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Proc Natl Acad Sci U S A. 2018 Oct 9;115(41):10333-10338. doi: 10.1073/pnas.1805621115. Epub 2018 Sep 4.

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

Author information

1
Collaborative Innovation Center for Bio-Med Physics Information Technology, College of Science, Zhejiang University of Technology, 310023 Hangzhou, China.
2
U1006 INSERM, Université Aix-Marseille, Parc Scientifique et Technologique de Luminy, 13009 Marseille, France.
3
Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065.
4
Weill Cornell/Rockefeller/Sloan Kettering Tri-Institutional MD-PhD Program, New York, NY 10065.
5
Channel-Receptors Unit, Institut Pasteur, CNRS UMR 3571, 75015 Paris, France.
6
U1006 INSERM, Université Aix-Marseille, Parc Scientifique et Technologique de Luminy, 13009 Marseille, France; sis2019@med.cornell.edu.
7
Department of Anesthesiology, Weill Cornell Medicine, New York, NY 10065.
8
Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY 10065.

Abstract

Gloeobacter violaceus 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.

KEYWORDS:

Cys-loop; GLIC; HS-AFM; conformational change; ion channel

PMID:
30181288
PMCID:
PMC6187180
DOI:
10.1073/pnas.1805621115
[Indexed for MEDLINE]
Free PMC Article

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