A chimeric prokaryotic pentameric ligand–gated channel reveals distinct pathways of activation

Abstract

A chimeric ligand–gated channel is activated by the ligands that activate both parent channels, which gate it through two distinct mechanisms.

A chimeric prokaryotic-eukaryotic pentameric ligand gated ion channel reveals interactions between the extracellular and transmembrane domains shape neurosteroid modulation

“…Consistent with previous studies (Alqazzaz et al, 2017; Bartos et al, 2009; Bouzat et al, 2008; Bouzat et al, 2004; Cooper et al, 1999; Duret et al, 2011; Eisele et al, 1993; Grutter et al, 2005a; Grutter et al, 2005b; Henault and Baenziger, 2017; Moraga-Cid et al, 2015; Schmandt et al, 2015; Tillman et al, 2014), our data underscore the modular nature of pLGICs. Several properties of the GABAρ TMD were preserved in our chimeric channels.…”

“…The precise location of the proton sensor in GLIC is still not clear (see (Alqazzaz et al, 2017; Duret et al, 2011; Henault and Baenziger, 2017; Schmandt et al, 2015; Wang et al, 2012)). Chimeric receptors containing the ECD of GLIC and the TMD of proton-insensitive pLGICs are activated by protons (Alqazzaz et al, 2017; Duret et al, 2011; Henault and Baenziger, 2017) suggesting that a proton sensor is located in the GLIC ECD.…”

“…Chimeric receptors containing the ECD of GLIC and the TMD of proton-insensitive pLGICs are activated by protons (Alqazzaz et al, 2017; Duret et al, 2011; Henault and Baenziger, 2017) suggesting that a proton sensor is located in the GLIC ECD. However, chimeric channels formed by fusing the proton-insensitive ECD of ELIC and TMD of GLIC are also activated by protons (Henault and Baenziger, 2017; Schmandt et al, 2015) suggesting that there is a proton binding site(s) in the GLIC TMD. Protonation of a histidine residue in the TMD of GLIC has been shown to be crtical for GLIC activation suggesting it is a proton sensor in GLIC (Rienzo et al, 2014; Wang et al, 2012).…”

The Synergetic Effects of Combining Structural Biology and EPR Spectroscopy on Membrane Proteins

“…The here selected advanced approach of cw and pulsed EPR spectroscopy in combination with X-ray crystallography demonstrates impressively the advantages of such a combination and how EPR spectroscopy is able to compensate for technical challenges related to crystallization. The paper investigated the activation mechanisms in a functional chimera of the extracellular domain (ECD) of amine-gated Erwinia chrysanthemi ligand-gated ion channel and the transmembrane domain (TMD) of Gloeobacter violaceus ligand-gated ion channel by applying cw and pulsed EPR spectroscopy [95]. However, this review focuses on the analyses of the cw EPR data proving that cw EPR studies at room temperature and the derived information about the spin label side chain dynamics yield valuable insights for the understanding of structural mechanism.…”

“…(A) Overlays of apo-ELIC (PDB 3RQU) and ELIC-GABA-flurazepam (PDB 4A96) with spin positions indicated and spin-normalized room temperature cw EPR spectra of interface domain residues L29R1 (β1-β2 loop), V82R1 (β4-β5 loop), M114R1, F116R1 (β6-β7 loop), and N184R1 (β6-β7 loop) in the apo state (black spectra), in the presence of 20 mM 3-AP (orange spectra), or at pH 3.0 (green spectra); (B) Overlay of GLIC structures in the closed (PDB 4NPQ, yellow) and open conformation (PDB 4HFI, green) with spin-labeled positions indicated and cw EPR spectra of K255R1 (M2-M3 linker) and F322R1 (M4) in the apo state (black spectra), in the presence of 20 mM 3-AP (orange spectra), and at pH 3.0 (green spectra). Taken from [95].…”