1
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Wu X, Hone AJ, Huang YH, Clark RJ, McIntosh JM, Kaas Q, Craik DJ. Computational Design of α-Conotoxins to Target Specific Nicotinic Acetylcholine Receptor Subtypes. Chemistry 2024; 30:e202302909. [PMID: 37910861 PMCID: PMC10872529 DOI: 10.1002/chem.202302909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 10/25/2023] [Accepted: 10/26/2023] [Indexed: 11/03/2023]
Abstract
Nicotinic acetylcholine receptors (nAChRs) are drug targets for neurological diseases and disorders, but selective targeting of the large number of nAChR subtypes is challenging. Marine cone snail α-conotoxins are potent blockers of nAChRs and some have been engineered to achieve subtype selectivity. This engineering effort would benefit from rapid computational methods able to predict mutational energies, but current approaches typically require high-resolution experimental structures, which are not widely available for α-conotoxin complexes. Herein, five mutational energy prediction methods were benchmarked using crystallographic and mutational data on two acetylcholine binding protein/α-conotoxin systems. Molecular models were developed for six nAChR subtypes in complex with five α-conotoxins that were studied through 150 substitutions. The best method was a combination of FoldX and molecular dynamics simulations, resulting in a predictive Matthews Correlation Coefficient (MCC) of 0.68 (85 % accuracy). Novel α-conotoxin mutants designed using this method were successfully validated by experimental assay with improved pharmaceutical properties. This work paves the way for the rapid design of subtype-specific nAChR ligands and potentially accelerated drug development.
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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, Queensland, 4072, Australia
- School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, 4072, Australia
| | - Arik J Hone
- School of Biological Science, University of Utah, Salt Lake City, Utah, 84112, USA
- MIRECC, George E. Whalen Veterans Affairs Medical Center, Salt Lake City, Utah, 84112, USA
| | - Yen-Hua Huang
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland, 4072, Australia
| | - Richard J Clark
- School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, 4072, Australia
| | - J Michael McIntosh
- School of Biological Science, University of Utah, Salt Lake City, Utah, 84112, USA
- Department of Psychiatry, University of Utah, Salt Lake City, Utah, 84112, USA
- George E. Whalen Veterans Affairs Medical Center, Salt Lake City, Utah, 84112, USA
| | - Quentin Kaas
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland, 4072, Australia
| | - 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, Queensland, 4072, Australia
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2
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Shelukhina I, Siniavin A, Kasheverov I, Ojomoko L, Tsetlin V, Utkin Y. α7- and α9-Containing Nicotinic Acetylcholine Receptors in the Functioning of Immune System and in Pain. Int J Mol Sci 2023; 24:ijms24076524. [PMID: 37047495 PMCID: PMC10095066 DOI: 10.3390/ijms24076524] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 03/26/2023] [Accepted: 03/28/2023] [Indexed: 04/03/2023] Open
Abstract
Nicotinic acetylcholine receptors (nAChRs) present as many different subtypes in the nervous and immune systems, muscles and on the cells of other organs. In the immune system, inflammation is regulated via the vagus nerve through the activation of the non-neuronal α7 nAChR subtype, affecting the production of cytokines. The analgesic properties of α7 nAChR-selective compounds are mostly based on the activation of the cholinergic anti-inflammatory pathway. The molecular mechanism of neuropathic pain relief mediated by the inhibition of α9-containing nAChRs is not fully understood yet, but the role of immune factors in this process is becoming evident. To obtain appropriate drugs, a search of selective agonists, antagonists and modulators of α7- and α9-containing nAChRs is underway. The naturally occurring three-finger snake α-neurotoxins and mammalian Ly6/uPAR proteins, as well as neurotoxic peptides α-conotoxins, are not only sophisticated tools in research on nAChRs but are also considered as potential medicines. In particular, the inhibition of the α9-containing nAChRs by α-conotoxins may be a pathway to alleviate neuropathic pain. nAChRs are involved in the inflammation processes during AIDS and other viral infections; thus they can also be means used in drug design. In this review, we discuss the role of α7- and α9-containing nAChRs in the immune processes and in pain.
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Affiliation(s)
| | | | | | | | | | - Yuri Utkin
- Correspondence: or ; Tel.: +7-495-3366522
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3
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Espiritu MJ, Taylor JK, Sugai CK, Thapa P, Loening NM, Gusman E, Baoanan ZG, Baumann MH, Bingham JP. Characterization of the Native Disulfide Isomers of the Novel χ-Conotoxin PnID: Implications for Further Increasing Conotoxin Diversity. Mar Drugs 2023; 21:61. [PMID: 36827103 PMCID: PMC9964023 DOI: 10.3390/md21020061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 01/11/2023] [Accepted: 01/17/2023] [Indexed: 01/21/2023] Open
Abstract
χ-Conotoxins are known for their ability to selectively inhibit norepinephrine transporters, an ability that makes them potential leads for treating various neurological disorders, including neuropathic pain. PnID, a peptide isolated from the venom of Conus pennaceus, shares high sequence homology with previously characterized χ-conotoxins. Whereas previously reported χ-conotoxins seem to only have a single native disulfide bonding pattern, PnID has three native isomers due to the formation of different disulfide bond patterns during its maturation in the venom duct. In this study, the disulfide connectivity and three-dimensional structure of these disulfide isomers were explored using regioselective synthesis, chromatographic coelution, and solution-state nuclear magnetic resonance spectroscopy. Of the native isomers, only the isomer with a ribbon disulfide configuration showed pharmacological activity similar to other χ-conotoxins. This isomer inhibited the rat norepinephrine transporter (IC50 = 10 ± 2 µM) and has the most structural similarity to previously characterized χ-conotoxins. In contrast, the globular isoform of PnID showed more than ten times less activity against this transporter and the beaded isoform did not display any measurable biological activity. This study is the first report of the pharmacological and structural characterization of an χ-conotoxin from a species other than Conus marmoreus and is the first report of the existence of natively-formed conotoxin isomers.
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Affiliation(s)
- Michael J. Espiritu
- Department of Molecular Biosciences and Bioengineering, College of Tropical Agriculture and Human Resources, University of Hawai’i, Honolulu, HI 96822, USA
- School of Pharmacy, Pacific University, 222 SE 8th Ave, Ste. 451, Hillsboro, OR 97123, USA
| | - Jonathan K. Taylor
- School of Pharmacy, Pacific University, 222 SE 8th Ave, Ste. 451, Hillsboro, OR 97123, USA
| | - Christopher K. Sugai
- Department of Molecular Biosciences and Bioengineering, College of Tropical Agriculture and Human Resources, University of Hawai’i, Honolulu, HI 96822, USA
| | - Parashar Thapa
- Department of Molecular Biosciences and Bioengineering, College of Tropical Agriculture and Human Resources, University of Hawai’i, Honolulu, HI 96822, USA
| | - Nikolaus M. Loening
- Department of Chemistry, Lewis & Clark College, 615 S Palatine Hill Road, Portland, OR 97219, USA
| | - Emma Gusman
- School of Pharmacy, Pacific University, 222 SE 8th Ave, Ste. 451, Hillsboro, OR 97123, USA
| | - Zenaida G. Baoanan
- Department of Molecular Biosciences and Bioengineering, College of Tropical Agriculture and Human Resources, University of Hawai’i, Honolulu, HI 96822, USA
- Department of Biology, College of Science, University of the Philippines Baguio, Baguio City 2600, Philippines
| | - Michael H. Baumann
- Designer Drug Research Unit, Intramural Research Program, National Institute on Drug Abuse (NIDA), National Institutes of Health (NIH), 333 Cassell Drive Suite 4400, Baltimore, MD 21224, USA
| | - Jon-Paul Bingham
- Department of Molecular Biosciences and Bioengineering, College of Tropical Agriculture and Human Resources, University of Hawai’i, Honolulu, HI 96822, USA
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4
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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] [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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5
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Turner MW, Marquart LA, Phillips PD, McDougal OM. Mutagenesis of α-Conotoxins for Enhancing Activity and Selectivity for Nicotinic Acetylcholine Receptors. Toxins (Basel) 2019; 11:E113. [PMID: 30781866 PMCID: PMC6409848 DOI: 10.3390/toxins11020113] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2019] [Revised: 02/10/2019] [Accepted: 02/11/2019] [Indexed: 02/04/2023] Open
Abstract
Nicotinic acetylcholine receptors (nAChRs) are found throughout the mammalian body and have been studied extensively because of their implication in a myriad of diseases. α-Conotoxins (α-CTxs) are peptide neurotoxins found in the venom of marine snails of genus Conus. α-CTxs are potent and selective antagonists for a variety of nAChR isoforms. Over the past 40 years, α-CTxs have proven to be valuable molecular probes capable of differentiating between closely related nAChR subtypes and have contributed greatly to understanding the physiological role of nAChRs in the mammalian nervous system. Here, we review the amino acid composition and structure of several α-CTxs that selectively target nAChR isoforms and explore strategies and outcomes for introducing mutations in native α-CTxs to direct selectivity and enhance binding affinity for specific nAChRs. This review will focus on structure-activity relationship studies involving native α-CTxs that have been rationally mutated and molecular interactions that underlie binding between ligand and nAChR isoform.
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Affiliation(s)
- Matthew W Turner
- Biomolecular Sciences Graduate Programs, Boise State University; Boise, ID 83725, USA.
| | - Leanna A Marquart
- Department of Chemistry and Biochemistry, Boise State University; Boise, ID 83725, USA.
| | - Paul D Phillips
- Department of Chemistry and Biochemistry, Boise State University; Boise, ID 83725, USA.
| | - Owen M McDougal
- Department of Chemistry and Biochemistry, Boise State University; Boise, ID 83725, USA.
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6
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Yu J, Zhu X, Zhang L, Kudryavtsev D, Kasheverov I, Lei Y, Zhangsun D, Tsetlin V, Luo S. Species specificity of rat and human α7 nicotinic acetylcholine receptors towards different classes of peptide and protein antagonists. Neuropharmacology 2018; 139:226-237. [DOI: 10.1016/j.neuropharm.2018.07.019] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 07/07/2018] [Accepted: 07/13/2018] [Indexed: 01/12/2023]
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7
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α-Conotoxins to explore the molecular, physiological and pathophysiological functions of neuronal nicotinic acetylcholine receptors. Neurosci Lett 2017; 679:24-34. [PMID: 29199094 DOI: 10.1016/j.neulet.2017.11.063] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [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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8
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Banerjee J, Yongye AB, Chang YP, Gyanda R, Medina-Franco JL, Armishaw CJ. Design and synthesis of α-conotoxin GID analogues as selective α4β2 nicotinic acetylcholine receptor antagonists. Biopolymers 2016; 102:78-87. [PMID: 24122487 DOI: 10.1002/bip.22413] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Revised: 08/30/2013] [Accepted: 09/09/2013] [Indexed: 01/01/2023]
Abstract
The α4β2 nicotinic acetylcholine receptor (nAChR) is an important target for currently approved smoking cessation therapeutics. However, the development of highly selective α4β2 nAChR antagonists remains a significant challenge. α-Conotoxin GID is an antagonist of α4β2 nAChRs, though it is significantly more potent toward the α3β2 and α7 subtypes. With the goal of obtaining further insights into α-conotoxin GID/nAChR interactions that could lead to the design of GID analogues with improved affinity for α4β2 nAChRs, we built a homology model of the GID/α4β2 complex using an X-ray co-crystal structure of an α-conotoxin/acetylcholine binding protein (AChBP) complex. Several additional interactions that could potentially enhance the affinity of GID for α4β2 nAChRs were observed in our model, which led to the design and synthesis of 22 GID analogues. Seven analogues displayed inhibitory activity toward α4β2 nAChRs that was comparable to GID. Significantly, both GID[A10S] and GID[V13I] demonstrated moderately improved selectivity toward α4β2 over α3β2 when compared with GID, while GID[V18N] exhibited no measurable inhibitory activity for the α3β2 subtype, yet retained inhibitory activity for α4β2. In this regard, GID[V18N] is the most α4β2 nAChR selective α-conotoxin analogue identified to date.
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Affiliation(s)
- Jayati Banerjee
- Torrey Pines Institute for Molecular Studies, Port St. Lucie, FL, 34987
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9
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Oldrati V, Arrell M, Violette A, Perret F, Sprüngli X, Wolfender JL, Stöcklin R. Advances in venomics. MOLECULAR BIOSYSTEMS 2016; 12:3530-3543. [DOI: 10.1039/c6mb00516k] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The term “venomics” was coined to describe the global study of venom and venom glands, targeting comprehensive characterization of the whole toxin profile of a venomous animal by means of proteomics, transcriptomics, genomics and bioinformatics studies.
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Affiliation(s)
- Vera Oldrati
- Atheris SA
- Geneva
- Switzerland
- School of Pharmaceutical Sciences
- EPGL
| | | | - Aude Violette
- Alphabiotoxine Laboratory Sprl
- Montroeul-au-Bois B-7911
- Belgium
| | | | | | - Jean-Luc Wolfender
- School of Pharmaceutical Sciences
- EPGL
- University of Geneva
- University of Lausanne
- CMU
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10
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Bach TB, Jensen AA, Petersen JG, Sørensen TE, Della Volpe S, Liu J, Blaazer AR, van Muijlwijk-Koezen JE, Balle T, Frølund B. Exploration of the molecular architecture of the orthosteric binding site in the α4β2 nicotinic acetylcholine receptor with analogs of 3-(dimethylamino)butyl dimethylcarbamate (DMABC) and 1-(pyridin-3-yl)-1,4-diazepane. Eur J Med Chem 2015; 102:425-44. [DOI: 10.1016/j.ejmech.2015.07.024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Revised: 07/10/2015] [Accepted: 07/13/2015] [Indexed: 10/23/2022]
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11
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Natural compounds interacting with nicotinic acetylcholine receptors: from low-molecular weight ones to peptides and proteins. Toxins (Basel) 2015; 7:1683-701. [PMID: 26008231 PMCID: PMC4448168 DOI: 10.3390/toxins7051683] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2015] [Accepted: 05/07/2015] [Indexed: 12/16/2022] Open
Abstract
Nicotinic acetylcholine receptors (nAChRs) fulfill a variety of functions making identification and analysis of nAChR subtypes a challenging task. Traditional instruments for nAChR research are d-tubocurarine, snake venom protein α-bungarotoxin (α-Bgt), and α-conotoxins, neurotoxic peptides from Conus snails. Various new compounds of different structural classes also interacting with nAChRs have been recently identified. Among the low-molecular weight compounds are alkaloids pibocin, varacin and makaluvamines C and G. 6-Bromohypaphorine from the mollusk Hermissenda crassicornis does not bind to Torpedo nAChR but behaves as an agonist on human α7 nAChR. To get more selective α-conotoxins, computer modeling of their complexes with acetylcholine-binding proteins and distinct nAChRs was used. Several novel three-finger neurotoxins targeting nAChRs were described and α-Bgt inhibition of GABA-A receptors was discovered. Information on the mechanisms of nAChR interactions with the three-finger proteins of the Ly6 family was found. Snake venom phospholipases A2 were recently found to inhibit different nAChR subtypes. Blocking of nAChRs in Lymnaea stagnalis neurons was shown for venom C-type lectin-like proteins, appearing to be the largest molecules capable to interact with the receptor. A huge nAChR molecule sensible to conformational rearrangements accommodates diverse binding sites recognizable by structurally very different compounds.
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12
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Upert G, Mourier G, Pastor A, Verdenaud M, Alili D, Servent D, Gilles N. High-throughput production of two disulphide-bridge toxins. Chem Commun (Camb) 2015; 50:8408-11. [PMID: 24947561 DOI: 10.1039/c4cc02679a] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
A quick and efficient production method compatible with high-throughput screening was developed using 36 toxins belonging to four different families of two disulphide-bridge toxins. Final toxins were characterized using HPLC co-elution, CD and pharmacological studies.
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Affiliation(s)
- Grégory Upert
- CEA, DSV, iBiTec-S, Service d'Ingénierie Moléculaire des Protéines (SIMOPRO), CEA Saclay, Gif sur Yvette F-91191, France.
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13
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Wan J, Huang JX, Vetter I, Mobli M, Lawson J, Tae HS, Abraham N, Paul B, Cooper MA, Adams DJ, Lewis RJ, Alewood PF. α-Conotoxin Dendrimers Have Enhanced Potency and Selectivity for Homomeric Nicotinic Acetylcholine Receptors. J Am Chem Soc 2015; 137:3209-12. [DOI: 10.1021/jacs.5b00244] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jingjing Wan
- Institute
of Molecular Bioscience, The University of Queensland, St Lucia Queensland 4072, Australia
| | - Johnny X. Huang
- Institute
of Molecular Bioscience, The University of Queensland, St Lucia Queensland 4072, Australia
| | - Irina Vetter
- Institute
of Molecular Bioscience, The University of Queensland, St Lucia Queensland 4072, Australia
- School
of Pharmacy, The University of Queensland, Woolloongabba, Queensland 4102, Australia
| | - Mehdi Mobli
- Centre
for Advanced Imaging, The University of Queensland, St Lucia Queensland 4072, Australia
| | - Joshua Lawson
- Health
Innovations Research Institute, RMIT University, Bundoora, Victoria 3083, Australia
| | - Han-Shen Tae
- Health
Innovations Research Institute, RMIT University, Bundoora, Victoria 3083, Australia
| | - Nikita Abraham
- Institute
of Molecular Bioscience, The University of Queensland, St Lucia Queensland 4072, Australia
| | - Blessy Paul
- Institute
of Molecular Bioscience, The University of Queensland, St Lucia Queensland 4072, Australia
| | - Matthew A. Cooper
- Institute
of Molecular Bioscience, The University of Queensland, St Lucia Queensland 4072, Australia
| | - David J. Adams
- Health
Innovations Research Institute, RMIT University, Bundoora, Victoria 3083, Australia
| | - Richard J. Lewis
- Institute
of Molecular Bioscience, The University of Queensland, St Lucia Queensland 4072, Australia
| | - Paul F. Alewood
- Institute
of Molecular Bioscience, The University of Queensland, St Lucia Queensland 4072, Australia
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14
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Thapa P, Espiritu MJ, Cabalteja CC, Bingham JP. Conotoxins and their regulatory considerations. Regul Toxicol Pharmacol 2014; 70:197-202. [PMID: 25013992 DOI: 10.1016/j.yrtph.2014.06.027] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Revised: 06/29/2014] [Accepted: 06/30/2014] [Indexed: 01/21/2023]
Abstract
Venom derived peptides from marine cone snails, conotoxins, have demonstrated unique pharmacological targeting properties that have been pivotal in advancing medical research. The awareness of their true toxic origins and potent pharmacological nature is emphasized by their 'select agent' classification by the US Centers for Disease Control and Prevention. We briefly introduce the biochemical and pharmacological aspects of conotoxins, highlighting current advancements into their biological engineering, and provide details to the present regulations that govern their use in research.
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Affiliation(s)
- Parashar Thapa
- Department of Molecular Biosciences and Bioengineering, College of Tropical Agriculture and Human Resources, University of Hawai'i, Honolulu, HI 96822, USA
| | - Michael J Espiritu
- Department of Molecular Biosciences and Bioengineering, College of Tropical Agriculture and Human Resources, University of Hawai'i, Honolulu, HI 96822, USA
| | - Chino C Cabalteja
- Department of Molecular Biosciences and Bioengineering, College of Tropical Agriculture and Human Resources, University of Hawai'i, Honolulu, HI 96822, USA
| | - Jon-Paul Bingham
- Department of Molecular Biosciences and Bioengineering, College of Tropical Agriculture and Human Resources, University of Hawai'i, Honolulu, HI 96822, USA.
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15
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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: 237] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [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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16
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Chu KO, Chan SO, Pang CP, Wang CC. Pro-oxidative and antioxidative controls and signaling modification of polyphenolic phytochemicals: contribution to health promotion and disease prevention? JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2014; 62:4026-4038. [PMID: 24779775 DOI: 10.1021/jf500080z] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Polyphenolic phytochemicals (PPs) have been extensively studied as potential nutriceuticals for maintenance of health and treatment of cancer, inflammation, and neurodegeneration. However, the reported beneficial outcomes are inconsistent. The biological activities of PPs have been attributed to their pro-oxidative and antioxidative actions and effects on signaling mechanisms and epigenomic modifications. These diversified properties were described or postulated on the basis of a variety of experimental studies using cell culture and animal models, even though most have not been replicated and results are not validated. This review attempts to give an overview of biological properties of PPs, based on the coherent results from relevant studies, and evaluate critically the experimental conditions and possible artifacts. Complicated molecular mechanisms and multitargeting genomic interactions of PPs are discussed, with a view that reasonable mechanistic propositions are usually obtained from well-designed in vivo studies.
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Affiliation(s)
- Kai On Chu
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong in Hong Kong Eye Hospital , Kowloon, Hong Kong
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17
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Chang YP, Banerjee J, Dowell C, Wu J, Gyanda R, Houghten RA, Toll L, McIntosh JM, Armishaw CJ. Discovery of a potent and selective α3β4 nicotinic acetylcholine receptor antagonist from an α-conotoxin synthetic combinatorial library. J Med Chem 2014; 57:3511-21. [PMID: 24649848 PMCID: PMC4358631 DOI: 10.1021/jm500183r] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
α-Conotoxins are disulfide-rich peptide neurotoxins that selectively inhibit neuronal nicotinic acetylcholine receptors (nAChRs). The α3β4 nAChR subtype has been identified as a novel target for managing nicotine addiction. Using a mixture-based positional-scanning synthetic combinatorial library (PS-SCL) with the α4/4-conotoxin BuIA framework, we discovered a highly potent and selective α3β4 nAChR antagonist. The initial PS-SCL consisted of a total of 113 379 904 sequences that were screened for α3β4 nAChR inhibition, which facilitated the design and synthesis of a second generation library of 64 individual α-conotoxin derivatives. Eleven analogues were identified as α3β4 nAChR antagonists, with TP-2212-59 exhibiting the most potent antagonistic activity and selectivity over the α3β2 and α4β2 nAChR subtypes. Final electrophysiological characterization demonstrated that TP-2212-59 inhibited acetylcholine evoked currents in α3β4 nAChRs heterogeneously expressed in Xenopus laevis oocytes with a calculated IC50 of 2.3 nM and exhibited more than 1000-fold selectivity over the α3β2 and α7 nAChR subtypes. As such, TP-2212-59 is among the most potent α3β4 nAChRs antagonists identified to date and further demonstrates the utility of mixture-based combinatorial libraries in the discovery of novel α-conotoxin derivatives with refined pharmacological activity.
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Affiliation(s)
- Yi-Pin Chang
- Torrey Pines Institute for Molecular Studies , 11350 SW Village Parkway, Port St. Lucie, Florida 34987, United States
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18
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Crestey F, Jensen AA, Borch M, Andreasen JT, Andersen J, Balle T, Kristensen JL. Design, Synthesis, and Biological Evaluation of Erythrina Alkaloid Analogues as Neuronal Nicotinic Acetylcholine Receptor Antagonists. J Med Chem 2013; 56:9673-82. [DOI: 10.1021/jm4013592] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- François Crestey
- Department
of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100 Copenhagen, Denmark
| | - Anders A. Jensen
- Department
of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100 Copenhagen, Denmark
| | - Morten Borch
- Department
of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100 Copenhagen, Denmark
| | - Jesper Tobias Andreasen
- Department
of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100 Copenhagen, Denmark
| | - Jacob Andersen
- Department
of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100 Copenhagen, Denmark
| | - Thomas Balle
- Faculty
of Pharmacy, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Jesper Langgaard Kristensen
- Department
of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100 Copenhagen, Denmark
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19
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Zaretsky S, Scully CCG, Lough AJ, Yudin AK. Exocyclic control of turn induction in macrocyclic peptide scaffolds. Chemistry 2013; 19:17668-72. [PMID: 24259185 DOI: 10.1002/chem.201303453] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Indexed: 11/08/2022]
Affiliation(s)
- Serge Zaretsky
- Davenport Research Laboratories, Department of Chemistry, University of Toronto, 80 St. George Str., Toronto, ON, M5S 3H6 (Canada)
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20
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Incorporation of post-translational modified amino acids as an approach to increase both chemical and biological diversity of conotoxins and conopeptides. Amino Acids 2013; 46:125-51. [DOI: 10.1007/s00726-013-1606-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2013] [Accepted: 10/17/2013] [Indexed: 02/06/2023]
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21
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Medina-Franco JL, Giulianotti MA, Welmaker GS, Houghten RA. Shifting from the single to the multitarget paradigm in drug discovery. Drug Discov Today 2013; 18:495-501. [PMID: 23340113 PMCID: PMC3642214 DOI: 10.1016/j.drudis.2013.01.008] [Citation(s) in RCA: 298] [Impact Index Per Article: 27.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Revised: 12/03/2012] [Accepted: 01/14/2013] [Indexed: 01/30/2023]
Abstract
Increasing evidence that several drug compounds exert their effects through interactions with multiple targets is boosting the development of research fields that challenge the data reductionism approach. In this article, we review and discuss the concepts of drug repurposing, polypharmacology, chemogenomics, phenotypic screening and high-throughput in vivo testing of mixture-based libraries in an integrated manner. These research fields offer alternatives to the current paradigm of drug discovery, from a one target-one drug model to a multiple-target approach. Furthermore, the goals of lead identification are being expanded accordingly to identify not only 'key' compounds that fit with a single-target 'lock', but also 'master key' compounds that favorably interact with multiple targets (i.e. operate a set of desired locks to gain access to the expected clinical effects).
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Affiliation(s)
- José L Medina-Franco
- Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, México, D.F. 04510, Mexico.
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22
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Armishaw CJ, Banerjee J, Ganno ML, Reilley KJ, Eans SO, Mizrachi E, Gyanda R, Hoot MR, Houghten RA, McLaughlin JP. Discovery of novel antinociceptive α-conotoxin analogues from the direct in vivo screening of a synthetic mixture-based combinatorial library. ACS COMBINATORIAL SCIENCE 2013; 15:153-61. [PMID: 23414173 DOI: 10.1021/co300152x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Marine cone snail venoms consist of large, naturally occurring combinatorial libraries of disulfide-constrained peptide neurotoxins known as conotoxins, which have profound potential in the development of analgesics. In this study, we report a synthetic combinatorial strategy that probes the hypervariable regions of conotoxin frameworks to discover novel analgesic agents by utilizing high diversity mixture-based positional-scanning synthetic combinatorial libraries (PS-SCLs). We hypothesized that the direct in vivo testing of these mixture-based combinatorial library samples during the discovery phase would facilitate the identification of novel individual compounds with desirable antinociceptive profiles while simultaneously eliminating many compounds with poor activity or liabilities of locomotion and respiration. A PS-SCL was designed based on the α-conotoxin RgIA-ΔR n-loop region and consisted of 10,648 compounds systematically arranged into 66 mixture samples. Mixtures were directly screened in vivo using the mouse 55 °C warm-water tail-withdrawal assay, which allowed deconvolution of amino acid residues at each position that confer antinociceptive activity. A second generation library of 36 individual α-conotoxin analogues was synthesized using systematic combinations of amino acids identified from PS-SCL deconvolution and further screened for antinociceptive activity. Six individual analogues exhibited comparable antinociceptive activity to that of the recognized analgesic α-conotoxin RgIA-ΔR, and were selected for further examination of antinociceptive, respiratory, and locomotor effects. Three lead compounds were identified that produced dose-dependent antinociception without significant respiratory depression or decreased locomotor activity. Our results represent a unique approach for rapidly developing novel lead α-conotoxin analogues as low-liability analgesics with promising therapeutic potential.
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Affiliation(s)
- Christopher J. Armishaw
- Torrey Pines Institute for Molecular Studies, 11350 SW Village Pkwy, Port St. Lucie, Florida
34987, United States
| | - Jayati Banerjee
- Torrey Pines Institute for Molecular Studies, 11350 SW Village Pkwy, Port St. Lucie, Florida
34987, United States
| | - Michelle L. Ganno
- Torrey Pines Institute for Molecular Studies, 11350 SW Village Pkwy, Port St. Lucie, Florida
34987, United States
| | - Kate J. Reilley
- Torrey Pines Institute for Molecular Studies, 11350 SW Village Pkwy, Port St. Lucie, Florida
34987, United States
| | - Shainnel O. Eans
- Torrey Pines Institute for Molecular Studies, 11350 SW Village Pkwy, Port St. Lucie, Florida
34987, United States
| | - Elisa Mizrachi
- Torrey Pines Institute for Molecular Studies, 11350 SW Village Pkwy, Port St. Lucie, Florida
34987, United States
| | - Reena Gyanda
- Torrey Pines Institute for Molecular Studies, 11350 SW Village Pkwy, Port St. Lucie, Florida
34987, United States
| | - Michelle R. Hoot
- Torrey Pines Institute for Molecular Studies, 11350 SW Village Pkwy, Port St. Lucie, Florida
34987, United States
| | - Richard A. Houghten
- Torrey Pines Institute for Molecular Studies, 11350 SW Village Pkwy, Port St. Lucie, Florida
34987, United States
| | - Jay P. McLaughlin
- Torrey Pines Institute for Molecular Studies, 11350 SW Village Pkwy, Port St. Lucie, Florida
34987, United States
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23
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Banerjee J, Gyanda R, Chang YP, Armishaw CJ. The chemical synthesis of α-conotoxins and structurally modified analogs with enhanced biological stability. Methods Mol Biol 2013; 1081:13-34. [PMID: 24014431 DOI: 10.1007/978-1-62703-652-8_2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
α-Conotoxins are peptide neurotoxins isolated from the venom ducts of carnivorous marine cone snails that exhibit exquisite pharmacological potency and selectivity for various nicotinic acetylcholine receptor subtypes. As such, they are important research tools and drug leads for treating various diseases of the central nervous system, including pain and tobacco addiction. Despite their therapeutic potential, the chemical synthesis of α-conotoxins for use in structure-activity relationship studies is complicated by the possibility of three disulfide bond isomers, where inefficient folding methods can lead to a poor recovery of the pharmacologically active isomer. In order to achieve higher yields of the native isomer, especially in high-throughput syntheses it is necessary to select appropriate oxidative folding conditions. Moreover, the poor biochemical stability exhibited by α-conotoxins limits their general therapeutic applicability in vivo. Numerous strategies to enhance their stability including the substitution of disulfide bond with diselenide bond and N-to-C cyclization via an oligopeptide spacer have successfully overcome these limitations. This chapter describes methods for performing both selective and nonselective disulfide bond oxidation strategies for controlling the yields and formation of α-conotoxin disulfide bond isomers, as well as methods for the production of highly stable diselenide-containing and N-to-C cyclized conotoxin analogs.
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Affiliation(s)
- Jayati Banerjee
- Torrey Pines Institute for Molecular Studies, Port St. Lucie, FL, USA
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24
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Gyanda R, Banerjee J, Chang YP, Phillips AM, Toll L, Armishaw CJ. Oxidative folding and preparation of α-conotoxins for use in high-throughput structure-activity relationship studies. J Pept Sci 2012. [PMID: 23193084 DOI: 10.1002/psc.2467] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
α-Conotoxins are peptide neurotoxins that selectively inhibit various subtypes of nicotinic acetylcholine receptors. They are important research tools for studying numerous pharmacological disorders, with profound potential for developing drug leads for treating pain, tobacco addiction, and other conditions. They are characterized by the presence of two disulfide bonds connected in a globular arrangement, which stabilizes a bioactive helical conformation. Despite extensive structure-activity relationship studies that have produced α-conotoxin analogs with increased potency and selectivity towards specific nicotinic acetylcholine receptor subtypes, the efficient production of diversity-oriented α-conotoxin combinatorial libraries has been limited by inefficient folding and purification procedures. We have investigated the optimized conditions for the reliable folding of α-conotoxins using simplified oxidation procedures for use in the accelerated production of synthetic combinatorial libraries of α-conotoxins. To this end, the effect of co-solvent, redox reagents, pH, and temperature on the proportion of disulfide bond isomers was determined for α-conotoxins exhibiting commonly known Cys loop spacing frameworks. In addition, we have developed high-throughput 'semi-purification' methods for the quick and efficient parallel preparation of α-conotoxin libraries for use in accelerated structure-activity relationship studies. Our simplified procedures represent an effective strategy for the preparation of large arrays of correctly folded α-conotoxin analogs and permit the rapid identification of active hits directly from high-throughput pharmacological screening assays.
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Affiliation(s)
- Reena Gyanda
- Torrey Pines Institute for Molecular Studies, Port St Lucie, Florida 34987, USA
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25
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Medina-Franco JL. Interrogating Novel Areas of Chemical Space for Drug Discovery using Chemoinformatics. Drug Dev Res 2012. [DOI: 10.1002/ddr.21034] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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26
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Bingham JP, Andrews EA, Kiyabu SM, Cabalteja CC. Drugs from slugs. Part II--conopeptide bioengineering. Chem Biol Interact 2012; 200:92-113. [PMID: 23063744 DOI: 10.1016/j.cbi.2012.09.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2012] [Revised: 08/27/2012] [Accepted: 09/17/2012] [Indexed: 11/27/2022]
Abstract
The biological transformation of toxins as research probes, or as pharmaceutical drug leads, is an onerous and drawn out process. Issues regarding changes to pharmacological specificity, desired potency, and bioavailability are compounded naturally by their inherent toxicity. These often scuttle their progress as they move up the narrowing drug development pipeline. Yet one class of peptide toxins, from the genus Conus, has in many ways spearheaded the expansion of new peptide bioengineering techniques to aid peptide toxin pharmaceutical development. What has now emerged is the sequential bioengineering of new research probes and drug leads that owe their lineage to these highly potent and isoform specific peptides. Here we discuss the progressive bioengineering steps that many conopeptides have transitioned through, and specifically illustrate some of the biochemical approaches that have been established to maximize their biological research potential and pharmaceutical worth.
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Affiliation(s)
- Jon-Paul Bingham
- Department of Molecular Biosciences and Bioengineering, University of Hawaii, Honolulu, HI 96822, USA.
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27
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Yu R, Craik DJ, Kaas Q. Blockade of neuronal α7-nAChR by α-conotoxin ImI explained by computational scanning and energy calculations. PLoS Comput Biol 2011; 7:e1002011. [PMID: 21390272 PMCID: PMC3048385 DOI: 10.1371/journal.pcbi.1002011] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Accepted: 01/05/2011] [Indexed: 01/01/2023] Open
Abstract
α-Conotoxins potently inhibit isoforms of nicotinic acetylcholine receptors (nAChRs), which are essential for neuronal and neuromuscular transmission. They are also used as neurochemical tools to study nAChR physiology and are being evaluated as drug leads to treat various neuronal disorders. A number of experimental studies have been performed to investigate the structure-activity relationships of conotoxin/nAChR complexes. However, the structural determinants of their binding interactions are still ambiguous in the absence of experimental structures of conotoxin-receptor complexes. In this study, the binding modes of α-conotoxin ImI to the α7-nAChR, currently the best-studied system experimentally, were investigated using comparative modeling and molecular dynamics simulations. The structures of more than 30 single point mutants of either the conotoxin or the receptor were modeled and analyzed. The models were used to explain qualitatively the change of affinities measured experimentally, including some nAChR positions located outside the binding site. Mutational energies were calculated using different methods that combine a conformational refinement procedure (minimization with a distance dependent dielectric constant or explicit water, or molecular dynamics using five restraint strategies) and a binding energy function (MM-GB/SA or MM-PB/SA). The protocol using explicit water energy minimization and MM-GB/SA gave the best correlations with experimental binding affinities, with an R2 value of 0.74. The van der Waals and non-polar desolvation components were found to be the main driving force for binding of the conotoxin to the nAChR. The electrostatic component was responsible for the selectivity of the various ImI mutants. Overall, this study provides novel insights into the binding mechanism of α-conotoxins to nAChRs and the methodological developments reported here open avenues for computational scanning studies of a rapidly expanding range of wild-type and chemically modified α-conotoxins. Conotoxins are peptide toxins extracted from the venom of carnivorous marine cone snails. Members of the α-conotoxin subfamily potently block nicotinic acetylcholine receptors (nAChRs), which are involved in signal transmission between two neurons or between neurons and muscle fibers. nAChRs are important pharmacological targets due to their involvement in the transmission of pain stimuli and also in numerous neurone diseases and disorders. Their potency and specificity have led to the development of α-conotoxins as drug leads, and also to their use in the investigation of the role of nAChRs in various physiological processes. The most studied conotoxin/nAChR system, ImI/α7, was modeled in this study, and several computational methods were tested for their ability to explain the perturbations observed experimentally after introducing single point mutations into either ImI or the α7 receptor. The aim of this study was to establish a theoretical basis to rapidly identify new α-conotoxin mutants that might have improved specificity and affinity for a given receptor subtype. Furthermore, hundreds of thousands of conotoxins are predicted to exist, and computational methods are needed to help streamline the discovery of their molecular targets.
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Affiliation(s)
- Rilei Yu
- Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia
| | - David J. Craik
- Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia
| | - Quentin Kaas
- Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia
- * E-mail:
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28
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Armishaw CJ, Jensen AA, Balle LD, Scott KCM, Sørensen L, Strømgaard K. Improving the stability of α-conotoxin AuIB through N-to-C cyclization: the effect of linker length on stability and activity at nicotinic acetylcholine receptors. Antioxid Redox Signal 2011; 14:65-76. [PMID: 20649464 DOI: 10.1089/ars.2010.3458] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Modification of α-conotoxin frameworks through cyclization via an oligopeptide linker has previously been shown as an effective strategy for improving in vivo stability. We have extended this strategy by investigating cyclic analogs of α-conotoxin AuIB, a selective α(3)β(4) nicotinic acetylcholine receptor (nAChR) antagonist, to examine a range of oligopeptide linker lengths on the oxidative formation of disulfide bonds, activity at nAChRs, and stability to degradation by chymotrypsin. Upon nondirected random oxidation, the ribbon isomer formed preferentially with the globular isomer occurring as a minor by-product. Therefore, a regioselective disulfide bond forming strategy was used to prepare the cAuIB-2 globular isomer in high yield and purity. The cAuIB-2 globular isomer exhibited a threefold decrease in activity for the α(3)β(4) nAChR compared to wild-type-AuIB, although it was selective for α(3)β(4) over α(7) and α(4)β(2) subtypes. On the other hand, the cAuIB-2 ribbon isomer was shown to be inactive at all three nAChR subtypes. Nonetheless, all of the cyclic analogs were found to be significantly more stable to degradation by chymotrypsin than wild-type AuIB. As such, the cAuIB-2 globular isomer could constitute a useful probe for studying the role of the α(3)β(4) nAChR in a range of in vivo experimental paradigms.
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29
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Yongye AB, Pinilla C, Medina-Franco JL, Giulianotti MA, Dooley CT, Appel JR, Nefzi A, Scior T, Houghten RA, Martínez-Mayorga K. Integrating computational and mixture-based screening of combinatorial libraries. J Mol Model 2010; 17:1473-82. [DOI: 10.1007/s00894-010-0850-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2010] [Accepted: 09/06/2010] [Indexed: 11/29/2022]
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30
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Mejia M, Heghinian MD, Busch A, Armishaw CJ, Marí F, Godenschwege TA. A novel approach for in vivo screening of toxins using the Drosophila Giant Fiber circuit. Toxicon 2010; 56:1398-407. [PMID: 20723555 DOI: 10.1016/j.toxicon.2010.08.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2010] [Revised: 08/09/2010] [Accepted: 08/11/2010] [Indexed: 11/19/2022]
Abstract
Finding compounds that affect neuronal or muscular function is of great interest as potential therapeutic agents for a variety of neurological disorders. Alternative applications for these compounds include their use as molecular probes as well as insecticides. We have developed a bioassay that requires small amounts of compounds and allows for unbiased screening of biological activity in vivo. For this, we paired administering compounds in a non-invasive manner with simultaneous electrophysiological recordings from a well-characterized neuronal circuit, the Giant Fiber System of Drosophila melanogaster, which mediates the escape response of the fly. The circuit encompasses a variety of neurons with cholinergic, glutamatergic, and electrical synapses as well as neuromuscular junctions. Electrophysiological recordings from this system allow for the detection of compound-related effects against any molecular target on these components. Here, we provide evidence that this novel bioassay works with small molecules such as the cholinergic receptor blocker mecamylamine hydrochloride and the potassium channel blocker tetraethylammonium hydroxide, as well as with venom from Conus brunneus and isolated conopeptides. Conopeptides have been developed into powerful drugs, such as the painkillers Prialt™ and Xen2174. However, most conopeptides have yet to be characterized, revealing the need for a rapid and straightforward screening method. Our findings show that mecamylamine hydrochloride, as well as the α-conotoxin ImI, which is known to be an antagonist of the human α7 nicotinic acetylcholine receptor, efficiently disrupted the synaptic transmission of a Drosophila α7 nicotinic acetylcholine receptor-dependent pathway in our circuit but did not affect the function of neurons with other types of synapses. This demonstrates that our bioassay is a valid tool for screening for compounds relevant to human health.
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Affiliation(s)
- Monica Mejia
- Department of Biological Sciences, Florida Atlantic University, 777 Glades Road, Boca Raton, FL 33431, USA
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31
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Diselenium, instead of disulfide, bonded analogs of conotoxins: novel synthesis and pharmacotherapeutic potential. Life Sci 2010; 87:451-6. [PMID: 20691706 DOI: 10.1016/j.lfs.2010.07.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2010] [Revised: 07/10/2010] [Accepted: 07/20/2010] [Indexed: 01/12/2023]
Abstract
The venoms of the cone snail (Conus) contain toxic peptides (conotoxins) that have remarkable selectivity for subtypes of a variety of mammalian voltage- and ligand-gated ion channels, G protein-coupled receptors, and neurotransmitter transporters. They thus have tremendous potential as pharmacologic tools. Less toxic analogs or mimetics could be highly-selective pharmacotherapeutic agents at their target sites. For this reason, conopeptides have been extensively studied and have progressed to clinical trials and even regulatory approval. However, the synthesis of the peptides remains difficult and stability and toxicity remain problems. A novel synthesis and testing of analogs incorporating diselenium bonds between selenocysteine residues in place of disulfide bonds between cysteine residues has recently been reported. The technique results in analogs that retain the folding of the native peptides, are more potent, and have the same or greater biological activity.
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32
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Armishaw CJ. Synthetic α-conotoxin mutants as probes for studying nicotinic acetylcholine receptors and in the development of novel drug leads. Toxins (Basel) 2010; 2:1471-99. [PMID: 22069647 PMCID: PMC3153239 DOI: 10.3390/toxins2061471] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2010] [Revised: 05/27/2010] [Accepted: 06/11/2010] [Indexed: 11/19/2022] Open
Abstract
α-Conotoxins are peptide neurotoxins isolated from venomous marine cone snails that are potent and selective antagonists for different subtypes of nicotinic acetylcholine receptors (nAChRs). As such, they are valuable probes for dissecting the role that nAChRs play in nervous system function. In recent years, extensive insight into the binding mechanisms of α-conotoxins with nAChRs at the molecular level has aided in the design of synthetic analogs with improved pharmacological properties. This review examines the structure-activity relationship studies involving α-conotoxins as research tools for studying nAChRs in the central and peripheral nervous systems and their use towards the development of novel therapeutics.
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Affiliation(s)
- Christopher J Armishaw
- Torrey Pines Institute for Molecular Studies, 11350 SW Village Pkwy, Port St Lucie, FL 34987, USA.
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