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Do HQ, Pirayesh E, Ferreira G, Pandhare A, Gallardo ZR, Jansen M. A bupropion modulatory site in the Gloeobacter violaceus ligand-gated ion channel. Biophys J 2024; 123:2185-2198. [PMID: 38678367 DOI: 10.1016/j.bpj.2024.04.027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 01/27/2024] [Accepted: 04/25/2024] [Indexed: 04/29/2024] Open
Abstract
Bupropion is an atypical antidepressant and smoking cessation drug that causes adverse effects such as insomnia, irritability, and anxiety. Bupropion inhibits dopamine and norepinephrine reuptake transporters and eukaryotic cation-conducting pentameric ligand-gated ion channels, such as nicotinic acetylcholine and serotonin type 3A receptors, at clinically relevant concentrations. Here, we demonstrate that bupropion also inhibits a prokaryotic homolog of pentameric ligand-gated ion channels, the Gloeobacter violaceus ligand-gated ion channel (GLIC). Using the GLIC as a model, we used molecular docking to predict binding sites for bupropion. Bupropion was found to bind to several sites within the transmembrane domain, with the predominant site being localized to the interface between transmembrane segments M1 and M3 of two adjacent subunits. Residues W213, T214, and W217 in the first transmembrane segment, M1, and F267 and I271 in the third transmembrane segment, M3, most frequently reside within a 4 Å distance from bupropion. We then used single amino acid substitutions at these positions and two-electrode voltage-clamp recordings to determine their impact on bupropion inhibitory effects. The substitution T214F alters bupropion potency by shifting the half-maximal inhibitory concentration to a 13-fold higher value compared to wild-type GLIC. Residue T214 is found within a previously identified binding pocket for neurosteroids and lipids in the GLIC. This intersubunit binding pocket is structurally conserved and almost identical to a binding pocket described for neurosteroids in γ-aminobutyric acid type A receptors. Our data thus suggest that the T214 that lines a previously identified lipophilic binding pocket in GLIC and γ-aminobutyric acid type A receptors is also a modulatory site for bupropion interaction with the GLIC.
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Affiliation(s)
- Hoa Quynh Do
- Cell Physiology and Molecular Biophysics, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Elham Pirayesh
- Cell Physiology and Molecular Biophysics, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Garren Ferreira
- Cell Physiology and Molecular Biophysics, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Akash Pandhare
- Cell Physiology and Molecular Biophysics, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Zackary Ryan Gallardo
- Cell Physiology and Molecular Biophysics, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Michaela Jansen
- Cell Physiology and Molecular Biophysics, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas.
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2
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Chintala SM, Tateiwa H, Qian M, Xu Y, Amtashar F, Chen ZW, Kirkpatrick CC, Bracamontes J, Germann AL, Akk G, Covey DF, Evers AS. Direct measurements of neurosteroid binding to specific sites on GABA A receptors. Br J Pharmacol 2024. [PMID: 38978389 DOI: 10.1111/bph.16490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 05/12/2024] [Accepted: 05/30/2024] [Indexed: 07/10/2024] Open
Abstract
BACKGROUND AND PURPOSE Neurosteroids are allosteric modulators of GABAA currents, acting through several functional binding sites although their affinity and specificity for each site are unknown. The goal of this study was to measure steady-state binding affinities of various neurosteroids for specific sites on the GABAA receptor. EXPERIMENTAL APPROACH Two methods were developed to measure neurosteroid binding affinity: (1) quenching of specific tryptophan residues in neurosteroid binding sites by the neurosteroid 17-methylketone group, and (2) FRET between MQ290 (an intrinsically fluorescent neurosteroid) and tryptophan residues in the binding sites. The assays were developed using ELIC-α1GABAAR, a chimeric receptor containing transmembrane domains of the α1-GABAA receptor. Tryptophan mutagenesis was used to identify specific interactions. KEY RESULTS Allopregnanolone (3α-OH neurosteroid) was shown to bind at intersubunit and intrasubunit sites with equal affinity, whereas epi-allopregnanolone (3β-OH neurosteroid) binds at the intrasubunit site. MQ290 formed a strong FRET pair with W246, acting as a site-specific probe for the intersubunit site. The affinity and site-specificity of several neurosteroid agonists and inverse agonists was measured using the MQ290 binding assay. The FRET assay distinguishes between competitive and allosteric inhibition of MQ290 binding and demonstrated an allosteric interaction between the two neurosteroid binding sites. CONCLUSIONS AND IMPLICATIONS The affinity and specificity of neurosteroid binding to two sites in the ELIC-α1GABAAR were directly measured and an allosteric interaction between the sites was revealed. Adaptation of the MQ290 FRET assay to a plate-reader format will enable screening for high affinity agonists and antagonists for neurosteroid binding sites.
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Affiliation(s)
- Satyanarayana M Chintala
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Hiroki Tateiwa
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri, USA
- Department of Anesthesiology and Intensive Care Medicine, Kochi Medical School, Kochi, Japan
| | - Mingxing Qian
- Department of Developmental Biology (Pharmacology), Washington University School of Medicine, St. Louis, Missouri, USA
| | - Yuanjian Xu
- Department of Developmental Biology (Pharmacology), Washington University School of Medicine, St. Louis, Missouri, USA
| | - Fatima Amtashar
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Zi-Wei Chen
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri, USA
- Taylor Family Institute for Innovative Psychiatric Research, St. Louis, Missouri, USA
| | | | - John Bracamontes
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Allison L Germann
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Gustav Akk
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri, USA
- Taylor Family Institute for Innovative Psychiatric Research, St. Louis, Missouri, USA
| | - Douglas F Covey
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri, USA
- Department of Anesthesiology and Intensive Care Medicine, Kochi Medical School, Kochi, Japan
- Taylor Family Institute for Innovative Psychiatric Research, St. Louis, Missouri, USA
- Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Alex S Evers
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri, USA
- Department of Anesthesiology and Intensive Care Medicine, Kochi Medical School, Kochi, Japan
- Taylor Family Institute for Innovative Psychiatric Research, St. Louis, Missouri, USA
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3
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Bharambe N, Li Z, Seiferth D, Balakrishna AM, Biggin PC, Basak S. Cryo-EM structures of prokaryotic ligand-gated ion channel GLIC provide insights into gating in a lipid environment. Nat Commun 2024; 15:2967. [PMID: 38580666 PMCID: PMC10997623 DOI: 10.1038/s41467-024-47370-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Accepted: 03/28/2024] [Indexed: 04/07/2024] Open
Abstract
GLIC, a proton-activated prokaryotic ligand-gated ion channel, served as a model system for understanding the eukaryotic counterparts due to their structural and functional similarities. Despite extensive studies conducted on GLIC, the molecular mechanism of channel gating in the lipid environment requires further investigation. Here, we present the cryo-EM structures of nanodisc-reconstituted GLIC at neutral and acidic pH in the resolution range of 2.6 - 3.4 Å. In our apo state at pH 7.5, the extracellular domain (ECD) displays conformational variations compared to the existing apo structures. At pH 4.0, three distinct conformational states (C1, C2 and O states) are identified. The protonated structures exhibit a compacted and counter-clockwise rotated ECD compared with our apo state. A gradual widening of the pore in the TMD is observed upon reducing the pH, with the widest pore in O state, accompanied by several layers of water pentagons. The pore radius and molecular dynamics (MD) simulations suggest that the O state represents an open conductive state. We also observe state-dependent interactions between several lipids and proteins that may be involved in the regulation of channel gating. Our results provide comprehensive insights into the importance of lipids impact on gating.
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Affiliation(s)
- Nikhil Bharambe
- School of Biological Sciences, Nanyang Technological University, Singapore, 637551, Singapore
| | - Zhuowen Li
- School of Biological Sciences, Nanyang Technological University, Singapore, 637551, Singapore
| | - David Seiferth
- Structural Bioinformatics and Computational Biochemistry, Department of Biochemistry, University of Oxford, Oxford, UK
| | | | - Philip C Biggin
- Structural Bioinformatics and Computational Biochemistry, Department of Biochemistry, University of Oxford, Oxford, UK
| | - Sandip Basak
- School of Biological Sciences, Nanyang Technological University, Singapore, 637551, Singapore.
- NTU Institute of Structural Biology, Nanyang Technological University, Singapore, 639798, Singapore.
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4
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Pirayesh E, Do HQ, Ferreira G, Pandhare A, Gallardo ZR, Jansen M. Identification of a binding site for bupropion in Gloeobacter violaceus ligand-gated ion channel. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.09.561596. [PMID: 37873398 PMCID: PMC10592773 DOI: 10.1101/2023.10.09.561596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Bupropion is an atypical antidepressant and smoking cessation drug which causes adverse effects such as insomnia, irritability, and anxiety. Bupropion inhibits dopamine and norepinephrine reuptake transporters and eukaryotic cation-conducting pentameric ligand-gated ion channels (pLGICs), such as nicotinic acetylcholine (nACh) and serotonin type 3A (5-HT3A) receptors, at clinically relevant concentrations. However, the binding sites and binding mechanisms of bupropion are still elusive. To further understand the inhibition of pLGICs by bupropion, in this work, using a prokaryotic homologue of pLGICs as a model, we examined the inhibitory potency of bupropion in Gloeobacter violaceus ligand-gated ion channel (GLIC), a proton-gated ion channel. Bupropion inhibited proton-induced currents in GLIC with an inhibitory potency of 14.9 ± 2.0 μM, comparable to clinically attainable concentrations previously shown to also modulate eukaryotic pLGICs. Using single amino acid substitutions in GLIC and two-electrode voltage-clamp recordings, we further determined a binding site for bupropion in the lower third of the first transmembrane segment M1 at residue T214. The sidechain of M1 T214 together with additional residues of M1 and also of M3 of the adjacent subunit have previously been shown to contribute to binding of other lipophilic molecules like allopregnanolone and pregnanolone.
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Affiliation(s)
- Elham Pirayesh
- Medical Student Summer Research Program, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, 79430 USA
| | - Hoa Quynh Do
- Medical Student Summer Research Program, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, 79430 USA
| | - Garren Ferreira
- Medical Student Summer Research Program, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, 79430 USA
| | - Akash Pandhare
- Medical Student Summer Research Program, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, 79430 USA
| | - Zackary Ryan Gallardo
- Medical Student Summer Research Program, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, 79430 USA
| | - Michaela Jansen
- Medical Student Summer Research Program, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, 79430 USA
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5
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Tateiwa H, Chintala SM, Chen Z, Wang L, Amtashar F, Bracamontes J, Germann AL, Pierce SR, Covey DF, Akk G, Evers AS. The Mechanism of Enantioselective Neurosteroid Actions on GABA A Receptors. Biomolecules 2023; 13:341. [PMID: 36830708 PMCID: PMC9953308 DOI: 10.3390/biom13020341] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 01/30/2023] [Accepted: 02/07/2023] [Indexed: 02/12/2023] Open
Abstract
The neurosteroid allopregnanolone (ALLO) and pregnanolone (PREG), are equally effective positive allosteric modulators (PAMs) of GABAA receptors. Interestingly, the PAM effects of ALLO are strongly enantioselective, whereas those of PREG are not. This study was aimed at determining the basis for this difference in enantioselectivity. The oocyte electrophysiology studies showed that ent-ALLO potentiates GABA-elicited currents in α1β3 GABAA receptors with lower potency and efficacy than ALLO, PREG or ent-PREG. The small PAM effect of ent-ALLO was prevented by the α1(Q242L) mutation in the intersubunit neurosteroid binding site between the β3 and α1 subunits. Consistent with this result, neurosteroid analogue photolabeling with mass spectrometric readout, showed that ent-ALLO binds weakly to the β3-α1 intersubunit binding site in comparison to ALLO, PREG and ent-PREG. Rigid body docking predicted that ent-ALLO binds in the intersubunit site with a preferred orientation 180° different than ALLO, PREG or ent-PREG, potentially explaining its weak binding and effect. Photolabeling studies did not identify differences between ALLO and ent-ALLO binding to the α1 or β3 intrasubunit binding sites that also mediate neurosteroid modulation of GABAA receptors. The results demonstrate that differential binding of ent-ALLO and ent-PREG to the β3-α1 intersubunit site accounts for the difference in enantioselectivity between ALLO and PREG.
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Affiliation(s)
- Hiroki Tateiwa
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA
- Department of Anesthesiology and Intensive Care Medicine, Kochi Medical School, Kochi 7838505, Japan
| | | | - Ziwei Chen
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA
- Taylor Institute for Innovative Psychiatric Research, St. Louis, MO 63110, USA
| | - Lei Wang
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA
- Department of Anesthesiology, Union Hospital, Tongji Medical College, Huazhong University of Sciences and Technology, Wuhan 430074, China
| | - Fatima Amtashar
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - John Bracamontes
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Allison L. Germann
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Spencer R. Pierce
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Douglas F. Covey
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA
- Taylor Institute for Innovative Psychiatric Research, St. Louis, MO 63110, USA
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO 63110, USA
- Department of Developmental Biology (Pharmacology), Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Gustav Akk
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA
- Taylor Institute for Innovative Psychiatric Research, St. Louis, MO 63110, USA
| | - Alex S. Evers
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA
- Taylor Institute for Innovative Psychiatric Research, St. Louis, MO 63110, USA
- Department of Developmental Biology (Pharmacology), Washington University School of Medicine, St. Louis, MO 63110, USA
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6
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Open-channel structure of a pentameric ligand-gated ion channel reveals a mechanism of leaflet-specific phospholipid modulation. Nat Commun 2022; 13:7017. [PMID: 36385237 PMCID: PMC9668969 DOI: 10.1038/s41467-022-34813-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Accepted: 11/08/2022] [Indexed: 11/18/2022] Open
Abstract
Pentameric ligand-gated ion channels (pLGICs) mediate synaptic transmission and are sensitive to their lipid environment. The mechanism of phospholipid modulation of any pLGIC is not well understood. We demonstrate that the model pLGIC, ELIC (Erwinia ligand-gated ion channel), is positively modulated by the anionic phospholipid, phosphatidylglycerol, from the outer leaflet of the membrane. To explore the mechanism of phosphatidylglycerol modulation, we determine a structure of ELIC in an open-channel conformation. The structure shows a bound phospholipid in an outer leaflet site, and structural changes in the phospholipid binding site unique to the open-channel. In combination with streamlined alchemical free energy perturbation calculations and functional measurements in asymmetric liposomes, the data support a mechanism by which an anionic phospholipid stabilizes the activated, open-channel state of a pLGIC by specific, state-dependent binding to this site.
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7
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Wagner AG, Stagnitta RT, Xu Z, Pezzullo JL, Kandel N, Giner JL, Covey DF, Wang C, Callahan BP. Nanomolar, Noncovalent Antagonism of Hedgehog Cholesterolysis: Exception to the "Irreversibility Rule" for Protein Autoprocessing Inhibition. Biochemistry 2022; 61:1022-1028. [PMID: 34941260 PMCID: PMC9382716 DOI: 10.1021/acs.biochem.1c00697] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Hedgehog (Hh) signaling ligands undergo carboxy terminal sterylation through specialized autoprocessing, called cholesterolysis. Sterylation is brought about intramolecularly in a single turnover by an adjacent enzymatic domain, called HhC, which is found in precursor Hh proteins only. Previous attempts to identify antagonists of the intramolecular activity of HhC have yielded inhibitors that bind HhC irreversibly through covalent mechanisms, as is common for protein autoprocessing inhibitors. Here, we report an exception to the "irreversibility rule" for autoprocessing inhibition. Using a fluorescence resonance energy transfer-based activity assay for HhC, we screened a focused library of sterol-like analogues for noncovalent inhibitors and identified and validated four structurally related molecules, which were then used for structure-activity relationship studies. The most effective derivative, tBT-HBT, inhibits HhC noncovalently with an IC50 of 300 nM. An allosteric binding site for tBT-HBT, encompassing residues from the two subdomains of HhC, is suggested by kinetic analysis, mutagenesis studies, and photoaffinity labeling. The inhibitors described here resemble a family of noncovalent, allosteric inducers of HhC paracatalysis which we have described previously. The inhibition and the induction appear to be mediated by a shared allosteric site on HhC.
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Affiliation(s)
- Andrew G Wagner
- Department of Chemistry, Binghamton University, State University of New York, Binghamton, New York 13902, United States
| | - Robert T Stagnitta
- Department of Chemistry, Binghamton University, State University of New York, Binghamton, New York 13902, United States
| | - Zihan Xu
- Department of Chemistry, Binghamton University, State University of New York, Binghamton, New York 13902, United States
| | - John L Pezzullo
- Department of Chemistry, SUNY-ESF, Syracuse, New York 13210, United States
| | - Nabin Kandel
- Department of Biological Sciences, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180, United States
| | - José-Luis Giner
- Department of Chemistry, SUNY-ESF, Syracuse, New York 13210, United States
| | - Douglas F Covey
- Department of Developmental Biology, Taylor Family Institute for Innovative Psychiatric Research, 660 South Euclid Avenue, St. Louis, Missouri 63110, United States
| | - Chunyu Wang
- Department of Biological Sciences, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180, United States
| | - Brian P Callahan
- Department of Chemistry, Binghamton University, State University of New York, Binghamton, New York 13902, United States
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8
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Cheng WWL, Arcario MJ, Petroff JT. Druggable Lipid Binding Sites in Pentameric Ligand-Gated Ion Channels and Transient Receptor Potential Channels. Front Physiol 2022; 12:798102. [PMID: 35069257 PMCID: PMC8777383 DOI: 10.3389/fphys.2021.798102] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Accepted: 12/02/2021] [Indexed: 12/17/2022] Open
Abstract
Lipids modulate the function of many ion channels, possibly through direct lipid-protein interactions. The recent outpouring of ion channel structures by cryo-EM has revealed many lipid binding sites. Whether these sites mediate lipid modulation of ion channel function is not firmly established in most cases. However, it is intriguing that many of these lipid binding sites are also known sites for other allosteric modulators or drugs, supporting the notion that lipids act as endogenous allosteric modulators through these sites. Here, we review such lipid-drug binding sites, focusing on pentameric ligand-gated ion channels and transient receptor potential channels. Notable examples include sites for phospholipids and sterols that are shared by anesthetics and vanilloids. We discuss some implications of lipid binding at these sites including the possibility that lipids can alter drug potency or that understanding protein-lipid interactions can guide drug design. Structures are only the first step toward understanding the mechanism of lipid modulation at these sites. Looking forward, we identify knowledge gaps in the field and approaches to address them. These include defining the effects of lipids on channel function in reconstituted systems using asymmetric membranes and measuring lipid binding affinities at specific sites using native mass spectrometry, fluorescence binding assays, and computational approaches.
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Affiliation(s)
- Wayland W L Cheng
- Department of Anesthesiology, Washington University in St. Louis, St. Louis, MO, United States
| | - Mark J Arcario
- Department of Anesthesiology, Washington University in St. Louis, St. Louis, MO, United States
| | - John T Petroff
- Department of Anesthesiology, Washington University in St. Louis, St. Louis, MO, United States
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9
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Dietzen NM, Arcario MJ, Chen LJ, Petroff JT, Moreland KT, Krishnan K, Brannigan G, Covey DF, Cheng WW. Polyunsaturated fatty acids inhibit a pentameric ligand-gated ion channel through one of two binding sites. eLife 2022; 11:74306. [PMID: 34982031 PMCID: PMC8786314 DOI: 10.7554/elife.74306] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Accepted: 12/31/2021] [Indexed: 01/01/2023] Open
Abstract
Polyunsaturated fatty acids (PUFAs) inhibit pentameric ligand-gated ion channels (pLGICs) but the mechanism of inhibition is not well understood. The PUFA, docosahexaenoic acid (DHA), inhibits agonist responses of the pLGIC, ELIC, more effectively than palmitic acid, similar to the effects observed in the GABAA receptor and nicotinic acetylcholine receptor. Using photo-affinity labeling and coarse-grained molecular dynamics simulations, we identified two fatty acid binding sites in the outer transmembrane domain (TMD) of ELIC. Fatty acid binding to the photolabeled sites is selective for DHA over palmitic acid, and specific for an agonist-bound state. Hexadecyl-methanethiosulfonate modification of one of the two fatty acid binding sites in the outer TMD recapitulates the inhibitory effect of PUFAs in ELIC. The results demonstrate that DHA selectively binds to multiple sites in the outer TMD of ELIC, but that state-dependent binding to a single intrasubunit site mediates DHA inhibition of ELIC.
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Affiliation(s)
- Noah M Dietzen
- Department of Anesthesiology, Washington University in St. Louis, St Louis, United States
| | - Mark J Arcario
- Department of Anesthesiology, Washington University in St. Louis, St Louis, United States
| | - Lawrence J Chen
- Department of Anesthesiology, Washington University in St. Louis, St Louis, United States
| | - John T Petroff
- Department of Anesthesiology, Washington University in St. Louis, St Louis, United States
| | - K Trent Moreland
- Department of Anesthesiology, Washington University in St. Louis, St Louis, United States
| | - Kathiresan Krishnan
- Department of Developmental Biology, Washington University in St. Louis, St Louis, United States
| | - Grace Brannigan
- Center for the Computational and Integrative Biology, Rutgers University, Camden, United States.,Department of Physics, Rutgers University, Camden, United States
| | - Douglas F Covey
- Department of Anesthesiology, Washington University in St. Louis, St Louis, United States.,Department of Developmental Biology, Washington University in St. Louis, St Louis, United States.,Department of Psychiatry, Washington University in St. Louis, St. Louis, United States.,Taylor Institute for Innovative Psychiatric Research, Washington University in St. Louis, St. Louis, United States
| | - Wayland Wl Cheng
- Department of Anesthesiology, Washington University in St. Louis, St Louis, United States
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10
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The interaction of steroids with phospholipid bilayers and membranes. Biophys Rev 2021; 14:163-179. [DOI: 10.1007/s12551-021-00918-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2021] [Accepted: 11/18/2021] [Indexed: 12/13/2022] Open
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11
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Krishnan K, Qian M, Feltes M, Chen ZW, Gale S, Wang L, Sugasawa Y, Reichert DE, Schaffer JE, Ory DS, Evers AS, Covey DF. Validation of Trifluoromethylphenyl Diazirine Cholesterol Analogues As Cholesterol Mimetics and Photolabeling Reagents. ACS Chem Biol 2021; 16:1493-1507. [PMID: 34355883 DOI: 10.1021/acschembio.1c00364] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Aliphatic diazirine analogues of cholesterol have been used previously to elaborate the cholesterol proteome and identify cholesterol binding sites on proteins. Cholesterol analogues containing the trifluoromethylphenyl diazirine (TPD) group have not been reported. Both classes of diazirines have been prepared for neurosteroid photolabeling studies and their combined use provided information that was not obtainable with either diazirine class alone. Hence, we prepared cholesterol TPD analogues and used them along with previously reported aliphatic diazirine analogues as photoaffinity labeling reagents to obtain additional information on the cholesterol binding sites of the pentameric Gloeobacter ligand-gated ion channel (GLIC). We first validated the TPD analogues as cholesterol substitutes and compared their actions with those of previously reported aliphatic diazirines in cell culture assays. All the probes bound to the same cholesterol binding site on GLIC but with differences in photolabeling efficiencies and residues identified. Photolabeling of mammalian (HEK) cell membranes demonstrated differences in the pattern of proteins labeled by the two classes of probes. Collectively, these date indicate that cholesterol photoaffinity labeling reagents containing an aliphatic diazirine or TPD group provide complementary information and will both be useful tools in future studies of cholesterol biology.
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12
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Ondrus AE, Zhang T. Structure, Bonding, and Photoaffinity Labeling Applications of Dialkyldiazirines. Synlett 2021. [DOI: 10.1055/a-1437-8202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
AbstractDialkyldiazirine photoaffinity probes are unparalleled tools for the study of small molecule–protein interactions. Here we summarize the basic principles of structure, bonding, and photoreactivity of dialkyldiazirines, current methods for their synthesis, and their practical application in photoaffinity labeling experiments. We demonstrate the unique utility of dialkyldiazirine probes in the context of our recent photoaffinity crosslinking-mass spectrometry analysis to reveal a hidden cholesterol binding site in the Hedgehog morphogen proteins.1 Introduction2 Structure, Bonding, and Spectral Properties3 Photoreactivity4 Synthesis5 Application in Photoaffinity Labeling6 Discovery of a Cholesterol–Hedgehog Protein Interface7 Conclusions and Outlook
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13
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Germann AL, Pierce SR, Tateiwa H, Sugasawa Y, Reichert DE, Evers AS, Steinbach JH, Akk G. Intrasubunit and Intersubunit Steroid Binding Sites Independently and Additively Mediate α1 β2 γ2L GABA A Receptor Potentiation by the Endogenous Neurosteroid Allopregnanolone. Mol Pharmacol 2021; 100:19-31. [PMID: 33958479 DOI: 10.1124/molpharm.121.000268] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Accepted: 04/22/2021] [Indexed: 12/18/2022] Open
Abstract
Prior work employing functional analysis, photolabeling, and X-ray crystallography have identified three distinct binding sites for potentiating steroids in the heteromeric GABAA receptor. The sites are located in the membrane-spanning domains of the receptor at the β-α subunit interface (site I) and within the α (site II) and β subunits (site III). Here, we have investigated the effects of mutations to these sites on potentiation of the rat α1β2γ2L GABAA receptor by the endogenous neurosteroid allopregnanolone (3α5αP). The mutations were introduced alone or in combination to probe the additivity of effects. We show that the effects of amino acid substitutions in sites I and II are energetically additive, indicating independence of the actions of the two steroid binding sites. In site III, none of the mutations tested reduced potentiation by 3α5αP, nor did a mutation in site III modify the effects of mutations in sites I or II. We infer that the binding sites for 3α5αP act independently. The independence of steroid action at each site is supported by photolabeling data showing that mutations in either site I or site II selectively change steroid orientation in the mutated site without affecting labeling at the unmutated site. The findings are discussed in the context of linking energetic additivity to empirical changes in receptor function and ligand binding. SIGNIFICANCE STATEMENT: Prior work has identified three distinct binding sites for potentiating steroids in the heteromeric γ-aminobutyric acid type A receptor. This study shows that the sites act independently and additively in the presence of the steroid allopregnanolone and provide estimates of energetic contributions made by steroid binding to each site.
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Affiliation(s)
- Allison L Germann
- Departments of Anesthesiology (A.L.G., S.R.P., H.T., A.S.E., J.H.S., G.A.) and Radiology (D.E.R.), and the Taylor Family Institute for Innovative Psychiatric Research (D.E.R., A.S.E., J.H.S., G.A.), Washington University School of Medicine, St. Louis, Missouri; and Department of Anesthesiology and Pain Medicine, Juntendo University School of Medicine, Tokyo, Japan (Y.S.)
| | - Spencer R Pierce
- Departments of Anesthesiology (A.L.G., S.R.P., H.T., A.S.E., J.H.S., G.A.) and Radiology (D.E.R.), and the Taylor Family Institute for Innovative Psychiatric Research (D.E.R., A.S.E., J.H.S., G.A.), Washington University School of Medicine, St. Louis, Missouri; and Department of Anesthesiology and Pain Medicine, Juntendo University School of Medicine, Tokyo, Japan (Y.S.)
| | - Hiroki Tateiwa
- Departments of Anesthesiology (A.L.G., S.R.P., H.T., A.S.E., J.H.S., G.A.) and Radiology (D.E.R.), and the Taylor Family Institute for Innovative Psychiatric Research (D.E.R., A.S.E., J.H.S., G.A.), Washington University School of Medicine, St. Louis, Missouri; and Department of Anesthesiology and Pain Medicine, Juntendo University School of Medicine, Tokyo, Japan (Y.S.)
| | - Yusuke Sugasawa
- Departments of Anesthesiology (A.L.G., S.R.P., H.T., A.S.E., J.H.S., G.A.) and Radiology (D.E.R.), and the Taylor Family Institute for Innovative Psychiatric Research (D.E.R., A.S.E., J.H.S., G.A.), Washington University School of Medicine, St. Louis, Missouri; and Department of Anesthesiology and Pain Medicine, Juntendo University School of Medicine, Tokyo, Japan (Y.S.)
| | - David E Reichert
- Departments of Anesthesiology (A.L.G., S.R.P., H.T., A.S.E., J.H.S., G.A.) and Radiology (D.E.R.), and the Taylor Family Institute for Innovative Psychiatric Research (D.E.R., A.S.E., J.H.S., G.A.), Washington University School of Medicine, St. Louis, Missouri; and Department of Anesthesiology and Pain Medicine, Juntendo University School of Medicine, Tokyo, Japan (Y.S.)
| | - Alex S Evers
- Departments of Anesthesiology (A.L.G., S.R.P., H.T., A.S.E., J.H.S., G.A.) and Radiology (D.E.R.), and the Taylor Family Institute for Innovative Psychiatric Research (D.E.R., A.S.E., J.H.S., G.A.), Washington University School of Medicine, St. Louis, Missouri; and Department of Anesthesiology and Pain Medicine, Juntendo University School of Medicine, Tokyo, Japan (Y.S.)
| | - Joe Henry Steinbach
- Departments of Anesthesiology (A.L.G., S.R.P., H.T., A.S.E., J.H.S., G.A.) and Radiology (D.E.R.), and the Taylor Family Institute for Innovative Psychiatric Research (D.E.R., A.S.E., J.H.S., G.A.), Washington University School of Medicine, St. Louis, Missouri; and Department of Anesthesiology and Pain Medicine, Juntendo University School of Medicine, Tokyo, Japan (Y.S.)
| | - Gustav Akk
- Departments of Anesthesiology (A.L.G., S.R.P., H.T., A.S.E., J.H.S., G.A.) and Radiology (D.E.R.), and the Taylor Family Institute for Innovative Psychiatric Research (D.E.R., A.S.E., J.H.S., G.A.), Washington University School of Medicine, St. Louis, Missouri; and Department of Anesthesiology and Pain Medicine, Juntendo University School of Medicine, Tokyo, Japan (Y.S.)
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14
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Pacherille A, Tuga B, Hallooman D, Dos Reis I, Vermette M, Issack BB, Rhyman L, Ramasami P, Sunasee R. BiCl 3-Facilitated removal of methoxymethyl-ether/ester derivatives and DFT study of –O–C–O– bond cleavage. NEW J CHEM 2021. [DOI: 10.1039/d1nj00449b] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
An experimental and DFT study of the cleavage of the MOM group mediated by an eco-friendly reagent, bismuth trichloride.
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Affiliation(s)
- Angela Pacherille
- Department of Chemistry
- State University of New York at Plattsburgh
- Plattsburgh
- USA
| | - Beza Tuga
- Department of Chemistry
- State University of New York at Plattsburgh
- Plattsburgh
- USA
| | - Dhanashree Hallooman
- Computational Chemistry Group, Department of Chemistry
- Faculty of Science, University of Mauritius
- Réduit 80837
- Mauritius
| | - Isaac Dos Reis
- Department of Chemistry
- State University of New York at Plattsburgh
- Plattsburgh
- USA
| | - Mélodie Vermette
- Département des Sciences Expérimentales
- Université de Saint-Boniface
- Winnipeg
- Canada
| | - Bilkiss B. Issack
- Département des Sciences Expérimentales
- Université de Saint-Boniface
- Winnipeg
- Canada
| | - Lydia Rhyman
- Computational Chemistry Group, Department of Chemistry
- Faculty of Science, University of Mauritius
- Réduit 80837
- Mauritius
- Department of Chemical Sciences
| | - Ponnadurai Ramasami
- Computational Chemistry Group, Department of Chemistry
- Faculty of Science, University of Mauritius
- Réduit 80837
- Mauritius
- Department of Chemical Sciences
| | - Rajesh Sunasee
- Department of Chemistry
- State University of New York at Plattsburgh
- Plattsburgh
- USA
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15
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Sugasawa Y, Cheng WW, Bracamontes JR, Chen ZW, Wang L, Germann AL, Pierce SR, Senneff TC, Krishnan K, Reichert DE, Covey DF, Akk G, Evers AS. Site-specific effects of neurosteroids on GABA A receptor activation and desensitization. eLife 2020; 9:55331. [PMID: 32955433 PMCID: PMC7532004 DOI: 10.7554/elife.55331] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 09/20/2020] [Indexed: 12/16/2022] Open
Abstract
This study examines how site-specific binding to three identified neurosteroid-binding sites in the α1β3 GABAA receptor (GABAAR) contributes to neurosteroid allosteric modulation. We found that the potentiating neurosteroid, allopregnanolone, but not its inhibitory 3β-epimer epi-allopregnanolone, binds to the canonical β3(+)–α1(-) intersubunit site that mediates receptor activation by neurosteroids. In contrast, both allopregnanolone and epi-allopregnanolone bind to intrasubunit sites in the β3 subunit, promoting receptor desensitization and the α1 subunit promoting effects that vary between neurosteroids. Two neurosteroid analogues with diazirine moieties replacing the 3-hydroxyl (KK148 and KK150) bind to all three sites, but do not potentiate GABAAR currents. KK148 is a desensitizing agent, whereas KK150 is devoid of allosteric activity. These compounds provide potential chemical scaffolds for neurosteroid antagonists. Collectively, these data show that differential occupancy and efficacy at three discrete neurosteroid-binding sites determine whether a neurosteroid has potentiating, inhibitory, or competitive antagonist activity on GABAARs.
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Affiliation(s)
- Yusuke Sugasawa
- Department of Anesthesiology, Washington University in St. Louis, St. Louis, United States
| | - Wayland Wl Cheng
- Department of Anesthesiology, Washington University in St. Louis, St. Louis, United States
| | - John R Bracamontes
- Department of Anesthesiology, Washington University in St. Louis, St. Louis, United States
| | - Zi-Wei Chen
- Department of Anesthesiology, Washington University in St. Louis, St. Louis, United States.,Taylor Family Institute for Innovative Psychiatric Research, Washington University in St. Louis, St. Louis, United States
| | - Lei Wang
- Department of Anesthesiology, Washington University in St. Louis, St. Louis, United States
| | - Allison L Germann
- Department of Anesthesiology, Washington University in St. Louis, St. Louis, United States
| | - Spencer R Pierce
- Department of Anesthesiology, Washington University in St. Louis, St. Louis, United States
| | - Thomas C Senneff
- Department of Anesthesiology, Washington University in St. Louis, St. Louis, United States
| | - Kathiresan Krishnan
- Department of Developmental Biology, Washington University in St. Louis, St. Louis, United States
| | - David E Reichert
- Taylor Family Institute for Innovative Psychiatric Research, Washington University in St. Louis, St. Louis, United States.,Department of Radiology, Washington University in St. Louis, St. Louis, United States
| | - Douglas F Covey
- Department of Anesthesiology, Washington University in St. Louis, St. Louis, United States.,Taylor Family Institute for Innovative Psychiatric Research, Washington University in St. Louis, St. Louis, United States.,Department of Developmental Biology, Washington University in St. Louis, St. Louis, United States.,Department of Psychiatry, Washington University in St. Louis, St. Louis, United States
| | - Gustav Akk
- Department of Anesthesiology, Washington University in St. Louis, St. Louis, United States.,Taylor Family Institute for Innovative Psychiatric Research, Washington University in St. Louis, St. Louis, United States
| | - Alex S Evers
- Department of Anesthesiology, Washington University in St. Louis, St. Louis, United States.,Taylor Family Institute for Innovative Psychiatric Research, Washington University in St. Louis, St. Louis, United States.,Department of Developmental Biology, Washington University in St. Louis, St. Louis, United States
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16
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Thompson MJ, Baenziger JE. Structural basis for the modulation of pentameric ligand-gated ion channel function by lipids. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183304. [DOI: 10.1016/j.bbamem.2020.183304] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 03/20/2020] [Accepted: 04/05/2020] [Indexed: 10/24/2022]
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17
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Tong A, Petroff JT, Hsu FF, Schmidpeter PA, Nimigean CM, Sharp L, Brannigan G, Cheng WW. Direct binding of phosphatidylglycerol at specific sites modulates desensitization of a ligand-gated ion channel. eLife 2019; 8:50766. [PMID: 31724949 PMCID: PMC6855808 DOI: 10.7554/elife.50766] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 10/09/2019] [Indexed: 12/31/2022] Open
Abstract
Pentameric ligand-gated ion channels (pLGICs) are essential determinants of synaptic transmission, and are modulated by specific lipids including anionic phospholipids. The exact modulatory effect of anionic phospholipids in pLGICs and the mechanism of this effect are not well understood. Using native mass spectrometry, coarse-grained molecular dynamics simulations and functional assays, we show that the anionic phospholipid, 1-palmitoyl-2-oleoyl phosphatidylglycerol (POPG), preferentially binds to and stabilizes the pLGIC, Erwinia ligand-gated ion channel (ELIC), and decreases ELIC desensitization. Mutations of five arginines located in the interfacial regions of the transmembrane domain (TMD) reduce POPG binding, and a subset of these mutations increase ELIC desensitization. In contrast, a mutation that decreases ELIC desensitization, increases POPG binding. The results support a mechanism by which POPG stabilizes the open state of ELIC relative to the desensitized state by direct binding at specific sites.
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Affiliation(s)
- Ailing Tong
- Department of Anesthesiology, Washington University, Saint Louis, United States
| | - John T Petroff
- Department of Anesthesiology, Washington University, Saint Louis, United States
| | - Fong-Fu Hsu
- Department of Internal Medicine, Mass Spectrometry Resource, Division of Endocrinology, Diabetes, Metabolism, and Lipid Research, Washington University, Saint Louis, United States
| | | | - Crina M Nimigean
- Department of Anesthesiology, Weill Cornell Medical College, New York, United States
| | - Liam Sharp
- Center for Computational and Integrative Biology, Rutgers University, Camden, United States
| | - Grace Brannigan
- Center for Computational and Integrative Biology, Rutgers University, Camden, United States.,Department of Physics, Rutgers University, Camden, United States
| | - Wayland Wl Cheng
- Department of Anesthesiology, Washington University, Saint Louis, United States
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18
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Cheng WW, Budelier MM, Sugasawa Y, Bergdoll L, Queralt-Martín M, Rosencrans W, Rostovtseva TK, Chen ZW, Abramson J, Krishnan K, Covey DF, Whitelegge JP, Evers AS. Multiple neurosteroid and cholesterol binding sites in voltage-dependent anion channel-1 determined by photo-affinity labeling. Biochim Biophys Acta Mol Cell Biol Lipids 2019; 1864:1269-1279. [PMID: 31176038 PMCID: PMC6681461 DOI: 10.1016/j.bbalip.2019.06.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 05/23/2019] [Accepted: 06/02/2019] [Indexed: 12/31/2022]
Abstract
Voltage-dependent anion channel-1 (VDAC1) is a mitochondrial porin that is implicated in cellular metabolism and apoptosis, and modulated by numerous small molecules including lipids. VDAC1 binds sterols, including cholesterol and neurosteroids such as allopregnanolone. Biochemical and computational studies suggest that VDAC1 binds multiple cholesterol molecules, but photolabeling studies have identified only a single cholesterol and neurosteroid binding site at E73. To identify all the binding sites of neurosteroids in VDAC1, we apply photo-affinity labeling using two sterol-based photolabeling reagents with complementary photochemistry: 5α-6-AziP which contains an aliphatic diazirine, and KK200 which contains a trifluoromethyl-phenyldiazirine (TPD) group. 5α-6-AziP and KK200 photolabel multiple residues within an E73 pocket confirming the presence of this site and mapping sterol orientation within this pocket. In addition, KK200 photolabels four other sites consistent with the finding that VDAC1 co-purifies with five cholesterol molecules. Both allopregnanolone and cholesterol competitively prevent photolabeling at E73 and three other sites indicating that these are common sterol binding sites shared by both neurosteroids and cholesterol. Binding at the functionally important residue E73 suggests a possible role for sterols in regulating VDAC1 signaling and interaction with partner proteins.
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Affiliation(s)
- Wayland W.L. Cheng
- Department of Anesthesiology, Washington University in St. Louis, MO 63110, USA
| | - Melissa M. Budelier
- Department of Anesthesiology, Washington University in St. Louis, MO 63110, USA,Department of Biochemistry and Molecular Biophysics, Washington University in St. Louis, MO 63110, USA
| | - Yusuke Sugasawa
- Department of Anesthesiology, Washington University in St. Louis, MO 63110, USA
| | - Lucie Bergdoll
- Department of Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - María Queralt-Martín
- Section on Molecular Transport, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - William Rosencrans
- Section on Molecular Transport, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Tatiana K. Rostovtseva
- Section on Molecular Transport, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Zi-Wei Chen
- Department of Anesthesiology, Washington University in St. Louis, MO 63110, USA,Taylor Family Institute for Innovative Psychiatric Research, Washington University in St. Louis, MO 63110, USA
| | - Jeff Abramson
- Department of Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Kathiresan Krishnan
- Department of Developmental Biology, Washington University in St. Louis, MO 63110, USA
| | - Douglas F. Covey
- Department of Anesthesiology, Washington University in St. Louis, MO 63110, USA,Department of Developmental Biology, Washington University in St. Louis, MO 63110, USA,Department of Psychiatry, Washington University in St. Louis, MO 63110, USA,Taylor Family Institute for Innovative Psychiatric Research, Washington University in St. Louis, MO 63110, USA
| | - Julian P. Whitelegge
- Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Alex S. Evers
- Department of Anesthesiology, Washington University in St. Louis, MO 63110, USA,Department of Developmental Biology, Washington University in St. Louis, MO 63110, USA,Department of Psychiatry, Washington University in St. Louis, MO 63110, USA,Taylor Family Institute for Innovative Psychiatric Research, Washington University in St. Louis, MO 63110, USA,Corresponding author at: Department of Anesthesiology, Washington University School of Medicine, Campus Box 8054, St. Louis, MO 63110, USA. (A.S. Evers)
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19
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Sugasawa Y, Bracamontes JR, Krishnan K, Covey DF, Reichert DE, Akk G, Chen Q, Tang P, Evers AS, Cheng WWL. The molecular determinants of neurosteroid binding in the GABA(A) receptor. J Steroid Biochem Mol Biol 2019; 192:105383. [PMID: 31150831 PMCID: PMC6708749 DOI: 10.1016/j.jsbmb.2019.105383] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Revised: 05/11/2019] [Accepted: 05/26/2019] [Indexed: 10/26/2022]
Abstract
Neurosteroids positively modulate GABA-A receptor (GABAAR) channel activity by binding to a transmembrane domain intersubunit site. Understanding the interactions in this site that determine neurosteroid binding and its effect is essential for the design of neurosteroid-based therapeutics. Using photo-affinity labeling and an ELIC-α1GABAAR chimera, we investigated the impact of mutations (Q242L, Q242W and W246L) within the intersubunit site on neurosteroid binding. These mutations, which abolish the thermal stabilizing effect of allopregnanolone on the chimera, reduce neither photolabeling within the intersubunit site nor competitive prevention of labeling by allopregnanolone. Instead, these mutations change the orientation of neurosteroid photolabeling. Molecular docking of allopregnanolone in WT and Q242W receptors confirms that the mutation favors re-orientation of allopregnanolone within the binding pocket. Collectively, the data indicate that mutations at Gln242 or Trp246 that eliminate neurosteroid effects do not eliminate neurosteroid binding within the intersubunit site, but significantly alter the preferred orientation of the neurosteroid within the site. The interactions formed by Gln242 and Trp246 within this pocket play a vital role in determining the orientation of the neurosteroid that may be necessary for its functional effect.
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Affiliation(s)
- Yusuke Sugasawa
- Department of Anesthesiology, Washington University in St. Louis, St. Louis, MO 63110, USA.
| | - John R Bracamontes
- Department of Anesthesiology, Washington University in St. Louis, St. Louis, MO 63110, USA.
| | - Kathiresan Krishnan
- Department of Developmental Biology, Washington University in St. Louis, St. Louis, MO 63110, USA.
| | - Douglas F Covey
- Department of Anesthesiology, Washington University in St. Louis, St. Louis, MO 63110, USA; Department of Developmental Biology, Washington University in St. Louis, St. Louis, MO 63110, USA; Department of Psychiatry, Washington University in St. Louis, St. Louis, MO 63110, USA; Taylor Family Institute for Innovative Psychiatric Research, Washington University in St. Louis, St. Louis, MO 63110, USA.
| | - David E Reichert
- Department of Radiology, Washington University in St. Louis, St. Louis, MO 63110, USA; Taylor Family Institute for Innovative Psychiatric Research, Washington University in St. Louis, St. Louis, MO 63110, USA.
| | - Gustav Akk
- Department of Anesthesiology, Washington University in St. Louis, St. Louis, MO 63110, USA; Taylor Family Institute for Innovative Psychiatric Research, Washington University in St. Louis, St. Louis, MO 63110, USA.
| | - Qiang Chen
- Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA.
| | - Pei Tang
- Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA; Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA; Department of Computational and Systems Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA.
| | - Alex S Evers
- Department of Anesthesiology, Washington University in St. Louis, St. Louis, MO 63110, USA; Department of Developmental Biology, Washington University in St. Louis, St. Louis, MO 63110, USA; Taylor Family Institute for Innovative Psychiatric Research, Washington University in St. Louis, St. Louis, MO 63110, USA.
| | - Wayland W L Cheng
- Department of Anesthesiology, Washington University in St. Louis, St. Louis, MO 63110, USA.
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20
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Hemmings HC, Riegelhaupt PM, Kelz MB, Solt K, Eckenhoff RG, Orser BA, Goldstein PA. Towards a Comprehensive Understanding of Anesthetic Mechanisms of Action: A Decade of Discovery. Trends Pharmacol Sci 2019; 40:464-481. [PMID: 31147199 DOI: 10.1016/j.tips.2019.05.001] [Citation(s) in RCA: 118] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 04/11/2019] [Accepted: 05/03/2019] [Indexed: 12/30/2022]
Abstract
Significant progress has been made in the 21st century towards a comprehensive understanding of the mechanisms of action of general anesthetics, coincident with progress in structural biology and molecular, cellular, and systems neuroscience. This review summarizes important new findings that include target identification through structural determination of anesthetic binding sites, details of receptors and ion channels involved in neurotransmission, and the critical roles of neuronal networks in anesthetic effects on memory and consciousness. These recent developments provide a comprehensive basis for conceptualizing pharmacological control of amnesia, unconsciousness, and immobility.
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Affiliation(s)
- Hugh C Hemmings
- Departments of Anesthesiology, Weill Cornell Medicine, 1300 York Avenue, New York, NY 10065, USA; Departments of Pharmacology, Weill Cornell Medicine, 1300 York Avenue, New York, NY 10065, USA
| | - Paul M Riegelhaupt
- Departments of Anesthesiology, Weill Cornell Medicine, 1300 York Avenue, New York, NY 10065, USA
| | - Max B Kelz
- Department of Anesthesiology and Critical Care, University of Pennsylvania Perelman School of Medicine, 3620 Hamilton Walk, 305 John Morgan, Philadelphia, PA 19104, USA
| | - Ken Solt
- Department of Anaesthesia, Harvard Medical School, GRB 444, 55 Fruit St., Boston, MA 02114, USA; Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114, USA
| | - Roderic G Eckenhoff
- Department of Anesthesiology and Critical Care, University of Pennsylvania Perelman School of Medicine, 3620 Hamilton Walk, 305 John Morgan, Philadelphia, PA 19104, USA
| | - Beverley A Orser
- Departments of Anesthesia and Physiology, Room 3318 Medical Sciences Building, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Peter A Goldstein
- Departments of Anesthesiology, Weill Cornell Medicine, 1300 York Avenue, New York, NY 10065, USA; Departments of Medicine, Weill Cornell Medicine, 1300 York Avenue, New York, NY 10065, USA.
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21
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Yu Z, Chiara DC, Savechenkov PY, Bruzik KS, Cohen JB. A photoreactive analog of allopregnanolone enables identification of steroid-binding sites in a nicotinic acetylcholine receptor. J Biol Chem 2019; 294:7892-7903. [PMID: 30923128 DOI: 10.1074/jbc.ra118.007172] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 03/27/2019] [Indexed: 11/06/2022] Open
Abstract
Many neuroactive steroids potently and allosterically modulate pentameric ligand-gated ion channels, including GABAA receptors (GABAAR) and nicotinic acetylcholine receptors (nAChRs). Allopregnanolone and its synthetic analog alphaxalone are GABAAR-positive allosteric modulators (PAMs), whereas alphaxalone and most neuroactive steroids are nAChR inhibitors. In this report, we used 11β-(p-azidotetrafluorobenzoyloxy)allopregnanolone (F4N3Bzoxy-AP), a general anesthetic and photoreactive allopregnanolone analog that is a potent GABAAR PAM, to characterize steroid-binding sites in the Torpedo α2βγδ nAChR in its native membrane environment. We found that F4N3Bzoxy-AP (IC50 = 31 μm) is 7-fold more potent than alphaxalone in inhibiting binding of the channel blocker [3H]tenocyclidine to nAChRs in the desensitized state. At 300 μm, neither steroid inhibited binding of [3H]tetracaine, a closed-state selective channel blocker, or of [3H]acetylcholine. Photolabeling identified three distinct [3H]F4N3Bzoxy-AP-binding sites in the nAChR transmembrane domain: 1) in the ion channel, identified by photolabeling in the M2 helices of βVal-261 and δVal-269 (position M2-13'); 2) at the interface between the αM1 and αM4 helices, identified by photolabeling in αM1 (αCys-222/αLeu-223); and 3) at the lipid-protein interface involving γTrp-453 (M4), a residue photolabeled by small lipophilic probes and promegestone, a steroid nAChR antagonist. Photolabeling in the ion channel and αM1 was higher in the nAChR-desensitized state than in the resting state and inhibitable by promegestone. These results directly indicate a steroid-binding site in the nAChR ion channel and identify additional steroid-binding sites also occupied by other lipophilic nAChR antagonists.
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Affiliation(s)
- Zhiyi Yu
- From the Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115 and
| | - David C Chiara
- From the Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115 and
| | - Pavel Y Savechenkov
- the Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago, Illinois 60612
| | - Karol S Bruzik
- the Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago, Illinois 60612
| | - Jonathan B Cohen
- From the Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115 and
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22
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Chen ZW, Bracamontes JR, Budelier MM, Germann AL, Shin DJ, Kathiresan K, Qian MX, Manion B, Cheng WWL, Reichert DE, Akk G, Covey DF, Evers AS. Multiple functional neurosteroid binding sites on GABAA receptors. PLoS Biol 2019; 17:e3000157. [PMID: 30845142 PMCID: PMC6424464 DOI: 10.1371/journal.pbio.3000157] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Revised: 03/19/2019] [Accepted: 02/05/2019] [Indexed: 11/18/2022] Open
Abstract
Neurosteroids are endogenous modulators of neuronal excitability and nervous system development and are being developed as anesthetic agents and treatments for psychiatric diseases. While gamma amino-butyric acid Type A (GABAA) receptors are the primary molecular targets of neurosteroid action, the structural details of neurosteroid binding to these proteins remain ill defined. We synthesized neurosteroid analogue photolabeling reagents in which the photolabeling groups were placed at three positions around the neurosteroid ring structure, enabling identification of binding sites and mapping of neurosteroid orientation within these sites. Using middle-down mass spectrometry (MS), we identified three clusters of photolabeled residues representing three distinct neurosteroid binding sites in the human α1β3 GABAA receptor. Novel intrasubunit binding sites were identified within the transmembrane helical bundles of both the α1 (labeled residues α1-N408, Y415) and β3 (labeled residue β3-Y442) subunits, adjacent to the extracellular domains (ECDs). An intersubunit site (labeled residues β3-L294 and G308) in the interface between the β3(+) and α1(−) subunits of the GABAA receptor pentamer was also identified. Computational docking studies of neurosteroid to the three sites predicted critical residues contributing to neurosteroid interaction with the GABAA receptors. Electrophysiological studies of receptors with mutations based on these predictions (α1-V227W, N408A/Y411F, and Q242L) indicate that both the α1 intrasubunit and β3-α1 intersubunit sites are critical for neurosteroid action. Novel neurosteroid analogue photolabeling reagents identify three specific neurosteroid binding sites on α1β3 GABAA receptors, showing that a site between the α and β subunits, as well as a site within the α-subunit, contribute to neurosteroid-mediated enhancement of GABAA currents. Neurosteroids are cholesterol metabolites produced by neurons and glial cells that participate in central nervous system (CNS) development, regulate neuronal excitability, and modulate complex behaviors such as mood. Exogenously administered neurosteroid analogues are effective sedative hypnotics and are being developed as antidepressants and anticonvulsants. Gamma amino-butyric acid Type A (GABAA) receptors, the principal ionotropic inhibitory neurotransmitter receptors in the brain, are the primary functional target of neurosteroids. Understanding the molecular details of neurosteroid interactions with GABAA receptors is critical to understanding their mechanism of action and developing specific and effective therapeutic agents. In the current study, we developed a suite of neurosteroid analogue affinity labeling reagents, which we used to identify three distinct binding sites on GABAA receptors and to determine the orientation of neurosteroid binding in each site. Electrophysiological studies performed on receptors with mutations designed to disrupt the identified binding sites showed that two of the three sites contribute to neurosteroid modulation of GABAA currents. The distinct patterns of neurosteroid affinity, binding orientation, and effect provide the potential for the development of isoform-specific agonists, partial agonists, and antagonists with targeted therapeutic effects.
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Affiliation(s)
- Zi-Wei Chen
- Department of Anesthesiology, Washington University in St Louis, St Louis, Missouri, United States of America.,Taylor Family Institute for Innovative Psychiatric Research, St Louis, Missouri, United States of America
| | - John R Bracamontes
- Department of Anesthesiology, Washington University in St Louis, St Louis, Missouri, United States of America
| | - Melissa M Budelier
- Department of Anesthesiology, Washington University in St Louis, St Louis, Missouri, United States of America
| | - Allison L Germann
- Department of Anesthesiology, Washington University in St Louis, St Louis, Missouri, United States of America
| | - Daniel J Shin
- Department of Anesthesiology, Washington University in St Louis, St Louis, Missouri, United States of America
| | - Krishnan Kathiresan
- Department of Developmental Biology, Washington University in St Louis, St Louis, Missouri, United States of America
| | - Ming-Xing Qian
- Department of Developmental Biology, Washington University in St Louis, St Louis, Missouri, United States of America
| | - Brad Manion
- Department of Anesthesiology, Washington University in St Louis, St Louis, Missouri, United States of America
| | - Wayland W L Cheng
- Department of Anesthesiology, Washington University in St Louis, St Louis, Missouri, United States of America
| | - David E Reichert
- Taylor Family Institute for Innovative Psychiatric Research, St Louis, Missouri, United States of America.,Department of Radiology, Washington University in St Louis, St Louis, Missouri, United States of America
| | - Gustav Akk
- Department of Anesthesiology, Washington University in St Louis, St Louis, Missouri, United States of America
| | - Douglas F Covey
- Department of Anesthesiology, Washington University in St Louis, St Louis, Missouri, United States of America.,Taylor Family Institute for Innovative Psychiatric Research, St Louis, Missouri, United States of America.,Department of Developmental Biology, Washington University in St Louis, St Louis, Missouri, United States of America
| | - Alex S Evers
- Department of Anesthesiology, Washington University in St Louis, St Louis, Missouri, United States of America.,Taylor Family Institute for Innovative Psychiatric Research, St Louis, Missouri, United States of America.,Department of Developmental Biology, Washington University in St Louis, St Louis, Missouri, United States of America
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23
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Ratner MH, Kumaresan V, Farb DH. Neurosteroid Actions in Memory and Neurologic/Neuropsychiatric Disorders. Front Endocrinol (Lausanne) 2019; 10:169. [PMID: 31024441 PMCID: PMC6465949 DOI: 10.3389/fendo.2019.00169] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Accepted: 02/28/2019] [Indexed: 12/24/2022] Open
Abstract
Memory dysfunction is a symptomatic feature of many neurologic and neuropsychiatric disorders; however, the basic underlying mechanisms of memory and altered states of circuitry function associated with disorders of memory remain a vast unexplored territory. The initial discovery of endogenous neurosteroids triggered a quest to elucidate their role as neuromodulators in normal and diseased brain function. In this review, based on the perspective of our own research, the advances leading to the discovery of positive and negative neurosteroid allosteric modulators of GABA type-A (GABAA), NMDA, and non-NMDA type glutamate receptors are brought together in a historical and conceptual framework. We extend the analysis toward a state-of-the art view of how neurosteroid modulation of neural circuitry function may affect memory and memory deficits. By aggregating the results from multiple laboratories using both animal models for disease and human clinical research on neuropsychiatric and age-related neurodegenerative disorders, elements of a circuitry level view begins to emerge. Lastly, the effects of both endogenously active and exogenously administered neurosteroids on neural networks across the life span of women and men point to a possible underlying pharmacological connectome by which these neuromodulators might act to modulate memory across diverse altered states of mind.
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24
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Budelier MM, Cheng WWL, Chen ZW, Bracamontes JR, Sugasawa Y, Krishnan K, Mydock-McGrane L, Covey DF, Evers AS. Common binding sites for cholesterol and neurosteroids on a pentameric ligand-gated ion channel. Biochim Biophys Acta Mol Cell Biol Lipids 2018; 1864:128-136. [PMID: 30471426 DOI: 10.1016/j.bbalip.2018.11.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 09/20/2018] [Accepted: 11/16/2018] [Indexed: 11/16/2022]
Abstract
Cholesterol is an essential component of cell membranes, and is required for mammalian pentameric ligand-gated ion channel (pLGIC) function. Computational studies suggest direct interactions between cholesterol and pLGICs but experimental evidence identifying specific binding sites is limited. In this study, we mapped cholesterol binding to Gloeobacter ligand-gated ion channel (GLIC), a model pLGIC chosen for its high level of expression, existing crystal structure, and previous use as a prototypic pLGIC. Using two cholesterol analogue photolabeling reagents with the photoreactive moiety on opposite ends of the sterol, we identified two cholesterol binding sites: an intersubunit site between TM3 and TM1 of adjacent subunits and an intrasubunit site between TM1 and TM4. In both the inter- and intrasubunit sites, cholesterol is oriented such that the 3‑OH group points toward the center of the transmembrane domains rather than toward either the cytosolic or extracellular surfaces. We then compared this binding to that of the cholesterol metabolite, allopregnanolone, a neurosteroid that allosterically modulates pLGICs. The same binding pockets were identified for allopregnanolone and cholesterol, but the binding orientation of the two ligands was markedly different, with the 3‑OH group of allopregnanolone pointing to the intra- and extracellular termini of the transmembrane domains rather than to their centers. We also found that cholesterol increases, whereas allopregnanolone decreases the thermal stability of GLIC. These data indicate that cholesterol and neurosteroids bind to common hydrophobic pockets in the model pLGIC, GLIC, but that their effects depend on the orientation and specific molecular interactions unique to each sterol.
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Affiliation(s)
- Melissa M Budelier
- Department of Anesthesiology, Washington University in St Louis, 660 S Euclid Ave, St Louis, MO 63110, USA
| | - Wayland W L Cheng
- Department of Anesthesiology, Washington University in St Louis, 660 S Euclid Ave, St Louis, MO 63110, USA
| | - Zi-Wei Chen
- Department of Anesthesiology, Washington University in St Louis, 660 S Euclid Ave, St Louis, MO 63110, USA; Taylor Family Institute for Innovative Psychiatric Research, Washington University in St Louis, 660 S Euclid Ave, St Louis, MO 63110, USA
| | - John R Bracamontes
- Department of Anesthesiology, Washington University in St Louis, 660 S Euclid Ave, St Louis, MO 63110, USA
| | - Yusuke Sugasawa
- Department of Anesthesiology, Washington University in St Louis, 660 S Euclid Ave, St Louis, MO 63110, USA
| | - Kathiresan Krishnan
- Department of Developmental Biology, Washington University in St Louis, 660 S Euclid Ave, St Louis, MO 63110, USA
| | - Laurel Mydock-McGrane
- Department of Developmental Biology, Washington University in St Louis, 660 S Euclid Ave, St Louis, MO 63110, USA
| | - Douglas F Covey
- Department of Anesthesiology, Washington University in St Louis, 660 S Euclid Ave, St Louis, MO 63110, USA; Taylor Family Institute for Innovative Psychiatric Research, Washington University in St Louis, 660 S Euclid Ave, St Louis, MO 63110, USA; Department of Developmental Biology, Washington University in St Louis, 660 S Euclid Ave, St Louis, MO 63110, USA; Department of Psychiatry, Washington University in St Louis, 660 S Euclid Ave, St Louis, MO 63110, USA
| | - Alex S Evers
- Department of Anesthesiology, Washington University in St Louis, 660 S Euclid Ave, St Louis, MO 63110, USA; Taylor Family Institute for Innovative Psychiatric Research, Washington University in St Louis, 660 S Euclid Ave, St Louis, MO 63110, USA; Department of Developmental Biology, Washington University in St Louis, 660 S Euclid Ave, St Louis, MO 63110, USA.
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25
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Wu B, Jayakar SS, Zhou X, Titterton K, Chiara DC, Szabo AL, Savechenkov PY, Kent DE, Cohen JB, Forman SA, Miller KW, Bruzik KS. Inhibitable photolabeling by neurosteroid diazirine analog in the β3-Subunit of human hetereopentameric type A GABA receptors. Eur J Med Chem 2018; 162:810-824. [PMID: 30544077 DOI: 10.1016/j.ejmech.2018.11.019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 11/06/2018] [Accepted: 11/08/2018] [Indexed: 12/22/2022]
Abstract
Pregnanolone and allopregnanolone-type ligands exert general anesthetic, anticonvulsant and anxiolytic effects due to their positive modulatory interactions with the GABAA receptors in the brain. Binding sites for these neurosteroids have been recently identified at subunit interfaces in the transmembrane domain (TMD) of homomeric β3 GABAA receptors using photoaffinity labeling techniques, and in homomeric chimeric receptors containing GABAA receptor α subunit TMDs by crystallography. Steroid binding sites have yet to be determined in human, heteromeric, functionally reconstituted, full-length, glycosylated GABAA receptors. Here, we report on the synthesis and pharmacological characterization of several photoaffinity analogs of pregnanolone and allopregnanolone, of which 21-[4-(3-(trifluoromethyl)-3H-diazirin-3-yl)benzoxy]allopregnanolone (21-pTFDBzox-AP) was the most potent ligand. It is a partial positive modulator of the human α1β3 and α1β3γ2L GABAA receptors at sub-micromolar concentrations. [3H]21-pTFDBzox-AP photoincorporated in a pharmacologically specific manner into the α and β subunits of those receptors, with the β3 subunit photolabeled most efficiently. Importantly, photolabeling by [3H]21-pTFDBzox-AP was inhibited by the positive steroid modulators alphaxalone, pregnanolone and allopregnanolone, but not by inhibitory neurosteroid pregnenolone sulfate or by two potent general anesthetics and GABAAR positive allosteric modulators, etomidate and an anesthetic barbiturate. The latter two ligands bind to sites at subunit interfaces in the GABAAR that are different from those interacting with neurosteroids. 21-pTFDBzox-AP's potency and pharmacological specificity of photolabeling indicate its suitability for characterizing neurosteroid binding sites in native GABAA receptors.
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Affiliation(s)
- Bo Wu
- Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, 833 South Wood Street, Chicago, IL, 60612, USA
| | - Selwyn S Jayakar
- Department of Neurobiology, 220 Longwood Avenue, Harvard Medical School, Boston, MA, 02115, USA
| | - Xiaojuan Zhou
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, 32 Fruit Street, Boston, MA, 02114, USA
| | - Katherine Titterton
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, 32 Fruit Street, Boston, MA, 02114, USA
| | - David C Chiara
- Department of Neurobiology, 220 Longwood Avenue, Harvard Medical School, Boston, MA, 02115, USA
| | - Andrea L Szabo
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, 32 Fruit Street, Boston, MA, 02114, USA
| | - Pavel Y Savechenkov
- Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, 833 South Wood Street, Chicago, IL, 60612, USA
| | - Daniel E Kent
- Department of Health Science, Northeastern University, 360 Huntington Ave, Boston, MA, 02115, USA
| | - Jonathan B Cohen
- Department of Neurobiology, 220 Longwood Avenue, Harvard Medical School, Boston, MA, 02115, USA
| | - Stuart A Forman
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, 32 Fruit Street, Boston, MA, 02114, USA
| | - Keith W Miller
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, 32 Fruit Street, Boston, MA, 02114, USA; Department of Biological Chemistry and Molecular Pharmacology, 220 Longwood Avenue, Harvard Medical School, Boston, MA, 02115, USA
| | - Karol S Bruzik
- Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, 833 South Wood Street, Chicago, IL, 60612, USA.
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26
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Atkovska K, Klingler J, Oberwinkler J, Keller S, Hub JS. Rationalizing Steroid Interactions with Lipid Membranes: Conformations, Partitioning, and Kinetics. ACS CENTRAL SCIENCE 2018; 4:1155-1165. [PMID: 30276248 PMCID: PMC6161064 DOI: 10.1021/acscentsci.8b00332] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2018] [Indexed: 05/18/2023]
Abstract
Steroids have numerous physiological functions associated with cellular signaling or modulation of the lipid membrane structure and dynamics, and as such, they have found broad pharmacological applications. Steroid-membrane interactions are relevant to multiple steps of steroid biosynthesis and action, as steroids are known to interact with neurotransmitter or membrane steroid receptors, and steroids must cross lipid membranes to exert their physiological functions. Therefore, rationalizing steroid function requires understanding of steroid-membrane interactions. We combined molecular dynamics simulations and isothermal titration calorimetry to characterize the conformations and the energetics of partitioning, in addition to the kinetics of flip-flop transitions and membrane exit, of 26 representative steroid compounds in a model lipid membrane. The steroid classes covered in this study include birth control and anabolic drugs, sex and corticosteroid hormones, neuroactive steroids, as well as steroids modulating the lipid membrane structure. We found that the conformational ensembles adopted by different steroids vary greatly, as quantified by their distributions of tilt angles and insertion depths into the membrane, ranging from well-defined steroid conformations with orientations either parallel or normal to the membrane, to wide conformational distributions. Surprisingly, despite their chemical diversity, the membrane/water partition coefficient is similar among most steroids, except for structural steroids such as cholesterol, leading to similar rates for exiting the membrane. By contrast, the rates of steroid flip-flop vary by at least 9 orders of magnitude, revealing that flip-flop is the rate-limiting step during cellular uptake of polar steroids. This study lays the ground for a quantitative understanding of steroid-membrane interactions, and it will hence be of use for studies of steroid biosynthesis and function as well as for the development and usage of steroids in a pharmacological context.
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Affiliation(s)
- Kalina Atkovska
- Institute
for Microbiology and Genetics and Goettingen Center for Molecular
Biosciences, University of Goettingen, 37077 Göttingen, Germany
| | - Johannes Klingler
- Molecular
Biophysics, Technische Universität
Kaiserslautern (TUK), 67663 Kaiserslautern, Germany
| | - Johannes Oberwinkler
- Institut
für Physiologie und Pathophysiologie, Philipps-Universität Marburg, 35037 Marburg, Germany
| | - Sandro Keller
- Molecular
Biophysics, Technische Universität
Kaiserslautern (TUK), 67663 Kaiserslautern, Germany
| | - Jochen S. Hub
- Institute
for Microbiology and Genetics and Goettingen Center for Molecular
Biosciences, University of Goettingen, 37077 Göttingen, Germany
- Theoretical
Physics, Saarland University, 66123 Saarbrücken, Germany
- E-mail:
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