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J Biol Chem
2013 Oct 18;28842:30373-30386. doi: 10.1074/jbc.M113.494583.
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Cysteine substitutions define etomidate binding and gating linkages in the α-M1 domain of γ-aminobutyric acid type A (GABAA) receptors.
Stewart DS
,
Hotta M
,
Li GD
,
Desai R
,
Chiara DC
,
Olsen RW
,
Forman SA
.
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Etomidate is a potent general anesthetic that acts as an allosteric co-agonist at GABAA receptors. Photoreactive etomidate derivatives labeled αMet-236 in transmembrane domain M1, which structural models locate in the β+/α- subunit interface. Other nearby residues may also contribute to etomidate binding and/or transduction through rearrangement of the site. In human α1β2γ2L GABAA receptors, we applied the substituted cysteine accessibility method to α1-M1 domain residues extending from α1Gln-229 to α1Gln-242. We used electrophysiology to characterize each mutant's sensitivity to GABA and etomidate. We also measured rates of sulfhydryl modification by p-chloromercuribenzenesulfonate (pCMBS) with and without GABA and tested if etomidate blocks modification of pCMBS-accessible cysteines. Cys substitutions in the outer α1-M1 domain impaired GABA activation and variably affected etomidate sensitivity. In seven of eight residues where pCMBS modification was evident, rates of modification were accelerated by GABA co-application, indicating that channel activation increases water and/or pCMBS access. Etomidate reduced the rate of modification for cysteine substitutions at α1Met-236, α1Leu-232 and α1Thr-237. We infer that these residues, predicted to face β2-M3 or M2 domains, contribute to etomidate binding. Thus, etomidate interacts with a short segment of the outer α1-M1 helix within a subdomain that undergoes significant structural rearrangement during channel gating. Our results are consistent with in silico docking calculations in a homology model that orient the long axis of etomidate approximately orthogonal to the transmembrane axis.
Akk,
Mutations of the GABA-A receptor alpha1 subunit M1 domain reveal unexpected complexity for modulation by neuroactive steroids.
2008, Pubmed
Akk,
Mutations of the GABA-A receptor alpha1 subunit M1 domain reveal unexpected complexity for modulation by neuroactive steroids.
2008,
Pubmed
Bali,
Gating-induced conformational rearrangement of the γ-aminobutyric acid type A receptor β-α subunit interface in the membrane-spanning domain.
2012,
Pubmed
,
Xenbase
Bali,
GABA-induced intersubunit conformational movement in the GABAA receptor alpha 1M1-beta 2M3 transmembrane subunit interface: experimental basis for homology modeling of an intravenous anesthetic binding site.
2009,
Pubmed
,
Xenbase
Bali,
Defining the propofol binding site location on the GABAA receptor.
2004,
Pubmed
,
Xenbase
Baumann,
Forced subunit assembly in alpha1beta2gamma2 GABAA receptors. Insight into the absolute arrangement.
2002,
Pubmed
,
Xenbase
Belelli,
The interaction of the general anesthetic etomidate with the gamma-aminobutyric acid type A receptor is influenced by a single amino acid.
1997,
Pubmed
,
Xenbase
Bocquet,
X-ray structure of a pentameric ligand-gated ion channel in an apparently open conformation.
2009,
Pubmed
Burkat,
Dominant gating governing transient GABA(A) receptor activity: a first latency and Po/o analysis.
2001,
Pubmed
Carlson,
A single glycine residue at the entrance to the first membrane-spanning domain of the gamma-aminobutyric acid type A receptor beta(2) subunit affects allosteric sensitivity to GABA and anesthetics.
2000,
Pubmed
Chiara,
Mapping general anesthetic binding site(s) in human α1β3 γ-aminobutyric acid type A receptors with [³H]TDBzl-etomidate, a photoreactive etomidate analogue.
2012,
Pubmed
Chiara,
Specificity of intersubunit general anesthetic-binding sites in the transmembrane domain of the human α1β3γ2 γ-aminobutyric acid type A (GABAA) receptor.
2013,
Pubmed
Desai,
Gamma-amino butyric acid type A receptor mutations at beta2N265 alter etomidate efficacy while preserving basal and agonist-dependent activity.
2009,
Pubmed
,
Xenbase
Forman,
Anesthetic sites and allosteric mechanisms of action on Cys-loop ligand-gated ion channels.
2011,
Pubmed
Franks,
General anaesthesia: from molecular targets to neuronal pathways of sleep and arousal.
2008,
Pubmed
Ghosh,
Propofol binding to the resting state of the gloeobacter violaceus ligand-gated ion channel (GLIC) induces structural changes in the inter- and intrasubunit transmembrane domain (TMD) cavities.
2013,
Pubmed
,
Xenbase
Gonzalez-Gutierrez,
Bridging the gap between structural models of nicotinic receptor superfamily ion channels and their corresponding functional states.
2010,
Pubmed
Graham,
A new technique for the assay of infectivity of human adenovirus 5 DNA.
1973,
Pubmed
Greenfield,
Mutation of the GABAA receptor M1 transmembrane proline increases GABA affinity and reduces barbiturate enhancement.
2002,
Pubmed
,
Xenbase
Guitchounts,
Two etomidate sites in α1β2γ2 γ-aminobutyric acid type A receptors contribute equally and noncooperatively to modulation of channel gating.
2012,
Pubmed
,
Xenbase
Hibbs,
Principles of activation and permeation in an anion-selective Cys-loop receptor.
2011,
Pubmed
Hilf,
Structure of a potentially open state of a proton-activated pentameric ligand-gated ion channel.
2009,
Pubmed
Hill-Venning,
Subunit-dependent interaction of the general anaesthetic etomidate with the gamma-aminobutyric acid type A receptor.
1997,
Pubmed
,
Xenbase
Hosie,
Endogenous neurosteroids regulate GABAA receptors through two discrete transmembrane sites.
2006,
Pubmed
Husain,
Synthesis of trifluoromethylaryl diazirine and benzophenone derivatives of etomidate that are potent general anesthetics and effective photolabels for probing sites on ligand-gated ion channels.
2006,
Pubmed
,
Xenbase
Husain,
2-(3-Methyl-3H-diaziren-3-yl)ethyl 1-(1-phenylethyl)-1H-imidazole-5-carboxylate: a derivative of the stereoselective general anesthetic etomidate for photolabeling ligand-gated ion channels.
2003,
Pubmed
,
Xenbase
Jansen,
State-dependent cross-linking of the M2 and M3 segments: functional basis for the alignment of GABAA and acetylcholine receptor M3 segments.
2006,
Pubmed
,
Xenbase
Jenkins,
Evidence for a common binding cavity for three general anesthetics within the GABAA receptor.
2001,
Pubmed
Jurd,
General anesthetic actions in vivo strongly attenuated by a point mutation in the GABA(A) receptor beta3 subunit.
2003,
Pubmed
Karlin,
Substituted-cysteine accessibility method.
1998,
Pubmed
Keramidas,
The pre-M1 segment of the alpha1 subunit is a transduction element in the activation of the GABAA receptor.
2006,
Pubmed
Krasowski,
Methionine 286 in transmembrane domain 3 of the GABAA receptor beta subunit controls a binding cavity for propofol and other alkylphenol general anesthetics.
2001,
Pubmed
Krasowski,
Trichloroethanol modulation of recombinant GABAA, glycine and GABA rho 1 receptors.
1998,
Pubmed
Li,
Identification of a GABAA receptor anesthetic binding site at subunit interfaces by photolabeling with an etomidate analog.
2006,
Pubmed
Li,
Numerous classes of general anesthetics inhibit etomidate binding to gamma-aminobutyric acid type A (GABAA) receptors.
2010,
Pubmed
Li,
Neurosteroids allosterically modulate binding of the anesthetic etomidate to gamma-aminobutyric acid type A receptors.
2009,
Pubmed
Mercado,
Charged residues in the alpha1 and beta2 pre-M1 regions involved in GABAA receptor activation.
2006,
Pubmed
,
Xenbase
Nury,
X-ray structures of general anaesthetics bound to a pentameric ligand-gated ion channel.
2011,
Pubmed
Olsen,
International Union of Pharmacology. LXX. Subtypes of gamma-aminobutyric acid(A) receptors: classification on the basis of subunit composition, pharmacology, and function. Update.
2008,
Pubmed
Parikh,
Structure of the M2 transmembrane segment of GLIC, a prokaryotic Cys loop receptor homologue from Gloeobacter violaceus, probed by substituted cysteine accessibility.
2011,
Pubmed
Reynolds,
Sedation and anesthesia mediated by distinct GABA(A) receptor isoforms.
2003,
Pubmed
Rüsch,
Gating allosterism at a single class of etomidate sites on alpha1beta2gamma2L GABA A receptors accounts for both direct activation and agonist modulation.
2004,
Pubmed
,
Xenbase
Rüsch,
Classic benzodiazepines modulate the open-close equilibrium in alpha1beta2gamma2L gamma-aminobutyric acid type A receptors.
2005,
Pubmed
,
Xenbase
Sauguet,
Structural basis for potentiation by alcohols and anaesthetics in a ligand-gated ion channel.
2013,
Pubmed
Scheller,
Coupled and uncoupled gating and desensitization effects by pore domain mutations in GABA(A) receptors.
2002,
Pubmed
Siegwart,
Mutational analysis of molecular requirements for the actions of general anaesthetics at the gamma-aminobutyric acidA receptor subtype, alpha1beta2gamma2.
2003,
Pubmed
Spurny,
Multisite binding of a general anesthetic to the prokaryotic pentameric Erwinia chrysanthemi ligand-gated ion channel (ELIC).
2013,
Pubmed
,
Xenbase
Stewart,
State-dependent etomidate occupancy of its allosteric agonist sites measured in a cysteine-substituted GABAA receptor.
2013,
Pubmed
,
Xenbase
Stewart,
Tryptophan mutations at azi-etomidate photo-incorporation sites on alpha1 or beta2 subunits enhance GABAA receptor gating and reduce etomidate modulation.
2008,
Pubmed
,
Xenbase
Tomlin,
Stereoselective effects of etomidate optical isomers on gamma-aminobutyric acid type A receptors and animals.
1998,
Pubmed
Yang,
Mechanisms of etomidate potentiation of GABAA receptor-gated currents in cultured postnatal hippocampal neurons.
1996,
Pubmed
