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Marine Origin Ligands of Nicotinic Receptors: Low Molecular Compounds, Peptides and Proteins for Fundamental Research and Practical Applications. Biomolecules 2022; 12:biom12020189. [PMID: 35204690 PMCID: PMC8961598 DOI: 10.3390/biom12020189] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 01/18/2022] [Accepted: 01/19/2022] [Indexed: 02/05/2023] Open
Abstract
The purpose of our review is to briefly show what different compounds of marine origin, from low molecular weight ones to peptides and proteins, offer for understanding the structure and mechanism of action of nicotinic acetylcholine receptors (nAChRs) and for finding novel drugs to combat the diseases where nAChRs may be involved. The importance of the mentioned classes of ligands has changed with time; a protein from the marine snake venom was the first excellent tool to characterize the muscle-type nAChRs from the electric ray, while at present, muscle and α7 receptors are labeled with the radioactive or fluorescent derivatives prepared from α-bungarotoxin isolated from the many-banded krait. The most sophisticated instruments to distinguish muscle from neuronal nAChRs, and especially distinct subtypes within the latter, are α-conotoxins. Such information is crucial for fundamental studies on the nAChR revealing the properties of their orthosteric and allosteric binding sites and mechanisms of the channel opening and closure. Similar data are provided by low-molecular weight compounds of marine origin, but here the main purpose is drug design. In our review we tried to show what has been obtained in the last decade when the listed classes of compounds were used in the nAChR research, applying computer modeling, synthetic analogues and receptor mutants, X-ray and electron-microscopy analyses of complexes with the nAChRs, and their models which are acetylcholine-binding proteins and heterologously-expressed ligand-binding domains.
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2
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Guo M, Yu J, Zhu X, Zhangsun D, Luo S. Characterization of an α 4/7-Conotoxin LvIF from Conus lividus That Selectively Blocks α3β2 Nicotinic Acetylcholine Receptor. Mar Drugs 2021; 19:md19070398. [PMID: 34356823 PMCID: PMC8306566 DOI: 10.3390/md19070398] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 07/12/2021] [Accepted: 07/14/2021] [Indexed: 11/16/2022] Open
Abstract
Nicotinic acetylcholine receptor (nAChR), a member of pentameric ligand-gated ion channel transmembrane protein composed of five subunits, is widely distributed in the central and peripheral nervous system. The nAChRs are associated with various neurological diseases, including schizophrenia, Alzheimer’s disease, Parkinson’s disease, epilepsy and neuralgia. Receptors containing the α3 subunit are associated with analgesia, generating our interest in their role in pharmacological studies. In this study, α-conotoxin (α-CTx) LvIF was identified as a 16 amino acid peptide using a genomic DNA clone of Conus lividus (C. lividus). The mature LvIF with natural structure was synthesized by a two-step oxidation method. The blocking potency of α-CTx lvIF on nAChR was detected by a two-electrode voltage clamp. Our results showed that α-CTx LvIF was highly potent against rα3β2 and rα6/α3β2β3 nAChR subtypes, The half-maximal inhibitory concentration (IC50) values of α-CTx LvIF against rα3β2 and rα6/α3β2β3 nAChRs expressed in Xenopus oocytes were 8.9 nM and 14.4 nM, respectively. Furthermore, α-CTx LvIF exhibited no obvious inhibition on other nAChR subtypes. Meanwhile, we also conducted a competitive binding experiment between α-CTxs MII and LvIF, which showed that α-CTxs LvIF and MII bind with rα3β2 nAChR at the partial overlapping domain. These results indicate that the α-CTx LvIF has high potential as a new candidate tool for the studying of rα3β2 nAChR related neurophysiology and pharmacology.
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Affiliation(s)
- Man Guo
- Key Laboratory of Tropical Biological Resources of Ministry of Education, Key Laboratory for Marine Drugs of Haikou, School of Life and Pharmaceutical Sciences, Hainan University, Haikou 570228, China;
| | - Jinpeng Yu
- Medical School, Guangxi University, Nanning 530004, China; (J.Y.); (X.Z.)
| | - Xiaopeng Zhu
- Medical School, Guangxi University, Nanning 530004, China; (J.Y.); (X.Z.)
| | - Dongting Zhangsun
- Key Laboratory of Tropical Biological Resources of Ministry of Education, Key Laboratory for Marine Drugs of Haikou, School of Life and Pharmaceutical Sciences, Hainan University, Haikou 570228, China;
- Medical School, Guangxi University, Nanning 530004, China; (J.Y.); (X.Z.)
- Correspondence: (D.Z.); (S.L.)
| | - Sulan Luo
- Key Laboratory of Tropical Biological Resources of Ministry of Education, Key Laboratory for Marine Drugs of Haikou, School of Life and Pharmaceutical Sciences, Hainan University, Haikou 570228, China;
- Medical School, Guangxi University, Nanning 530004, China; (J.Y.); (X.Z.)
- Correspondence: (D.Z.); (S.L.)
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3
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Bukharaeva EA, Skorinkin AI. Cholinergic Modulation of Acetylcholine
Secretion at the Neuromuscular Junction. J EVOL BIOCHEM PHYS+ 2021. [DOI: 10.1134/s0022093021020174] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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4
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Zhu X, Pan S, Xu M, Zhang L, Yu J, Yu J, Wu Y, Fan Y, Li H, Kasheverov IE, Kudryavtsev DS, Tsetlin VI, Xue Y, Zhangsun D, Wang X, Luo S. High Selectivity of an α-Conotoxin LvIA Analogue for α3β2 Nicotinic Acetylcholine Receptors Is Mediated by β2 Functionally Important Residues. J Med Chem 2020; 63:13656-13668. [PMID: 33196189 DOI: 10.1021/acs.jmedchem.0c00975] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The α3β2 and α3β4 nicotinic acetylcholine receptors (nAChRs) are widely expressed in the central and peripheral nervous systems, playing critical roles in various physiological processes and in such pathologies as addiction to nicotine and other drugs of abuse. α-Conotoxin LvIA, which we previously isolated from Conus lividus, modestly discriminates α3β2 and α3β4 rat nAChRs exhibiting a ∼17-fold tighter binding to the former. Here, alanine scanning resulted in two more selective analogues [N9A]LvIA and [D11A]LvIA, the former having a >2000-fold higher selectivity for α3β2. The determined crystal structures of [N9A]LvIA and [D11A]LvIA bound to the acetylcholine-binding protein (AChBP) were followed by homologous modeling of the complexes with the α3β2 and α3β4 nAChRs and by receptor mutagenesis, which revealed Phe106, Ser108, Ser113, and Ser168 residues in the β2 subunit as essential for LvIA binding. These results may be useful for the design of novel compounds of therapeutic potential targeting α3β2 nAChRs.
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Affiliation(s)
- Xiaopeng Zhu
- Medical School, Guangxi University, Nanning 530004, China.,Key Laboratory of Tropical Biological Resources of Ministry of Education, Key Laboratory for Marine Drugs of Haikou, School of Life and Pharmaceutical Sciences, Hainan University, Haikou 570228, China
| | - Si Pan
- The Ministry of Education Key Laboratory of Protein Science, School of Life Sciences, Beijing Advanced Innovation Center for Structural Biology, Collaborative Innovation Center for Biotherapy, Tsinghua University, Beijing 100084, China
| | - Manyu Xu
- The Ministry of Education Key Laboratory of Protein Science, School of Life Sciences, Beijing Advanced Innovation Center for Structural Biology, Collaborative Innovation Center for Biotherapy, Tsinghua University, Beijing 100084, China
| | - Lu Zhang
- Key Laboratory of Tropical Biological Resources of Ministry of Education, Key Laboratory for Marine Drugs of Haikou, School of Life and Pharmaceutical Sciences, Hainan University, Haikou 570228, China
| | - Jinfang Yu
- The Ministry of Education Key Laboratory of Protein Science, School of Life Sciences, Beijing Advanced Innovation Center for Structural Biology, Collaborative Innovation Center for Biotherapy, Tsinghua University, Beijing 100084, China
| | - Jinpeng Yu
- Medical School, Guangxi University, Nanning 530004, China
| | - Yong Wu
- Medical School, Guangxi University, Nanning 530004, China
| | - Yingxu Fan
- Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Haonan Li
- Key Laboratory of Tropical Biological Resources of Ministry of Education, Key Laboratory for Marine Drugs of Haikou, School of Life and Pharmaceutical Sciences, Hainan University, Haikou 570228, China
| | - Igor E Kasheverov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Street 16/10, Moscow 117997, Russia.,Sechenov First Moscow State Medical University, Institute of Molecular Medicine, Trubetskaya Street 8, bld. 2, Moscow 119991, Russia
| | - Denis S Kudryavtsev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Street 16/10, Moscow 117997, Russia
| | - Victor I Tsetlin
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Street 16/10, Moscow 117997, Russia.,PhysBio of MePhi, Kashirskoe Ave. 31, Moscow 115409, Russia
| | - Yi Xue
- Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Dongting Zhangsun
- Medical School, Guangxi University, Nanning 530004, China.,Key Laboratory of Tropical Biological Resources of Ministry of Education, Key Laboratory for Marine Drugs of Haikou, School of Life and Pharmaceutical Sciences, Hainan University, Haikou 570228, China
| | - Xinquan Wang
- The Ministry of Education Key Laboratory of Protein Science, School of Life Sciences, Beijing Advanced Innovation Center for Structural Biology, Collaborative Innovation Center for Biotherapy, Tsinghua University, Beijing 100084, China
| | - Sulan Luo
- Medical School, Guangxi University, Nanning 530004, China.,Key Laboratory of Tropical Biological Resources of Ministry of Education, Key Laboratory for Marine Drugs of Haikou, School of Life and Pharmaceutical Sciences, Hainan University, Haikou 570228, China
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5
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Interactions of the α3β2 Nicotinic Acetylcholine Receptor Interfaces with α-Conotoxin LsIA and its Carboxylated C-terminus Analogue: Molecular Dynamics Simulations. Mar Drugs 2020; 18:md18070349. [PMID: 32635340 PMCID: PMC7401271 DOI: 10.3390/md18070349] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Revised: 06/27/2020] [Accepted: 06/30/2020] [Indexed: 12/22/2022] Open
Abstract
Notably, α-conotoxins with carboxy-terminal (C-terminal) amidation are inhibitors of the pentameric nicotinic acetylcholine receptors (nAChRs), which are therapeutic targets for neurological diseases and disorders. The (α3)2(β2)3 nAChR subunit arrangement comprises a pair of α3(+)β2(−) and β2(+)α3(−) interfaces, and a β2(+)β2(−) interface. The β2(+)β2(−) interface has been suggested to have higher agonist affinity relative to the α3(+)β2(−) and β2(+)α3(−) interfaces. Nevertheless, the interactions formed by these subunit interfaces with α-conotoxins are not well understood. Therefore, in order to address this, we modelled the interactions between α-conotoxin LsIA and the α3β2 subtype. The results suggest that the C-terminal carboxylation of LsIA predominantly influenced the enhanced contacts of the conotoxin via residues P7, P14 and C17 on LsIA at the α3(+)β2(−) and β2(+)α3(−) interfaces. However, this enhancement is subtle at the β2(+)β2(−) site, which can compensate the augmented interactions by LsIA at α3(+)β2(−) and β2(+)α3(−) binding sites. Therefore, the divergent interactions at the individual binding interface may account for the minor changes in binding affinity to α3β2 subtype by C-terminal carboxylation of LsIA versus its wild type, as shown in previous experimental results. Overall, these findings may facilitate the development of new drug leads or subtype-selective probes.
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6
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Abstract
In order to improve stability of a peptide marine drug lead, α-conotoxin TxID, we synthesized and modified TxID at the N-terminal with DSPE-PEG-NHS by a nucleophilic substitution reaction to prepare the DSPE-PEG-TxID for the first time. The reaction conditions, including solvent, ratio, pH, and reaction time, were optimized systematically and the optimal one was reacted in dimethyl formamide at pH 8.2 with triethylamine at room temperature for 120 h. The in vitro stabilities in serum, simulated gastric juice, and intestinal fluid were tested, and improved dramatically compared with TxID. The PEG-modified peptide was functionally tested on α3β4 nicotinic acetylcholine receptor (nAChR) heterologously expressed in Xenopus laevis oocytes. The DSPE-PEG-TxID showed an obvious inhibition effect on α3β4 nAChR. All in all, the PEG modification of TxID was improved in stability, resistance to enzymatic degradation, and may prolong the half-life in vivo, which may pave the way for the future application in smoking cessation and drug rehabilitation, as well as small cell lung cancer.
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7
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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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8
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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] [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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9
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Hone AJ, Talley TT, Bobango J, Huidobro Melo C, Hararah F, Gajewiak J, Christensen S, Harvey PJ, Craik DJ, McIntosh JM. Molecular determinants of α-conotoxin potency for inhibition of human and rat α6β4 nicotinic acetylcholine receptors. J Biol Chem 2018; 293:17838-17852. [PMID: 30249616 DOI: 10.1074/jbc.ra118.005649] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 09/20/2018] [Indexed: 12/15/2022] Open
Abstract
Nicotinic acetylcholine receptors (nAChRs) containing α6 and β4 subunits are expressed by dorsal root ganglion neurons and have been implicated in neuropathic pain. Rodent models are often used to evaluate the efficacy of analgesic compounds, but species differences may affect the activity of some nAChR ligands. A previous candidate α-conotoxin-based therapeutic yielded promising results in rodent models, but failed in human clinical trials, emphasizing the importance of understanding species differences in ligand activity. Here, we show that human and rat α6/α3β4 nAChRs expressed in Xenopus laevis oocytes exhibit differential sensitivity to α-conotoxins. Sequence homology comparisons of human and rat α6β4 nAChR subunits indicated that α6 residues forming the ligand-binding pocket are highly conserved between the two species, but several residues of β4 differed, including a Leu-Gln difference at position 119. X-ray crystallography of α-conotoxin PeIA complexed with the Aplysia californica acetylcholine-binding protein (AChBP) revealed that binding of PeIA orients Pro13 in close proximity to residue 119 of the AChBP complementary subunit. Site-directed mutagenesis studies revealed that Leu119 of human β4 contributes to higher sensitivity of human α6/α3β4 nAChRs to α-conotoxins, and structure-activity studies indicated that PeIA Pro13 is critical for high potency. Human and rat α6/α3β4 nAChRs displayed differential sensitivities to perturbations of the interaction between PeIA Pro13 and residue 119 of the β4 subunit. These results highlight the potential significance of species differences in α6β4 nAChR pharmacology that should be taken into consideration when evaluating the activity of candidate human therapeutics in rodent models.
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Affiliation(s)
| | | | - Janet Bobango
- Department of Biomedical and Pharmaceutical Sciences, University of Montana, Missoula, Montana 59812
| | | | | | | | | | - Peta J Harvey
- Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland 4072, Australia
| | - David J Craik
- Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland 4072, Australia
| | - J Michael McIntosh
- From the Departments of Biology; Psychiatry, University of Utah, Salt Lake City, Utah 84112; George E. Whalen Veterans Affairs Medical Center, Salt Lake City, Utah 84148.
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10
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Abraham N, Lewis RJ. Neuronal Nicotinic Acetylcholine Receptor Modulators from Cone Snails. Mar Drugs 2018; 16:E208. [PMID: 29899286 PMCID: PMC6024932 DOI: 10.3390/md16060208] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Revised: 05/25/2018] [Accepted: 06/06/2018] [Indexed: 12/15/2022] Open
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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11
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Xu M, Zhu X, Yu J, Yu J, Luo S, Wang X. The crystal structure of Ac-AChBP in complex with α-conotoxin LvIA reveals the mechanism of its selectivity towards different nAChR subtypes. Protein Cell 2017; 8:675-685. [PMID: 28585176 PMCID: PMC5563285 DOI: 10.1007/s13238-017-0426-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Accepted: 04/27/2017] [Indexed: 12/15/2022] Open
Abstract
The α3* nAChRs, which are considered to be promising drug targets for problems such as pain, addiction, cardiovascular function, cognitive disorders etc., are found throughout the central and peripheral nervous system. The α-conotoxin (α-CTx) LvIA has been identified as the most selective inhibitor of α3β2 nAChRs known to date, and it can distinguish the α3β2 nAChR subtype from the α6/α3β2β3 and α3β4 nAChR subtypes. However, the mechanism of its selectivity towards α3β2, α6/α3β2β3, and α3β4 nAChRs remains elusive. Here we report the co-crystal structure of LvIA in complex with Aplysia californica acetylcholine binding protein (Ac-AChBP) at a resolution of 3.4 Å. Based on the structure of this complex, together with homology modeling based on other nAChR subtypes and binding affinity assays, we conclude that Asp-11 of LvIA plays an important role in the selectivity of LvIA towards α3β2 and α3/α6β2β3 nAChRs by making a salt bridge with Lys-155 of the rat α3 subunit. Asn-9 lies within a hydrophobic pocket that is formed by Met-36, Thr-59, and Phe-119 of the rat β2 subunit in the α3β2 nAChR model, revealing the reason for its more potent selectivity towards the α3β2 nAChR subtype. These results provide molecular insights that can be used to design ligands that selectively target α3β2 nAChRs, with significant implications for the design of new therapeutic α-CTxs.
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Affiliation(s)
- Manyu Xu
- The Ministry of Education Key Laboratory of Protein Science, School of Life Sciences, Beijing Advanced Innovation Center for Structural Biology, Collaborative Innovation Center for Biotherapy, Tsinghua University, Beijing, 100084, China
| | - Xiaopeng Zhu
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Lab for Marine Drugs of Haikou, Hainan University, Haikou, 570228, China
| | - Jinfang Yu
- The Ministry of Education Key Laboratory of Protein Science, School of Life Sciences, Beijing Advanced Innovation Center for Structural Biology, Collaborative Innovation Center for Biotherapy, Tsinghua University, Beijing, 100084, China
| | - Jinpeng Yu
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Lab for Marine Drugs of Haikou, Hainan University, Haikou, 570228, China
| | - Sulan Luo
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Lab for Marine Drugs of Haikou, Hainan University, Haikou, 570228, China.
| | - Xinquan Wang
- The Ministry of Education Key Laboratory of Protein Science, School of Life Sciences, Beijing Advanced Innovation Center for Structural Biology, Collaborative Innovation Center for Biotherapy, Tsinghua University, Beijing, 100084, China.
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12
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Residues Responsible for the Selectivity of α-Conotoxins for Ac-AChBP or nAChRs. Mar Drugs 2016; 14:md14100173. [PMID: 27727162 PMCID: PMC5082321 DOI: 10.3390/md14100173] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Revised: 09/20/2016] [Accepted: 09/21/2016] [Indexed: 12/22/2022] Open
Abstract
Nicotinic acetylcholine receptors (nAChRs) are targets for developing new drugs to treat severe pain, nicotine addiction, Alzheimer disease, epilepsy, etc. α-Conotoxins are biologically and chemically diverse. With 12–19 residues and two disulfides, they can be specifically selected for different nAChRs. Acetylcholine-binding proteins from Aplysia californica (Ac-AChBP) are homologous to the ligand-binding domains of nAChRs and pharmacologically similar. X-ray structures of the α-conotoxin in complex with Ac-AChBP in addition to computer modeling have helped to determine the binding site of the important residues of α-conotoxin and its affinity for nAChR subtypes. Here, we present the various α-conotoxin residues that are selective for Ac-AChBP or nAChRs by comparing the structures of α-conotoxins in complex with Ac-AChBP and by modeling α-conotoxins in complex with nAChRs. The knowledge of these binding sites will assist in the discovery and design of more potent and selective α-conotoxins as drug leads.
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13
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Cuny H, Kompella SN, Tae HS, Yu R, Adams DJ. Key Structural Determinants in the Agonist Binding Loops of Human β2 and β4 Nicotinic Acetylcholine Receptor Subunits Contribute to α3β4 Subtype Selectivity of α-Conotoxins. J Biol Chem 2016; 291:23779-23792. [PMID: 27646000 DOI: 10.1074/jbc.m116.730804] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2016] [Indexed: 12/16/2022] Open
Abstract
α-Conotoxins represent a large group of pharmacologically active peptides that antagonize nicotinic acetylcholine receptors (nAChRs). The α3β4 nAChR, a predominant subtype in the peripheral nervous system, has been implicated in various pathophysiological conditions. As many α-conotoxins have multiple pharmacological targets, compounds specifically targeting individual nAChR subtypes are needed. In this study, we performed mutational analyses to evaluate the key structural components of human β2 and β4 nAChR subunits that determine α-conotoxin selectivity for α3β4 nAChR. α-Conotoxin RegIIA was used to evaluate the impact of non-conserved human β2 and β4 residues on peptide affinity. Two mutations, α3β2[T59K] and α3β2[S113R], strongly enhanced RegIIA affinity compared with wild-type α3β2, as seen by substantially increased inhibitory potency and slower off-rate kinetics. Opposite point mutations in α3β4 had the contrary effect, emphasizing the importance of loop D residue 59 and loop E residue 113 as determinants for RegIIA affinity. Molecular dynamics simulation revealed the side chains of β4 Lys59 and β4 Arg113 formed hydrogen bonds with RegIIA loop 2 atoms, whereas the β2 Thr59 and β2 Ser113 side chains were not long enough to form such interactions. Residue β4 Arg113 has been identified for the first time as a crucial component facilitating antagonist binding. Another α-conotoxin, AuIB, exhibited low activity at human α3β2 and α3β4 nAChRs. Molecular dynamics simulation indicated the key interactions with the β subunit are different to RegIIA. Taken together, these data elucidate the interactions with specific individual β subunit residues that critically determine affinity and pharmacological activity of α-conotoxins RegIIA and AuIB at human nAChRs.
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Affiliation(s)
- Hartmut Cuny
- From the Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, New South Wales 2522, Australia.,the Health Innovations Research Institute, RMIT University, Melbourne, Victoria 3083, Australia, and
| | - Shiva N Kompella
- the Health Innovations Research Institute, RMIT University, Melbourne, Victoria 3083, Australia, and
| | - Han-Shen Tae
- From the Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Rilei Yu
- the Key Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, Qingdao 266003, China
| | - David J Adams
- From the Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, New South Wales 2522, Australia, .,the Health Innovations Research Institute, RMIT University, Melbourne, Victoria 3083, Australia, and
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14
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Zhu X, Bi J, Yu J, Li X, Zhang Y, Zhangsun D, Luo S. Recombinant Expression and Characterization of α-Conotoxin LvIA in Escherichia coli. Mar Drugs 2016; 14:11. [PMID: 26742048 PMCID: PMC4728508 DOI: 10.3390/md14010011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Revised: 12/11/2015] [Accepted: 12/28/2015] [Indexed: 01/17/2023] Open
Abstract
α-Conotoxin LvIA is derived from Conus lividus, native to Hainan, and is the most selective inhibitor of α3β2 nicotinic acetylcholine receptors (nAChRs) known to date. In this study, an efficient approach for the production of recombinant α-Conotoxin LvIA is described. Tandem repeats of a LvIA gene fragment were constructed and fused with a KSI gene and a His6 tag in a Escherichia coli (E. coli) expression vector pET-31b(+). The recombinant plasmids were transformed into E. coli and were found to express well. The KSI-(LvIA)n-His6 fusion protein was purified by metal affinity chromatography and then cleaved with CNBr to release recombinant LvIA (rLvIA). High yields of fusion protein ranging from 100 to 500 mg/L culture were obtained. The pharmacological profile of rLvIA was determined by two-electrode voltage-clamp electrophysiology in Xenopus laevis oocytes expressing rat nAChR subtypes. The rLvIA antagonized the α3β2 nAChR subtype selectively with a nano-molar IC50. The rLvIA was analgesic in a mouse hot-plate test model of pain. Overall, this study provides an effective method to synthesize α-conotoxin LvIA in an E. coli recombinant expression system, and this approach could be useful to obtain active conopeptides in large quantity and at low cost.
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Affiliation(s)
- Xiaopeng Zhu
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Laboratory for Marine Drugs of Haikou, Hainan University, Haikou 570228, China.
- College of Horticulture and Landscapes, Hainan University, Haikou 570228, China.
- College of Marine Science, Hainan University, Haikou 570228, China.
| | - Jianpeng Bi
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Laboratory for Marine Drugs of Haikou, Hainan University, Haikou 570228, China.
| | - Jinpeng Yu
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Laboratory for Marine Drugs of Haikou, Hainan University, Haikou 570228, China.
| | - Xiaodan Li
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Laboratory for Marine Drugs of Haikou, Hainan University, Haikou 570228, China.
| | - Yaning Zhang
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Laboratory for Marine Drugs of Haikou, Hainan University, Haikou 570228, China.
| | - Dongting Zhangsun
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Laboratory for Marine Drugs of Haikou, Hainan University, Haikou 570228, China.
- College of Marine Science, Hainan University, Haikou 570228, China.
| | - Sulan Luo
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Laboratory for Marine Drugs of Haikou, Hainan University, Haikou 570228, China.
- College of Marine Science, Hainan University, Haikou 570228, China.
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15
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Kompella SN, Cuny H, Hung A, Adams DJ. Molecular Basis for Differential Sensitivity of α-Conotoxin RegIIA at Rat and Human Neuronal Nicotinic Acetylcholine Receptors. Mol Pharmacol 2015; 88:993-1001. [DOI: 10.1124/mol.115.100503] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 10/01/2015] [Indexed: 11/22/2022] Open
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