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Structural titration of receptor ion channel GLIC gating by HS-AFM.

TitleStructural titration of receptor ion channel GLIC gating by HS-AFM.
Publication TypeJournal Article
Year of Publication2018
AuthorsRuan Y, Kao K, Lefebvre S, Marchesi A, Corringer P-J, Hite RK, Scheuring S
JournalProc Natl Acad Sci U S A
Date Published2018 Sep 04
ISSN1091-6490
Abstract

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.

DOI10.1073/pnas.1805621115
Alternate JournalProc. Natl. Acad. Sci. U.S.A.
PubMed ID30181288