We are grateful to the staff at the OHSU Multiscale Microscopy Core and Advanced Computing center, and to the Pacific Northwest Center for CryoEM (supported by NIH Grant U24GM129547), and accessed through EMSL (grid.436923.9). J.A.F. and B. G.H. are supported by the National Institutes of Health NRSA fellowships F31-EY030409 and F31-EY031580, respectively. K.A.D. is supported by National Institutes of Health BUILD EXITO Program (TL4-GM118965) and Berkeley Molecular Biophysics Training Grant (T32-GM008295). C.C.Y. is supported by OHSU. J.C. and D.M.Z. are supported by the OHSU Center for Spatial Systems Biomedicine, by the National Science Foundation (MCB 1715823), and by the National Institutes of Health (R01-GM115805). S.L.R. is supported by the National Institutes of Health (R35-GM124779).
Connexins -- Analysis, Cell interaction, Gap junctions (Cell biology) -- Molecular aspects, Lipids -- Microstructure
Gap junctions establish direct pathways for cells to transfer metabolic and electrical messages. The local lipid environment is known to affect the structure, stability and intercellular channel activity of gap junctions; however, the molecular basis for these effects remains unknown. Here, we incorporate native connexin-46/50 (Cx46/50) intercellular channels into a dual lipid nanodisc system, mimicking a native cell-to-cell junction. Structural characterization by CryoEM reveals a lipid-induced stabilization to the channel, resulting in a 3D reconstruction at 1.9 Å resolution. Together with all-atom molecular dynamics simulations, it is shown that Cx46/50 in turn imparts long-range stabilization to the dynamic local lipid environment that is specific to the extracellular lipid leaflet. In addition, ~400 water molecules are resolved in the CryoEM map, localized throughout the intercellular permeation pathway and contributing to the channel architecture. These results illustrate how the aqueous-lipid environment is integrated with the architectural stability, structure and function of gap junction communication channels.
Flores, J.A., Haddad, B.G., Dolan, K.A. et al. Connexin-46/50 in a dynamic lipid environment resolved by CryoEM at 1.9 Å. Nat Commun 11, 4331 (2020). https://doi.org/10.1038/s41467-020-18120-5