Download MendeleyDynamic closed states of a ligand-gated ion channel captured by cryo-EM and simulations.
Rovsnik, U., Zhuang, Y., Forsberg, B.O., Carroni, M., Yvonnesdotter, L., Howard, R.J., Lindahl, E.(2021) Life Sci Alliance 4
- PubMed: 34210687
- DOI: https://doi.org/10.26508/lsa.202101011
- Primary Citation of Related Structures:
6ZGD, 6ZGJ, 6ZGK - PubMed Abstract:
Ligand-gated ion channels are critical mediators of electrochemical signal transduction across evolution. Biophysical and pharmacological characterization of these receptor proteins relies on high-quality structures in multiple, subtly distinct functional states. However, structural data in this family remain limited, particularly for resting and intermediate states on the activation pathway. Here, we report cryo-electron microscopy (cryo-EM) structures of the proton-activated Gloeobacter violaceus ligand-gated ion channel (GLIC) under three pH conditions. Decreased pH was associated with improved resolution and side chain rearrangements at the subunit/domain interface, particularly involving functionally important residues in the β1-β2 and M2-M3 loops. Molecular dynamics simulations substantiated flexibility in the closed-channel extracellular domains relative to the transmembrane ones and supported electrostatic remodeling around E35 and E243 in proton-induced gating. Exploration of secondary cryo-EM classes further indicated a low-pH population with an expanded pore. These results allow us to define distinct protonation and activation steps in pH-stimulated conformational cycling in GLIC, including interfacial rearrangements largely conserved in the pentameric channel family.
Organizational Affiliation:
Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, Solna, Sweden.
