1
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Mansbach R, Patel LA, Watson NA, Kubicek-Sutherland JZ, Gnanakaran S. Inferring Pathways of Oxidative Folding from Prefolding Free Energy Landscapes of Disulfide-Rich Toxins. J Phys Chem B 2023; 127:1689-1703. [PMID: 36791259 PMCID: PMC9987446 DOI: 10.1021/acs.jpcb.2c07124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 12/07/2022] [Indexed: 02/17/2023]
Abstract
Short, cysteine-rich peptides can exist in stable or metastable structural ensembles due to the number of possible patterns of formation of their disulfide bonds. One interesting subset of this peptide group is the conotoxins, which are produced by aquatic snails in the family Conidae. The μ conotoxins, which are antagonists and blockers of the voltage-gated sodium channel, exist in a folding spectrum: on one end of the spectrum are more hirudin-like folders, which form disulfide bonds and then reshuffle them, leading to an ensemble of kinetically trapped isomers, and on the other end are more BPTI-like folders, which form the native disulfide bonds one by one in a particular order, leading to a preponderance of conformations existing in a single stable state. In this Article, we employ the composite diffusion map approach to study the unified free energy surface of prefolding μ-conotoxin equilibrium. We identify the two most important nonlinear collective modes of the unified folding landscape and demonstrate that in the absence of their disulfides, the conotoxins can be thought of as largely disordered polymers. A small increase in the number of hydrophobic residues in the protein shifts the free energy landscape toward hydrophobically collapsed coil conformations responsible for cysteine proximity in hirudin-like folders, compared to semiextended coil conformations with more distal cysteines in BPTI-like folders. Overall, this work sheds important light on the folding processes and free energy landscapes of cysteine-rich peptides and demonstrates the extent to which sequence and length contribute to these landscapes.
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Affiliation(s)
| | - Lara A. Patel
- OpenEye
Scientific Research, Santa Fe, New Mexico 87508, United States
| | - Natalya A. Watson
- Physics
Department, University of Concordia, Montreal, QC H4B 1R6, Canada
| | | | - S. Gnanakaran
- Physical
Chemistry and Applied Spectroscopy Group, Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
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2
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Tae HS, Adams DJ. Nicotinic acetylcholine receptor subtype expression, function, and pharmacology: Therapeutic potential of α-conotoxins. Pharmacol Res 2023; 191:106747. [PMID: 37001708 DOI: 10.1016/j.phrs.2023.106747] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 03/22/2023] [Accepted: 03/27/2023] [Indexed: 04/03/2023]
Abstract
The pentameric nicotinic acetylcholine receptors (nAChRs) are typically classed as muscle- or neuronal-type, however, the latter has also been reported in non-neuronal cells. Given their broad distribution, nAChRs mediate numerous physiological and pathological processes including synaptic transmission, presynaptic modulation of transmitter release, neuropathic pain, inflammation, and cancer. There are 17 different nAChR subunits and combinations of these subunits produce subtypes with diverse pharmacological properties. The expression and role of some nAChR subtypes have been extensively deciphered with the aid of knock-out models. Many nAChR subtypes expressed in heterologous systems are selectively targeted by the disulfide-rich α-conotoxins. α-Conotoxins are small peptides isolated from the venom of cone snails, and a number of them have potential pharmaceutical value.
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3
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Straub CJ, Rusali LE, Kremiller KM, Riley AP. What We Have Gained from Ibogaine: α3β4 Nicotinic Acetylcholine Receptor Inhibitors as Treatments for Substance Use Disorders. J Med Chem 2023; 66:107-121. [PMID: 36440853 PMCID: PMC10034762 DOI: 10.1021/acs.jmedchem.2c01562] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
For decades, ibogaine─the main psychoactive alkaloid found in Tabernanthe iboga─has been investigated as a possible treatment for substance use disorders (SUDs) due to its purported ability to interrupt the addictive properties of multiple drugs of abuse. Of the numerous pharmacological actions of ibogaine and its derivatives, the inhibition of α3β4 nicotinic acetylcholine receptors (nAChRs), represents a probable mechanism of action for their apparent anti-addictive activity. In this Perspective, we examine several classes of compounds that have been discovered and developed to target α3β4 nAChRs. Specifically, by focusing on compounds that have proven efficacious in pre-clinical models of drug abuse and have been evaluated clinically, we highlight the promising potential of the α3β4 nAChRs as viable targets to treat a wide array of SUDs. Additionally, we discuss the challenges faced by the existing classes of α3β4 nAChR ligands that must be overcome to develop them into therapeutic treatments.
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Affiliation(s)
- Carolyn J Straub
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Illinois at Chicago, Chicago, Illinois 60612, United States
| | - Lisa E Rusali
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Illinois at Chicago, Chicago, Illinois 60612, United States
| | - Kyle M Kremiller
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Illinois at Chicago, Chicago, Illinois 60612, United States
| | - Andrew P Riley
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Illinois at Chicago, Chicago, Illinois 60612, United States
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4
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Wei Y, Zhang M, Yu S, Huang Q, Chen R, Xu S, Huang Y, Yu Y, Liao M, Dai Q. A Single Amino Acid Replacement Boosts the Analgesic Activity of α-Conotoxin AuIB through the Inhibition of the GABA(B)R-Coupled N-Type Calcium Channel. Mar Drugs 2022; 20. [PMID: 36547897 DOI: 10.3390/md20120750] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 11/17/2022] [Accepted: 11/22/2022] [Indexed: 11/30/2022] Open
Abstract
α-conotoxin AuIB is the only one of the 4/6 type α-conotoxins (α-CTxs) that inhibits the γ-aminobutyric acid receptor B (GABABR)-coupled N-type calcium channel (CaV2.2). To improve its inhibitory activity, a series of variants were synthesized and evaluated according to the structure-activity relationships of 4/7 type α-CTxs targeting GABABR-coupled CaV2.2. Surprisingly, only the substitution of Pro7 with Arg results in a 2-3-fold increase in the inhibition of GABABR-coupled CaV2.2 (IC50 is 0.74 nM); substitutions of position 9-12 with basic or hydrophobic amino acid and the addition of hydrophobic amino acid Leu or Ile at the second loop to mimic 4/7 type α-CTxs all failed to improve the inhibitory activity of AuIB against GABABR-coupled CaV2.2. Interestingly, the most potent form of AuIB[P7R] has disulfide bridges of "1-4, 2-3" (ribbon), which differs from the "1-3, 2-4" (globular) in the isoforms of wildtype AuIB. In addition, AuIB[P7R](globular) displays potent analgesic activity in the acetic acid writhing model and the partial sciatic nerve injury (PNL) model. Our study demonstrated that 4/6 type α-CTxs, with the disulfide bridge connectivity "1-4, 2-3," are also potent inhibitors for GABABR-coupled CaV2.2, exhibiting potent analgesic activity.
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5
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Ma Y, Cao Q, Yang M, Gao Y, Fu S, Du W, Adams DJ, Jiang T, Tae H, Yu R. Single-Disulfide Conopeptide Czon1107, an Allosteric Antagonist of the Human α3β4 Nicotinic Acetylcholine Receptor. Mar Drugs 2022; 20:497. [PMID: 36005500 PMCID: PMC9409646 DOI: 10.3390/md20080497] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 07/27/2022] [Accepted: 07/29/2022] [Indexed: 11/16/2022] Open
Abstract
Conopeptides are peptides in the venom of marine cone snails that are used for capturing prey or as a defense against predators. A new cysteine-poor conopeptide, Czon1107, has exhibited non-competitive inhibition with an undefined allosteric mechanism in the human (h) α3β4 nicotinic acetylcholine receptors (nAChRs). In this study, the binding mode of Czon1107 to hα3β4 nAChR was investigated using molecular dynamics simulations coupled with mutagenesis studies of the peptide and electrophysiology studies on heterologous hα3β4 nAChRs. Overall, this study clarifies the structure–activity relationship of Czon1107 and hα3β4 nAChR and provides an important experimental and theoretical basis for the development of new peptide drugs.
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6
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Wu X, Craik DJ, Kaas Q. Interactions of Globular and Ribbon [γ4E]GID with α4β2 Neuronal Nicotinic Acetylcholine Receptor. Mar Drugs 2021; 19:md19090482. [PMID: 34564144 PMCID: PMC8469569 DOI: 10.3390/md19090482] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 08/24/2021] [Accepted: 08/24/2021] [Indexed: 02/05/2023] Open
Abstract
The α4β2 nAChR is implicated in a range of diseases and disorders including nicotine addiction, epilepsy and Parkinson's and Alzheimer's diseases. Designing α4β2 nAChR selective inhibitors could help define the role of the α4β2 nAChR in such disease states. In this study, we aimed to modify globular and ribbon α-conotoxin GID to selectively target the α4β2 nAChR through competitive inhibition of the α4(+)β2(-) or α4(+)α4(-) interfaces. The binding modes of the globular α-conotoxin [γ4E]GID with rat α3β2, α4β2 and α7 nAChRs were deduced using computational methods and were validated using published experimental data. The binding mode of globular [γ4E]GID at α4β2 nAChR can explain the experimental mutagenesis data, suggesting that it could be used to design GID variants. The predicted mutational energy results showed that globular [γ4E]GID is optimal for binding to α4β2 nAChR and its activity could not likely be further improved through amino-acid substitutions. The binding mode of ribbon GID with the (α4)3(β2)2 nAChR was deduced using the information from the cryo-electron structure of (α4)3(β2)2 nAChR and the binding mode of ribbon AuIB. The program FoldX predicted the mutational energies of ribbon [γ4E]GID at the α4(+)α4(-) interface, and several ribbon[γ4E]GID mutants were suggested to have desirable properties to inhibit (α4)3(β2)2 nAChR.
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Affiliation(s)
- Xiaosa Wu
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, QLD 4072, Australia;
- National Institutes of Health, Building 35A, Room 3D-953B, 35 Convent Drive, Bethesda, MD 20892-3701, USA
| | - David J. Craik
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, QLD 4072, Australia;
- Correspondence: (D.J.C.); (Q.K.)
| | - Quentin Kaas
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, QLD 4072, Australia;
- Correspondence: (D.J.C.); (Q.K.)
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7
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Tae HS, Gao B, Jin AH, Alewood PF, Adams DJ. Globular and ribbon isomers of Conus geographus α-conotoxins antagonize human nicotinic acetylcholine receptors. Biochem Pharmacol 2021; 190:114638. [PMID: 34062129 DOI: 10.1016/j.bcp.2021.114638] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 05/27/2021] [Accepted: 05/27/2021] [Indexed: 11/29/2022]
Abstract
The short disulfide-rich α-conotoxins derived from the venom of Conus snails comprise a conserved CICII(m)CIII(n)CIV cysteine framework (m and n, number of amino acids) and the majority antagonize nicotinic acetylcholine receptors (nAChRs). Depending on disulfide connectivity, α-conotoxins can exist as either globular (CI-CIII, CII-CIV), ribbon (CI-CIV, CII-CIII) or bead (CI-CII, CIII-CIV) isomers. In the present study, C. geographus α-conotoxins GI, GIB, G1.5 and G1.9 were chemically synthesized as globular and ribbon isomers and their activity investigated at human nAChRs expressed in Xenopus oocytes using the two-electrode voltage clamp recording technique. Both the globular and ribbon isomers of the 3/5 (m/n) α-conotoxins GI and GIB selectively inhibit heterologous human muscle-type α1β1δε nAChRs, whereas G1.5, a 4/7 α-conotoxin, selectively antagonizes neuronal (non-muscle) nAChR subtypes particularly human α3β2, α7 and α9α10 nAChRs. In contrast, globular and ribbon isomers of G1.9, a novel C-terminal elongated 4/8 α-conotoxin exhibited no activity at the human nAChR subtypes studied. This study reinforces earlier observations that 3/5 α-conotoxins selectively target the muscle nAChR subtypes, although interestingly, GIB is also active at α7 and α9 α10 nAChRs. The 4/7 α-conotoxins target human neuronal nAChR subtypes whereas the pharmacology of the 4/8 α-conotoxin remains unknown.
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Affiliation(s)
- Han-Shen Tae
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW 2522, Australia.
| | - Bingmiao Gao
- Key Laboratory of Tropical Translational Medicine of Ministry of Education, Hainan Key Laboratory for Research and Development of Tropical Herbs, Hainan Medical University, Haikou 571199, China
| | - Ai-Hua Jin
- Institute for Molecular Bioscience, University of Queensland, St Lucia, QLD 4072, Australia
| | - Paul F Alewood
- Institute for Molecular Bioscience, University of Queensland, St Lucia, QLD 4072, Australia
| | - David J Adams
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW 2522, Australia.
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8
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Wang S, Ren J, Li R, Li X, Zhangsun D, Wu Y, Luo S. Synthesis and evaluation of disulfide-rich cyclic α-conotoxin [S9A]TxID analogues as novel α3β4 nAChR antagonists. Bioorg Chem 2021; 112:104875. [PMID: 33823404 DOI: 10.1016/j.bioorg.2021.104875] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 03/25/2021] [Accepted: 03/25/2021] [Indexed: 12/30/2022]
Abstract
Head-to-tail cyclization is an effective strategy to improve the biological stability of peptides. The α-conotoxin [S9A]TxID is a peptide that inhibits α3β4 nAChR with high activity and selectivity. Herein, we established a method for cyclizing and oxidative folding of [S9A]TxID, and six cyclic analogues of [S9A]TxID were chemically synthesized with various linker lengths. We used the electrophysiology assay to measure activity values of these cyclic analogues, and obtained the most potent analogue c[S9A]TxID-6, which was more stable than native [S9A]TxID against proteinase K.
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9
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Abstract
Molecular grafting is a strategy for the engineering of molecular scaffolds into new functional agents, such as next-generation therapeutics. Despite its wide use, studies so far have focused almost exclusively on demonstrating its utility rather than understanding the factors that lead to either poor or successful grafting outcomes. Here, we examine protein evolution and identify parallels between the natural process of protein functional diversification and the artificial process of molecular grafting. We discuss features of natural proteins that are correlated to innovability-the capacity to acquire new functions-and describe their implications to molecular grafting scaffolds. Disulfide-rich peptides are used as exemplars because they are particularly promising scaffolds onto which new functions can be grafted. This article provides a perspective on why some scaffolds are more suitable for grafting than others, identifying opportunities on how molecular grafting might be improved.
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Affiliation(s)
- Conan K Wang
- Institute for Molecular Bioscience and Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland, Australia.
| | - David J Craik
- Institute for Molecular Bioscience and Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland, Australia
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10
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Scholze P, Huck S. The α5 Nicotinic Acetylcholine Receptor Subunit Differentially Modulates α4β2 * and α3β4 * Receptors. Front Synaptic Neurosci 2020; 12:607959. [PMID: 33343327 PMCID: PMC7744819 DOI: 10.3389/fnsyn.2020.607959] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 11/11/2020] [Indexed: 11/30/2022] Open
Abstract
Nicotine, the principal reinforcing compound in tobacco, acts in the brain by activating neuronal nicotinic acetylcholine receptors (nAChRs). This review summarizes our current knowledge regarding how the α5 accessory nAChR subunit, encoded by the CHRNA5 gene, differentially modulates α4β2* and α3β4* receptors at the cellular level. Genome-wide association studies have linked a gene cluster in chromosomal region 15q25 to increased susceptibility to nicotine addiction, lung cancer, chronic obstructive pulmonary disease, and peripheral arterial disease. Interestingly, this gene cluster contains a non-synonymous single-nucleotide polymorphism (SNP) in the human CHRNA5 gene, causing an aspartic acid (D) to asparagine (N) substitution at amino acid position 398 in the α5 nAChR subunit. Although other SNPs have been associated with tobacco smoking behavior, efforts have focused predominantly on the D398 and N398 variants in the α5 subunit. In recent years, significant progress has been made toward understanding the role that the α5 nAChR subunit—and the role of the D398 and N398 variants—plays on nAChR function at the cellular level. These insights stem primarily from a wide range of experimental models, including receptors expressed heterologously in Xenopus oocytes, various cell lines, and neurons derived from human induced pluripotent stem cells (iPSCs), as well as endogenous receptors in genetically engineered mice and—more recently—rats. Despite providing a wealth of available data, however, these studies have yielded conflicting results, and our understanding of the modulatory role that the α5 subunit plays remains incomplete. Here, we review these reports and the various techniques used for expression and analysis in order to examine how the α5 subunit modulates key functions in α4β2* and α3β4* receptors, including receptor trafficking, sensitivity, efficacy, and desensitization. In addition, we highlight the strikingly different role that the α5 subunit plays in Ca2+ signaling between α4β2* and α3β4* receptors, and we discuss whether the N398 α5 subunit variant can partially replace the D398 variant.
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Affiliation(s)
- Petra Scholze
- Department of Pathobiology of the Nervous System, Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | - Sigismund Huck
- Department of Pathobiology of the Nervous System, Center for Brain Research, Medical University of Vienna, Vienna, Austria
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11
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Sajeevan KA, Roy D. Simulation of differential structure and dynamics of disulfide bond isoforms of conopeptide
AuIB
in presence of human
α
3
β
4
nAChR. Pept Sci (Hoboken) 2020. [DOI: 10.1002/pep2.24183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Karuna Anna Sajeevan
- Department of Chemistry Birla Institute of Technology and Science‐Pilani Hyderabad Telangana India
| | - Durba Roy
- Department of Chemistry Birla Institute of Technology and Science‐Pilani Hyderabad Telangana India
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12
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Arias HR, Tae HS, Micheli L, Yousuf A, Ghelardini C, Adams DJ, Di Cesare Mannelli L. Coronaridine congeners decrease neuropathic pain in mice and inhibit α9α10 nicotinic acetylcholine receptors and Ca V2.2 channels. Neuropharmacology 2020; 175:108194. [PMID: 32540451 DOI: 10.1016/j.neuropharm.2020.108194] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 06/04/2020] [Accepted: 06/08/2020] [Indexed: 12/24/2022]
Abstract
The primary aim of this study was to determine the anti-neuropathic activity of (±)-18-methoxycoronaridine [(±)-18-MC] and (+)-catharanthine in mice by using the oxaliplatin-induced neuropathic pain paradigm and cold plate test. The results showed that both coronaridine congeners induce anti-neuropathic pain activity at a dose of 72 mg/kg (per os), whereas a lower dose (36 mg/kg) of (+)-catharanthine decreased the progress of oxaliplatin-induced neuropathic pain. To determine the underlying molecular mechanism, electrophysiological recordings were performed on α9α10, α3β4, and α4β2 nAChRs as well as voltage-gated calcium (CaV2.2) channels modulated by G protein-coupled γ-aminobutyric acid type B receptors (GABABRs). The results showed that (±)-18-MC and (+)-catharanthine competitively inhibit α9α10 nAChRs with potencies higher than that at α3β4 and α4β2 nAChRs and directly block CaV2.2 channels without activating GABABRs. Considering the potency of the coronaridine congeners at Cav2.2 channels and α9α10 nAChRs, and the calculated brain concentration of (+)-catharanthine, it is plausible that the observed anti-neuropathic pain effects are mediated by peripheral and central mechanisms involving the inhibition of α9α10 nAChRs and/or CaV2.2 channels.
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Affiliation(s)
- Hugo R Arias
- Department of Pharmacology and Physiology, Oklahoma State University College of Osteopathic Medicine, Tahlequah, OK, USA.
| | - Han-Shen Tae
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW, 2522, Australia.
| | - Laura Micheli
- Department of Neurosciences, Psychology, Drug Research and Child Health (NEUROFARBA), Section of Pharmacology and Toxicology, University of Florence, 50139, Florence, Italy
| | - Arsalan Yousuf
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW, 2522, Australia
| | - Carla Ghelardini
- Department of Neurosciences, Psychology, Drug Research and Child Health (NEUROFARBA), Section of Pharmacology and Toxicology, University of Florence, 50139, Florence, Italy
| | - David J Adams
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW, 2522, Australia
| | - Lorenzo Di Cesare Mannelli
- Department of Neurosciences, Psychology, Drug Research and Child Health (NEUROFARBA), Section of Pharmacology and Toxicology, University of Florence, 50139, Florence, Italy
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13
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Muttenthaler M, Nevin ST, Inserra M, Lewis RJ, Adams DJ, Alewood P. On-resin strategy to label α-conotoxins: Cy5-RgIA, a potent α9α10 nicotinic acetylcholine receptor imaging probe. Aust J Chem 2019; 73:327-333. [PMID: 32394983 PMCID: PMC7212043 DOI: 10.1071/ch19456] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
In-solution conjugation is the most commonly used strategy to label peptides and proteins with fluorophores. However, lack of site-specific control and high costs of fluorophores are recognised limitations of this approach. Here, we established facile access to grams of Cy5-COOH via a two-step synthetic route, demonstrated that Cy5 is stable to HF treatment and therefore compatible with Boc-SPPS, and coupled Cy5 to the N-terminus of α-conotoxin RgIA while still attached to the resin. Folding of the two-disulfide containing Cy5-RgIA benefitted from the hydrophobic nature of Cy5 resulting in only the globular disulfide bond isomer. In contrast, wild-type α-RgIA folded into the inactive ribbon and bioactive globular isomer under the same conditions. Labelled α-RgIA retained its ability to inhibit acetylcholine(100 μM)-evoked current reversibly with an IC50 of 5.0 nM (Hill coefficient = 1.7) for α-RgIA and an IC50 of 1.6 (Hill coefficient = 1.2) for Cy5-RgIA at the α9α10 nicotinic acetylcholine receptors (nAChRs) heterologeously expressed in Xenopus oocytes. Cy5-RgIA was then used to successfully visualise nAChRs in RAW264.7 mouse macrophage cell line. This work introduced not only a new and valuable nAChR probe, but also a new versatile synthetic strategy that facilitates production of milligram to gram quantities of fluorophore-labelled peptides at low cost, which is often required for in vivo experiments. The strategy is compatible with Boc- and Fmoc-chemistry, allows for site-specific labelling of free amines anywhere in the peptide sequence, and can also be used for the introduction of Cy3/Cy5 FRET pairs.
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Affiliation(s)
- Markus Muttenthaler
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
- Institute of Biological Chemistry, Faculty of Chemistry, University of Vienna, Vienna, Austria
| | - Simon T Nevin
- Centre for Advanced Imaging, The University of Queensland, Brisbane, Australia
| | - Marco Inserra
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
| | - Richard J Lewis
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
| | - David J Adams
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, Australia
| | - Paul Alewood
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
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14
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Marquart LA, Turner MW, Warner LR, King MD, Groome JR, McDougal OM. Ribbon α-Conotoxin KTM Exhibits Potent Inhibition of Nicotinic Acetylcholine Receptors. Mar Drugs 2019; 17:E669. [PMID: 31795126 PMCID: PMC6950571 DOI: 10.3390/md17120669] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2019] [Revised: 11/21/2019] [Accepted: 11/21/2019] [Indexed: 01/26/2023] Open
Abstract
KTM is a 16 amino acid peptide with the sequence WCCSYPGCYWSSSKWC. Here, we present the nuclear magnetic resonance (NMR) structure and bioactivity of this rationally designed α-conotoxin (α-CTx) that demonstrates potent inhibition of rat α3β2-nicotinic acetylcholine receptors (rα3β2-nAChRs). Two bioassays were used to test the efficacy of KTM. First, a qualitative PC12 cell-based assay confirmed that KTM acts as a nAChR antagonist. Second, bioactivity evaluation by two-electrode voltage clamp electrophysiology was used to measure the inhibition of rα3β2-nAChRs by KTM (IC50 = 0.19 ± 0.02 nM), and inhibition of the same nAChR isoform by α-CTx MII (IC50 = 0.35 ± 0.8 nM). The three-dimensional structure of KTM was determined by NMR spectroscopy, and the final set of 20 structures derived from 32 distance restraints, four dihedral angle constraints, and two disulfide bond constraints overlapped with a mean global backbone root-mean-square deviation (RMSD) of 1.7 ± 0.5 Å. The structure of KTM did not adopt the disulfide fold of α-CTx MII for which it was designed, but instead adopted a flexible ribbon backbone and disulfide connectivity of C2-C16 and C3-C8 with an estimated 12.5% α-helical content. In contrast, α-CTx MII, which has a native fold of C2-C8 and C3-C16, has an estimated 38.1% α-helical secondary structure. KTM is the first reported instance of a Framework I (CC-C-C) α-CTx with ribbon connectivity to display sub-nanomolar inhibitory potency of rα3β2-nAChR subtypes.
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Affiliation(s)
- Leanna A. Marquart
- Department of Chemistry and Biochemistry, Boise State University, Boise, ID 83725, USA; (L.A.M.); (L.R.W.); (M.D.K.)
| | - Matthew W. Turner
- Biomolecular Sciences PhD Program, Boise State University, Boise, ID 83725, USA;
| | - Lisa R. Warner
- Department of Chemistry and Biochemistry, Boise State University, Boise, ID 83725, USA; (L.A.M.); (L.R.W.); (M.D.K.)
| | - Matthew D. King
- Department of Chemistry and Biochemistry, Boise State University, Boise, ID 83725, USA; (L.A.M.); (L.R.W.); (M.D.K.)
| | - James R. Groome
- Department of Biological Sciences, Idaho State University, Pocatello, ID 83209, USA;
| | - Owen M. McDougal
- Department of Chemistry and Biochemistry, Boise State University, Boise, ID 83725, USA; (L.A.M.); (L.R.W.); (M.D.K.)
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15
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Gharpure A, Teng J, Zhuang Y, Noviello CM, Walsh RM, Cabuco R, Howard RJ, Zaveri NT, Lindahl E, Hibbs RE. Agonist Selectivity and Ion Permeation in the α3β4 Ganglionic Nicotinic Receptor. Neuron 2019; 104:501-511.e6. [PMID: 31488329 DOI: 10.1016/j.neuron.2019.07.030] [Citation(s) in RCA: 111] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Revised: 07/01/2019] [Accepted: 07/25/2019] [Indexed: 12/16/2022]
Abstract
Nicotinic acetylcholine receptors are pentameric ion channels that mediate fast chemical neurotransmission. The α3β4 nicotinic receptor subtype forms the principal relay between the central and peripheral nervous systems in the autonomic ganglia. This receptor is also expressed focally in brain areas that affect reward circuits and addiction. Here, we present structures of the α3β4 nicotinic receptor in lipidic and detergent environments, using functional reconstitution to define lipids appropriate for structural analysis. The structures of the receptor in complex with nicotine, as well as the α3β4-selective ligand AT-1001, complemented by molecular dynamics, suggest principles of agonist selectivity. The structures further reveal much of the architecture of the intracellular domain, where mutagenesis experiments and simulations define residues governing ion conductance.
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Affiliation(s)
- Anant Gharpure
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Jinfeng Teng
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Yuxuan Zhuang
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, Solna 17121, Sweden
| | - Colleen M Noviello
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Richard M Walsh
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Rico Cabuco
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Rebecca J Howard
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, Solna 17121, Sweden
| | | | - Erik Lindahl
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, Solna 17121, Sweden; Department of Applied Physics, Swedish e-Science Research Center, KTH Royal Institute of Technology, Solna 17121, Sweden
| | - Ryan E Hibbs
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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16
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El Hamdaoui Y, Wu X, Clark RJ, Giribaldi J, Anangi R, Craik DJ, King GF, Dutertre S, Kaas Q, Herzig V, Nicke A. Periplasmic Expression of 4/7 α-Conotoxin TxIA Analogs in E. coli Favors Ribbon Isomer Formation - Suggestion of a Binding Mode at the α7 nAChR. Front Pharmacol 2019; 10:577. [PMID: 31214027 PMCID: PMC6554660 DOI: 10.3389/fphar.2019.00577] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Accepted: 05/06/2019] [Indexed: 01/02/2023] Open
Abstract
Peptides derived from animal venoms provide important research tools for biochemical and pharmacological characterization of receptors, ion channels, and transporters. Some venom peptides have been developed into drugs (such as the synthetic ω-conotoxin MVIIA, ziconotide) and several are currently undergoing clinical trials for various clinical indications. Challenges in the development of peptides include their usually limited supply from natural sources, cost-intensive chemical synthesis, and potentially complicated stereoselective disulfide-bond formation in the case of disulfide-rich peptides. In particular, if extended structure–function analysis is performed or incorporation of stable isotopes for NMR studies is required, the comparatively low yields and high costs of synthesized peptides might constitute a limiting factor. Here we investigated the expression of the 4/7 α-conotoxin TxIA, a potent blocker at α3β2 and α7 nicotinic acetylcholine receptors (nAChRs), and three analogs in the form of maltose binding protein fusion proteins in Escherichia coli. Upon purification via nickel affinity chromatography and release of the toxins by protease cleavage, HPLC analysis revealed one major peak with the correct mass for all peptides. The final yield was 1–2 mg of recombinant peptide per liter of bacterial culture. Two-electrode voltage clamp analysis on oocyte-expressed nAChR subtypes demonstrated the functionality of these peptides but also revealed a 30 to 100-fold potency decrease of expressed TxIA compared to chemically synthesized TxIA. NMR spectroscopy analysis of TxIA and two of its analogs confirmed that the decreased activity was due to an alternative disulfide linkage rather than the missing C-terminal amidation, a post-translational modification that is common in α-conotoxins. All peptides preferentially formed in the ribbon conformation rather than the native globular conformation. Interestingly, in the case of the α7 nAChR, but not the α3β2 subtype, the loss of potency could be rescued by an R5D substitution. In conclusion, we demonstrate efficient expression of functional but alternatively folded ribbon TxIA variants in E. coli and provide the first structure–function analysis for a ribbon 4/7-α-conotoxin at α7 and α3β2 nAChRs. Computational analysis based on these data provide evidence for a ribbon α-conotoxin binding mode that might be exploited to design ligands with optimized selectivity.
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Affiliation(s)
- Yamina El Hamdaoui
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Xiaosa Wu
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, Australia
| | - Richard J Clark
- School of Biomedical Sciences, The University of Queensland, Brisbane, QLD, Australia
| | - Julien Giribaldi
- CNRS, Institut des Biomolécules Max Mousseron, UMR 5247, Université de Montpellier, Montpellier, France
| | - Raveendra Anangi
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, Australia
| | - David J Craik
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, Australia
| | - Glenn F King
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, Australia
| | - Sebastien Dutertre
- CNRS, Institut des Biomolécules Max Mousseron, UMR 5247, Université de Montpellier, Montpellier, France
| | - Quentin Kaas
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, Australia
| | - Volker Herzig
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, Australia
| | - Annette Nicke
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, Ludwig-Maximilians-Universität München, Munich, Germany
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17
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Bavan S, Kim CH, Henderson BJ, Lester HA. Chronic Menthol Does Not Change Stoichiometry or Functional Plasma Membrane Levels of Mouse α3 β4-Containing Nicotinic Acetylcholine Receptors. Mol Pharmacol 2019; 95:398-407. [PMID: 30670481 PMCID: PMC6399576 DOI: 10.1124/mol.118.114769] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 01/12/2019] [Indexed: 11/22/2022] Open
Abstract
Heteromeric α3β4 nicotinic acetylcholine (ACh) receptors (nAChRs) are pentameric ligand-gated cation channels that include at least two α3 and two β4 subunits. They have functions in peripheral tissue and peripheral and central nervous systems. We examined the effects of chronic treatment with menthol, a major flavor additive in tobacco cigarettes and electronic nicotine delivery systems, on mouse α3β4 nAChRs transiently transfected into neuroblastoma-2a cells. Chronic menthol treatment at 500 nM, near the estimated menthol concentration in the brain following cigarette smoking, altered neither the [ACh]-response relationship nor Zn2+ sensitivity of ACh-evoked currents, suggesting that menthol does not change α3β4 nAChR subunit stoichiometry. Chronic menthol treatment failed to change the current density (peak current amplitude/cell capacitance) of 100 μM ACh-evoked currents. Chronic menthol treatment accelerated desensitization of 100 and 200 μM ACh-evoked currents. Chronic nicotine treatment (250 μM) decreased ACh-induced currents, and we found no additional effect of including chronic menthol. These data contrast with previously reported, marked effects of chronic menthol on β2* nAChRs studied in the same expression system. Mechanistically, the data support the emerging interpretation that both chronic menthol and chronic nicotine act on nAChRs in the early exocytotic pathway, and that this pathway does not present a rate-limiting step to the export of α3β4 nAChRs; these nAChRs include endoplasmic reticulum (ER) export motifs but not ER retention motifs. Previous reports show that smoking mentholated cigarettes enhances tobacco addiction; but our results show that this effect is unlikely to arise via menthol actions on α3β4 nAChRs.
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Affiliation(s)
- Selvan Bavan
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California (S.B., C.H.K., H.A.L.); and Department of Biomedical Sciences, Joan C. Edwards School of Medicine at Marshall University, Huntington, West Virginia (B.J.H.)
| | - Charlene H Kim
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California (S.B., C.H.K., H.A.L.); and Department of Biomedical Sciences, Joan C. Edwards School of Medicine at Marshall University, Huntington, West Virginia (B.J.H.)
| | - Brandon J Henderson
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California (S.B., C.H.K., H.A.L.); and Department of Biomedical Sciences, Joan C. Edwards School of Medicine at Marshall University, Huntington, West Virginia (B.J.H.)
| | - Henry A Lester
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California (S.B., C.H.K., H.A.L.); and Department of Biomedical Sciences, Joan C. Edwards School of Medicine at Marshall University, Huntington, West Virginia (B.J.H.)
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18
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Mansbach RA, Travers T, McMahon BH, Fair JM, Gnanakaran S. Snails In Silico: A Review of Computational Studies on the Conopeptides. Mar Drugs 2019; 17:E145. [PMID: 30832207 PMCID: PMC6471681 DOI: 10.3390/md17030145] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 02/21/2019] [Accepted: 02/22/2019] [Indexed: 12/26/2022] Open
Abstract
Marine cone snails are carnivorous gastropods that use peptide toxins called conopeptides both as a defense mechanism and as a means to immobilize and kill their prey. These peptide toxins exhibit a large chemical diversity that enables exquisite specificity and potency for target receptor proteins. This diversity arises in terms of variations both in amino acid sequence and length, and in posttranslational modifications, particularly the formation of multiple disulfide linkages. Most of the functionally characterized conopeptides target ion channels of animal nervous systems, which has led to research on their therapeutic applications. Many facets of the underlying molecular mechanisms responsible for the specificity and virulence of conopeptides, however, remain poorly understood. In this review, we will explore the chemical diversity of conopeptides from a computational perspective. First, we discuss current approaches used for classifying conopeptides. Next, we review different computational strategies that have been applied to understanding and predicting their structure and function, from machine learning techniques for predictive classification to docking studies and molecular dynamics simulations for molecular-level understanding. We then review recent novel computational approaches for rapid high-throughput screening and chemical design of conopeptides for particular applications. We close with an assessment of the state of the field, emphasizing important questions for future lines of inquiry.
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Affiliation(s)
- Rachael A Mansbach
- Theoretical Biology and Biophysics Group, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
| | - Timothy Travers
- Theoretical Biology and Biophysics Group, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
- Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
| | - Benjamin H McMahon
- Theoretical Biology and Biophysics Group, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
| | - Jeanne M Fair
- Biosecurity and Public Health Group, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
| | - S Gnanakaran
- Theoretical Biology and Biophysics Group, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
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19
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Cabalteja CC, Mihalko DS, Seth Horne W. Heterogeneous-Backbone Foldamer Mimics of a Computationally Designed, Disulfide-Rich Miniprotein. Chembiochem 2019; 20:103-110. [PMID: 30326175 PMCID: PMC6314896 DOI: 10.1002/cbic.201800558] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Indexed: 12/29/2022]
Abstract
Disulfide-rich peptides have found widespread use in the development of bioactive agents; however, low proteolytic stability and the difficulty of exerting synthetic control over chain topology present barriers to their application in some systems. Herein, we report a method that enables the creation of artificial backbone ("foldamer") mimics of compact, disulfide-rich tertiary folds. Systematic replacement of a subset of natural α-residues with various artificial building blocks in the context of a computationally designed prototype sequence leads to "heterogeneous-backbone" variants that undergo clean oxidative folding, adopt tertiary structures indistinguishable from that of the prototype, and enjoy proteolytic protection beyond that inherent to the topologically constrained scaffold. Collectively, these results demonstrate systematic backbone substitution to be a viable method to engineer the properties of disulfide-rich sequences and expands the repertoire of protein mimicry by foldamers to an exciting new structural class.
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Affiliation(s)
- Chino C. Cabalteja
- Department of Chemistry, University of Pittsburgh, 219 Parkman Ave., Pittsburgh, PA 15260 (USA)
| | - Daniel S. Mihalko
- Department of Chemistry, University of Pittsburgh, 219 Parkman Ave., Pittsburgh, PA 15260 (USA)
| | - W. Seth Horne
- Department of Chemistry, University of Pittsburgh, 219 Parkman Ave., Pittsburgh, PA 15260 (USA)
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20
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Shi J, So LY, Chen F, Liang J, Chow HY, Wong KY, Wan S, Jiang T, Yu R. Influences of disulfide connectivity on structure and antimicrobial activity of tachyplesin I. J Pept Sci 2018; 24:e3087. [PMID: 29870123 DOI: 10.1002/psc.3087] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Revised: 04/06/2018] [Accepted: 04/10/2018] [Indexed: 12/15/2022]
Abstract
Tachyplesin I is a potent antimicrobial peptide with broad spectrum of antimicrobial activity. It has 2 disulfide bonds and can form 3 disulfide bond isomers. In this study, the structure and antimicrobial activity of 3 tachyplesin I isomers (tachyplesin I, 3C12C, 3C7C) were investigated using molecular dynamic simulations, circular dichroism structural study, as well as antimicrobial activity and hemolysis assay. Our results suggest that in comparison to the native peptide, the 2 isomers (3C12C, 3C7C) have substantial structural and activity variations. The native peptide is in the ribbon conformation, while 3C12C and 3C7C possess remarkably different secondary structures, which are referred as "globular" and "beads" isomers, respectively. The substantially decreased hemolysis effects for these 2 isomers is accompanied by significantly decreased anti-gram-positive bacterial activity.
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Affiliation(s)
- Juan Shi
- Key Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, Qingdao, 266003, China.,Laboratory for Marine Drugs and Bioproducts of Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266003, China
| | - Lok-Yan So
- Department of Applied Biology and Chemical Technology and the State Key Laboratory of Chirosciences, The Hong Kong Polytechnic University, Hong Kong
| | - Fangling Chen
- Key Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, Qingdao, 266003, China.,Laboratory for Marine Drugs and Bioproducts of Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266003, China
| | - Jiazhen Liang
- Key Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, Qingdao, 266003, China.,Laboratory for Marine Drugs and Bioproducts of Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266003, China
| | - Ho-Yin Chow
- Department of Applied Biology and Chemical Technology and the State Key Laboratory of Chirosciences, The Hong Kong Polytechnic University, Hong Kong
| | - Kwok-Yin Wong
- Department of Applied Biology and Chemical Technology and the State Key Laboratory of Chirosciences, The Hong Kong Polytechnic University, Hong Kong
| | - Shengbiao Wan
- Key Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, Qingdao, 266003, China.,Laboratory for Marine Drugs and Bioproducts of Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266003, China
| | - Tao Jiang
- Key Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, Qingdao, 266003, China.,Laboratory for Marine Drugs and Bioproducts of Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266003, China
| | - Rilei Yu
- Key Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, Qingdao, 266003, China.,Laboratory for Marine Drugs and Bioproducts of Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266003, China
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21
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Yu J, Zhu X, Harvey PJ, Kaas Q, Zhangsun D, Craik DJ, Luo S. Single Amino Acid Substitution in α-Conotoxin TxID Reveals a Specific α3β4 Nicotinic Acetylcholine Receptor Antagonist. J Med Chem 2018; 61:9256-9265. [DOI: 10.1021/acs.jmedchem.8b00967] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Jinpeng Yu
- Key Laboratory of Tropical Biological Resources, Ministry of Education; Key Laboratory for Marine Drugs of Haikou, Hainan University, Haikou 570228, China
| | - Xiaopeng Zhu
- Key Laboratory of Tropical Biological Resources, Ministry of Education; Key Laboratory for Marine Drugs of Haikou, Hainan University, Haikou 570228, China
| | - Peta J. Harvey
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Quentin Kaas
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Dongting Zhangsun
- Key Laboratory of Tropical Biological Resources, Ministry of Education; Key Laboratory for Marine Drugs of Haikou, Hainan University, Haikou 570228, China
| | - David J. Craik
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Sulan Luo
- Key Laboratory of Tropical Biological Resources, Ministry of Education; Key Laboratory for Marine Drugs of Haikou, Hainan University, Haikou 570228, China
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22
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Wu X, Tae HS, Huang YH, Adams DJ, Craik DJ, Kaas Q. Stoichiometry dependent inhibition of rat α3β4 nicotinic acetylcholine receptor by the ribbon isomer of α-conotoxin AuIB. Biochem Pharmacol 2018; 155:288-297. [PMID: 30009767 DOI: 10.1016/j.bcp.2018.07.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Accepted: 07/11/2018] [Indexed: 11/17/2022]
Abstract
The ribbon isomer of α-conotoxin AuIB has 10-fold greater potency than the wild-type globular isomer at inhibiting nicotinic acetylcholine receptors (nAChRs) in rat parasympathetic neurons, and unlike its globular isoform, ribbon AuIB only targets a specific stoichiometry of the α3β4 nAChR subtype. Previous electrophysiological recordings of AuIB indicated that ribbon AuIB binds to the α3(+)α3(-) interface within the nAChR extracellular domain, which is displayed by the (α3)3(β4)2 stoichiometry but not by (α3)2(β4)3. This specificity for a particular stoichiometry is remarkable and suggests that ribbon isoforms of α-conotoxins might have great potential in drug design. In this study, we investigated the binding mode and structure-activity relationships of ribbon AuIB using a combination of molecular modeling and electrophysiology recording to determine the features that underpin its selectivity. An alanine scan showed that positions 4 and 9 of ribbon AuIB are the main determinants of the interaction with (α3)3(β4)2 nAChR. Our computational models indicate that the first loop of ribbon AuIB binds in the "aromatic box" of the acetylcholine orthosteric binding site, similar to that of globular AuIB. In contrast, the second loop and the termini of the ribbon isomer have different orientations and interactions in the binding sites to those of the globular isomer. The structure-activity relationships reported herein should be useful to design peptides displaying a ribbon α-conotoxin scaffold for inhibition of nAChR subtypes that have hitherto been difficult to selectively target.
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Affiliation(s)
- Xiaosa Wu
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Han-Shen Tae
- Illawarra Health and Medical Research Institute (IHMRI), The University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Yen-Hua Huang
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - David J Adams
- Illawarra Health and Medical Research Institute (IHMRI), The University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - David J Craik
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia.
| | - Quentin Kaas
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia.
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23
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Abstract
Marine cone snails are a large family of gastropods that have evolved highly potent venoms for predation and defense. The cone snail venom has exceptional molecular diversity in neuropharmacologically active compounds, targeting a range of receptors, ion channels, and transporters. These conotoxins have helped to dissect the structure and function of many of these therapeutically significant targets in the central and peripheral nervous systems, as well as unravelling the complex cellular mechanisms modulated by these receptors and ion channels. This review provides an overview of α-conotoxins targeting neuronal nicotinic acetylcholine receptors. The structure and activity of both classical and non-classical α-conotoxins are discussed, along with their contributions towards understanding nicotinic acetylcholine receptor (nAChR) structure and function.
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Affiliation(s)
- Nikita Abraham
- IMB Centre for Pain Research, Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072, Australia.
| | - Richard J Lewis
- IMB Centre for Pain Research, Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072, Australia.
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24
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Sajeevan KA, Roy D. Peptide Sequence and Solvent as Levers to Control Disulfide Connectivity in Multiple Cysteine Containing Venom Toxins. J Phys Chem B 2018; 122:5776-5789. [DOI: 10.1021/acs.jpcb.8b01437] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Karuna Anna Sajeevan
- Department of Chemistry, Birla Institute of Technology and Science-Pilani, Hyderabad Campus, Jawahar Nagar, Shameerpet Mandal, Hyderabad, Telangana 500078, India
| | - Durba Roy
- Department of Chemistry, Birla Institute of Technology and Science-Pilani, Hyderabad Campus, Jawahar Nagar, Shameerpet Mandal, Hyderabad, Telangana 500078, India
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25
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Sajeevan KA, Roy D. Aqueous ionic liquids influence the disulfide bond isoform equilibrium in conotoxin AuIB: a consequence of the Hofmeister effect? Biophys Rev 2018; 10:769-80. [PMID: 29294259 DOI: 10.1007/s12551-017-0391-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Accepted: 12/13/2017] [Indexed: 12/13/2022] Open
Abstract
The appearance of several disulfide bond isoforms in multiple cysteine containing venom peptides poses a significant challenge in their synthesis and purification under laboratory conditions. Recent experiments suggest that careful tuning of solvent and temperature conditions can propel the disulfide bond isoform equilibrium in favor of the most potent, native form. Certain aqueous ionic liquids (ILs) have proven significantly useful as solvents for this purpose, while exceptions have also been noted. To elucidate the molecular level origin behind such a preference, we report a detailed explicit solvent replica exchange molecular dynamics study of a conotoxin, AuIB, in pure water and four different aqueous IL solutions (~45-60% v/v). The ILs studied here are comprised of cations like 1-ethyl-3-methyl-imidazolium (Im21+) or 1-butyl-3-methyl-imidazolium (Im41+) coupled with either acetate (OAc-) or chloride (Cl-) as the counter anion. Our simulations unfold interesting features of the conformational spaces sampled by the peptide and its solvation in pure water and aqueous IL solutions. Detailed investigation into populations of the globular disulfide bond isoform of AuIB in aqueous IL solutions reveal distinct trends which might be related to the Hofmeister effect of the cation and anion of the IL and of specific interactions of the aqueous IL solutions with the peptide. In accordance with experimental observations, the aqueous [Im21][OAc] solution is found to promote the highest globular isoform population in AuIB.
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Giribaldi J, Dutertre S. α-Conotoxins to explore the molecular, physiological and pathophysiological functions of neuronal nicotinic acetylcholine receptors. Neurosci Lett 2018; 679:24-34. [PMID: 29199094 DOI: 10.1016/j.neulet.2017.11.063] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 11/28/2017] [Accepted: 11/29/2017] [Indexed: 12/22/2022]
Abstract
The vast diversity of neuronal nicotinic acetylcholine subunits expressed in the central and peripheral nervous systems, as well as in non-neuronal tissues, constitutes a formidable challenge for researchers and clinicians to decipher the role of particular subtypes, including complex subunit associations, in physiological and pathophysiological functions. Many natural products target the nAChRs, but there is no richer source of nicotinic ligands than the venom of predatory gastropods known as cone snails. Indeed, every single species of cone snail was shown to produce at least one type of such α-conotoxins. These tiny peptides (10-25 amino acids), constrained by disulfide bridges, proved to be unvaluable tools to investigate the structure and function of nAChRs, some of them having also therapeutic potential. In this review, we provide a recent update on the pharmacology and subtype specificity of several major α-conotoxins.
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Zhangsun D, Zhu X, Kaas Q, Wu Y, Craik DJ, McIntosh JM, Luo S. αO-Conotoxin GeXIVA disulfide bond isomers exhibit differential sensitivity for various nicotinic acetylcholine receptors but retain potency and selectivity for the human α9α10 subtype. Neuropharmacology 2017; 127:243-252. [PMID: 28416445 PMCID: PMC6029978 DOI: 10.1016/j.neuropharm.2017.04.015] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2017] [Revised: 03/14/2017] [Accepted: 04/11/2017] [Indexed: 11/30/2022]
Abstract
Nicotinic acetylcholine receptor (nAChR) subtypes exhibit distinct neuropharmacological properties that are involved in a range of neuropathological conditions, including pain, addiction, epilepsy, autism, schizophrenia, Tourette's syndrome, Alzheimer's and Parkinson's diseases, as well as many types of cancer. The α9α10 nAChR is a potential target in chronic pain, wound healing, the pathophysiology of the auditory system, and breast and lung cancers. αO-conotoxin GeXIVA is a potent antagonist of rat α9α10 nAChRs, with the 'bead' disulfide bond isomer displaying the lowest IC50 of the three possible isomers. In the rat chronic constriction injury model of neuropathic pain, this isomer reduced mechanical hyperalgesia without affecting motor performance. Here, we report the effects of the three disulfide bond isomers of GeXIVA on human α9α10 nAChRs, other human nAChR subtypes, various rat nAChR subtypes, and 10 rat α9α10 nAChR mutants. The three isomers displayed only ∼5-fold difference in potency on the human vs rat α9α10 receptors and had similar affinities at wild-type rat α9α10 nAChRs and all 10 α9α10 receptor mutants. From these findings, the binding site and mechanism of action of GeXIVA on rat and human α9α10 nAChR was deduced to be different from that of other conotoxins targeting this nAChR subtype. GeXIVA is therefore a unique ligand that might prove useful for further probing of binding sites on the α9α10 nAChR. This article is part of the Special Issue entitled 'Venom-derived Peptides as Pharmacological Tools.'
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Affiliation(s)
- Dongting Zhangsun
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Laboratory for Marine Drug of Haikou, Hainan University, Haikou, Hainan, 570228 China
| | - Xiaopeng Zhu
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Laboratory for Marine Drug of Haikou, Hainan University, Haikou, Hainan, 570228 China
| | - Quentin Kaas
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072 Australia
| | - Yong Wu
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Laboratory for Marine Drug of Haikou, Hainan University, Haikou, Hainan, 570228 China
| | - David J Craik
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072 Australia
| | - J Michael McIntosh
- Department of Biology and Psychiatry, University of Utah, Salt Lake City, UT 84112, USA; George E. Wahlen Department of Veterans Affairs Medical Center, Salt Lake City, UT, 84108, USA
| | - Sulan Luo
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Laboratory for Marine Drug of Haikou, Hainan University, Haikou, Hainan, 570228 China.
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Yu J, Zhu X, Yang Y, Luo S, Zhangsun D. Expression in Escherichia coli of fusion protein comprising α-conotoxin TxIB and preservation of selectivity to nicotinic acetylcholine receptors in the purified product. Chem Biol Drug Des 2017; 91:349-358. [PMID: 28891599 DOI: 10.1111/cbdd.13104] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 06/04/2017] [Accepted: 08/21/2017] [Indexed: 12/19/2022]
Abstract
Nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels, which are widely distributed in the central and peripheral nervous system. The α6β2* nAChR is an important subtype, which is closely associated with nicotine addiction and movement disorders etc. α-conotoxin TxIB with 16-amino acid residues specifically targets α6β2* nAChR with no obvious effect on other nAChR subtypes. However, chemical synthesis of TxIB is expensive, and the quantity of native TxIB extracted from cone snail is limited. In the present study, we attempted to obtain TxIB using biological method based on the recombinant expression in Escherichia coli (E. coli). The synthetic gene encoding mature peptide of TxIB was inserted in pET-31b(+) vector and transformed into E. coli strain BLR(DE3)pLysS for expression. The recombinant fusion protein KSI-TxIB-His6 (KSI, ketosteroid isomerase) was expressed successfully as inclusion body in E. coli, which was purified by Ni-NTA affinity chromatography column and cleaved by cyanogen bromide (CNBr) to release recombinant α-conotoxin TxIB (rTxIB). Then, rTxIB was purified by reverse-phase high-performance liquid chromatography (RP-HPLC) and was identified by electrospray ionization mass spectrometry (ESI-MS). Pharmacological activity of rTxIB was assessed by electrophysiological approaches. The results indicated that it preserved about 50% of potency, but, was even more important, had the same selectivity as the natural conotoxin which may provide an alternative method for quantity production of small peptides with low cost on the premise of not changing their potency.
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Affiliation(s)
- Jinpeng Yu
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Laboratory for Marine Drugs of Haikou, Hainan University, Haikou, China.,College of Agriculture, Hainan University, Haikou, China
| | - Xiaopeng Zhu
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Laboratory for Marine Drugs of Haikou, Hainan University, Haikou, China
| | - Yang Yang
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Laboratory for Marine Drugs of Haikou, Hainan University, Haikou, China.,College of Agriculture, Hainan University, Haikou, China
| | - Sulan Luo
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Laboratory for Marine Drugs of Haikou, Hainan University, Haikou, China
| | - Dongting Zhangsun
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Laboratory for Marine Drugs of Haikou, Hainan University, Haikou, China
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Tabassum N, Tae HS, Jia X, Kaas Q, Jiang T, Adams DJ, Yu R. Role of Cys I-Cys III Disulfide Bond on the Structure and Activity of α-Conotoxins at Human Neuronal Nicotinic Acetylcholine Receptors. ACS Omega 2017; 2:4621-4631. [PMID: 30023726 PMCID: PMC6044955 DOI: 10.1021/acsomega.7b00639] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Accepted: 08/04/2017] [Indexed: 06/08/2023]
Abstract
α-Conotoxins preferentially antagonize muscle and neuronal nicotinic acetylcholine receptors (nAChRs). Native α-conotoxins have two disulfide links, CI-CIII and CII-CIV, and owing to the inherent properties of disulfide bonds, α-conotoxins have been systematically engineered to improve their chemical and biological properties. In this study, we explored the possibility of simplifying the disulfide framework of α-conotoxins Vc1.1, BuIA, ImI, and AuIB, by introducing [C2H,C8F] modification to the CI-CIII bond. We therefore explored the possibility of using hydrophobic packing of standard amino acid side chains to replace disulfide bonds as an alternative strategy to nonnatural amino acid cross-links. The impact of CI-CIII disulfide bond replacement on the conformation of the α-conotoxins was investigated using molecular dynamics (MD) simulations and nuclear magnetic resonance chemical shift index study. Two-electrode voltage clamp techniques and MD simulations were used to study the impact of disulfide bond deletion on the activities of the peptides at human neuronal nAChRs. All disulfide-deleted variants except ImI[C2H,C8F] had reduced potency for inhibiting nAChRs. Our results suggest that the CI-CIII disulfide bond is important to stabilize the secondary structure of α-conotoxins as well as their interaction with neuronal nAChR targets. Results from this study enrich our understanding of the function of the CI-CIII disulfide bond and are useful in guiding future structural engineering of the α-conotoxins.
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Affiliation(s)
- Nargis Tabassum
- Key
Laboratory of Marine Drugs, Chinese Ministry of Education, School
of Medicine and Pharmacy, Ocean University
of China, Qingdao 266003, China
- Laboratory
for Marine Drugs and Bioproducts of Qingdao National Laboratory for
Marine Science and Technology, Qingdao 266003, China
| | - Han-Shen Tae
- Illawarra
Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Xinying Jia
- The Centre for Advanced Imaging and Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072 Australia
| | - Quentin Kaas
- The Centre for Advanced Imaging and Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072 Australia
| | - Tao Jiang
- Key
Laboratory of Marine Drugs, Chinese Ministry of Education, School
of Medicine and Pharmacy, Ocean University
of China, Qingdao 266003, China
| | - David J. Adams
- Illawarra
Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Rilei Yu
- Key
Laboratory of Marine Drugs, Chinese Ministry of Education, School
of Medicine and Pharmacy, Ocean University
of China, Qingdao 266003, China
- Laboratory
for Marine Drugs and Bioproducts of Qingdao National Laboratory for
Marine Science and Technology, Qingdao 266003, China
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Abstract
The nicotinic acetylcholine receptor (nAChR) represents the prototype of ligand-gated ion channels. It is vital for neuromuscular transmission and an important regulator of neurotransmission. A variety of toxic compounds derived from diverse species target this receptor and have been of elemental importance in basic and applied research. They enabled milestone discoveries in pharmacology and biochemistry ranging from the original formulation of the receptor concept, the first isolation and structural analysis of a receptor protein (the nAChR) to the identification, localization, and differentiation of its diverse subtypes and their validation as a target for therapeutic intervention. Among the venom-derived compounds, α-neurotoxins and α-conotoxins provide the largest families and still represent indispensable pharmacological tools. Application of modified α-neurotoxins provided substantial structural and functional details of the nAChR long before high resolution structures were available. α-bungarotoxin represents not only a standard pharmacological tool and label in nAChR research but also for unrelated proteins tagged with a minimal α-bungarotoxin binding motif. A major advantage of α-conotoxins is their smaller size, as well as superior selectivity for diverse nAChR subtypes that allows their development into ligands with optimized pharmacological and chemical properties and potentially novel drugs. In the following, these two groups of nAChR antagonists will be described focusing on their respective roles in the structural and functional characterization of nAChRs and their development into research tools. In addition, we provide a comparative overview of the diverse α-conotoxin selectivities that can serve as a practical guide for both structure activity studies and subtype classification. This article is part of the Special Issue entitled 'Venom-derived Peptides as Pharmacological Tools.'
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Affiliation(s)
- Sébastien Dutertre
- Institut des Biomolécules Max Mousseron, UMR 5247, Université Montpellier - CNRS, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France
| | - Annette Nicke
- Walther Straub Institute for Pharmacology and Toxicology, Ludwig-Maximilians-Universität, Nußbaumstr. 26, 80336 Munich, Germany.
| | - Victor I Tsetlin
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya str.16/10, Moscow 117999, Russian Federation
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Cuny H, Yu R, Tae HS, Kompella SN, Adams DJ. α-Conotoxins active at α3-containing nicotinic acetylcholine receptors and their molecular determinants for selective inhibition. Br J Pharmacol 2017; 175:1855-1868. [PMID: 28477355 DOI: 10.1111/bph.13852] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2017] [Revised: 04/13/2017] [Accepted: 04/24/2017] [Indexed: 01/22/2023] Open
Abstract
Neuronal α3-containing nicotinic acetylcholine receptors (nAChRs) in the peripheral nervous system (PNS) and non-neuronal tissues are implicated in a number of severe disease conditions ranging from cancer to cardiovascular diseases and chronic pain. However, despite the physiological characterization of mouse models and cell lines, the precise pathophysiology of nAChRs outside the CNS remains not well understood, in part because there is a lack of subtype-selective antagonists. α-Conotoxins isolated from cone snail venom exhibit characteristic individual selectivity profiles for nAChRs and, therefore, are excellent tools to study the determinants for nAChR-antagonist interactions. Given that human α3β4 subtype selective α-conotoxins are scarce and this is a major nAChR subtype in the PNS, the design of new peptides targeting this nAChR subtype is desirable. Recent studies using α-conotoxins RegIIA and AuIB, in combination with nAChR site-directed mutagenesis and computational modelling, have shed light onto specific nAChR residues, which determine the selectivity of the α-conotoxins for the human α3β2 and α3β4 subtypes. Publications describing the selectivity profile and binding sites of other α-conotoxins confirm that subtype-selective nAChR antagonists often work through common mechanisms by interacting with the same structural components and sites on the receptor. LINKED ARTICLES This article is part of a themed section on Nicotinic Acetylcholine Receptors. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.11/issuetoc.
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Affiliation(s)
- Hartmut Cuny
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW, Australia.,Victor Chang Cardiac Research Institute, Developmental and Stem Cell Biology Division, Sydney, NSW, Australia
| | - Rilei Yu
- Key Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, Qingdao, China.,Laboratory for Marine Drugs and Bioproducts of Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
| | - Han-Shen Tae
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW, Australia
| | - Shiva N Kompella
- Faculty of Pharmacy, University of Sydney, Sydney, NSW, Australia
| | - David J Adams
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW, Australia
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Jin X, McCollum MM, Germann AL, Akk G, Steinbach JH. The E Loop of the Transmitter Binding Site Is a Key Determinant of the Modulatory Effects of Physostigmine on Neuronal Nicotinic α4β2 Receptors. Mol Pharmacol 2017; 91:100-109. [PMID: 27895161 PMCID: PMC5267520 DOI: 10.1124/mol.116.106484] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Accepted: 11/23/2016] [Indexed: 11/22/2022] Open
Abstract
Physostigmine is a well known inhibitor of acetylcholinesterase, which can also activate, potentiate, and inhibit acetylcholine receptors, including neuronal nicotinic receptors comprising α4 and β2 subunits. We have found that the two stoichiometric forms of this receptor differ in the effects of physostigmine. The form containing three copies of α4 and two of β2 was potentiated at low concentrations of acetylcholine chloride (ACh) and physostigmine, whereas the form containing two copies of α4 and three of β2 was inhibited. Chimeric constructs of subunits indicated that the presence of inhibition or potentiation depended on the source of the extracellular ligand binding domain of the subunit. Further sets of chimeric constructs demonstrated that a portion of the ACh binding domain, the E loop, is a key determinant. Transferring the E loop from the β2 subunit to the α4 subunit resulted in strong inhibition, whereas the reciprocal transfer reduced inhibition. To control the number and position of the incorporated chimeric subunits, we expressed chimeric constructs with subunit dimers. Surprisingly, incorporation of a subunit with an altered E loop had similar effects whether it contributed either to an intersubunit interface containing a canonical ACh binding site or to an alternative interface. The observation that the α4 E loop is involved suggests that physostigmine interacts with regions of subunits that contribute to the ACh binding site, whereas the lack of interface specificity indicates that interaction with a particular ACh binding site is not the critical factor.
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Affiliation(s)
- Xiaochun Jin
- Department of Anesthesiology (X.J., M.M.C., A.L.G., G.A., J.H.S.) and Taylor Family Institute for Innovative Psychiatric Research (G.A., J.H.S.), Washington University School of Medicine, St. Louis, Missouri
| | - Megan M McCollum
- Department of Anesthesiology (X.J., M.M.C., A.L.G., G.A., J.H.S.) and Taylor Family Institute for Innovative Psychiatric Research (G.A., J.H.S.), Washington University School of Medicine, St. Louis, Missouri
| | - Allison L Germann
- Department of Anesthesiology (X.J., M.M.C., A.L.G., G.A., J.H.S.) and Taylor Family Institute for Innovative Psychiatric Research (G.A., J.H.S.), Washington University School of Medicine, St. Louis, Missouri
| | - Gustav Akk
- Department of Anesthesiology (X.J., M.M.C., A.L.G., G.A., J.H.S.) and Taylor Family Institute for Innovative Psychiatric Research (G.A., J.H.S.), Washington University School of Medicine, St. Louis, Missouri
| | - Joe Henry Steinbach
- Department of Anesthesiology (X.J., M.M.C., A.L.G., G.A., J.H.S.) and Taylor Family Institute for Innovative Psychiatric Research (G.A., J.H.S.), Washington University School of Medicine, St. Louis, Missouri
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Suresh A, Hung A. Molecular simulation study of the unbinding of α-conotoxin [ϒ4E]GID at the α7 and α4β2 neuronal nicotinic acetylcholine receptors. J Mol Graph Model 2016; 70:109-121. [PMID: 27721068 DOI: 10.1016/j.jmgm.2016.09.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Revised: 08/11/2016] [Accepted: 09/05/2016] [Indexed: 12/27/2022]
Abstract
The α7 and α4β2 neuronal nicotinic receptors belonging to the family of ligand-gated ion channels are most prevalent in the brain, and are implicated in various neurodegenerative disorders. α-conotoxin GID (and its analogue [ϒ4E]GID) specifically inhibits these subtypes, with more affinity towards the human α7 (hα7) subtype, and is valuable in understanding the physiological roles of these receptors. In this study, we use umbrella-sampling molecular dynamics simulations to understand the mechanism of interaction between [ϒ4E]GID and the agonist binding pockets of the α4β2 and the hα7 receptors, and to estimate their relative binding affinities (ΔGbind). The obtained ΔGbind values indicate stronger interaction with the hα7 receptor, in agreement with previous experimental studies. Simulations also revealed different unbinding pathways between the two receptor subtypes, enabling identification of a number of interactions at locations far from the orthosteric binding site which may explain the difference in [ϒ4E]GID potency. The pathways identified will help in the design of novel conotoxins with increased potency at α4β2, for which there is currently no known highly potent conotoxin inhibitor. Computational mutational free energy analyses also revealed a number of possible single-site mutations to GID which might enhance its selective binding to α4β2 over α7.
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Affiliation(s)
- Abishek Suresh
- School of Science, RMIT University, GPO Box 2476, Melbourne, Victoria 3001, Australia
| | - Andrew Hung
- School of Science, RMIT University, GPO Box 2476, Melbourne, Victoria 3001, Australia.
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Vulfius CA, Spirova EN, Serebryakova MV, Shelukhina IV, Kudryavtsev DS, Kryukova EV, Starkov VG, Kopylova NV, Zhmak MN, Ivanov IA, Kudryashova KS, Andreeva TV, Tsetlin VI, Utkin YN. Peptides from puff adder Bitis arietans venom, novel inhibitors of nicotinic acetylcholine receptors. Toxicon 2016; 121:70-76. [PMID: 27576061 DOI: 10.1016/j.toxicon.2016.08.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2016] [Revised: 07/19/2016] [Accepted: 08/25/2016] [Indexed: 11/17/2022]
Abstract
Phospholipase A2 (named bitanarin) possessing capability to block nicotinic acetylcholine receptors (nAChRs) was isolated earlier (Vulfius et al., 2011) from puff adder Bitis arietans venom. Further studies indicated that low molecular weight fractions of puff adder venom inhibit nAChRs as well. In this paper, we report on isolation from this venom and characterization of three novel peptides called baptides 1, 2 and 3 that reversibly block nAChRs. To isolate the peptides, the venom of B. arietans was fractionated by gel-filtration and reversed phase chromatography. The amino acid sequences of peptides were established by de novo sequencing using MALDI mass spectrometry. Baptide 1 comprised 7, baptides 2 and 3-10 amino acid residues, the latter being acetylated at the N-terminus. This is the first indication for the presence of such post-translational modification in snake venom proteins. None of the peptides contain cysteine residues. For biological activity studies the peptides were prepared by solid phase peptide synthesis. Baptide 3 and 2 blocked acetylcholine-elicited currents in isolated Lymnaea stagnalis neurons with IC50 of about 50 μM and 250 μM, respectively. In addition baptide 2 blocked acetylcholine-induced currents in muscle nAChR heterologously expressed in Xenopus oocytes with IC50 of about 3 μM. The peptides did not compete with radioactive α-bungarotoxin for binding to Torpedo and α7 nAChRs at concentration up to 200 μM that suggests non-competitive mode of inhibition. Calcium imaging studies on α7 and muscle nAChRs heterologously expressed in mouse neuroblastoma Neuro2a cells showed that on α7 receptor baptide 2 inhibited acetylcholine-induced increasing intracellular calcium concentration with IC50 of 20.6 ± 3.93 μM. On both α7 and muscle nAChRs the suppression of maximal response to acetylcholine by about 50% was observed at baptide 2 concentration of 25 μM, the value being close to IC50 on α7 nAChR. These data are in accord with non-competitive inhibition as follows from α-bungarotoxin binding experiments. The described peptides are the shortest peptides without disulfide bridges isolated from animal venom and capable to inhibit nAChR by non-competitive way.
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Affiliation(s)
- Catherine A Vulfius
- Institute of Cell Biophysics, Russian Academy of Sciences, Ul. Institutskaya 3, Pushchino Moscow Region, 142290, Russia
| | - Ekaterina N Spirova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Ul. Miklukho-Maklaya 16/10, Moscow, 117997, Russia
| | - Marina V Serebryakova
- Belozersky Institute for Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992, Russia
| | - Irina V Shelukhina
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Ul. Miklukho-Maklaya 16/10, Moscow, 117997, Russia
| | - Denis S Kudryavtsev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Ul. Miklukho-Maklaya 16/10, Moscow, 117997, Russia
| | - Elena V Kryukova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Ul. Miklukho-Maklaya 16/10, Moscow, 117997, Russia
| | - Vladislav G Starkov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Ul. Miklukho-Maklaya 16/10, Moscow, 117997, Russia
| | - Nina V Kopylova
- Moscow State Pedagogical University, Ul. M. Pirogovskaya 1/1, Moscow, 119991, Russia
| | - Maxim N Zhmak
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Ul. Miklukho-Maklaya 16/10, Moscow, 117997, Russia; OOO Syneuro, Ul. Miklukho-Maklaya 16/10, Moscow, 117997, Russia
| | - Igor A Ivanov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Ul. Miklukho-Maklaya 16/10, Moscow, 117997, Russia
| | - Ksenia S Kudryashova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Ul. Miklukho-Maklaya 16/10, Moscow, 117997, Russia
| | - Tatyana V Andreeva
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Ul. Miklukho-Maklaya 16/10, Moscow, 117997, Russia
| | - Victor I Tsetlin
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Ul. Miklukho-Maklaya 16/10, Moscow, 117997, Russia
| | - Yuri N Utkin
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Ul. Miklukho-Maklaya 16/10, Moscow, 117997, Russia.
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Affiliation(s)
- Xiaosa Wu
- Institute for Molecular BioscienceThe University of Queensland306 Carmody Road (Building 80)4072BrisbaneAustralia
| | - Yen‐Hua Huang
- Institute for Molecular BioscienceThe University of Queensland306 Carmody Road (Building 80)4072BrisbaneAustralia
| | - Quentin Kaas
- Institute for Molecular BioscienceThe University of Queensland306 Carmody Road (Building 80)4072BrisbaneAustralia
| | - David J. Craik
- Institute for Molecular BioscienceThe University of Queensland306 Carmody Road (Building 80)4072BrisbaneAustralia
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Roy D, Lakshminarayanan M. Scrambling of disulfide bond scaffolds in neurotoxin AuIB: A molecular dynamics simulation study. Biopolymers 2016; 106:196-209. [DOI: 10.1002/bip.22799] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Revised: 12/05/2015] [Accepted: 12/18/2015] [Indexed: 12/13/2022]
Affiliation(s)
- Durba Roy
- Department of Chemistry; Birla Institute of Technology and Science-Pilani; Hyderabad Campus, Jawahar Nagar, Shameerpet Mandal Hyderabad Telangana 500078 India
| | - Madhavkrishnan Lakshminarayanan
- Department of Chemistry; Birla Institute of Technology and Science-Pilani; Hyderabad Campus, Jawahar Nagar, Shameerpet Mandal Hyderabad Telangana 500078 India
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Carstens BB, Berecki G, Daniel JT, Lee HS, Jackson KAV, Tae H, Sadeghi M, Castro J, O'Donnell T, Deiteren A, Brierley SM, Craik DJ, Adams DJ, Clark RJ. Structure–Activity Studies of Cysteine‐Rich α‐Conotoxins that Inhibit High‐Voltage‐Activated Calcium Channels via GABA
B
Receptor Activation Reveal a Minimal Functional Motif. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201600297] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Bodil B. Carstens
- Institute for Molecular Biosciences The University of Queensland Brisbane Qld 4072 Australia
| | - Géza Berecki
- Health Innovations Research Institute RMIT University Melbourne Vic 3083 Australia
| | - James T. Daniel
- School of Biomedical Science The University of Queensland Brisbane Qld 4072 Australia
| | - Han Siean Lee
- School of Biomedical Science The University of Queensland Brisbane Qld 4072 Australia
| | - Kathryn A. V. Jackson
- School of Biomedical Science The University of Queensland Brisbane Qld 4072 Australia
| | - Han‐Shen Tae
- Health Innovations Research Institute RMIT University Melbourne Vic 3083 Australia
- Illawarra Health and Medical Research Institute (IHMRI) University of Wollongong Wollongong NSW 2522 Australia
| | - Mahsa Sadeghi
- Health Innovations Research Institute RMIT University Melbourne Vic 3083 Australia
- Illawarra Health and Medical Research Institute (IHMRI) University of Wollongong Wollongong NSW 2522 Australia
| | - Joel Castro
- Visceral Pain Group, Centre for Nutrition and Gastrointestinal Diseases Discipline of Medicine The University of Adelaide South Australian Health and Medical Research Institute (SAHMRI) Adelaide SA 5000 Australia
| | - Tracy O'Donnell
- Visceral Pain Group, Centre for Nutrition and Gastrointestinal Diseases Discipline of Medicine The University of Adelaide South Australian Health and Medical Research Institute (SAHMRI) Adelaide SA 5000 Australia
| | - Annemie Deiteren
- Visceral Pain Group, Centre for Nutrition and Gastrointestinal Diseases Discipline of Medicine The University of Adelaide South Australian Health and Medical Research Institute (SAHMRI) Adelaide SA 5000 Australia
| | - Stuart M. Brierley
- Visceral Pain Group, Centre for Nutrition and Gastrointestinal Diseases Discipline of Medicine The University of Adelaide South Australian Health and Medical Research Institute (SAHMRI) Adelaide SA 5000 Australia
| | - David J. Craik
- Institute for Molecular Biosciences The University of Queensland Brisbane Qld 4072 Australia
| | - David J. Adams
- Health Innovations Research Institute RMIT University Melbourne Vic 3083 Australia
- Illawarra Health and Medical Research Institute (IHMRI) University of Wollongong Wollongong NSW 2522 Australia
| | - Richard J. Clark
- School of Biomedical Science The University of Queensland Brisbane Qld 4072 Australia
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Carstens BB, Berecki G, Daniel JT, Lee HS, Jackson KAV, Tae H, Sadeghi M, Castro J, O'Donnell T, Deiteren A, Brierley SM, Craik DJ, Adams DJ, Clark RJ. Structure–Activity Studies of Cysteine‐Rich α‐Conotoxins that Inhibit High‐Voltage‐Activated Calcium Channels via GABA
B
Receptor Activation Reveal a Minimal Functional Motif. Angew Chem Int Ed Engl 2016; 55:4692-6. [DOI: 10.1002/anie.201600297] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Indexed: 01/29/2023]
Affiliation(s)
- Bodil B. Carstens
- Institute for Molecular Biosciences The University of Queensland Brisbane Qld 4072 Australia
| | - Géza Berecki
- Health Innovations Research Institute RMIT University Melbourne Vic 3083 Australia
| | - James T. Daniel
- School of Biomedical Science The University of Queensland Brisbane Qld 4072 Australia
| | - Han Siean Lee
- School of Biomedical Science The University of Queensland Brisbane Qld 4072 Australia
| | - Kathryn A. V. Jackson
- School of Biomedical Science The University of Queensland Brisbane Qld 4072 Australia
| | - Han‐Shen Tae
- Health Innovations Research Institute RMIT University Melbourne Vic 3083 Australia
- Illawarra Health and Medical Research Institute (IHMRI) University of Wollongong Wollongong NSW 2522 Australia
| | - Mahsa Sadeghi
- Health Innovations Research Institute RMIT University Melbourne Vic 3083 Australia
- Illawarra Health and Medical Research Institute (IHMRI) University of Wollongong Wollongong NSW 2522 Australia
| | - Joel Castro
- Visceral Pain Group, Centre for Nutrition and Gastrointestinal Diseases Discipline of Medicine The University of Adelaide South Australian Health and Medical Research Institute (SAHMRI) Adelaide SA 5000 Australia
| | - Tracy O'Donnell
- Visceral Pain Group, Centre for Nutrition and Gastrointestinal Diseases Discipline of Medicine The University of Adelaide South Australian Health and Medical Research Institute (SAHMRI) Adelaide SA 5000 Australia
| | - Annemie Deiteren
- Visceral Pain Group, Centre for Nutrition and Gastrointestinal Diseases Discipline of Medicine The University of Adelaide South Australian Health and Medical Research Institute (SAHMRI) Adelaide SA 5000 Australia
| | - Stuart M. Brierley
- Visceral Pain Group, Centre for Nutrition and Gastrointestinal Diseases Discipline of Medicine The University of Adelaide South Australian Health and Medical Research Institute (SAHMRI) Adelaide SA 5000 Australia
| | - David J. Craik
- Institute for Molecular Biosciences The University of Queensland Brisbane Qld 4072 Australia
| | - David J. Adams
- Health Innovations Research Institute RMIT University Melbourne Vic 3083 Australia
- Illawarra Health and Medical Research Institute (IHMRI) University of Wollongong Wollongong NSW 2522 Australia
| | - Richard J. Clark
- School of Biomedical Science The University of Queensland Brisbane Qld 4072 Australia
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40
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Hamouda AK, Wang ZJ, Stewart DS, Jain AD, Glennon RA, Cohen JB. Desformylflustrabromine (dFBr) and [3H]dFBr-Labeled Binding Sites in a Nicotinic Acetylcholine Receptor. Mol Pharmacol 2015; 88:1-11. [PMID: 25870334 PMCID: PMC4468644 DOI: 10.1124/mol.115.098913] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Accepted: 04/13/2015] [Indexed: 12/11/2022] Open
Abstract
Desformylflustrabromine (dFBr) is a positive allosteric modulator (PAM) of α4β2 and α2β2 nAChRs that, at concentrations >1 µM, also inhibits these receptors and α7 nAChRs. However, its interactions with muscle-type nAChRs have not been characterized, and the locations of its binding site(s) in any nAChR are not known. We report here that dFBr inhibits human muscle (αβεδ) and Torpedo (αβγδ) nAChR expressed in Xenopus oocytes with IC50 values of ∼ 1 μM. dFBr also inhibited the equilibrium binding of ion channel blockers to Torpedo nAChRs with higher affinity in the nAChR desensitized state ([(3)H]phencyclidine; IC50 = 4 μM) than in the resting state ([(3)H]tetracaine; IC50 = 60 μM), whereas it bound with only very low affinity to the ACh binding sites ([(3)H]ACh, IC50 = 1 mM). Upon irradiation at 312 nm, [(3)H]dFBr photoincorporated into amino acids within the Torpedo nAChR ion channel with the efficiency of photoincorporation enhanced in the presence of agonist and the agonist-enhanced photolabeling inhibitable by phencyclidine. In the presence of agonist, [(3)H]dFBr also photolabeled amino acids in the nAChR extracellular domain within binding pockets identified previously for the nonselective nAChR PAMs galantamine and physostigmine at the canonical α-γ interface containing the transmitter binding sites and at the noncanonical δ-β subunit interface. These results establish that dFBr inhibits muscle-type nAChR by binding in the ion channel and that [(3)H]dFBr is a photoaffinity probe with broad amino acid side chain reactivity.
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Affiliation(s)
- Ayman K Hamouda
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts (A.K.H., D.S.S., J.B.C.); Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, Virginia (A.D.J., R.A.G.); and Department of Pharmaceutical Sciences, Rangel College of Pharmacy, Texas A&M Health Sciences Center, Kingsville,Texas (A.K.H., Z.-J.W.)
| | - Ze-Jun Wang
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts (A.K.H., D.S.S., J.B.C.); Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, Virginia (A.D.J., R.A.G.); and Department of Pharmaceutical Sciences, Rangel College of Pharmacy, Texas A&M Health Sciences Center, Kingsville,Texas (A.K.H., Z.-J.W.)
| | - Deirdre S Stewart
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts (A.K.H., D.S.S., J.B.C.); Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, Virginia (A.D.J., R.A.G.); and Department of Pharmaceutical Sciences, Rangel College of Pharmacy, Texas A&M Health Sciences Center, Kingsville,Texas (A.K.H., Z.-J.W.)
| | - Atul D Jain
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts (A.K.H., D.S.S., J.B.C.); Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, Virginia (A.D.J., R.A.G.); and Department of Pharmaceutical Sciences, Rangel College of Pharmacy, Texas A&M Health Sciences Center, Kingsville,Texas (A.K.H., Z.-J.W.)
| | - Richard A Glennon
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts (A.K.H., D.S.S., J.B.C.); Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, Virginia (A.D.J., R.A.G.); and Department of Pharmaceutical Sciences, Rangel College of Pharmacy, Texas A&M Health Sciences Center, Kingsville,Texas (A.K.H., Z.-J.W.)
| | - Jonathan B Cohen
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts (A.K.H., D.S.S., J.B.C.); Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, Virginia (A.D.J., R.A.G.); and Department of Pharmaceutical Sciences, Rangel College of Pharmacy, Texas A&M Health Sciences Center, Kingsville,Texas (A.K.H., Z.-J.W.)
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41
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Kompella SN, Hung A, Clark RJ, Marí F, Adams DJ. Alanine scan of α-conotoxin RegIIA reveals a selective α3β4 nicotinic acetylcholine receptor antagonist. J Biol Chem 2014; 290:1039-48. [PMID: 25411242 DOI: 10.1074/jbc.m114.605592] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Activation of the α3β4 nicotinic acetylcholine receptor (nAChR) subtype has recently been implicated in the pathophysiology of various conditions, including development and progression of lung cancer and in nicotine addiction. As selective α3β4 nAChR antagonists, α-conotoxins are valuable tools to evaluate the functional roles of this receptor subtype. We previously reported the discovery of a new α4/7-conotoxin, RegIIA. RegIIA was isolated from Conus regius and inhibits acetylcholine (ACh)-evoked currents mediated by α3β4, α3β2, and α7 nAChR subtypes. The current study used alanine scanning mutagenesis to understand the selectivity profile of RegIIA at the α3β4 nAChR subtype. [N11A] and [N12A] RegIIA analogs exhibited 3-fold more selectivity for the α3β4 than the α3β2 nAChR subtype. We also report synthesis of [N11A,N12A]RegIIA, a selective α3β4 nAChR antagonist (IC50 of 370 nM) that could potentially be used in the treatment of lung cancer and nicotine addiction. Molecular dynamics simulations of RegIIA and [N11A,N12A]RegIIA bound to α3β4 and α3β2 suggest that destabilization of toxin contacts with residues at the principal and complementary faces of α3β2 (α3-Tyr(92), Ser(149), Tyr(189), Cys(192), and Tyr(196); β2-Trp(57), Arg(81), and Phe(119)) may form the molecular basis for the selectivity shift.
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Affiliation(s)
- Shiva N Kompella
- From the Health Innovations Research Institute, RMIT University, Melbourne, Victoria 3083, Australia
| | - Andrew Hung
- From the Health Innovations Research Institute, RMIT University, Melbourne, Victoria 3083, Australia
| | - Richard J Clark
- the School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia, and
| | - Frank Marí
- the Department of Chemistry & Biochemistry, Florida Atlantic University, Boca Raton, Florida 33431
| | - David J Adams
- From the Health Innovations Research Institute, RMIT University, Melbourne, Victoria 3083, Australia,
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42
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Lebbe EKM, Peigneur S, Maiti M, Mille BG, Devi P, Ravichandran S, Lescrinier E, Waelkens E, D'Souza L, Herdewijn P, Tytgat J. Discovery of a new subclass of α-conotoxins in the venom of Conus australis. Toxicon 2014; 91:145-54. [PMID: 25194747 DOI: 10.1016/j.toxicon.2014.08.074] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 08/22/2014] [Accepted: 08/27/2014] [Indexed: 11/19/2022]
Abstract
Cone snails (Conus sp.) are poisonous animals that can be found in all oceans where they developed a venomous strategy to prey or to defend. The venom of these species contains an undeniable source of unique and potent pharmacologically active compounds. Their peptide compounds, called conotoxins, are not only interesting for the development of new pharmaceutical ligands, but they are also useful for studying their broad spectrum of targets. One conotoxin family in particular, the α-conotoxins, acts on nicotinic acetylcholine receptors (nAChRs) which dysfunctions play important roles in pathologies such as epilepsy, myasthenic syndromes, schizophrenia, Parkinson's disease and Alzheimer's disease. Here we define a new subclass of the α-conotoxin family. We purified the venom of a yet unexplored cone snail species, i.e. Conus australis, and we isolated a 16-amino acid peptide named α-conotoxin AusIA. The peptide has the typical α-conotoxin CC-Xm-C-Xn-C framework, but both loops (m/n) contain 5 amino acids, which has never been described before. Using conventional electrophysiology we investigated the response of synthetically made globular (I-III, II-IV) and ribbon (I-IV, II-III) AusIA to different nicotinic acetylcholine receptors. The α7 nAChR was the only receptor found to be blocked with a similar potency by both peptide-configurations. This suggests that both α5/5 conotoxin isomers might be present in the venom gland of C. australis. NMR spectroscopy showed that no secondary structures define the peptides' three-dimensional topology. Moreover, the ribbon configuration, which is generally considered to be non-native, is more stable than the globular isomer. Accordingly, our findings show relevancy concerning the α-conotoxin classification which might be helpful in the design of novel therapeutic compounds.
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Affiliation(s)
- Eline K M Lebbe
- Toxicology and Pharmacology, University of Leuven-KU Leuven, O&N2-P.O. Box 922, Herestraat 49, 3000 Leuven, Belgium
| | - Steve Peigneur
- Toxicology and Pharmacology, University of Leuven-KU Leuven, O&N2-P.O. Box 922, Herestraat 49, 3000 Leuven, Belgium
| | - Mohitosh Maiti
- Laboratory of Medicinal Chemistry, University of Leuven-KU Leuven, Rega Institute for Medical Research, Dept. of Pharmaceutical & Pharmacological Sciences, Minderbroedersstraat 10, 3000 Leuven, Belgium
| | - Bea G Mille
- Toxicology and Pharmacology, University of Leuven-KU Leuven, O&N2-P.O. Box 922, Herestraat 49, 3000 Leuven, Belgium
| | - Prabha Devi
- CSIR-National Institute of Oceanography, Dona Paula, 403 004 Goa, India
| | | | - Eveline Lescrinier
- Laboratory of Medicinal Chemistry, University of Leuven-KU Leuven, Rega Institute for Medical Research, Dept. of Pharmaceutical & Pharmacological Sciences, Minderbroedersstraat 10, 3000 Leuven, Belgium
| | - Etienne Waelkens
- Laboratorium voor Proteïne Fosforylatie en Proteomics, University of Leuven-KU Leuven, O&N I-P.O. Box 901, Herestraat 49, 3000 Leuven, Belgium
| | - Lisette D'Souza
- CSIR-National Institute of Oceanography, Dona Paula, 403 004 Goa, India
| | - Piet Herdewijn
- Laboratory of Medicinal Chemistry, University of Leuven-KU Leuven, Rega Institute for Medical Research, Dept. of Pharmaceutical & Pharmacological Sciences, Minderbroedersstraat 10, 3000 Leuven, Belgium
| | - Jan Tytgat
- Toxicology and Pharmacology, University of Leuven-KU Leuven, O&N2-P.O. Box 922, Herestraat 49, 3000 Leuven, Belgium.
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Akondi KB, Muttenthaler M, Dutertre S, Kaas Q, Craik DJ, Lewis RJ, Alewood PF. Discovery, synthesis, and structure-activity relationships of conotoxins. Chem Rev 2014; 114:5815-47. [PMID: 24720541 PMCID: PMC7610532 DOI: 10.1021/cr400401e] [Citation(s) in RCA: 224] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
| | | | - Sébastien Dutertre
- Institute for Molecular Bioscience, The University of Queensland, Brisbane QLD 4072, Australia
| | - Quentin Kaas
- Institute for Molecular Bioscience, The University of Queensland, Brisbane QLD 4072, Australia
| | - David J Craik
- Institute for Molecular Bioscience, The University of Queensland, Brisbane QLD 4072, Australia
| | - Richard J Lewis
- Institute for Molecular Bioscience, The University of Queensland, Brisbane QLD 4072, Australia
| | - Paul F Alewood
- Institute for Molecular Bioscience, The University of Queensland, Brisbane QLD 4072, Australia
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Lebbe EK, Peigneur S, Wijesekara I, Tytgat J. Conotoxins targeting nicotinic acetylcholine receptors: an overview. Mar Drugs. 2014;12:2970-3004. [PMID: 24857959 PMCID: PMC4052327 DOI: 10.3390/md12052970] [Citation(s) in RCA: 113] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Revised: 04/24/2014] [Accepted: 04/28/2014] [Indexed: 12/19/2022] Open
Abstract
Marine snails of the genus Conus are a large family of predatory gastropods with an unparalleled molecular diversity of pharmacologically active compounds in their venom. Cone snail venom comprises of a rich and diverse cocktail of peptide toxins which act on a wide variety of ion channels such as voltage-gated sodium- (NaV), potassium- (KV), and calcium- (CaV) channels as well as nicotinic acetylcholine receptors (nAChRs) which are classified as ligand-gated ion channels. The mode of action of several conotoxins has been the subject of investigation, while for many others this remains unknown. This review aims to give an overview of the knowledge we have today on the molecular pharmacology of conotoxins specifically interacting with nAChRs along with the structure–function relationship data.
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Indurthi DC, Pera E, Kim HL, Chu C, McLeod MD, McIntosh JM, Absalom NL, Chebib M. Presence of multiple binding sites on α9α10 nAChR receptors alludes to stoichiometric-dependent action of the α-conotoxin, Vc1.1. Biochem Pharmacol 2014; 89:131-40. [PMID: 24548457 DOI: 10.1016/j.bcp.2014.02.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Revised: 02/04/2014] [Accepted: 02/06/2014] [Indexed: 01/23/2023]
Abstract
Nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels involved in fast synaptic transmission. nAChRs are pentameric receptors formed from a combination of different or similar subunits to produce heteromeric or homomeric channels. The heteromeric, α9α10 nAChR subtype is well-known for its role in the auditory system, being expressed in cochlear hair cells. These nAChRs have also been shown to be involved in immune-modulation. Antagonists of α9α10 nAChRs, like the α-conotoxin Vc1.1, have analgesic effects in neuropathic pain. Unlike other nAChR subtypes there is no evidence that functional receptor stoichiometries of α9α10 exist. By using 2-electrode voltage clamp methods and maintaining a constant intracellular Ca(2+) concentration, we observed a biphasic activation curve for ACh that is dependent on receptor stoichiometry. Vc1.1, but not the α9α10 antagonists RgIA or atropine, inhibits ACh-evoked currents in a biphasic manner. Characteristics of the ACh and Vc1.1 activation and inhibition curves can be altered by varying the ratio of α9 and α10 mRNA injected into oocytes, changing the curves from biphasic to monophasic when an excess of α10 mRNA is used. These results highlight the difference in the pharmacological profiles of at least two different α9α10 nAChR stoichiometries, possibly (α9)₃(α10)₂ and (α9)₂(α10)₃. As a result, we infer that there is an additional binding site for ACh and Vc1.1 at the α9-α9 interface on the hypothesized (α9)₃(α10)₂ nAChR, in addition to the α10-α9 and or α9-α10 interfaces that are common to both stoichiometries. This study provides further evidence that receptor stoichiometry contributes another layer of complexity in understanding Cys-loop receptors.
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Affiliation(s)
- Dinesh C Indurthi
- Faculty of Pharmacy, University of Sydney, Sydney 2006, NSW, Australia
| | - Elena Pera
- Faculty of Pharmacy, University of Sydney, Sydney 2006, NSW, Australia
| | - Hye-Lim Kim
- Faculty of Pharmacy, University of Sydney, Sydney 2006, NSW, Australia
| | - Cindy Chu
- Faculty of Pharmacy, University of Sydney, Sydney 2006, NSW, Australia
| | - Malcolm D McLeod
- Research School of Chemistry, Australian National University, Canberra 0200, ACT, Australia
| | - J Michael McIntosh
- George E. Wahlen Veterans Affairs Medical Center, Salt Lake City, UT 84108, USA; Departments of Psychiatry and Biology, University of Utah, Salt Lake City, UT 84112, USA
| | - Nathan L Absalom
- Faculty of Pharmacy, University of Sydney, Sydney 2006, NSW, Australia.
| | - Mary Chebib
- Faculty of Pharmacy, University of Sydney, Sydney 2006, NSW, Australia.
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Grishin AA, Cuny H, Hung A, Clark RJ, Brust A, Akondi K, Alewood PF, Craik DJ, Adams DJ. Identifying key amino acid residues that affect α-conotoxin AuIB inhibition of α3β4 nicotinic acetylcholine receptors. J Biol Chem 2013; 288:34428-42. [PMID: 24100032 DOI: 10.1074/jbc.m113.512582] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
α-Conotoxin AuIB is a selective α3β4 nicotinic acetylcholine receptor (nAChR) subtype inhibitor. Its analgesic properties are believed to result from it activating GABAB receptors and subsequently inhibiting CaV2.2 voltage-gated calcium channels. The structural determinants that mediate diverging AuIB activity at these targets are unknown. We performed alanine scanning mutagenesis of AuIB and α3β4 nAChR, homology modeling, and molecular dynamics simulations to identify the structural determinants of the AuIB·α3β4 nAChR interaction. Two alanine-substituted AuIB analogues, [P6A]AuIB and [F9A]AuIB, did not inhibit the α3β4 nAChR. NMR and CD spectroscopy studies demonstrated that [F9A]AuIB retains its native globular structure, so its activity loss is probably due to loss of specific toxin-receptor residue pairwise contacts. Compared with AuIB, the concentration-response curve for inhibition of α3β4 by [F9A]AuIB shifted rightward more than 10-fold, and its subtype selectivity profile changed. Homology modeling and molecular dynamics simulations suggest that Phe-9 of AuIB interacts with a two-residue binding pocket on the β4 nAChR subunit. This hypothesis was confirmed by site-directed mutagenesis of the β4-Trp-59 and β4-Lys-61 residues of loop D, which form a putative binding pocket. AuIB analogues with Phe-9 substitutions corroborated the finding of a binding pocket on the β4 subunit and gave further insight into how AuIB Phe-9 interacts with the β4 subunit. In summary, we identified critical residues that mediate interactions between AuIB and its cognate nAChR subtype. These findings might help improve the design of analgesic conopeptides that selectively "avoid" nAChR receptors while targeting receptors involved with nociception.
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Affiliation(s)
- Anton A Grishin
- From the Health Innovations Research Institute, RMIT University, Melbourne, Victoria 3083, Australia and
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48
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Adams D, Harper A, Grishin A, Cuny H. Actions of α-conotoxins on neuronal nicotinic acetylcholine receptors and synaptic transmission in rat parasympathetic ganglia. Auton Neurosci 2013; 177:306. [DOI: 10.1016/j.autneu.2013.08.027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Wu X, Wu Y, Zhu F, Yang Q, Wu Q, Zhangsun D, Luo S. Optimal cleavage and oxidative folding of α-conotoxin TxIB as a therapeutic candidate peptide. Mar Drugs 2013; 11:3537-53. [PMID: 24048271 DOI: 10.3390/md11093537] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Revised: 08/16/2013] [Accepted: 08/19/2013] [Indexed: 12/19/2022] Open
Abstract
Alpha6beta2 nicotinic acetylcholine receptors (nAChRs) are potential therapeutic targets for the treatment of several neuropsychiatric diseases, including addiction and Parkinson’s disease. Alpha-conotoxin (α-CTx) TxIB is a uniquely selective ligand, which blocks α6/α3β2β3 nAChRs only, but does not block the other subtypes. Therefore, α-CTx TxIB is a valuable therapeutic candidate peptide. Synthesizing enough α-CTx TxIB with high yield production is required for conducting wide-range testing of its potential medicinal applications. The current study optimized the cleavage of synthesized α-CTx TxIB resin-bounded peptide and folding of the cleaved linear peptide. Key parameters influencing cleavage and oxidative folding of α-CTx TxIB were examined, such as buffer, redox agents, pH, salt, co-solvent and temperature. Twelve conditions were used for cleavage optimization. Fifty-four kinds of one-step oxidative solution were used to assess their effects on each α-CTx TxIB isomers’ yield. The result indicated that co-solvent choices were particularly important. Completely oxidative folding of globular isomer was achieved when the NH4HCO3 or Tris-HCl folding buffer at 4 °C contained 40% of co-solvent DMSO, and GSH:GSSG (2:1) or GSH only with pH 8~8.7.
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Molgó J, Aráoz R, Benoit E, Iorga BI. Physical and virtual screening methods for marine toxins and drug discovery targeting nicotinic acetylcholine receptors. Expert Opin Drug Discov 2013; 8:1203-23. [DOI: 10.1517/17460441.2013.822365] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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