangement. The features of the Cx43 GJC and hemichannel 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.

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Qi, C., Acosta-Gutierrez, S., Lavriha, P., Othman, A., Lopez-Pigozzi, D., Bayraktar, E., Schuster, D., Picotti, P., Zamboni, N., Bortolozzi, M., Gervasio, F. L., Korkhov, V. M.. 2022-03-27. Structure of the connexin-43 gap junction channel reveals a closed sieve-like molecular gate. https://doi.org/10.1101/2022.03.26.485947

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