PDBsum entry 6f11

Membrane protein

PDB id: 6f11

Contents

Protein chains

311 a.a.

Ligands

ACT ×10

LMT ×6

PLC ×2

Metals

_CL ×7

_NA ×6

Waters ×36

PDB id:

6f11

Name:

Membrane protein

Title:

Glic mutant d86a

Structure:

Proton-gated ion channel. Chain: a, b, c, d, e. Synonym: glic,ligand-gated ion channel,lgic. Engineered: yes

Source:

Gloeobacter violaceus (strain pcc 7421). Organism_taxid: 251221. Strain: pcc 7421. Gene: glvi, glr4197. Expressed in: escherichia coli. Expression_system_taxid: 562

Resolution:

2.95Å R-factor: 0.196 R-free: 0.216

Authors:

H.D.Hu,M.Delarue

Key ref:

�.�.Nemecz et al. (2017). Full mutational mapping of titratable residues helps to identify proton-sensors involved in the control of channel gating in the Gloeobacter violaceus pentameric ligand-gated ion channel. PLoS Biol, 15, e2004470. PubMed id: 29281623

Date:

21-Nov-17 Release date: 10-Jan-18

Protein chains

Q7NDN8  (GLIC_GLOVI) -  Proton-gated ion channel from Gloeobacter violaceus (strain ATCC 29082 / PCC 7421)

Seq: 359 a.a.

Struc: 311 a.a.*

* PDB and UniProt seqs differ at 1 residue position (black cross)

Enzyme reactions

• Enzyme class: E.C.?

PLoS Biol 15:e2004470 (2017)

PubMed id: 29281623

Full mutational mapping of titratable residues helps to identify proton-sensors involved in the control of channel gating in the Gloeobacter violaceus pentameric ligand-gated ion channel.

�.�.Nemecz, H.Hu, Z.Fourati, C.Van Renterghem, M.Delarue, P.J.Corringer.

ABSTRACT

The Gloeobacter violaceus ligand-gated ion channel (GLIC) has been extensively studied by X-ray crystallography and other biophysical techniques. This provided key insights into the general gating mechanism of pentameric ligand-gated ion channel (pLGIC) signal transduction. However, the GLIC is activated by lowering the pH and the location of its putative proton activation site(s) still remain(s) unknown. To this end, every Asp, Glu, and His residue was mutated individually or in combination and investigated by electrophysiology. In addition to the mutational analysis, key mutations were structurally resolved to address whether particular residues contribute to proton sensing, or alternatively to GLIC-gating, independently of the side chain protonation. The data show that multiple residues located below the orthosteric site, notably E26, D32, E35, and D122 in the lower part of the extracellular domain (ECD), along with E222, H235, E243, and H277 in the transmembrane domain (TMD), alter GLIC activation. D122 and H235 were found to also alter GLIC expression. E35 is identified as a key proton-sensing residue, whereby neutralization of its side chain carboxylate stabilizes the active state. Thus, proton activation occurs allosterically to the orthosteric site, at the level of multiple loci with a key contribution of the coupling interface between the ECD and TMD.