1
|
Hone AJ, Santiago U, Harvey PJ, Tekarli B, Gajewiak J, Craik DJ, Camacho CJ, McIntosh JM. Design, Synthesis, and Structure-Activity Relationships of Novel Peptide Derivatives of the Severe Acute Respiratory Syndrome-Coronavirus-2 Spike-Protein that Potently Inhibit Nicotinic Acetylcholine Receptors. J Med Chem 2024; 67:9587-9598. [PMID: 38814877 DOI: 10.1021/acs.jmedchem.4c00735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2024]
Abstract
The spike-protein of SARS-CoV-2 has a distinctive amino-acid sequence (682RRARS686) that forms a cleavage site for the enzyme furin. Strikingly, the structure of the spike-protein loop containing the furin cleavage site bears substantial similarity to neurotoxin peptides found in the venoms of certain snakes and marine cone snails. Leveraging this relationship, we designed and synthesized disulfide-constrained peptides with amino-acid sequences corresponding to the furin cleavage-sites of wild-type (B.1 variant) SARS-CoV-2 or the Alpha, Delta, and Omicron variants. Remarkably, some of these peptides potently inhibited α7 and α9α10 nicotinic acetylcholine receptors (nAChR) with nM affinity and showed SARS-CoV-2 variant and nAChR subtype-dependent potencies. Nuclear magnetic resonance spectroscopy and molecular dynamics were used to rationalize structure-activity relationships between peptides and their cognate receptors. These findings delineate nAChR subtypes that can serve as high-affinity spike-protein targets in tissues central to COVID-19 pathophysiology and identify ligands and target receptors to inform the development of novel SARS-CoV-2 therapeutics.
Collapse
Affiliation(s)
- Arik J Hone
- School of Biological Sciences, University of Utah, Salt Lake City, Utah 84112, United States
- MIRECC, George E. Whalen Veterans Affairs Medical Center, Salt Lake City, Utah 84148, United States
| | - Ulises Santiago
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, United States
| | - Peta J Harvey
- Institute for Molecular Bioscience, ARC Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Bassel Tekarli
- School of Biological Sciences, University of Utah, Salt Lake City, Utah 84112, United States
| | - Joanna Gajewiak
- School of Biological Sciences, University of Utah, Salt Lake City, Utah 84112, United States
| | - David J Craik
- Institute for Molecular Bioscience, ARC Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Carlos J Camacho
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, United States
| | - J Michael McIntosh
- School of Biological Sciences, University of Utah, Salt Lake City, Utah 84112, United States
- Department of Psychiatry, University of Utah, Salt Lake City, Utah 84112, United States
- George E. Whalen Veterans Affairs Medical Center, Salt Lake City, Utah 84148, United States
| |
Collapse
|
2
|
O’Brien BCV, Thao S, Weber L, Danielson HL, Boldt AD, Hueffer K, Weltzin MM. The human alpha7 nicotinic acetylcholine receptor is a host target for the rabies virus glycoprotein. Front Cell Infect Microbiol 2024; 14:1394713. [PMID: 38836054 PMCID: PMC11148329 DOI: 10.3389/fcimb.2024.1394713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2024] [Accepted: 04/29/2024] [Indexed: 06/06/2024] Open
Abstract
The rabies virus enters the nervous system by interacting with several molecular targets on host cells to modify behavior and trigger receptor-mediated endocytosis of the virion by poorly understood mechanisms. The rabies virus glycoprotein (RVG) interacts with the muscle acetylcholine receptor and the neuronal α4β2 subtype of the nicotinic acetylcholine receptor (nAChR) family by the putative neurotoxin-like motif. Given that the neurotoxin-like motif is highly homologous to the α7 nAChR subtype selective snake toxin α-bungarotoxin (αBTX), other nAChR subtypes are likely involved. The purpose of this study is to determine the activity of the RVG neurotoxin-like motif on nAChR subtypes that are expressed in brain regions involved in rabid animal behavior. nAChRs were expressed in Xenopus laevis oocytes, and two-electrode voltage clamp electrophysiology was used to collect concentration-response data to measure the functional effects. The RVG peptide preferentially and completely inhibits α7 nAChR ACh-induced currents by a competitive antagonist mechanism. Tested heteromeric nAChRs are also inhibited, but to a lesser extent than the α7 subtype. Residues of the RVG peptide with high sequence homology to αBTX and other neurotoxins were substituted with alanine. Altered RVG neurotoxin-like peptides showed that residues phenylalanine 192, arginine 196, and arginine 199 are important determinants of RVG peptide apparent potency on α7 nAChRs, while serine 195 is not. The evaluation of the rabies ectodomain reaffirmed the observations made with the RVG peptide, illustrating a significant inhibitory impact on α7 nAChR with potency in the nanomolar range. In a mammalian cell culture model of neurons, we confirm that the RVG peptide binds preferentially to cells expressing the α7 nAChR. Defining the activity of the RVG peptide on nAChRs expands our understanding of basic mechanisms in host-pathogen interactions that result in neurological disorders.
Collapse
Affiliation(s)
- Brittany C. V. O’Brien
- Department of Chemistry and Biochemistry, University of Alaska Fairbanks, Fairbanks, AK, United States
| | - Shelly Thao
- Department of Chemistry and Biochemistry, University of Alaska Fairbanks, Fairbanks, AK, United States
| | - Lahra Weber
- Department of Chemistry and Biochemistry, University of Alaska Fairbanks, Fairbanks, AK, United States
| | - Helen L. Danielson
- Department of Chemistry and Biochemistry, University of Alaska Fairbanks, Fairbanks, AK, United States
| | - Agatha D. Boldt
- Department of Chemistry and Biochemistry, University of Alaska Fairbanks, Fairbanks, AK, United States
| | - Karsten Hueffer
- Department of Veterinary Medicine, University of Alaska Fairbanks, Fairbanks, AK, United States
| | - Maegan M. Weltzin
- Department of Chemistry and Biochemistry, University of Alaska Fairbanks, Fairbanks, AK, United States
| |
Collapse
|
3
|
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.
Collapse
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
| |
Collapse
|
4
|
George AA, John SJ, Lucero LM, Eaton JB, Jaiswal E, Christensen SB, Gajewiak J, Watkins M, Cao Y, Olivera BM, Im W, McIntosh JM, Whiteaker P. Analogs of α-conotoxin PnIC selectively inhibit α7β2- over α7-only subtype nicotinic acetylcholine receptors via a novel allosteric mechanism. FASEB J 2024; 38:e23374. [PMID: 38161283 PMCID: PMC10782225 DOI: 10.1096/fj.202302079] [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: 10/12/2023] [Accepted: 12/01/2023] [Indexed: 01/03/2024]
Abstract
This study was undertaken to identify and characterize the first ligands capable of selectively identifying nicotinic acetylcholine receptors containing α7 and β2 subunits (α7β2-nAChR subtype). Basal forebrain cholinergic neurons express α7β2-nAChR. Here, they appear to mediate neuronal dysfunction induced by the elevated levels of oligomeric amyloid-β associated with early Alzheimer's disease. Additional work indicates that α7β2-nAChR are expressed across several further critically important cholinergic and GABAergic neuronal circuits within the central nervous system. Further studies, however, are significantly hindered by the inability of currently available ligands to distinguish heteromeric α7β2-nAChR from the closely related and more widespread homomeric α7-only-nAChR subtype. Functional screening using two-electrode voltage-clamp electrophysiology identified a family of α7β2-nAChR-selective analogs of α-conotoxin PnIC (α-CtxPnIC). A combined electrophysiology, functional kinetics, site-directed mutagenesis, and molecular dynamics approach was used to further characterize the α7β2-nAChR selectivity and site of action of these α-CtxPnIC analogs. We determined that α7β2-nAChR selectivity of α-CtxPnIC analogs arises from interactions at a site distinct from the orthosteric agonist-binding site shared between α7β2- and α7-only-nAChR. As numerous previously identified α-Ctx ligands are competitive antagonists of orthosteric agonist-binding sites, this study profoundly expands the scope of use of α-Ctx ligands (which have already provided important nAChR research and translational breakthroughs). More immediately, analogs of α-CtxPnIC promise to enable, for the first time, both comprehensive mapping of the distribution of α7β2-nAChR and detailed investigations of their physiological roles.
Collapse
Affiliation(s)
- Andrew A. George
- Department of Pharmacology and Toxicology, School of MedicineVirginia Commonwealth UniversityRichmondVirginiaUSA
| | - Sabin J. John
- Department of Pharmacology and Toxicology, School of MedicineVirginia Commonwealth UniversityRichmondVirginiaUSA
- Department of Life SciencesUniversity of BathBathUK
| | - Linda M. Lucero
- Department of NeurobiologyBarrow Neurological InstitutePhoenixArizonaUSA
| | - J. Brek Eaton
- Department of NeurobiologyBarrow Neurological InstitutePhoenixArizonaUSA
| | - Ekta Jaiswal
- Department of NeurobiologyBarrow Neurological InstitutePhoenixArizonaUSA
| | | | - Joanna Gajewiak
- School of Biological SciencesUniversity of UtahSalt Lake CityUtahUSA
| | - Maren Watkins
- School of Biological SciencesUniversity of UtahSalt Lake CityUtahUSA
| | - Yiwei Cao
- Department of ChemistryLehigh UniversityBethlehemPennsylvaniaUSA
| | | | - Wonpil Im
- Department of ChemistryLehigh UniversityBethlehemPennsylvaniaUSA
| | - J. Michael McIntosh
- School of Biological SciencesUniversity of UtahSalt Lake CityUtahUSA
- George E. Wahlen Veterans Affairs Medical CenterSalt Lake CityUtahUSA
- Department of PsychiatryUniversity of UtahSalt Lake CityUtahUSA
| | - Paul Whiteaker
- Department of Pharmacology and Toxicology, School of MedicineVirginia Commonwealth UniversityRichmondVirginiaUSA
| |
Collapse
|
5
|
Xie T, Qin Y, Zhao J, Dong J, Qi P, Zhang P, Zhangsun D, Zhu X, Yu J, Luo S. Molecular Determinants of Species Specificity of α-Conotoxin TxIB towards Rat and Human α6/α3β4 Nicotinic Acetylcholine Receptors. Int J Mol Sci 2023; 24:ijms24108618. [PMID: 37239959 DOI: 10.3390/ijms24108618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Revised: 05/05/2023] [Accepted: 05/10/2023] [Indexed: 05/28/2023] Open
Abstract
Conotoxins are widely distributed and important for studying ligand-gated ion channels. TxIB, a conotoxin consisting of 16 amino acids derived from Conus textile, is a unique selective ligand that blocks rat α6/α3β2β3 nAChR (IC50 = 28 nM) without affecting other rat subtypes. However, when the activity of TxIB against human nAChRs was examined, it was unexpectedly found that TxIB had a significant blocking effect on not only human α6/α3β2β3 nAChR but also human α6/α3β4 nAChR, with an IC50 of 537 nM. To investigate the molecular mechanism of this species specificity and to establish a theoretical basis for drug development studies of TxIB and its analogs, different amino acid residues between human and rat α6/α3 and β4 nAChR subunits were identified. Each residue of the human species was then substituted with the corresponding residue of the rat species via PCR-directed mutagenesis. The potencies of TxIB towards the native α6/α3β4 nAChRs and their mutants were evaluated through electrophysiological experiments. The results showed that the IC50 of TxIB against h[α6V32L, K61R/α3]β4L107V, V115I was 22.5 μM, a 42-fold decrease in potency compared to the native hα6/α3β4 nAChR. Val-32 and Lys-61 in the human α6/α3 subunit and Leu-107 and Val-115 in the human β4 subunit, together, were found to determine the species differences in the α6/α3β4 nAChR. These results also demonstrate that the effects of species differences between humans and rats should be fully considered when evaluating the efficacy of drug candidates targeting nAChRs in rodent models.
Collapse
Affiliation(s)
- Ting Xie
- School of Medicine, Guangxi University, Nanning 530004, China
| | - Yuan Qin
- School of Medicine, Guangxi University, Nanning 530004, China
| | - Jinyuan Zhao
- School of Medicine, Guangxi University, Nanning 530004, China
| | - Jianying Dong
- School of Medicine, Guangxi University, Nanning 530004, China
| | - Panpan Qi
- School of Medicine, Guangxi University, Nanning 530004, China
| | - Panpan Zhang
- School of Medicine, Guangxi University, Nanning 530004, China
| | - Dongting Zhangsun
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Laboratory for Marine Drugs of Haikou, Hainan University, Haikou 570228, China
| | - Xiaopeng Zhu
- School of Medicine, Guangxi University, Nanning 530004, China
| | - Jinpeng Yu
- School of Medicine, Guangxi University, Nanning 530004, China
| | - Sulan Luo
- School of Medicine, Guangxi University, Nanning 530004, China
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Laboratory for Marine Drugs of Haikou, Hainan University, Haikou 570228, China
| |
Collapse
|
6
|
Lee MF, Poh CL. Strategies to improve the physicochemical properties of peptide-based drugs. Pharm Res 2023; 40:617-632. [PMID: 36869247 DOI: 10.1007/s11095-023-03486-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Accepted: 02/17/2023] [Indexed: 03/05/2023]
Abstract
Peptides are a rapid-growing class of therapeutics with unique and desirable physicochemical properties. Due to disadvantages such as low membrane permeability and susceptibility to proteolytic degradation, peptide-based drugs have limited bioavailability, a short half-life, and rapid in vivo elimination. Various strategies can be applied to improve the physicochemical properties of peptide-based drugs to overcome limitations such as limited tissue residence time, metabolic instability, and low permeability. Applied strategies including backbone modifications, side chain modifications, conjugation with polymers, modification of peptide termini, fusion to albumin, conjugation with the Fc portion of antibodies, cyclization, stapled peptides, pseudopeptides, cell-penetrating peptide conjugates, conjugation with lipids, and encapsulation in nanocarriers are discussed.
Collapse
Affiliation(s)
- Michelle Felicia Lee
- Centre for Virus and Vaccine Research, School of Medical and Life Sciences, Sunway University, 5, Jalan Universiti, Selangor 47500, Bandar Sunway, Malaysia
| | - Chit Laa Poh
- Centre for Virus and Vaccine Research, School of Medical and Life Sciences, Sunway University, 5, Jalan Universiti, Selangor 47500, Bandar Sunway, Malaysia.
| |
Collapse
|
7
|
Hone AJ, McIntosh JM. Alkaloid ligands enable function of homomeric human α10 nicotinic acetylcholine receptors. Front Pharmacol 2022; 13:981760. [PMID: 36188578 PMCID: PMC9523446 DOI: 10.3389/fphar.2022.981760] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 08/23/2022] [Indexed: 01/29/2023] Open
Abstract
In the nervous system, nicotinic acetylcholine receptors (nAChRs) rapidly transduce a chemical signal into one that is electrical via ligand-gated ion flux through the central channel of the receptor. However, some nAChR subunits are expressed by non-excitable cells where signal transduction apparently occurs through non-ionic mechanisms. One such nAChR subunit, α10, is present in a discreet subset of immune cells and has been implicated in pathologies including cancer, neuropathic pain, and chronic inflammation. Longstanding convention holds that human α10 subunits require co-assembly with α9 subunits for function. Here we assessed whether cholinergic ligands can enable or uncover ionic functions from homomeric α10 nAChRs. Xenopus laevis oocytes expressing human α10 subunits were exposed to a panel of ligands and examined for receptor activation using voltage-clamp electrophysiology. Functional expression of human α10 nAChRs was achieved by exposing the oocytes to the alkaloids strychnine, brucine, or methyllycaconitine. Furthermore, acute exposure to the alkaloid ligands significantly enhanced ionic responses. Acetylcholine-gated currents mediated by α10 nAChRs were potently inhibited by the snake toxins α-bungarotoxin and α-cobratoxin but not by α-conotoxins that target α9 and α9α10 nAChRs. Our findings indicate that human α10 homomers are expressed in oocytes and exposure to certain ligands can enable ionic functions. To our knowledge, this is the first demonstration that human α10 subunits can assemble as functional homomeric nAChRs. These findings have potential implications for receptor regulatory-mechanisms and will enable structural, functional, and further pharmacological characterization of human α10 nAChRs.
Collapse
Affiliation(s)
- Arik J. Hone
- School of Biological Sciences, University of Utah, Salt Lake City, UT, United States
- MIRECC, George E. Whalen Veterans Affairs Medical Center, Salt Lake City, UT, United States
| | - J. Michael McIntosh
- School of Biological Sciences, University of Utah, Salt Lake City, UT, United States
- Department of Psychiatry, University of Utah, Salt Lake City, UT, United States
- George E. Whalen Veterans Affairs Medical Center, Salt Lake City, UT, United States
| |
Collapse
|
8
|
Therapeutic peptides: current applications and future directions. Signal Transduct Target Ther 2022; 7:48. [PMID: 35165272 PMCID: PMC8844085 DOI: 10.1038/s41392-022-00904-4] [Citation(s) in RCA: 437] [Impact Index Per Article: 218.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 01/13/2022] [Accepted: 01/17/2022] [Indexed: 02/08/2023] Open
Abstract
Peptide drug development has made great progress in the last decade thanks to new production, modification, and analytic technologies. Peptides have been produced and modified using both chemical and biological methods, together with novel design and delivery strategies, which have helped to overcome the inherent drawbacks of peptides and have allowed the continued advancement of this field. A wide variety of natural and modified peptides have been obtained and studied, covering multiple therapeutic areas. This review summarizes the efforts and achievements in peptide drug discovery, production, and modification, and their current applications. We also discuss the value and challenges associated with future developments in therapeutic peptides.
Collapse
|
9
|
Ho TNT, Abraham N, Lewis RJ. Unique Pharmacological Properties of α-Conotoxin OmIA at α7 nAChRs. Front Pharmacol 2021; 12:803397. [PMID: 34955864 PMCID: PMC8692984 DOI: 10.3389/fphar.2021.803397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 11/22/2021] [Indexed: 11/13/2022] Open
Abstract
OmIA, isolated from Conus omaria venom, is a potent antagonist at α7 nAChRs. We determined the co-crystal structure of OmIA with Lymnae stagnalis acetylcholine binding protein (Ls-AChBP) that identified His5, Val10 and Asn11 as key determinants for the high potency of OmIA at α7 nAChRs. Remarkably, despite a competitive binding mode observed in the co-crystal structure, OmIA and analogues displayed functional insurmountable antagonism at α7 and α3β4 nAChRs, except OmIA analogues having long side chain at position 10 ([V10Q]OmIA and [V10L]OmIA), which were partial insurmountable antagonist at α7 nAChRs in the presence of type II positive allosteric modulators (PAMs). A “two-state, two-step” model was used to explain these observations, with [V10Q]OmIA and [V10L]OmIA co-existing in a fast reversible/surmountable as well as a tight binding/insurmountable state. OmIA and analogues also showed biphasic-inhibition at α7 nAChRs in the presence of PNU120596, with a preference for the high-affinity binding site following prolonged exposure. The molecular basis of binding and complex pharmacological profile of OmIA at α7 nAChRs presented in here expands on the potential of α-conotoxins to probe the pharmacological properties of nAChRs and may help guide the development novel α7 modulators.
Collapse
Affiliation(s)
- Thao N T Ho
- Centre for Pain Research, Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD, Australia
| | - Nikita Abraham
- Centre for Pain Research, Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD, Australia
| | - Richard J Lewis
- Centre for Pain Research, Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD, Australia
| |
Collapse
|
10
|
Bekbossynova A, Zharylgap A, Filchakova O. Venom-Derived Neurotoxins Targeting Nicotinic Acetylcholine Receptors. Molecules 2021; 26:molecules26113373. [PMID: 34204855 PMCID: PMC8199771 DOI: 10.3390/molecules26113373] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 05/05/2021] [Accepted: 05/07/2021] [Indexed: 01/02/2023] Open
Abstract
Acetylcholine was the first neurotransmitter described. The receptors targeted by acetylcholine are found within organisms spanning different phyla and position themselves as very attractive targets for predation, as well as for defense. Venoms of snakes within the Elapidae family, as well as those of marine snails within the Conus genus, are particularly rich in proteins and peptides that target nicotinic acetylcholine receptors (nAChRs). Such compounds are invaluable tools for research seeking to understand the structure and function of the cholinergic system. Proteins and peptides of venomous origin targeting nAChR demonstrate high affinity and good selectivity. This review aims at providing an overview of the toxins targeting nAChRs found within venoms of different animals, as well as their activities and the structural determinants important for receptor binding.
Collapse
|
11
|
Ning H, Huang B, Tae HS, Liu Z, Yu S, Li L, Zhang L, Adams DJ, Guo C, Dai Q. α-Conotoxin Bt1.8 from Conus betulinus selectively inhibits α6/α3β2β3 and α3β2 nicotinic acetylcholine receptor subtypes. J Neurochem 2021; 159:90-100. [PMID: 34008858 DOI: 10.1111/jnc.15434] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2020] [Revised: 04/16/2021] [Accepted: 04/27/2021] [Indexed: 12/01/2022]
Abstract
α-Conotoxins are small disulfide-rich peptides found in the venom of marine cone snails and are potent antagonists of nicotinic acetylcholine receptors (nAChRs). They are valuable pharmacological tools and have potential therapeutic applications for the treatment of chronic pain or neurological diseases and disorders. In the present study, we synthesized and functionally characterized a novel α-conotoxin Bt1.8, which was cloned from Conus betulinus. Bt1.8 selectively inhibited ACh-evoked currents in Xenopus oocytes expressing rat(r) α6/α3β2β3 and rα3β2 nAChRs with an IC50 of 2.1 nM and 9.4 nM, respectively, and similar potency for human (h) α6/α3β2β3 and hα3β2 nAChRs. Additionally, Bt1.8 had higher binding affinity with a slower dissociation rate for the rα6/α3β2β3 subtype compared to rα3β2. The amino acid sequence of Bt1.8 is significantly different from other reported α-conotoxins targeting the two nAChR subtypes. Further Alanine scanning analyses demonstrated that residues Ile9, Leu10, Asn11, Asn12 and Asn14 are critical for its inhibitory activity at the α6/α3β2β3 and α3β2 subtypes. Moreover, the NMR structure of Bt1.8 indicated the presence of a relatively larger hydrophobic zone than other α4/7-conotoxins which may explain its potent inhibition at α6/α3β2β3 nAChRs.
Collapse
Affiliation(s)
- Huying Ning
- Beijing Institute of Biotechnology, Beijing, China
| | - Biling Huang
- Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, China
| | - Han-Shen Tae
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW, Australia
| | - Zhuguo Liu
- Beijing Institute of Biotechnology, Beijing, China
| | - Shuo Yu
- Beijing Institute of Biotechnology, Beijing, China
| | - Liang Li
- Beijing Institute of Biotechnology, Beijing, China
| | | | - David J Adams
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW, Australia
| | - Chenyun Guo
- Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, China
| | - Qiuyun Dai
- Beijing Institute of Biotechnology, Beijing, China
| |
Collapse
|
12
|
Hone AJ, Kaas Q, Kearns I, Hararah F, Gajewiak J, Christensen S, Craik DJ, McIntosh JM. Computational and Functional Mapping of Human and Rat α6β4 Nicotinic Acetylcholine Receptors Reveals Species-Specific Ligand-Binding Motifs. J Med Chem 2021; 64:1685-1700. [PMID: 33523678 PMCID: PMC8382285 DOI: 10.1021/acs.jmedchem.0c01973] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Nicotinic acetylcholine receptors (nAChRs) are pharmacological targets for the treatment of neuropathic pain, and the α6β4 subtype has been identified as particularly promising. Rat α6β4 nAChRs are less sensitive to some ligands than the human homologue potentially complicating the use of rodent α6β4 receptors for screening therapeutic compounds. We used molecular dynamics simulations coupled with functional assays to study the interaction between α-conotoxin PeIA and α6β4 nAChRs and to identify key ligand-receptor interactions that contribute to species differences in α-conotoxin potency. Our results show that human and rat α6β4 nAChRs have distinct ligand-binding motifs and show markedly different sensitivities to α-conotoxins. These studies facilitated the creation of PeIA-5667, a peptide that shows 270-fold higher potency for rat α6β4 nAChRs over native PeIA and similar potency for the human homologue. Our results may inform the design of therapeutic ligands that target α6β4 nAChRs for the treatment of neuropathic pain.
Collapse
Affiliation(s)
- Arik J Hone
- MIRECC, George E. Whalen Veterans Affairs Medical Center, Salt Lake City, Utah 84148 United States
| | - 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
| | - J Michael McIntosh
- George E. Whalen Veterans Affairs Medical Center, Salt Lake City, Utah 84148 United States
| |
Collapse
|
13
|
Hone AJ, Rueda-Ruzafa L, Gordon TJ, Gajewiak J, Christensen S, Dyhring T, Albillos A, McIntosh JM. Expression of α3β2β4 nicotinic acetylcholine receptors by rat adrenal chromaffin cells determined using novel conopeptide antagonists. J Neurochem 2020; 154:158-176. [PMID: 31967330 DOI: 10.1111/jnc.14966] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 12/17/2019] [Accepted: 01/13/2020] [Indexed: 01/07/2023]
Abstract
Adrenal chromaffin cells release neurotransmitters in response to stress and may be involved in conditions such as post-traumatic stress and anxiety disorders. Neurotransmitter release is triggered, in part, by activation of nicotinic acetylcholine receptors (nAChRs). However, despite decades of use as a model system for studying exocytosis, the nAChR subtypes involved have not been pharmacologically identified. Quantitative real-time PCR of rat adrenal medulla revealed an abundance of mRNAs for α3, α7, β2, and β4 subunits. Whole-cell patch-clamp electrophysiology of chromaffin cells and subtype-selective ligands were used to probe for nAChRs derived from the mRNAs found in adrenal medulla. A novel conopeptide antagonist, PeIA-5469, was created that is highly selective for α3β2 over other nAChR subtypes heterologously expressed in Xenopus laevis oocytes. Experiments using PeIA-5469 and the α3β4-selective α-conotoxin TxID revealed that rat adrenal medulla contain two populations of chromaffin cells that express either α3β4 nAChRs alone or α3β4 together with the α3β2β4 subtype. Conclusions were derived from observations that acetylcholine-gated currents in some cells were sensitive to inhibition by PeIA-5469 and TxID, while in other cells, currents were sensitive only to TxID. Expression of functional α7 nAChRs was determined using three α7-selective ligands: the agonist PNU282987, the positive allosteric modulator PNU120596, and the antagonist α-conotoxin [V11L,V16D]ArIB. The results of these studies identify for the first time the expression of α3β2β4 nAChRs as well as functional α7 nAChRs by rat adrenal chromaffin cells.
Collapse
Affiliation(s)
- Arik J Hone
- George E. Whalen Veterans Affairs Medical Center, Salt Lake City, Utah, USA.,School of Biological Sciences and University of Utah, Salt Lake City, Utah, USA.,Departament of Pharmacology and Therapeutics, Universidad Autónoma de Madrid, Madrid, Spain
| | - Lola Rueda-Ruzafa
- Departament of Pharmacology and Therapeutics, Universidad Autónoma de Madrid, Madrid, Spain.,Biomedical Research Center (CINBIO), University of Vigo, Vigo, Spain
| | - Thomas J Gordon
- School of Biological Sciences and University of Utah, Salt Lake City, Utah, USA
| | - Joanna Gajewiak
- School of Biological Sciences and University of Utah, Salt Lake City, Utah, USA
| | - Sean Christensen
- School of Biological Sciences and University of Utah, Salt Lake City, Utah, USA
| | | | - Almudena Albillos
- Departament of Pharmacology and Therapeutics, Universidad Autónoma de Madrid, Madrid, Spain
| | - J Michael McIntosh
- George E. Whalen Veterans Affairs Medical Center, Salt Lake City, Utah, USA.,School of Biological Sciences and University of Utah, Salt Lake City, Utah, USA.,Department of Psychiatry, University of Utah, Salt Lake City, Utah, USA
| |
Collapse
|
14
|
van Hout M, Valdes A, Christensen SB, Tran PT, Watkins M, Gajewiak J, Jensen AA, Olivera BM, McIntosh JM. α-Conotoxin VnIB from Conus ventricosus is a potent and selective antagonist of α6β4* nicotinic acetylcholine receptors. Neuropharmacology 2019; 157:107691. [PMID: 31255696 DOI: 10.1016/j.neuropharm.2019.107691] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 06/05/2019] [Accepted: 06/26/2019] [Indexed: 01/20/2023]
Abstract
α6-containing (α6*) nicotinic acetylcholine receptors (nAChRs) are expressed throughout the periphery and the central nervous system and constitute putative therapeutic targets in pain, addiction and movement disorders. The α6β2* nAChRs are relatively well studied, in part due to the availability of target specific α-conotoxins (α-Ctxs). In contrast, all native α-Ctxs identified that potently block α6β4 nAChRs exhibit higher potencies for the closely related α6β2β3 and/or α3β4 subtypes. In this study, we have identified a novel peptide from Conus ventricosus with pronounced selectivity for the α6β4 nAChR. The peptide-encoding gene was cloned from genomic DNA and the predicted mature peptide, α-Ctx VnIB, was synthesized. The functional properties of VnIB were characterized at rat and human nAChRs expressed in Xenopus oocytes by two-electrode voltage clamp electrophysiology. VnIB potently inhibited ACh-evoked currents at rα6β4 and rα6/α3β4 nAChRs, displayed ∼20-fold and ∼250-fold lower potencies at rα3β4 and rα6/α3β2β3 receptors, respectively, and exhibited negligible effects at eight other nAChR subtypes. Interestingly, even higher degrees of selectivity were observed for hα6/α3β4 over hα6/α3β2β3 and hα3β4 receptors. Finally, VnIB displayed fast binding kinetics at rα6/α3β4 (on-rate t½ = 0.87 min-1, off-rate t½ = 2.7 min-1). The overall preference of VnIB for β4* over β2* nAChRs is similar to the selectivity profiles of other 4/6 α-Ctxs. However, in contrast to previously identified native α-Ctxs targeting α6* nAChRs, VnIB displays pronounced selectivity for α6β4 nAChRs over both α3β4 and α6β2β3 receptors. VnIB thus represents a novel molecular probe for elucidating the physiological role and therapeutic properties of α6β4* nAChRs.
Collapse
Affiliation(s)
- Marloes van Hout
- Department of Biology, University of Utah, Salt Lake City, UT, 84112, USA; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
| | - Amanda Valdes
- Department of Biology, University of Utah, Salt Lake City, UT, 84112, USA
| | - Sean B Christensen
- Department of Biology, University of Utah, Salt Lake City, UT, 84112, USA.
| | - Phuong T Tran
- Department of Biology, University of Utah, Salt Lake City, UT, 84112, USA
| | - Maren Watkins
- Department of Biology, University of Utah, Salt Lake City, UT, 84112, USA; Department of Pathology, University of Utah, Salt Lake City, UT, 84112, USA.
| | - Joanna Gajewiak
- Department of Biology, University of Utah, Salt Lake City, UT, 84112, USA.
| | - Anders A Jensen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
| | | | - J Michael McIntosh
- Department of Biology, University of Utah, Salt Lake City, UT, 84112, USA; Department of Psychiatry, University of Utah, Salt Lake City, UT, 84108, USA; George E. Wahlen Veterans Affair Medical Center, Salt Lake City, UT, 84148, USA.
| |
Collapse
|