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Purohit P, Auerbach A. Glycine hinges with opposing actions at the acetylcholine receptor-channel transmitter binding site. Mol Pharmacol 2010; 79:351-9. [PMID: 21115636 DOI: 10.1124/mol.110.068767] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The extent to which agonists activate synaptic receptor-channels depends on both the intrinsic tendency of the unliganded receptor to open and the amount of agonist binding energy realized in the channel-opening process. We examined mutations of the nicotinic acetylcholine receptor transmitter binding site (α subunit loop B) with regard to both of these parameters. αGly147 is an "activation" hinge where backbone flexibility maintains high values for intrinsic gating, the affinity of the resting conformation for agonists and net ligand binding energy. αGly153 is a "deactivation" hinge that maintains low values for these parameters. αTrp149 (between these two glycines) serves mainly to provide ligand binding energy for gating. We propose that a concerted motion of the two glycine hinges (plus other structural elements at the binding site) positions αTrp149 so that it provides physiologically optimal binding and gating function at the nerve-muscle synapse.
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Affiliation(s)
- Prasad Purohit
- Department of Physiology and Biophysics, SUNY at Buffalo, Buffalo, NY 14214, USA
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252
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Johnson JA, Lu YY, Van Deventer JA, Tirrell DA. Residue-specific incorporation of non-canonical amino acids into proteins: recent developments and applications. Curr Opin Chem Biol 2010; 14:774-80. [PMID: 21071259 DOI: 10.1016/j.cbpa.2010.09.013] [Citation(s) in RCA: 244] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2010] [Accepted: 09/20/2010] [Indexed: 12/30/2022]
Abstract
Residue-specific incorporation of non-canonical amino acids into proteins allows facile alteration and enhancement of protein properties. In this review, we describe recent technical developments and applications of residue-specific incorporation to problems ranging from elucidation of biochemical mechanisms to engineering of protein-based biomaterials. We hope to inform the reader of the ease and broad utility of residue-specific non-canonical amino acid incorporation with the goal of inspiring investigators outside the field to consider applying this tool to their own research.
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Affiliation(s)
- Jeremiah A Johnson
- Division of Chemistry and Chemical Engineering, Joseph J. Jacobs Institute for Molecular Engineering for Medicine, California Institute of Technology, Pasadena, CA 91125, USA
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253
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Abstract
Cys-loop receptors are membrane-spanning neurotransmitter-gated ion channels that are responsible for fast excitatory and inhibitory transmission in the peripheral and central nervous systems. The best studied members of the Cys-loop family are nACh, 5-HT3, GABAA and glycine receptors. All these receptors share a common structure of five subunits, pseudo-symmetrically arranged to form a rosette with a central ion-conducting pore. Some are cation selective (e.g. nACh and 5-HT3) and some are anion selective (e.g. GABAA and glycine). Each receptor has an extracellular domain (ECD) that contains the ligand-binding sites, a transmembrane domain (TMD) that allows ions to pass across the membrane, and an intracellular domain (ICD) that plays a role in channel conductance and receptor modulation. Cys-loop receptors are the targets for many currently used clinically relevant drugs (e.g. benzodiazepines and anaesthetics). Understanding the molecular mechanisms of these receptors could therefore provide the catalyst for further development in this field, as well as promoting the development of experimental techniques for other areas of neuroscience.In this review, we present our current understanding of Cys-loop receptor structure and function. The ECD has been extensively studied. Research in this area has been stimulated in recent years by the publication of high-resolution structures of nACh receptors and related proteins, which have permitted the creation of many Cys loop receptor homology models of this region. Here, using the 5-HT3 receptor as a typical member of the family, we describe how homology modelling and ligand docking can provide useful but not definitive information about ligand interactions. We briefly consider some of the many Cys-loop receptors modulators. We discuss the current understanding of the structure of the TMD, and how this links to the ECD to allow channel gating, and consider the roles of the ICD, whose structure is poorly understood. We also describe some of the current methods that are beginning to reveal the differences between different receptor states, and may ultimately show structural details of transitions between them.
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de Kloe GE, Retra K, Geitmann M, Källblad P, Nahar T, van Elk R, Smit AB, van Muijlwijk-Koezen JE, Leurs R, Irth H, Danielson UH, de Esch IJP. Surface Plasmon Resonance Biosensor Based Fragment Screening Using Acetylcholine Binding Protein Identifies Ligand Efficiency Hot Spots (LE Hot Spots) by Deconstruction of Nicotinic Acetylcholine Receptor α7 Ligands. J Med Chem 2010; 53:7192-201. [DOI: 10.1021/jm100834y] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Gerdien E. de Kloe
- Leiden/Amsterdam Center for Drug Research (LACDR), Division of Medicinal Chemistry, Faculty of Sciences, VU University Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
| | - Kim Retra
- Leiden/Amsterdam Center for Drug Research (LACDR), Division of BioMolecular Analysis, Faculty of Sciences, VU University Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
| | | | | | - Tariq Nahar
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University Amsterdam, De Boelelaan 1085, 1081 HV, Amsterdam, The Netherlands
| | - René van Elk
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University Amsterdam, De Boelelaan 1085, 1081 HV, Amsterdam, The Netherlands
| | - August B. Smit
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University Amsterdam, De Boelelaan 1085, 1081 HV, Amsterdam, The Netherlands
| | - Jacqueline E. van Muijlwijk-Koezen
- Leiden/Amsterdam Center for Drug Research (LACDR), Division of Medicinal Chemistry, Faculty of Sciences, VU University Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
| | - Rob Leurs
- Leiden/Amsterdam Center for Drug Research (LACDR), Division of Medicinal Chemistry, Faculty of Sciences, VU University Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
| | - Hubertus Irth
- Leiden/Amsterdam Center for Drug Research (LACDR), Division of BioMolecular Analysis, Faculty of Sciences, VU University Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
| | - U. Helena Danielson
- Beactica AB, Box 567, SE-751 22 Uppsala, Sweden
- Department of Biochemistry and Organic Chemistry, Uppsala University, BMC, Box 576, SE-751 23, Uppsala, Sweden
| | - Iwan J. P. de Esch
- Leiden/Amsterdam Center for Drug Research (LACDR), Division of Medicinal Chemistry, Faculty of Sciences, VU University Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
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255
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Nicotinic pharmacophore: the pyridine N of nicotine and carbonyl of acetylcholine hydrogen bond across a subunit interface to a backbone NH. Proc Natl Acad Sci U S A 2010; 107:13206-11. [PMID: 20616056 DOI: 10.1073/pnas.1007140107] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Pharmacophore models for nicotinic agonists have been proposed for four decades. Central to these models is the presence of a cationic nitrogen and a hydrogen bond acceptor. It is now well-established that the cationic center makes an important cation-pi interaction to a conserved tryptophan, but the donor to the proposed hydrogen bond acceptor has been more challenging to identify. A structure of nicotine bound to the acetylcholine binding protein predicted that the binding partner of the pharmacophore's second component was a water molecule, which also hydrogen bonds to the backbone of the complementary subunit of the receptors. Here we use unnatural amino acid mutagenesis coupled with agonist analogs to examine whether such a hydrogen bond is functionally significant in the alpha4beta2 neuronal nAChR, the receptor most associated with nicotine addiction. We find evidence for the hydrogen bond with the agonists nicotine, acetylcholine, carbamylcholine, and epibatidine. These data represent a completed nicotinic pharmacophore and offer insight into the design of new therapeutic agents that selectively target these receptors.
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257
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Iturriaga-Vásquez P, Carbone A, García-Beltrán O, Livingstone PD, Biggin PC, Cassels BK, Wonnacott S, Zapata-Torres G, Bermudez I. Molecular determinants for competitive inhibition of alpha4beta2 nicotinic acetylcholine receptors. Mol Pharmacol 2010; 78:366-75. [PMID: 20547737 DOI: 10.1124/mol.110.065490] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The Erythrina alkaloids erysodine and dihydro-beta-erythroidine (DHbetaE) are potent and selective competitive inhibitors of alpha4beta2 nicotinic acetylcholine receptors (nAChRs), but little is known about the molecular determinants of the sensitivity of this receptor subtype to inhibition by this class of antagonists. We addressed this issue by examining the effects of DHbetaE and a range of aromatic Erythrina alkaloids on [(3)H]cytisine binding and receptor function in conjunction with homology models of the alpha4beta2 nAChR, mutagenesis, and functional assays. The lactone group of DHbetaE and a hydroxyl group at position C-16 in aromatic Erythrina alkaloids were identified as major determinants of potency, which was decreased when the conserved residue Tyr126 in loop A of the alpha4 subunit was substituted by alanine. Sensitivity to inhibition was also decreased by substituting the conserved aromatic residues alpha4Trp182 (loop B), alpha4Tyr230 (loop C), and beta2Trp82 (loop D) and the nonconserved beta2Thr84; however, only alpha4Trp182 was predicted to contact bound antagonist, suggesting alpha4Tyr230, beta2Trp82, and beta2Thr84 contribute allosterically to the closed state elicited by bound antagonist. In addition, homology modeling predicted strong ionic interactions between the ammonium center of the Erythrina alkaloids and beta2Asp196, leading to the uncapping of loop C. Consistent with this, beta2D196A abolished sensitivity to inhibition by DHbetaE or erysodine but not by epierythratidine, which is not predicted to form ionic bonds with beta2Asp196. This residue is not conserved in subunits that comprise nAChRs with low sensitivity to inhibition by DHbetaE or erysodine, which highlights beta2Asp196 as a major determinant of the receptor selectivity of Erythrina alkaloids.
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258
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Site-directed mutagenesis of charged amino acids of the human mitochondrial carnitine/acylcarnitine carrier: Insight into the molecular mechanism of transport. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1797:839-45. [DOI: 10.1016/j.bbabio.2010.03.017] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2010] [Revised: 03/03/2010] [Accepted: 03/19/2010] [Indexed: 11/19/2022]
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259
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Bush JC, Minitti MP, Weber PM. Ultrafast formation of an intramolecular cation–pi bond. J Photochem Photobiol A Chem 2010. [DOI: 10.1016/j.jphotochem.2010.05.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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260
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The cessation and detoxification effect of tea filters on cigarette smoke. SCIENCE CHINA-LIFE SCIENCES 2010; 53:533-41. [DOI: 10.1007/s11427-010-0097-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2009] [Accepted: 03/04/2010] [Indexed: 10/19/2022]
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261
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Bruhova I, Zhorov BS. A homology model of the pore domain of a voltage-gated calcium channel is consistent with available SCAM data. ACTA ACUST UNITED AC 2010; 135:261-74. [PMID: 20176854 PMCID: PMC2828909 DOI: 10.1085/jgp.200910288] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
In the absence of x-ray structures of calcium channels, their homology models are used to rationalize experimental data and design new experiments. The modeling relies on sequence alignments between calcium and potassium channels. Zhen et al. (2005. J. Gen. Physiol. doi:10.1085/jgp.200509292) used the substituted cysteine accessibility method (SCAM) to identify pore-lining residues in the Cav2.1 channel and concluded that their data are inconsistent with the symmetric architecture of the pore domain and published sequence alignments between calcium and potassium channels. Here, we have built Kv1.2-based models of the Cav2.1 channel with 2-(trimethylammonium)ethyl methanethiosulfonate (MTSET)-modified engineered cysteines and used Monte Carlo energy minimizations to predict their energetically optimal orientations. We found that depending on the position of an engineered cysteine in S6 and S5 helices, the ammonium group in the long flexible MTSET-modified side chain can orient into the inner pore, an interface between domains (repeats), or an interface between S5 and S6 helices. Different local environments of equivalent positions in the four repeats can lead to different SCAM results. The reported current inhibition by MTSET generally decreases with the predicted distances between the ammonium nitrogen and the pore axis. A possible explanation for outliers of this correlation is suggested. Our calculations rationalize the SCAM data, validate one of several published sequence alignments between calcium and potassium channels, and suggest similar spatial dispositions of S5 and S6 helices in voltage-gated potassium and calcium channels.
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Affiliation(s)
- Iva Bruhova
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario L8N 3Z5, Canada
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262
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Ghiron C, Haydar SN, Aschmies S, Bothmann H, Castaldo C, Cocconcelli G, Comery TA, Di L, Dunlop J, Lock T, Kramer A, Kowal D, Jow F, Grauer S, Harrison B, La Rosa S, Maccari L, Marquis KL, Micco I, Nencini A, Quinn J, Robichaud AJ, Roncarati R, Scali C, Terstappen GC, Turlizzi E, Valacchi M, Varrone M, Zanaletti R, Zanelli U. Novel Alpha-7 Nicotinic Acetylcholine Receptor Agonists Containing a Urea Moiety: Identification and Characterization of the Potent, Selective, and Orally Efficacious Agonist 1-[6-(4-Fluorophenyl)pyridin-3-yl]-3-(4-piperidin-1-ylbutyl) Urea (SEN34625/WYE-103914). J Med Chem 2010; 53:4379-89. [DOI: 10.1021/jm901692q] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Chiara Ghiron
- Siena Biotech SpA, Strada del Petriccio e Belriguardo 35, 53100 Siena, Italy
| | - Simon N. Haydar
- Chemical Sciences and Neuroscience Discovery Research, Wyeth Research, CN 8000, Princeton, New Jersey 08543-8000
| | - Suzan Aschmies
- Chemical Sciences and Neuroscience Discovery Research, Wyeth Research, CN 8000, Princeton, New Jersey 08543-8000
| | - Hendrick Bothmann
- Siena Biotech SpA, Strada del Petriccio e Belriguardo 35, 53100 Siena, Italy
| | - Cristiana Castaldo
- Siena Biotech SpA, Strada del Petriccio e Belriguardo 35, 53100 Siena, Italy
| | | | - Thomas A. Comery
- Chemical Sciences and Neuroscience Discovery Research, Wyeth Research, CN 8000, Princeton, New Jersey 08543-8000
| | - Li Di
- Chemical Sciences and Neuroscience Discovery Research, Wyeth Research, CN 8000, Princeton, New Jersey 08543-8000
| | - John Dunlop
- Chemical Sciences and Neuroscience Discovery Research, Wyeth Research, CN 8000, Princeton, New Jersey 08543-8000
| | - Tim Lock
- Chemical Sciences and Neuroscience Discovery Research, Wyeth Research, CN 8000, Princeton, New Jersey 08543-8000
| | - Angela Kramer
- Chemical Sciences and Neuroscience Discovery Research, Wyeth Research, CN 8000, Princeton, New Jersey 08543-8000
| | - Dianne Kowal
- Chemical Sciences and Neuroscience Discovery Research, Wyeth Research, CN 8000, Princeton, New Jersey 08543-8000
| | - Flora Jow
- Chemical Sciences and Neuroscience Discovery Research, Wyeth Research, CN 8000, Princeton, New Jersey 08543-8000
| | - Steve Grauer
- Chemical Sciences and Neuroscience Discovery Research, Wyeth Research, CN 8000, Princeton, New Jersey 08543-8000
| | - Boyd Harrison
- Chemical Sciences and Neuroscience Discovery Research, Wyeth Research, CN 8000, Princeton, New Jersey 08543-8000
| | - Salvatore La Rosa
- Siena Biotech SpA, Strada del Petriccio e Belriguardo 35, 53100 Siena, Italy
| | - Laura Maccari
- Siena Biotech SpA, Strada del Petriccio e Belriguardo 35, 53100 Siena, Italy
| | - Karen L. Marquis
- Chemical Sciences and Neuroscience Discovery Research, Wyeth Research, CN 8000, Princeton, New Jersey 08543-8000
| | - Iolanda Micco
- Siena Biotech SpA, Strada del Petriccio e Belriguardo 35, 53100 Siena, Italy
| | - Arianna Nencini
- Siena Biotech SpA, Strada del Petriccio e Belriguardo 35, 53100 Siena, Italy
| | - Joanna Quinn
- Siena Biotech SpA, Strada del Petriccio e Belriguardo 35, 53100 Siena, Italy
| | - Albert J. Robichaud
- Chemical Sciences and Neuroscience Discovery Research, Wyeth Research, CN 8000, Princeton, New Jersey 08543-8000
| | - Renza Roncarati
- Siena Biotech SpA, Strada del Petriccio e Belriguardo 35, 53100 Siena, Italy
| | - Carla Scali
- Siena Biotech SpA, Strada del Petriccio e Belriguardo 35, 53100 Siena, Italy
| | - Georg C. Terstappen
- Siena Biotech SpA, Strada del Petriccio e Belriguardo 35, 53100 Siena, Italy
| | - Elisa Turlizzi
- Siena Biotech SpA, Strada del Petriccio e Belriguardo 35, 53100 Siena, Italy
| | - Michela Valacchi
- Siena Biotech SpA, Strada del Petriccio e Belriguardo 35, 53100 Siena, Italy
| | - Maurizio Varrone
- Siena Biotech SpA, Strada del Petriccio e Belriguardo 35, 53100 Siena, Italy
| | - Riccardo Zanaletti
- Siena Biotech SpA, Strada del Petriccio e Belriguardo 35, 53100 Siena, Italy
| | - Ugo Zanelli
- Siena Biotech SpA, Strada del Petriccio e Belriguardo 35, 53100 Siena, Italy
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263
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Abin-Carriquiry JA, Zunini MP, Cassels BK, Wonnacott S, Dajas F. In silico characterization of cytisinoids docked into an acetylcholine binding protein. Bioorg Med Chem Lett 2010; 20:3683-7. [PMID: 20493692 DOI: 10.1016/j.bmcl.2010.04.092] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2009] [Revised: 04/20/2010] [Accepted: 04/21/2010] [Indexed: 10/19/2022]
Abstract
Homology models of nicotinic acetylcholine receptors (nAChRs) suggest that subtype specificity is due to non-conserved residues in the complementary subunit of the ligand-binding pocket. Cytisine and its derivatives generally show a strong preference for heteromeric alpha4beta2* nAChRs over the homomeric alpha7 subtype, and the structural modifications studied do not cause large changes in their nAChR subtype selectivity. In the present work we docked cytisine, N-methylcytisine, and several pyridone ring-substituted cytisinoids into the crystallographic structure of the Lymnaea stagnalis acetylcholine binding protein (AChBP) co-crystallized with nicotine (1UW6). The graphical analysis of the best poses showed that cytisinoids have weak interactions with the side chains of the non-conserved amino acids in the complementary subunit justifying the use of PDB 1UWB as a surrogate for nAChR. Furthermore, we found a high correlation (R(2)=0.96) between the experimental pIC(50) values at alpha4beta2* nAChR and docking energy (S) of the best cytisinoid poses within the AChBP. Due to the quality of the correlation we suggest that this equation might be used as a predictive model to propose new cytisine-derived nAChRs ligands. Our docking results also suggest that further structural modifications of these cytisinoids will not greatly alter their alpha4beta2*/alpha7 selectivity.
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Affiliation(s)
- Juan Andrés Abin-Carriquiry
- Department of Neurochemistry, Instituto de Investigaciones Biológicas Clemente Estable, Montevideo, Uruguay.
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264
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Wang CY, Xiang YT, Weng YZ, Bo QJ, Chiu HFK, Chan SSM, Lee EHM, Ungvari GS. Cigarette smoking in patients with schizophrenia in China: prospective, multicentre study. Aust N Z J Psychiatry 2010; 44:456-62. [PMID: 20397788 DOI: 10.3109/00048670903493348] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE The aim of the present study was to explore the rate of cigarette smoking and its sociodemographic and clinical characteristics in Chinese schizophrenia patients. METHODS In a multicentre, randomized, controlled, longitudinal study, 374 clinically stable patients with schizophrenia were interviewed at entry using standardized assessment instruments, and followed up for 1-2 years. RESULTS The rate of cigarette smoking was 13.9% in the whole sample, and 26.2% in men and 3.5% in women. On univariate analysis, male sex, unemployment, alcohol consumption, older age, older age at onset, longer duration of illness, more frequent admissions, more severe hostility-excitement at entry and less deterioration in hostility-excitement over the study period were significantly associated with cigarette smoking. On multivariate analysis, male sex, unemployment, alcohol consumption, more frequent admissions, less severe positive and negative symptoms at entry, smaller decline in negative symptoms and more deterioration in disorganized thoughts over the study period were independently associated with cigarette smoking. CONCLUSION The rate of cigarette smoking in Chinese schizophrenia patients is considerably lower than most figures reported in the Western literature.
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Affiliation(s)
- Chuan-Yue Wang
- Beijing Anding Hospital, Capital Medical University, Beijing, China
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265
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A revolutionary approach for the cessation of smoking. SCIENCE CHINA. LIFE SCIENCES 2010; 53:631-2. [PMID: 20596947 DOI: 10.1007/s11427-010-0107-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2010] [Accepted: 03/31/2010] [Indexed: 10/19/2022]
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266
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Wang R, Xie T. Macroscopic evidence of strong cation–π interactions in a synthetic polymer system. Chem Commun (Camb) 2010; 46:1341-3. [DOI: 10.1039/b916204f] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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267
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268
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Whiting AL, Neufeld NM, Hof F. A tryptophan-analog host whose interactions with ammonium ions in water are dominated by the hydrophobic effect. Tetrahedron Lett 2009. [DOI: 10.1016/j.tetlet.2009.09.161] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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269
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Minnihan EC, Yokoyama K, Stubbe J. Unnatural amino acids: better than the real things? F1000 BIOLOGY REPORTS 2009; 1:88. [PMID: 20948602 PMCID: PMC2948271 DOI: 10.3410/b1-88] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Considerable effort has been dedicated to the development of technology for the site-specific incorporation of unnatural amino acids into proteins, with nonsense codon suppression and expressed protein ligation emerging as two of the most promising methods. Recent research advances in which these methods have been applied to study protein function and mechanism are briefly highlighted, and the potential of the methods for efficient, widespread future use in vitro and in vivo is critically evaluated.
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Affiliation(s)
- Ellen C Minnihan
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139-4307, USA
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270
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Lu Y, Wang Y, Xu Z, Yan X, Luo X, Jiang H, Zhu W. C-X...H contacts in biomolecular systems: how they contribute to protein-ligand binding affinity. J Phys Chem B 2009; 113:12615-21. [PMID: 19708644 DOI: 10.1021/jp906352e] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The hydrogen bond acceptor capability of halogens has long been underappreciated in the field of biology. In this work, we have surveyed structures of protein complexes with halogenated ligands to characterize geometrical preferences of C-X...H contacts and contributions of such interactions to protein-ligand binding affinity. Notably, F...H interactions in biomolecules exhibit a remarkably different behavior as compared to three other kinds of X...H (X = Cl, Br, I) interactions, which has been rationalized by means of ab initio calculations using simple model systems. The C-X...H contacts in biological systems are characterized as weak hydrogen bonding interactions. Furthermore, the electrophile "head on" and nucleophile "side on" interactions of halogens have been extensively investigated through the examination of interactions in protein structures and a two-layer ONIOM-based QM/MM method. In biomolecular systems, C-X...H contacts are recognized as secondary interaction contributions to C-X...O halogen bonds that play important roles in conferring specificity and affinity for halogenated ligands. The results presented here are within the context of their potential applications in drug design, including relevance to the development of accurate force fields for halogens.
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Affiliation(s)
- Yunxiang Lu
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
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271
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Alkorta I, Blanco F, Deyà PM, Elguero J, Estarellas C, Frontera A, Quiñonero D. Cooperativity in multiple unusual weak bonds. Theor Chem Acc 2009. [DOI: 10.1007/s00214-009-0690-1] [Citation(s) in RCA: 196] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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272
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Liu LT, Willenbring D, Xu Y, Tang P. General anesthetic binding to neuronal alpha4beta2 nicotinic acetylcholine receptor and its effects on global dynamics. J Phys Chem B 2009; 113:12581-9. [PMID: 19697903 DOI: 10.1021/jp9039513] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The neuronal alpha4beta2 nicotinic acetylcholine receptor (nAChR) is a target for general anesthetics. Currently available experimental structural information is inadequate to understand where anesthetics bind and how they modulate the receptor motions essential to function. Using our published open-channel structure model of alpha4beta2 nAChR, we identified and evaluated six amphiphilic interaction sites for the volatile anesthetic halothane via flexible ligand docking and subsequent 20-ns molecular dynamics simulations. Halothane binding energies ranged from -6.8 to -2.4 kcal/mol. The primary binding sites were located at the interface of extracellular and transmembrane domains, where halothane perturbed conformations of, and widened the gap among, the Cys loop, the beta1-beta2 loop, and the TM2-TM3 linker. The halothane with the highest binding affinity at the interface between the alpha4 and beta2 subunits altered interactions between the protein and nearby lipids by competing for hydrogen bonds. Gaussian network model analyses of the alpha4beta2 nAChR structures at the end of 20-ns simulations in the absence or presence of halothane revealed profound changes in protein residue mobility. The concerted motions critical to protein function were also perturbed considerably. Halothane's effect on protein dynamics was not confined to the residues adjacent to the binding sites, indicating an action on a more global scale.
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Affiliation(s)
- Lu Tian Liu
- Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
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273
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Bartos M, Corradi J, Bouzat C. Structural basis of activation of cys-loop receptors: the extracellular-transmembrane interface as a coupling region. Mol Neurobiol 2009; 40:236-52. [PMID: 19859835 DOI: 10.1007/s12035-009-8084-x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2009] [Accepted: 09/22/2009] [Indexed: 10/25/2022]
Abstract
Cys-loop receptors mediate rapid transmission throughout the nervous system by converting a chemical signal into an electric one. They are pentameric proteins with an extracellular domain that carries the transmitter binding sites and a transmembrane region that forms the ion pore. Their essential function is to couple the binding of the agonist at the extracellular domain to the opening of the ion pore. How the structural changes elicited by agonist binding are propagated through a distance of 50 A to the gate is therefore central for the understanding of the receptor function. A step forward toward the identification of the structures involved in gating has been given by the recently elucidated high-resolution structures of Cys-loop receptors and related proteins. The extracellular-transmembrane interface has attracted attention because it is a structural transition zone where beta-sheets from the extracellular domain merge with alpha-helices from the transmembrane domain. Within this zone, several regions form a network that relays structural changes from the binding site toward the pore, and therefore, this interface controls the beginning and duration of a synaptic response. In this review, the most recent findings on residues and pairwise interactions underlying channel gating are discussed, the main focus being on the extracellular-transmembrane interface.
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Affiliation(s)
- Mariana Bartos
- Instituto de Investigaciones Bioquímicas, UNS-CONICET, Bahía Blanca, Argentina
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274
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Rucktooa P, Smit AB, Sixma TK. Insight in nAChR subtype selectivity from AChBP crystal structures. Biochem Pharmacol 2009; 78:777-87. [DOI: 10.1016/j.bcp.2009.06.098] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2009] [Revised: 06/19/2009] [Accepted: 06/22/2009] [Indexed: 10/20/2022]
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275
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Nicotinic receptors: allosteric transitions and therapeutic targets in the nervous system. Nat Rev Drug Discov 2009; 8:733-50. [PMID: 19721446 DOI: 10.1038/nrd2927] [Citation(s) in RCA: 527] [Impact Index Per Article: 35.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Nicotinic receptors - a family of ligand-gated ion channels that mediate the effects of the neurotransmitter acetylcholine - are among the most well understood allosteric membrane proteins from a structural and functional perspective. There is also considerable interest in modulating nicotinic receptors to treat nervous-system disorders such as Alzheimer's disease, schizophrenia, depression, attention deficit hyperactivity disorder and tobacco addiction. This article describes both recent advances in our understanding of the assembly, activity and conformational transitions of nicotinic receptors, as well as developments in the therapeutic application of nicotinic receptor ligands, with the aim of aiding novel drug discovery by bridging the gap between these two rapidly developing fields.
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276
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Sletten E, Bertozzi C. Bioorthogonale Chemie - oder: in einem Meer aus Funktionalität nach Selektivität fischen. Angew Chem Int Ed Engl 2009. [DOI: 10.1002/ange.200900942] [Citation(s) in RCA: 522] [Impact Index Per Article: 34.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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277
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Breining SR, Bencherif M, Grady SR, Whiteaker P, Marks MJ, Wageman CR, Lester HA, Yohannes D. Evaluation of structurally diverse neuronal nicotinic receptor ligands for selectivity at the alpha6( *) subtype. Bioorg Med Chem Lett 2009; 19:4359-63. [PMID: 19560354 PMCID: PMC6107347 DOI: 10.1016/j.bmcl.2009.05.085] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2009] [Revised: 05/15/2009] [Accepted: 05/20/2009] [Indexed: 11/15/2022]
Abstract
Direct comparison of pyridine versus pyrimidine substituents on a small but diverse set of ligands indicates that the pyrimidine substitution has the potential to enhance affinity and/or functional activity at alpha6 subunit-containing neuronal nicotinic receptors (NNRs) and decrease activation of ganglionic nicotinic receptors, depending on the scaffold. The ramifications of this structure-activity relationship are discussed in the context of the design of small molecules targeting smoking cessation.
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Affiliation(s)
- Scott R Breining
- Department of Medicinal Chemistry, Targacept, Inc., 200 East First St., Suite 300, Winston-Salem, NC 27101, USA
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278
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Srivastava S, Hamouda AK, Pandhare A, Duddempudi PK, Sanghvi M, Cohen JB, Blanton MP. [(3)H]Epibatidine photolabels non-equivalent amino acids in the agonist binding site of Torpedo and alpha4beta2 nicotinic acetylcholine receptors. J Biol Chem 2009; 284:24939-47. [PMID: 19620239 DOI: 10.1074/jbc.m109.019083] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Nicotinic acetylcholine receptor (nAChR) agonists, such as epibatidine and its molecular derivatives, are potential therapeutic agents for a variety of neurological disorders. In order to identify determinants for subtype-selective agonist binding, it is important to determine whether an agonist binds in a common orientation in different nAChR subtypes. To compare the mode of binding of epibatidine in a muscle and a neuronal nAChR, we photolabeled Torpedo alpha(2)betagammadelta and expressed human alpha4beta2 nAChRs with [(3)H]epibatidine and identified by Edman degradation the photolabeled amino acids. Irradiation at 254 nm resulted in photolabeling of alphaTyr(198) in agonist binding site Segment C of the principal (+) face in both alpha subunits and of gammaLeu(109) and gammaTyr(117) in Segment E of the complementary (-) face, with no labeling detected in the delta subunit. For affinity-purified alpha4beta2 nAChRs, [(3)H]epibatidine photolabeled alpha4Tyr(195) (equivalent to Torpedo alphaTyr(190)) in Segment C as well as beta2Val(111) and beta2Ser(113) in Segment E (equivalent to Torpedo gammaLeu(109) and gammaTyr(111), respectively). Consideration of the location of the photolabeled amino acids in homology models of the nAChRs based upon the acetylcholine-binding protein structure and the results of ligand docking simulations suggests that epibatidine binds in a single preferred orientation within the alpha-gamma transmitter binding site, whereas it binds in two distinct orientations in the alpha4beta2 nAChR.
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Affiliation(s)
- Shouryadeep Srivastava
- Department of Pharmacology and Neuroscience and the Center for Membrane Protein Research, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas 79430, USA
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279
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Probing the role of the cation-pi interaction in the binding sites of GPCRs using unnatural amino acids. Proc Natl Acad Sci U S A 2009; 106:11919-24. [PMID: 19581583 DOI: 10.1073/pnas.0903260106] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We describe a general application of the nonsense suppression methodology for unnatural amino acid incorporation to probe drug-receptor interactions in functional G protein-coupled receptors (GPCRs), evaluating the binding sites of both the M2 muscarinic acetylcholine receptor and the D2 dopamine receptor. Receptors were expressed in Xenopus oocytes, and activation of a G protein-coupled, inward-rectifying K(+) channel (GIRK) provided, after optimization of conditions, a quantitative readout of receptor function. A number of aromatic amino acids thought to be near the agonist-binding site were evaluated. Incorporation of a series of fluorinated tryptophan derivatives at W6.48 of the D2 receptor establishes a cation-pi interaction between the agonist dopamine and W6.48, suggesting a reorientation of W6.48 on agonist binding, consistent with proposed "rotamer switch" models. Interestingly, no comparable cation-pi interaction was found at the aligning residue in the M2 receptor.
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280
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Shimizu A, Mori T, Inoue Y, Yamada S. Combined Experimental and Quantum Chemical Investigation of Chiroptical Properties of Nicotinamide Derivatives with and without Intramolecular Cation−π Interactions. J Phys Chem A 2009; 113:8754-64. [DOI: 10.1021/jp904243w] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Akinori Shimizu
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita 565-0871, Japan, and Department of Chemistry, Graduate School of Science, Ochanomizu University, Tokyo 112-8610, Japan
| | - Tadashi Mori
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita 565-0871, Japan, and Department of Chemistry, Graduate School of Science, Ochanomizu University, Tokyo 112-8610, Japan
| | - Yoshihisa Inoue
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita 565-0871, Japan, and Department of Chemistry, Graduate School of Science, Ochanomizu University, Tokyo 112-8610, Japan
| | - Shinji Yamada
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita 565-0871, Japan, and Department of Chemistry, Graduate School of Science, Ochanomizu University, Tokyo 112-8610, Japan
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281
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Hamouda AK, Jin X, Sanghvi M, Srivastava S, Pandhare A, Duddempudi PK, Steinbach JH, Blanton MP. Photoaffinity labeling the agonist binding domain of alpha4beta4 and alpha4beta2 neuronal nicotinic acetylcholine receptors with [(125)I]epibatidine and 5[(125)I]A-85380. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1788:1987-95. [PMID: 19545536 DOI: 10.1016/j.bbamem.2009.06.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2009] [Revised: 06/15/2009] [Accepted: 06/16/2009] [Indexed: 11/26/2022]
Abstract
The development of nicotinic acetylcholine receptor (nAChR) agonists, particularly those that discriminate between neuronal nAChR subtypes, holds promise as potential therapeutic agents for many neurological diseases and disorders. To this end, we photoaffinity labeled human alpha4beta2 and rat alpha4beta4 nAChRs affinity-purified from stably transfected HEK-293 cells, with the agonists [(125)I]epibatidine and 5[(125)I]A-85380. Our results show that both agonists photoincorporated into the beta4 subunit with little or no labeling of the beta2 and alpha4 subunits respectively. [(125)I]epibatidine labeling in the beta4 subunit was mapped to two overlapping proteolytic fragments that begin at beta4V102 and contain Loop E (beta4I109-P120) of the agonist binding site. We were unable to identify labeled amino acid(s) in Loop E by protein sequencing, but we were able to demonstrate that beta4Q117 in Loop E is the principal site of [(125)I]epibatidine labeling. This was accomplished by substituting residues in the beta2 subunit with the beta4 homologs and finding [(125)I]epibatidine labeling in beta4 and beta2F119Q subunits with little, if any, labeling in alpha4, beta2, or beta2S113R subunits. Finally, functional studies established that the beta2F119/beta4Q117 position is an important determinant of the receptor subtype-selectivity of the agonist 5I-A-85380, affecting both binding affinity and channel activation.
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Affiliation(s)
- Ayman K Hamouda
- Department of Pharmacology and Neuroscience and the Center for Membrane Protein Research, School of Medicine, Texas Tech University Health Sciences Center, 3601 4th Street, Lubbock, TX 79430, USA
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282
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Bartos M, Price KL, Lummis SCR, Bouzat C. Glutamine 57 at the complementary binding site face is a key determinant of morantel selectivity for {alpha}7 nicotinic receptors. J Biol Chem 2009; 284:21478-87. [PMID: 19506073 PMCID: PMC2755872 DOI: 10.1074/jbc.m109.013797] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Nicotinic receptors (AChRs) play key roles in synaptic transmission. We explored activation of neuronal α7 and mammalian muscle AChRs by morantel and oxantel. Our results revealed a novel action of morantel as a high efficacy and more potent agonist than ACh of α7 receptors. The EC50 for activation by morantel of both α7 and α7-5HT3A receptors is 7-fold lower than that determined for ACh. The minimum morantel concentration required to activate α7-5HT3A channels is 6-fold lower than that of ACh, and activation episodes are more prolonged than in the presence of ACh. By contrast, oxantel is a weak agonist of α7 and α7-5HT3A, and both drugs are very low efficacy agonists of muscle AChRs. The replacement of Gln57 in α7 by glycine, which is found in the equivalent position of the muscle AChR, decreases the efficacy for activation and turns morantel into a partial agonist. The reverse mutation in the muscle AChR (ϵG57Q) increases 7-fold the efficacy of morantel. The mutations do not affect activation by ACh or oxantel, indicating that this position is selective for morantel. In silico studies show that the tetrahydropyrimidinyl group, common to both drugs, is close to Trp149 of the principal face of the binding site, whereas the other cyclic group is proximal to Gln57 of the complementary face in morantel but not in oxantel. Thus, position 57 at the complementary face is a key determinant of the high selectivity of morantel for α7. These results provide new information for further progress in drug design.
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Affiliation(s)
- Mariana Bartos
- Instituto de Investigaciones Bioquímicas, UNS-CONICET, Bahía Blanca 8000, Argentina
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283
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Williams DK, Stokes C, Horenstein NA, Papke RL. Differential regulation of receptor activation and agonist selectivity by highly conserved tryptophans in the nicotinic acetylcholine receptor binding site. J Pharmacol Exp Ther 2009; 330:40-53. [PMID: 19339660 DOI: 10.1124/jpet.109.151225] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We have shown previously that a highly conserved Tyr in the nicotinic acetylcholine receptor (nAChR) ligand-binding domain (LBD) (alpha7 Tyr188 or alpha4 Tyr195) differentially regulates the activity of acetylcholine (ACh) and the alpha7-selective agonist 3-(4-hydroxy,2-methoxybenzylidene)anabaseine (4OH-GTS-21) in alpha4beta2 and alpha7 nAChR. In this study, we mutated two highly conserved LBD Trp residues in human alpha7 and alpha4beta2 and expressed the receptors in Xenopus laevis oocytes. Alpha7 receptors with Trp55 mutated to Gly or Tyr became less responsive to 4OH-GTS-21, whereas mutation of the homologous Trp57 in beta2 to Gly, Tyr, Phe, or Ala resulted in alpha4beta2 receptors that showed increased responses to 4OH-GTS-21. Mutation of alpha7 Trp55 to Val resulted in receptors for which the partial agonist 4OH-GTS-21 became equally efficacious as ACh, whereas alpha4beta2 receptors with the homologous mutation remained nonresponsive to 4OH-GTS-21. In contrast to the striking alterations in agonist activity profiles that were observed with mutations of alpha7 Trp55 and beta2 Trp57, mutations of alpha7 Trp149 or alpha4 Trp154 universally resulted in receptors with reduced function. Our data support the hypothesis that some conserved residues in the nAChR LBD differentially regulate receptor activation by subtype-selective agonists, whereas other equally well conserved residues play fundamental roles in receptor activation by any agonist. Residues like alpha7 Trp149 (alpha4 Trp154) may be considered pillars upon which basic receptor function depends, whereas alpha7 Trp55 (beta2 Trp57) and alpha7 Tyr188 (alpha4 Tyr195) may be fulcra upon which agonists may operate differentially in specific receptor subtypes, consistent with the hypothesis that ACh and 4OH-GTS-21 are able to activate nAChR in distinct ways.
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Affiliation(s)
- Dustin K Williams
- Department of Pharmacology and Therapeutics, University of Florida College of Medicine, P.O. Box 100267, Gainesville, FL 32610-0267, USA
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284
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Lester HA, Xiao C, Srinivasan R, Son CD, Miwa J, Pantoja R, Banghart MR, Dougherty DA, Goate AM, Wang JC. Nicotine is a selective pharmacological chaperone of acetylcholine receptor number and stoichiometry. Implications for drug discovery. AAPS JOURNAL 2009; 11:167-77. [PMID: 19280351 DOI: 10.1208/s12248-009-9090-7] [Citation(s) in RCA: 132] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2008] [Accepted: 02/07/2009] [Indexed: 01/11/2023]
Abstract
The acronym SePhaChARNS, for "selective pharmacological chaperoning of acetylcholine receptor number and stoichiometry," is introduced. We hypothesize that SePhaChARNS underlies classical observations that chronic exposure to nicotine causes "upregulation" of nicotinic receptors (nAChRs). If the hypothesis is proven, (1) SePhaChARNS is the molecular mechanism of the first step in neuroadaptation to chronic nicotine; and (2) nicotine addiction is partially a disease of excessive chaperoning. The chaperone is a pharmacological one, nicotine; and the chaperoned molecules are alpha4beta2* nAChRs. SePhaChARNS may also underlie two inadvertent therapeutic effects of tobacco use: (1) the inverse correlation between tobacco use and Parkinson's disease; and (2) the suppression of seizures by nicotine in autosomal dominant nocturnal frontal lobe epilepsy. SePhaChARNS arises from the thermodynamics of pharmacological chaperoning: ligand binding, especially at subunit interfaces, stabilizes AChRs during assembly and maturation, and this stabilization is most pronounced for the highest-affinity subunit compositions, stoichiometries, and functional states of receptors. Several chemical and pharmacokinetic characteristics render exogenous nicotine a more potent pharmacological chaperone than endogenous acetylcholine. SePhaChARNS is modified by desensitized states of nAChRs, by acid trapping of nicotine in organelles, and by other aspects of proteostasis. SePhaChARNS is selective at the cellular, and possibly subcellular, levels because of variations in the detailed nAChR subunit composition, as well as in expression of auxiliary proteins such as lynx. One important implication of the SePhaChARNS hypothesis is that therapeutically relevant nicotinic receptor drugs could be discovered by studying events in intracellular compartments rather than exclusively at the surface membrane.
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Affiliation(s)
- Henry A Lester
- Division of Biology 156-29, California Institute of Technology, Pasadena, CA 91125, USA.
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285
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Sletten EM, Bertozzi CR. Bioorthogonal chemistry: fishing for selectivity in a sea of functionality. Angew Chem Int Ed Engl 2009; 48:6974-98. [PMID: 19714693 PMCID: PMC2864149 DOI: 10.1002/anie.200900942] [Citation(s) in RCA: 2361] [Impact Index Per Article: 157.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The study of biomolecules in their native environments is a challenging task because of the vast complexity of cellular systems. Technologies developed in the last few years for the selective modification of biological species in living systems have yielded new insights into cellular processes. Key to these new techniques are bioorthogonal chemical reactions, whose components must react rapidly and selectively with each other under physiological conditions in the presence of the plethora of functionality necessary to sustain life. Herein we describe the bioorthogonal chemical reactions developed to date and how they can be used to study biomolecules.
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Affiliation(s)
- Ellen M. Sletten
- Department of Chemistry, University of California, Berkeley, CA 94720 (USA)
| | - Carolyn R. Bertozzi
- Departments of Chemistry and Molecular and Cell Biology and Howard Hughes Medical Institute, University of California and The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (USA), Fax: (+1)510-643-2628
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