|Title||Structural titration of receptor ion channel GLIC gating by HS-AFM.|
|Publication Type||Journal Article|
|Year of Publication||2018|
|Authors||Ruan Y, Kao K, Lefebvre S, Marchesi A, Corringer P-J, Hite RK, Scheuring S|
|Journal||Proc Natl Acad Sci U S A|
|Date Published||2018 Sep 04|
ligand-gated ion channel (GLIC), a proton-gated, cation-selective channel, is a prokaryotic homolog of the pentameric Cys-loop receptor ligand-gated ion channel family. Despite large changes in ion conductance, small conformational changes were detected in X-ray structures of detergent-solubilized GLIC at pH 4 (active/desensitized state) and pH 7 (closed state). Here, we used high-speed atomic force microscopy (HS-AFM) combined with a buffer exchange system to perform structural titration experiments to visualize GLIC gating at the single-molecule level under native conditions. Reference-free 2D classification revealed channels in multiple conformational states during pH gating. We find changes of protein-protein interactions so far elusive and conformational dynamics much larger than previously assumed. Asymmetric pentamers populate early stages of activation, which provides evidence for an intermediate preactivated state.
|Alternate Journal||Proc. Natl. Acad. Sci. U.S.A.|