An ion selectivity filter in the extracellular domain of Cys-loop receptors reveals determinants for ion conductance

Scott B. Hansen, Hai Long Wang, Palmer Taylor, Steven M Sine

Research output: Contribution to journalArticle

46 Citations (Scopus)

Abstract

Neurotransmitter binding to Cys-loop receptors promotes a prodigious transmembrane flux of several million ions/s, but to date, structural determinants of ion flux have been identified flanking the membrane-spanning region. Using x-ray crystallography, sequence analysis, and single-channel recording, we identified a novel determinant of ion conductance near the point of entry of permeant ions. Co-crystallization of acetylcholine-binding protein with sulfate anions revealed coordination of SO42- with a ring of lysines at a position equivalent to 24 Å above the lipid membrane in homologous Cys-loop receptors. Analysis of multiple sequence alignments revealed that residues equivalent to the ring of lysines are negatively charged in cation-selective receptors but are positively charged in anion-selective receptors. Charge reversal of side chains at homologous positions in the nicotinic receptor from the motor end plate decreases unitary conductance up to 80%. Selectivity filters stemming from transmembrane α-helices have similar pore diameters and compositions of amino acids. These findings establish that when the channel opens under a physiological electrochemical gradient, permeant ions are initially stabilized within the extracellular vestibule of Cys-loop receptors, and this stabilization is a major determinant of ion conductance.

Original languageEnglish (US)
Pages (from-to)36066-36070
Number of pages5
JournalJournal of Biological Chemistry
Volume283
Issue number52
DOIs
StatePublished - Dec 26 2008

Fingerprint

Cysteine Loop Ligand-Gated Ion Channel Receptors
Ions
Lysine
Anions
Motor Endplate
Fluxes
Crystallography
Sequence Alignment
Nicotinic Receptors
Membrane Lipids
Crystallization
Sulfates
Acetylcholine
Neurotransmitter Agents
Sequence Analysis
Cations
Carrier Proteins
Stabilization
X-Rays
Membranes

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology
  • Molecular Biology

Cite this

An ion selectivity filter in the extracellular domain of Cys-loop receptors reveals determinants for ion conductance. / Hansen, Scott B.; Wang, Hai Long; Taylor, Palmer; Sine, Steven M.

In: Journal of Biological Chemistry, Vol. 283, No. 52, 26.12.2008, p. 36066-36070.

Research output: Contribution to journalArticle

@article{269bb456b3cb43a18904a095effeddca,
title = "An ion selectivity filter in the extracellular domain of Cys-loop receptors reveals determinants for ion conductance",
abstract = "Neurotransmitter binding to Cys-loop receptors promotes a prodigious transmembrane flux of several million ions/s, but to date, structural determinants of ion flux have been identified flanking the membrane-spanning region. Using x-ray crystallography, sequence analysis, and single-channel recording, we identified a novel determinant of ion conductance near the point of entry of permeant ions. Co-crystallization of acetylcholine-binding protein with sulfate anions revealed coordination of SO42- with a ring of lysines at a position equivalent to 24 {\AA} above the lipid membrane in homologous Cys-loop receptors. Analysis of multiple sequence alignments revealed that residues equivalent to the ring of lysines are negatively charged in cation-selective receptors but are positively charged in anion-selective receptors. Charge reversal of side chains at homologous positions in the nicotinic receptor from the motor end plate decreases unitary conductance up to 80{\%}. Selectivity filters stemming from transmembrane α-helices have similar pore diameters and compositions of amino acids. These findings establish that when the channel opens under a physiological electrochemical gradient, permeant ions are initially stabilized within the extracellular vestibule of Cys-loop receptors, and this stabilization is a major determinant of ion conductance.",
author = "Hansen, {Scott B.} and Wang, {Hai Long} and Palmer Taylor and Sine, {Steven M}",
year = "2008",
month = "12",
day = "26",
doi = "10.1074/jbc.C800194200",
language = "English (US)",
volume = "283",
pages = "36066--36070",
journal = "Journal of Biological Chemistry",
issn = "0021-9258",
publisher = "American Society for Biochemistry and Molecular Biology Inc.",
number = "52",

}

TY - JOUR

T1 - An ion selectivity filter in the extracellular domain of Cys-loop receptors reveals determinants for ion conductance

AU - Hansen, Scott B.

AU - Wang, Hai Long

AU - Taylor, Palmer

AU - Sine, Steven M

PY - 2008/12/26

Y1 - 2008/12/26

N2 - Neurotransmitter binding to Cys-loop receptors promotes a prodigious transmembrane flux of several million ions/s, but to date, structural determinants of ion flux have been identified flanking the membrane-spanning region. Using x-ray crystallography, sequence analysis, and single-channel recording, we identified a novel determinant of ion conductance near the point of entry of permeant ions. Co-crystallization of acetylcholine-binding protein with sulfate anions revealed coordination of SO42- with a ring of lysines at a position equivalent to 24 Å above the lipid membrane in homologous Cys-loop receptors. Analysis of multiple sequence alignments revealed that residues equivalent to the ring of lysines are negatively charged in cation-selective receptors but are positively charged in anion-selective receptors. Charge reversal of side chains at homologous positions in the nicotinic receptor from the motor end plate decreases unitary conductance up to 80%. Selectivity filters stemming from transmembrane α-helices have similar pore diameters and compositions of amino acids. These findings establish that when the channel opens under a physiological electrochemical gradient, permeant ions are initially stabilized within the extracellular vestibule of Cys-loop receptors, and this stabilization is a major determinant of ion conductance.

AB - Neurotransmitter binding to Cys-loop receptors promotes a prodigious transmembrane flux of several million ions/s, but to date, structural determinants of ion flux have been identified flanking the membrane-spanning region. Using x-ray crystallography, sequence analysis, and single-channel recording, we identified a novel determinant of ion conductance near the point of entry of permeant ions. Co-crystallization of acetylcholine-binding protein with sulfate anions revealed coordination of SO42- with a ring of lysines at a position equivalent to 24 Å above the lipid membrane in homologous Cys-loop receptors. Analysis of multiple sequence alignments revealed that residues equivalent to the ring of lysines are negatively charged in cation-selective receptors but are positively charged in anion-selective receptors. Charge reversal of side chains at homologous positions in the nicotinic receptor from the motor end plate decreases unitary conductance up to 80%. Selectivity filters stemming from transmembrane α-helices have similar pore diameters and compositions of amino acids. These findings establish that when the channel opens under a physiological electrochemical gradient, permeant ions are initially stabilized within the extracellular vestibule of Cys-loop receptors, and this stabilization is a major determinant of ion conductance.

UR - http://www.scopus.com/inward/record.url?scp=61349137676&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=61349137676&partnerID=8YFLogxK

U2 - 10.1074/jbc.C800194200

DO - 10.1074/jbc.C800194200

M3 - Article

C2 - 18940802

AN - SCOPUS:61349137676

VL - 283

SP - 36066

EP - 36070

JO - Journal of Biological Chemistry

JF - Journal of Biological Chemistry

SN - 0021-9258

IS - 52

ER -