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Shi YJ, Chiou JT, Wang LJ, Huang CH, Lee YC, Chen YJ, Chang LS. Blocking of negative charged carboxyl groups converts Naja atra neurotoxin to cardiotoxin-like protein. Int J Biol Macromol 2020; 164:2953-2963. [PMID: 32846183 DOI: 10.1016/j.ijbiomac.2020.08.163] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Accepted: 08/20/2020] [Indexed: 11/28/2022]
Abstract
Naja atra cobrotoxin and cardiotoxin 3 (CTX3) exhibit neurotoxicity and cytotoxicity, respectively. In the present study, we aimed to investigate whether the carboxyl groups of cobrotoxin play a role in structural constraints, thereby preventing cobrotoxin from exhibiting cytotoxic activity. Six of the seven carboxyl groups in cobrotoxin were conjugated with semicarbazide. Measurement of circular dichroism spectra and Trp fluorescence quenching showed that the gross conformation of semicarbazide-modified cobrotoxin (SEM-cobrotoxin) and cobrotoxin differed. In sharp contrast to cobrotoxin, SEM-cobrotoxin demonstrated membrane-damaging activity and cytotoxicity, which are feature more characteristic of CTX3. Furthermore, both SEM-cobrotoxin and CTX3 induced cell death through AMPK activation. Analyses of the interaction between polydiacetylene/lipid vesicles and fluorescence-labeled lipids revealed that SEM-cobrotoxin and cobrotoxin adopted different membrane-bound states. The structural characteristics of SEM-cobrotoxin were similar to those of CTX3, including trifluoroethanol (TFE)-induced structural transformation and membrane binding-induced conformational change. Conversely, cobrotoxin was insensitive to the TFE-induced effect. Collectively, the data of this study indicate that blocking negatively charged residues confers cobrotoxin with membrane-damaging activity and cytotoxicity. The findings also suggest that the structural constraints imposed by carboxyl groups control the functional properties of snake venom α-neurotoxins during the divergent evolution of snake venom neurotoxins and cardiotoxins.
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Affiliation(s)
- Yi-Jun Shi
- Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung 804, Taiwan
| | - Jing-Ting Chiou
- Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung 804, Taiwan
| | - Liang-Jun Wang
- Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung 804, Taiwan
| | - Chia-Hui Huang
- Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung 804, Taiwan
| | - Yuan-Chin Lee
- Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung 804, Taiwan
| | - Ying-Jung Chen
- Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, Kaohsiung 807, Taiwan
| | - Long-Sen Chang
- Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung 804, Taiwan; Department of Biotechnology, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
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2
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Nirthanan S. Snake three-finger α-neurotoxins and nicotinic acetylcholine receptors: molecules, mechanisms and medicine. Biochem Pharmacol 2020; 181:114168. [PMID: 32710970 DOI: 10.1016/j.bcp.2020.114168] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 07/20/2020] [Accepted: 07/20/2020] [Indexed: 12/13/2022]
Abstract
Snake venom three-finger α-neurotoxins (α-3FNTx) act on postsynaptic nicotinic acetylcholine receptors (nAChRs) at the neuromuscular junction (NMJ) to produce skeletal muscle paralysis. The discovery of the archetypal α-bungarotoxin (α-BgTx), almost six decades ago, exponentially expanded our knowledge of membrane receptors and ion channels. This included the localisation, isolation and characterization of the first receptor (nAChR); and by extension, the pathophysiology and pharmacology of neuromuscular transmission and associated pathologies such as myasthenia gravis, as well as our understanding of the role of α-3FNTxs in snakebite envenomation leading to novel concepts of targeted treatment. Subsequent studies on a variety of animal venoms have yielded a plethora of novel toxins that have revolutionized molecular biomedicine and advanced drug discovery from bench to bedside. This review provides an overview of nAChRs and their subtypes, classification of α-3FNTxs and the challenges of typifying an increasing arsenal of structurally and functionally unique toxins, and the three-finger protein (3FP) fold in the context of the uPAR/Ly6/CD59/snake toxin superfamily. The pharmacology of snake α-3FNTxs including their mechanisms of neuromuscular blockade, variations in reversibility of nAChR interactions, specificity for nAChR subtypes or for distinct ligand-binding interfaces within a subtype and the role of α-3FNTxs in neurotoxic envenomation are also detailed. Lastly, a reconciliation of structure-function relationships between α-3FNTx and nAChRs, derived from historical mutational and biochemical studies and emerging atomic level structures of nAChR models in complex with α-3FNTxs is discussed.
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Affiliation(s)
- Selvanayagam Nirthanan
- School of Medical Science, Griffith Health Group, Griffith University, Gold Coast, Queensland, Australia.
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3
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Sato A, Menez A. External release of entropy by synchronized movements of local secondary structures drives folding of a small, disulfide-bonded protein. PLoS One 2018; 13:e0198276. [PMID: 29894484 PMCID: PMC5997310 DOI: 10.1371/journal.pone.0198276] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Accepted: 05/16/2018] [Indexed: 11/22/2022] Open
Abstract
A crucial mechanism to the formation of native, fully functional, 3D structures from local secondary structures is unraveled in this study. Through the introduction of various amino acid substitutions at four canonical β-turns in a three-fingered protein, Toxin α from Naja nigricollis, we found that the release of internal entropy to the external environment through the globally synchronized movements of local substructures plays a crucial role. Throughout the folding process, the folding species were saturated with internal entropy so that intermediates accumulated at the equilibrium state. Their relief from the equilibrium state was accomplished by the formation of a critical disulfide bridge, which could guide the synchronized movement of one of the peripheral secondary structure. This secondary structure collided with a core central structure, which flanked another peripheral secondary structure. This collision displaced the internal thermal fluctuations from the first peripheral structure to the second peripheral structure, where the displaced thermal fluctuations were ultimately released as entropy. Two protein folding processes that acted in succession were identified as the means to establish the flow of thermal fluctuations. The first process was the time-consuming assembly process, where stochastic combinations of colliding, native-like, secondary structures provided candidate structures for the folded protein. The second process was the activation process to establish the global mutual relationships of the native protein in the selected candidate. This activation process was initiated and propagated by a positive feedback process between efficient entropy release and well-packed local structures, which moved in synchronization. The molecular mechanism suggested by this experiment was assessed with a well-defined 3D structure of erabutoxin b because one of the turns that played a critical role in folding was shared with erabutoxin b.
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Affiliation(s)
- Atsushi Sato
- Department of Information Science, Faculty of Liberal Arts, Tohoku Gakuin University, Sendai, Japan
- * E-mail:
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4
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Kessler P, Marchot P, Silva M, Servent D. The three-finger toxin fold: a multifunctional structural scaffold able to modulate cholinergic functions. J Neurochem 2017; 142 Suppl 2:7-18. [PMID: 28326549 DOI: 10.1111/jnc.13975] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Revised: 01/12/2017] [Accepted: 01/30/2017] [Indexed: 12/26/2022]
Abstract
Three-finger fold toxins are miniproteins frequently found in Elapidae snake venoms. This fold is characterized by three distinct loops rich in β-strands and emerging from a dense, globular core reticulated by four highly conserved disulfide bridges. The number and diversity of receptors, channels, and enzymes identified as targets of three-finger fold toxins is increasing continuously. Such manifold diversity highlights the specific adaptability of this fold for generating pleiotropic functions. Although this toxin superfamily disturbs many biological functions by interacting with a large diversity of molecular targets, the most significant target is the cholinergic system. By blocking the activity of the nicotinic and muscarinic acetylcholine receptors or by inhibiting the enzyme acetylcholinesterase, three-finger fold toxins interfere most drastically with neuromuscular junction functioning. Several of these toxins have become powerful pharmacological tools for studying the function and structure of their molecular targets. Most importantly, since dysfunction of these receptors/enzyme is involved in many diseases, exploiting the three-finger scaffold to create novel, highly specific therapeutic agents may represent a major future endeavor. This is an article for the special issue XVth International Symposium on Cholinergic Mechanisms.
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Affiliation(s)
- Pascal Kessler
- Service d'Ingénierie Moléculaire des Protéines (SIMOPRO), IBITECS, CEA, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Pascale Marchot
- Aix-Marseille Université/Centre National de la Recherche Scientifique, Architecture et Fonction des Macromolécules Biologiques laboratory, Faculté des Sciences Campus Luminy, Marseille, France
| | - Marcela Silva
- Service d'Ingénierie Moléculaire des Protéines (SIMOPRO), IBITECS, CEA, Université Paris-Saclay, Gif-sur-Yvette, France.,Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Denis Servent
- Service d'Ingénierie Moléculaire des Protéines (SIMOPRO), IBITECS, CEA, Université Paris-Saclay, Gif-sur-Yvette, France
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5
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Couesnon A, Aráoz R, Iorga BI, Benoit E, Reynaud M, Servent D, Molgó J. The Dinoflagellate Toxin 20-Methyl Spirolide-G Potently Blocks Skeletal Muscle and Neuronal Nicotinic Acetylcholine Receptors. Toxins (Basel) 2016; 8:E249. [PMID: 27563924 PMCID: PMC5037475 DOI: 10.3390/toxins8090249] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 08/06/2016] [Accepted: 08/12/2016] [Indexed: 11/16/2022] Open
Abstract
The cyclic imine toxin 20-methyl spirolide G (20-meSPX-G), produced by the toxigenic dinoflagellate Alexandrium ostenfeldii/Alexandrium peruvianum, has been previously reported to contaminate shellfish in various European coastal locations, as revealed by mouse toxicity bioassay. The aim of the present study was to determine its toxicological profile and its molecular target selectivity. 20-meSPX-G blocked nerve-evoked isometric contractions in isolated mouse neuromuscular preparations, while it had no action on contractions elicited by direct electrical stimulation, and reduced reversibly nerve-evoked compound muscle action potential amplitudes in anesthetized mice. Voltage-clamp recordings in Xenopus oocytes revealed that 20-meSPX-G potently inhibited currents evoked by ACh on Torpedo muscle-type and human α7 nicotinic acetylcholine receptors (nAChR), whereas lower potency was observed in human α4β2 nAChR. Competition-binding assays showed that 20-meSPX-G fully displaced [³H]epibatidine binding to HEK-293 cells expressing the human α3β2 (Ki = 0.040 nM), whereas a 90-fold lower affinity was detected in human α4β2 nAChR. The spirolide displaced [(125)I]α-bungarotoxin binding to Torpedo membranes (Ki = 0.028 nM) and in HEK-293 cells expressing chick chimeric α7-5HT₃ nAChR (Ki = 0.11 nM). In conclusion, this is the first study to demonstrate that 20-meSPX-G is a potent antagonist of nAChRs, and its subtype selectivity is discussed on the basis of molecular docking models.
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MESH Headings
- Action Potentials
- Animals
- Binding Sites
- Binding, Competitive
- Bridged Bicyclo Compounds, Heterocyclic/metabolism
- Chickens
- Cholinergic Fibers/drug effects
- Cholinergic Fibers/metabolism
- Dose-Response Relationship, Drug
- Electric Stimulation
- Female
- HEK293 Cells
- Humans
- In Vitro Techniques
- Isometric Contraction/drug effects
- Mice
- Molecular Docking Simulation
- Muscle, Skeletal/drug effects
- Muscle, Skeletal/innervation
- Muscle, Skeletal/metabolism
- Neuromuscular Junction/drug effects
- Neuromuscular Junction/metabolism
- Nicotinic Antagonists/chemistry
- Nicotinic Antagonists/metabolism
- Nicotinic Antagonists/toxicity
- Protein Binding
- Protein Conformation
- Pyridines/metabolism
- Receptors, Nicotinic/chemistry
- Receptors, Nicotinic/drug effects
- Receptors, Nicotinic/genetics
- Receptors, Nicotinic/metabolism
- Spiro Compounds/chemistry
- Spiro Compounds/metabolism
- Spiro Compounds/toxicity
- Structure-Activity Relationship
- Torpedo
- Transfection
- Xenopus laevis
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Affiliation(s)
- Aurélie Couesnon
- Institut des Neurosciences Paris-Saclay, UMR 9197 CNRS/Université Paris-Sud, F-91190 Gif-sur-Yvette, France.
| | - Rómulo Aráoz
- Institut des Neurosciences Paris-Saclay, UMR 9197 CNRS/Université Paris-Sud, F-91190 Gif-sur-Yvette, France.
- Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institut de Biologie et Technologies de Saclay (IBITECS), Université Paris-Saclay, Service d'Ingénierie Moléculaire des Protéines, bâtiment 152, F-91191 Gif-sur-Yvette, France.
| | - Bogdan I Iorga
- Centre National de la Recherche Scientifique (CNRS), Institut de Chimie des Substances Naturelles, UPR 2301, Labex LERMIT, F-91198 Gif-sur-Yvette, France.
| | - Evelyne Benoit
- Institut des Neurosciences Paris-Saclay, UMR 9197 CNRS/Université Paris-Sud, F-91190 Gif-sur-Yvette, France.
- Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institut de Biologie et Technologies de Saclay (IBITECS), Université Paris-Saclay, Service d'Ingénierie Moléculaire des Protéines, bâtiment 152, F-91191 Gif-sur-Yvette, France.
| | - Morgane Reynaud
- Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institut de Biologie et Technologies de Saclay (IBITECS), Université Paris-Saclay, Service d'Ingénierie Moléculaire des Protéines, bâtiment 152, F-91191 Gif-sur-Yvette, France.
| | - Denis Servent
- Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institut de Biologie et Technologies de Saclay (IBITECS), Université Paris-Saclay, Service d'Ingénierie Moléculaire des Protéines, bâtiment 152, F-91191 Gif-sur-Yvette, France.
| | - Jordi Molgó
- Institut des Neurosciences Paris-Saclay, UMR 9197 CNRS/Université Paris-Sud, F-91190 Gif-sur-Yvette, France.
- Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institut de Biologie et Technologies de Saclay (IBITECS), Université Paris-Saclay, Service d'Ingénierie Moléculaire des Protéines, bâtiment 152, F-91191 Gif-sur-Yvette, France.
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6
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Lyukmanova EN, Shulepko MA, Shenkarev ZO, Kasheverov IE, Chugunov AO, Kulbatskii DS, Myshkin MY, Utkin YN, Efremov RG, Tsetlin VI, Arseniev AS, Kirpichnikov MP, Dolgikh DA. Central loop of non-conventional toxin WTX from Naja kaouthia is important for interaction with nicotinic acetylcholine receptors. Toxicon 2016; 119:274-9. [PMID: 27343701 DOI: 10.1016/j.toxicon.2016.06.012] [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: 04/15/2016] [Revised: 06/09/2016] [Accepted: 06/21/2016] [Indexed: 10/21/2022]
Abstract
'Three-finger' toxin WTX from Naja kaouthia interacts with nicotinic and muscarinic acetylcholine receptors (nAChRs and mAChRs). Mutagenesis and competition experiments with (125)I-α-bungarotoxin revealed that Arg31 and Arg32 residues from the WTX loop II are important for binding to Torpedo californica and human α7 nAChRs. Computer modeling suggested that loop II occupies the orthosteric binding site at α7 nAChR. The similar toxin interface was previously described as a major determinant of allosteric interactions with mAChRs.
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Affiliation(s)
- Ekaterina N Lyukmanova
- Lomonosov Moscow State University, Leninskie Gori 1, Moscow 119234, Russian Federation; Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RAS, Miklukho-Maklaya Street 16/10, Moscow 117997, Russian Federation.
| | - Mikhail A Shulepko
- Lomonosov Moscow State University, Leninskie Gori 1, Moscow 119234, Russian Federation; Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RAS, Miklukho-Maklaya Street 16/10, Moscow 117997, Russian Federation
| | - Zakhar O Shenkarev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RAS, Miklukho-Maklaya Street 16/10, Moscow 117997, Russian Federation; Moscow Institute of Physics and Technology, Institutskiy Pereulok 9, Dolgoprudny, Moscow Region 141700, Russian Federation
| | - Igor E Kasheverov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RAS, Miklukho-Maklaya Street 16/10, Moscow 117997, Russian Federation
| | - Anton O Chugunov
- Lomonosov Moscow State University, Leninskie Gori 1, Moscow 119234, Russian Federation; Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RAS, Miklukho-Maklaya Street 16/10, Moscow 117997, Russian Federation
| | - Dmitrii S Kulbatskii
- Lomonosov Moscow State University, Leninskie Gori 1, Moscow 119234, Russian Federation; Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RAS, Miklukho-Maklaya Street 16/10, Moscow 117997, Russian Federation
| | - Mikhail Yu Myshkin
- Lomonosov Moscow State University, Leninskie Gori 1, Moscow 119234, Russian Federation; Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RAS, Miklukho-Maklaya Street 16/10, Moscow 117997, Russian Federation
| | - Yuri N Utkin
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RAS, Miklukho-Maklaya Street 16/10, Moscow 117997, Russian Federation
| | - Roman G Efremov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RAS, Miklukho-Maklaya Street 16/10, Moscow 117997, Russian Federation; National Research University Higher School of Economics, Myasnitskaya ul. 20, 101000 Moscow, Russian Federation; Moscow Institute of Physics and Technology, Institutskiy Pereulok 9, Dolgoprudny, Moscow Region 141700, Russian Federation
| | - Victor I Tsetlin
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RAS, Miklukho-Maklaya Street 16/10, Moscow 117997, Russian Federation
| | - Alexander S Arseniev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RAS, Miklukho-Maklaya Street 16/10, Moscow 117997, Russian Federation; Moscow Institute of Physics and Technology, Institutskiy Pereulok 9, Dolgoprudny, Moscow Region 141700, Russian Federation
| | - Mikhail P Kirpichnikov
- Lomonosov Moscow State University, Leninskie Gori 1, Moscow 119234, Russian Federation; Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RAS, Miklukho-Maklaya Street 16/10, Moscow 117997, Russian Federation
| | - Dmitry A Dolgikh
- Lomonosov Moscow State University, Leninskie Gori 1, Moscow 119234, Russian Federation; Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RAS, Miklukho-Maklaya Street 16/10, Moscow 117997, Russian Federation
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7
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Saviola AJ, Peichoto ME, Mackessy SP. Rear-fanged snake venoms: an untapped source of novel compounds and potential drug leads. TOXIN REV 2014. [DOI: 10.3109/15569543.2014.942040] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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8
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Wilburn DB, Bowen KE, Doty KA, Arumugam S, Lane AN, Feldhoff PW, Feldhoff RC. Structural insights into the evolution of a sexy protein: novel topology and restricted backbone flexibility in a hypervariable pheromone from the red-legged salamander, Plethodon shermani. PLoS One 2014; 9:e96975. [PMID: 24849290 PMCID: PMC4029566 DOI: 10.1371/journal.pone.0096975] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Accepted: 04/15/2014] [Indexed: 11/18/2022] Open
Abstract
In response to pervasive sexual selection, protein sex pheromones often display rapid mutation and accelerated evolution of corresponding gene sequences. For proteins, the general dogma is that structure is maintained even as sequence or function may rapidly change. This phenomenon is well exemplified by the three-finger protein (TFP) superfamily: a diverse class of vertebrate proteins co-opted for many biological functions - such as components of snake venoms, regulators of the complement system, and coordinators of amphibian limb regeneration. All of the >200 structurally characterized TFPs adopt the namesake "three-finger" topology. In male red-legged salamanders, the TFP pheromone Plethodontid Modulating Factor (PMF) is a hypervariable protein such that, through extensive gene duplication and pervasive sexual selection, individual male salamanders express more than 30 unique isoforms. However, it remained unclear how this accelerated evolution affected the protein structure of PMF. Using LC/MS-MS and multidimensional NMR, we report the 3D structure of the most abundant PMF isoform, PMF-G. The high resolution structural ensemble revealed a highly modified TFP structure, including a unique disulfide bonding pattern and loss of secondary structure, that define a novel protein topology with greater backbone flexibility in the third peptide finger. Sequence comparison, models of molecular evolution, and homology modeling together support that this flexible third finger is the most rapidly evolving segment of PMF. Combined with PMF sequence hypervariability, this structural flexibility may enhance the plasticity of PMF as a chemical signal by permitting potentially thousands of structural conformers. We propose that the flexible third finger plays a critical role in PMF:receptor interactions. As female receptors co-evolve, this flexibility may allow PMF to still bind its receptor(s) without the immediate need for complementary mutations. Consequently, this unique adaptation may establish new paradigms for how receptor:ligand pairs co-evolve, in particular with respect to sexual conflict.
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Affiliation(s)
- Damien B. Wilburn
- Department of Biochemistry and Molecular Biology, University of Louisville, Louisville, Kentucky, United States of America
| | - Kathleen E. Bowen
- Department of Biochemistry and Molecular Biology, University of Louisville, Louisville, Kentucky, United States of America
| | - Kari A. Doty
- Department of Biochemistry and Molecular Biology, University of Louisville, Louisville, Kentucky, United States of America
| | - Sengodagounder Arumugam
- J.G. Brown Cancer Center, University of Louisville, Louisville, Kentucky, United States of America
| | - Andrew N. Lane
- J.G. Brown Cancer Center, University of Louisville, Louisville, Kentucky, United States of America
| | - Pamela W. Feldhoff
- Department of Biochemistry and Molecular Biology, University of Louisville, Louisville, Kentucky, United States of America
| | - Richard C. Feldhoff
- Department of Biochemistry and Molecular Biology, University of Louisville, Louisville, Kentucky, United States of America
- * E-mail:
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Pharmacological characterization of α-elapitoxin-Al2a from the venom of the Australian pygmy copperhead (Austrelaps labialis): An atypical long-chain α-neurotoxin with only weak affinity for α7 nicotinic receptors. Biochem Pharmacol 2012; 84:851-63. [DOI: 10.1016/j.bcp.2012.06.024] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2012] [Revised: 06/22/2012] [Accepted: 06/25/2012] [Indexed: 11/19/2022]
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10
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Fruchart-Gaillard C, Mourier G, Blanchet G, Vera L, Gilles N, Ménez R, Marcon E, Stura EA, Servent D. Engineering of three-finger fold toxins creates ligands with original pharmacological profiles for muscarinic and adrenergic receptors. PLoS One 2012; 7:e39166. [PMID: 22720062 PMCID: PMC3375269 DOI: 10.1371/journal.pone.0039166] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2012] [Accepted: 05/16/2012] [Indexed: 01/26/2023] Open
Abstract
Protein engineering approaches are often a combination of rational design and directed evolution using display technologies. Here, we test “loop grafting,” a rational design method, on three-finger fold proteins. These small reticulated proteins have exceptional affinity and specificity for their diverse molecular targets, display protease-resistance, and are highly stable and poorly immunogenic. The wealth of structural knowledge makes them good candidates for protein engineering of new functionality. Our goal is to enhance the efficacy of these mini-proteins by modifying their pharmacological properties in order to extend their use in imaging, diagnostics and therapeutic applications. Using the interaction of three-finger fold toxins with muscarinic and adrenergic receptors as a model, chimeric toxins have been engineered by substituting loops on toxin MT7 by those from toxin MT1. The pharmacological impact of these grafts was examined using binding experiments on muscarinic receptors M1 and M4 and on the α1A-adrenoceptor. Some of the designed chimeric proteins have impressive gain of function on certain receptor subtypes achieving an original selectivity profile with high affinity for muscarinic receptor M1 and α1A-adrenoceptor. Structure-function analysis supported by crystallographic data for MT1 and two chimeras permits a molecular based interpretation of these gains and details the merits of this protein engineering technique. The results obtained shed light on how loop permutation can be used to design new three-finger proteins with original pharmacological profiles.
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Affiliation(s)
- Carole Fruchart-Gaillard
- CEA, iBiTecS, Service d’Ingénierie Moléculaire des Protéines, Laboratoire de Toxinologie Moléculaire et Biotechnologies, Gif-sur-Yvette, France
| | - Gilles Mourier
- CEA, iBiTecS, Service d’Ingénierie Moléculaire des Protéines, Laboratoire de Toxinologie Moléculaire et Biotechnologies, Gif-sur-Yvette, France
| | - Guillaume Blanchet
- CEA, iBiTecS, Service d’Ingénierie Moléculaire des Protéines, Laboratoire de Toxinologie Moléculaire et Biotechnologies, Gif-sur-Yvette, France
- Université Pierre et Marie Curie, Paris, France
| | - Laura Vera
- CEA, iBiTecS, Service d’Ingénierie Moléculaire des Protéines, Laboratoire de Toxinologie Moléculaire et Biotechnologies, Gif-sur-Yvette, France
| | - Nicolas Gilles
- CEA, iBiTecS, Service d’Ingénierie Moléculaire des Protéines, Laboratoire de Toxinologie Moléculaire et Biotechnologies, Gif-sur-Yvette, France
| | - Renée Ménez
- CEA, iBiTecS, Service d’Ingénierie Moléculaire des Protéines, Laboratoire de Toxinologie Moléculaire et Biotechnologies, Gif-sur-Yvette, France
| | - Elodie Marcon
- CEA, iBiTecS, Service d’Ingénierie Moléculaire des Protéines, Laboratoire de Toxinologie Moléculaire et Biotechnologies, Gif-sur-Yvette, France
| | - Enrico A. Stura
- CEA, iBiTecS, Service d’Ingénierie Moléculaire des Protéines, Laboratoire de Toxinologie Moléculaire et Biotechnologies, Gif-sur-Yvette, France
| | - Denis Servent
- CEA, iBiTecS, Service d’Ingénierie Moléculaire des Protéines, Laboratoire de Toxinologie Moléculaire et Biotechnologies, Gif-sur-Yvette, France
- * E-mail:
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Lyukmanova EN, Shulepko MA, Shenkarev ZO, Dolgikh DA, Kirpichnikov MP. In vitro production of three-finger neurotoxins from snake venoms, a disulfide rich proteins. Problems and their solutions (Review). RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2010; 36:149-58. [DOI: 10.1134/s1068162010020019] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Aguilar MB, de la Rosa RAC, Falcón A, Olivera BM, Heimer de la Cotera EP. Peptide pal9a from the venom of the turrid snail Polystira albida from the Gulf of Mexico: purification, characterization, and comparison with P-conotoxin-like (framework IX) conoidean peptides. Peptides 2009; 30:467-76. [PMID: 18948154 PMCID: PMC2728929 DOI: 10.1016/j.peptides.2008.09.016] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2008] [Revised: 09/12/2008] [Accepted: 09/17/2008] [Indexed: 11/17/2022]
Abstract
A novel peptide, pal9a, was purified from the venom duct extract of the turrid snail, Polystira albida (superfamily Conoidea, family Turridae), collected in the Gulf of Mexico. Its primary structure was determined by automated Edman degradation and confirmed by mass spectrometry. Turritoxin pal9a contains 34 amino acid residues, including 6 Cys residues arranged in the pattern C-C-C-C-C-C (framework IX, where "-" represents one or more non-Cys amino acids), which characterizes the P-conotoxins. Peptide pal9a is the first P-conotoxin-like turritoxin characterized from a member of family Turridae of the Western Atlantic. The primary structure of turritoxin pal9a, NVCDGDACPDGVCRSGCTCDFNVAQRKDTCFYPQ-nh(2) (-nh(2), amidated C-terminus; calculated monoisotopic mass, 3679.48Da; experimental monoisotopic mass, 3678.84Da), shows variable degrees of low sequence similarity with framework IX-toxins from turrid (three species of Lophiotoma, and four species of Gemmula), terebrid (Hastula hectica), and Conus species of the Indo-Pacific (C. textile, C. gloriamaris, C. amadis, and C. litteratus) and of the Western Atlantic (C. regius). During the comparison of peptide pal9a with the other framework IX-toxins known to date, we realized that, in general, these peptides are hydrophilic, acidic compounds that have not been found in the fish-hunting Conus species studied thus far; we also found support for the notion that they may belong to several distinct gene superfamilies, even those from the same species. Given the broad distribution of framework IX-toxins within superfamily Conoidea, it will be interesting to identify the still-unknown molecular targets of P-conotoxins, P-conotoxin-like turritoxins, and P-conotoxin-like augertoxins.
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Affiliation(s)
- Manuel B Aguilar
- Laboratorio de Neurofarmacología Marina, Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de Mexico, Campus Juriquilla, Querétaro 76230, Mexico.
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Fruchart-Gaillard C, Mourier G, Marquer C, Stura E, Birdsall NJM, Servent D. Different Interactions between MT7 Toxin and the Human Muscarinic M1 Receptor in Its Free and N-Methylscopolamine-Occupied States. Mol Pharmacol 2008; 74:1554-63. [DOI: 10.1124/mol.108.050773] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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14
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Lyukmanova EN, Shenkarev ZO, Schulga AA, Ermolyuk YS, Mordvintsev DY, Utkin YN, Shoulepko MA, Hogg RC, Bertrand D, Dolgikh DA, Tsetlin VI, Kirpichnikov MP. Bacterial Expression, NMR, and Electrophysiology Analysis of Chimeric Short/Long-chain α-Neurotoxins Acting on Neuronal Nicotinic Receptors. J Biol Chem 2007; 282:24784-91. [PMID: 17576769 DOI: 10.1074/jbc.m611263200] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Different snake venom neurotoxins block distinct subtypes of nicotinic acetylcholine receptors (nAChR). Short-chain alpha-neurotoxins preferentially inhibit muscle-type nAChRs, whereas long-chain alpha-neurotoxins block both muscle-type and alpha7 homooligomeric neuronal nAChRs. An additional disulfide in the central loop of alpha- and kappa-neurotoxins is essential for their action on the alpha7 and alpha3beta2 nAChRs, respectively. Design of novel toxins may help to better understand their subtype specificity. To address this problem, two chimeric toxins were produced by bacterial expression, a short-chain neurotoxin II Naja oxiana with the grafted disulfide-containing loop from long-chain neurotoxin I from N. oxiana, while a second chimera contained an additional A29K mutation, the most pronounced difference in the central loop tip between long-chain alpha-neurotoxins and kappa-neurotoxins. The correct folding and structural stability for both chimeras were shown by (1)H and (1)H-(15)N NMR spectroscopy. Electrophysiology experiments on the nAChRs expressed in Xenopus oocytes revealed that the first chimera and neurotoxin I blockalpha7 nAChRs with similar potency (IC(50) 6.1 and 34 nM, respectively). Therefore, the disulfide-confined loop endows neurotoxin II with full activity of long-chain alpha-neurotoxin and the C-terminal tail in neurotoxin I is not essential for binding. The A29K mutation of the chimera considerably diminished the affinity for alpha7 nAChR (IC(50) 126 nM) but did not convey activity at alpha3beta2 nAChRs. Docking of both chimeras toalpha7 andalpha3beta2 nAChRs was possible, but complexes with the latter were not stable at molecular dynamics simulations. Apparently, some other residues and dimeric organization of kappa-neurotoxins underlie their selectivity for alpha3beta2 nAChRs.
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Affiliation(s)
- Ekaterina N Lyukmanova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya Str., 117997 Moscow, Russia
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15
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Chowdhury P, Gondry M, Genet R, Martin JL, Ménez A, Négrerie M, Petrich JW. Picosecond Dynamics of a Peptide from the Acetylcholine Receptor Interacting with a Neurotoxin Probed by Tailored Tryptophan Fluorescence¶. Photochem Photobiol 2007. [DOI: 10.1562/0031-8655(2003)0770151pdoapf2.0.co2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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16
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Pawlak J, Mackessy SP, Fry BG, Bhatia M, Mourier G, Fruchart-Gaillard C, Servent D, Ménez R, Stura E, Ménez A, Kini RM. Denmotoxin, a three-finger toxin from the colubrid snake Boiga dendrophila (Mangrove Catsnake) with bird-specific activity. J Biol Chem 2006; 281:29030-41. [PMID: 16864572 DOI: 10.1074/jbc.m605850200] [Citation(s) in RCA: 151] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Boiga dendrophila (mangrove catsnake) is a colubrid snake that lives in Southeast Asian lowland rainforests and mangrove swamps and that preys primarily on birds. We have isolated, purified, and sequenced a novel toxin from its venom, which we named denmotoxin. It is a monomeric polypeptide of 77 amino acid residues with five disulfide bridges. In organ bath experiments, it displayed potent postsynaptic neuromuscular activity and irreversibly inhibited indirectly stimulated twitches in chick biventer cervicis nerve-muscle preparations. In contrast, it induced much smaller and readily reversible inhibition of electrically induced twitches in mouse hemidiaphragm nerve-muscle preparations. More precisely, the chick muscle alpha(1)betagammadelta-nicotinic acetylcholine receptor was 100-fold more susceptible compared with the mouse receptor. These data indicate that denmotoxin has a bird-specific postsynaptic activity. We chemically synthesized denmotoxin, crystallized it, and solved its crystal structure at 1.9 A by the molecular replacement method. The toxin structure adopts a non-conventional three-finger fold with an additional (fifth) disulfide bond in the first loop and seven additional residues at its N terminus, which is blocked by a pyroglutamic acid residue. This is the first crystal structure of a three-finger toxin from colubrid snake venom and the first fully characterized bird-specific toxin. Denmotoxin illustrates the relationship between toxin specificity and the primary prey type that constitutes the snake's diet.
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Affiliation(s)
- Joanna Pawlak
- Department of Biological Sciences, Faculty of Science, National University of Singapore
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17
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Fruchart-Gaillard C, Mourier G, Marquer C, Ménez A, Servent D. Identification of Various Allosteric Interaction Sites on M1Muscarinic Receptor Using125I-Met35-Oxidized Muscarinic Toxin 7. Mol Pharmacol 2006; 69:1641-51. [PMID: 16439611 DOI: 10.1124/mol.105.020883] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Monoiodinated, Met35-oxidized muscarinic toxin 7 (MT7ox) was synthesized, and its affinity constants for free or N-methyl scopolamine (NMS)-occupied hM1 receptor were measured directly by equilibrium and kinetic binding experiments. Identical values were obtained with the two types of assay methods, 14 pM and 0.9 nM in free or NMS-liganded receptor states, respectively, highlighting a strong negative cooperativity between this allosteric toxin and NMS. Identical results were obtained with indirect binding experiments with [3H]NMS using the ternary complex model, clearly demonstrating the reciprocal nature of this cooperativity. Furthermore, the effects of various orthosteric and allosteric agents on the dissociation kinetic of 125I-MT7ox were measured and show that, except for the MT1 toxin, all of the ligands studied [NMS, atropine, gallamine, brucine, tacrine, staurosporine, and (9S,10S,12R)-2,3,9,10,11-hexahydro-10-hydroxy-9-methyl-1-oxo-9,12-epoxy-1H-diindolo[1,2,3-fg:3',2',1'-kl]pyrrolo[3,4-i][1,6]benzodiazocine-10-carboxylic acid hexyl ester (KT5720)] interact allosterically with muscarinic toxin 7. Equilibrium binding experiments with 125I-MT7ox and [3H]NMS were conducted to reveal the effects of these ligands on the free receptor, and affinity constants (pKx values) were calculated using the allosteric ternary complex model. Our results suggest that MT7 toxin interacts with hM1 receptor at a specific allosteric site, which may partially overlap those identified previously for "classic" or "atypical" allosteric agents and highlight the potential of this new allosteric tracer in studying allosterism at muscarinic receptors.
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Thai R, Moine G, Desmadril M, Servent D, Tarride JL, Ménez A, Léonetti M. Antigen Stability Controls Antigen Presentation. J Biol Chem 2004; 279:50257-66. [PMID: 15364925 DOI: 10.1074/jbc.m405738200] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We investigated whether protein stability controls antigen presentation using a four disulfide-containing snake toxin and three derivatives carrying one or two mutations (L1A, L1A/H4Y, and H4Y). These mutations were anticipated to increase (H4Y) or decrease (L1A) the antigen non-covalent stabilizing interactions, H4Y being naturally and frequently observed in neurotoxins. The chemically synthesized derivatives shared similar three-dimensional structure, biological activity, and T epitope pattern. However, they displayed differential thermal unfolding capacities, ranging from 65 to 98 degrees C. Using these differentially stable derivatives, we demonstrated that antigen stability controls antigen proteolysis, antigen processing in antigen-presenting cells, T cell stimulation, and kinetics of expression of T cell determinants. Therefore, non-covalent interactions that control the unfolding capacity of an antigen are key parameters in the efficacy of antigen presentation. By affecting the stabilizing interaction network of proteins, some natural mutations may modulate the subsequent T-cell stimulation and might help microorganisms to escape the immune response.
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Affiliation(s)
- Robert Thai
- Département d'Ingénierie et d'Etudes des Protéines, Commissariat à l'Energie Atomique, C.E. Saclay, 91191 Gif-sur-Yvette, France
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19
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Gilquin B, Bourgoin M, Ménez R, Le Du MH, Servent D, Zinn-Justin S, Ménez A. Motions and structural variability within toxins: implication for their use as scaffolds for protein engineering. Protein Sci 2003; 12:266-77. [PMID: 12538890 PMCID: PMC2312431 DOI: 10.1110/ps.0227703] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Animal toxins are small proteins built on the basis of a few disulfide bonded frameworks. Because of their high variability in sequence and biologic function, these proteins are now used as templates for protein engineering. Here we report the extensive characterization of the structure and dynamics of two toxin folds, the "three-finger" fold and the short alpha/beta scorpion fold found in snake and scorpion venoms, respectively. These two folds have a very different architecture; the short alpha/beta scorpion fold is highly compact, whereas the "three-finger" fold is a beta structure presenting large flexible loops. First, the crystal structure of the snake toxin alpha was solved at 1.8-A resolution. Then, long molecular dynamics simulations (10 ns) in water boxes of the snake toxin alpha and the scorpion charybdotoxin were performed, starting either from the crystal or the solution structure. For both proteins, the crystal structure is stabilized by more hydrogen bonds than the solution structure, and the trajectory starting from the X-ray structure is more stable than the trajectory started from the NMR structure. The trajectories started from the X-ray structure are in agreement with the experimental NMR and X-ray data about the protein dynamics. Both proteins exhibit fast motions with an amplitude correlated to their secondary structure. In contrast, slower motions are essentially only observed in toxin alpha. The regions submitted to rare motions during the simulations are those that exhibit millisecond time-scale motions. Lastly, the structural variations within each fold family are described. The localization and the amplitude of these variations suggest that the regions presenting large-scale motions should be those tolerant to large insertions or deletions.
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Affiliation(s)
- Bernard Gilquin
- Département d'Ingénierie et d'Etude des Protéines, CEA, 91191 Gif sur Yvette, France.
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Chowdhury P, Gondry M, Genet R, Martin JL, Ménez A, Négrerie M, Petrich JW. Picosecond dynamics of a peptide from the acetylcholine receptor interacting with a neurotoxin probed by tailored tryptophan fluorescence. Photochem Photobiol 2003; 77:151-7. [PMID: 12785053 DOI: 10.1562/0031-8655(2003)077<0151:pdoapf>2.0.co;2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
A tryptophan analog, dehydro-N-acetyl-L-tryptophanamide (delta-NATA), which is produced enzymatically via L-tryptophan 2',3'-oxidase from Chromobacterium violaceum, is newly used for time-resolved fluorescence. The absorption and emission maxima of delta-NATA at 332 and 417 nm, respectively, in 20% dimethylformamide-water are significantly shifted to the red with respect to those of tryptophan in water, permitting us to measure its fluorescence in the presence of tryptophan residues. We demonstrate that the steady-state spectra and the fluorescence decay of delta-NATA are very sensitive to environment, changing dramatically with solvent as the chromophore is localized within a protein and when this tagged protein binds to a peptide. The tryptophan oxidase was also used to modify the single Trp of a neurotoxin from snake (Naja nigricollis) venom. Modification of the toxin alpha (dehydrotryptophan-toxin alpha) permitted its investigation in complex with a synthetic 15-amino acid peptide corresponding to a loop of the agonist-binding site of acetylcholine receptor (AchR) from Torpedo marmorata species. The peptide alpha-185 possesses a single Trp at the third position (Trp187 of AchR) and a disulfide bridge between Cys192 and Cys193. A single-exponential rotational diffusion time with a constant of 1.65 ns is measured for the isolated 15-amino acid peptide. This suggests that Trp motion in the peptide in solution is strongly correlated with the residues downstream the peptide sequence, which may in part be attributed to long-range order imposed by the disulfide bond. The dynamics of the bound peptide are very different: the presence of two correlation times indicates that the Trp187 of the peptide has a fast motion (taur1 = 140 ps and r(0)1 = 0.14) relative to the overall rotation of the complex (taur2 = 3.4 ns and r(0)2 = 0.04). The correlation of the Trp residue with its neighboring amino acid residues and with the overall motion of the peptide is lost, giving rise to its rapid restricted motion. Thus, the internal dynamics of interacting peptides change on binding.
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21
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Mourier G, Dutertre S, Fruchart-Gaillard C, Ménez A, Servent D. Chemical synthesis of MT1 and MT7 muscarinic toxins: critical role of Arg-34 in their interaction with M1 muscarinic receptor. Mol Pharmacol 2003; 63:26-35. [PMID: 12488533 DOI: 10.1124/mol.63.1.26] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Two muscarinic toxins, MT1 and MT7, were obtained by one-step solid-phase synthesis using the 9-fluorenylmethoxycarbonyl-based method. The synthetic and natural toxins, isolated from the snake venom or recombinantly expressed, display identical physicochemical properties and pharmacological profiles. High protein recovery allowed us to specify the selectivity of these toxins for various muscarinic receptor subtypes. Thus, sMT7 has a selectivity for the M1 receptor that is at least 20,000 times that for the other subtypes. The stability of the toxin-receptor complexes indicates that sMT1 interacts reversibly with the M1 receptor, unlike sMT7, which binds it quasi-irreversibly. The effect of the synthetic toxins on the atropine-induced [3H]N-methylscopolamine (NMS) dissociation confirms that sMT7 targets the allosteric site on the M1 receptor, whereas sMT1 seems interact on the orthosteric one. The great decreases in the binding potencies observed after the R34A modification in sMT1 and sMT7 toxins highlight the functional role of this conserved residue in their interactions with the M1 receptor. Interestingly, after the R34A modification, the sMT7 toxin binds reversibly on the M1 receptor. Furthermore, the potency of sMT7-R34A for the NMS-occupied receptor is lower compared with unmodified toxin, supporting the role of this residue in the allosteric interaction of sMT7. All these results and the different charge distributions observed at the two toxin surfaces of their structure models support the hypothesis that the two toxins recognize the M1 receptor differently.
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Affiliation(s)
- Gilles Mourier
- Commissariat à l'Energie Atomique, Département d'Ingénierie et d'Etude des Protéines, Gif-sur-Yvette, France
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22
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Miles LA, Dy CY, Nielsen J, Barnham KJ, Hinds MG, Olivera BM, Bulaj G, Norton RS. Structure of a novel P-superfamily spasmodic conotoxin reveals an inhibitory cystine knot motif. J Biol Chem 2002; 277:43033-40. [PMID: 12193600 DOI: 10.1074/jbc.m206690200] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Conotoxin gm9a, a putative 27-residue polypeptide encoded by Conus gloriamaris, was recently identified as a homologue of the "spasmodic peptide", tx9a, isolated from the venom of the mollusk-hunting cone shell Conus textile (Lirazan, M. B., Hooper, D., Corpuz, G. P., Ramilo, C. A., Bandyopadhyay, P., Cruz, L. J., and Olivera, B. M. (2000) Biochemistry 39, 1583-1588). The C. gloriamaris spasmodic peptide has been synthesized, and the refolded polypeptide was shown to be biologically active using a mouse bioassay. The chemically synthesized gm9a elicited the same symptomatology described previously for natively folded tx9a, and gm9a and tx9a were of similar potency, implying that neither the two gamma-carboxyglutamate (Gla) residues found in tx9a (Ser(8) and Ala(13) in gm9a) nor Gly(1) (Ser(1) in gm9a) are crucial for biological activity. We have determined the three-dimensional structure of gm9a in aqueous solution and demonstrated that the molecule adopts the well known inhibitory cystine knot motif constrained by three disulfide bonds involving Cys(2)-Cys(16), Cys(6)-Cys(18) and Cys(12)-Cys(23). Based on the gm9a structure, the sites of Gla substitution in tx9a are in loops located on one surface of the molecule, which is unlikely to be involved directly in receptor binding. Because this is the first structure reported for a member of the newly defined P-superfamily conotoxins, a comparison has been made with structurally related conotoxins. This shows that the structural scaffold that characterizes the P-conotoxins has the greatest potential for exhibiting structural diversity among the robust inhibitory cystine knot-containing conotoxins, a finding that has implications for functional epitope mimicry and protein engineering.
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Affiliation(s)
- Luke A Miles
- The Walter and Eliza Hall Institute of Medical Research, NMR Laboratory, 381 Royal Parade, Parkville 3052, Australia
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Poh SL, Mourier G, Thai R, Armugam A, Molgó J, Servent D, Jeyaseelan K, Ménez A. A synthetic weak neurotoxin binds with low affinity to Torpedo and chicken alpha7 nicotinic acetylcholine receptors. EUROPEAN JOURNAL OF BIOCHEMISTRY 2002; 269:4247-56. [PMID: 12199703 DOI: 10.1046/j.1432-1033.2002.03113.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Weak neurotoxins from snake venom are small proteins with five disulfide bonds, which have been shown to be poor binders of nicotinic acetylcholine receptors. We report on the cloning and sequencing of four cDNAs encoding weak neurotoxins from Naja sputatrix venom glands. The protein encoded by one of them, Wntx-5, has been synthesized by solid-phase synthesis and characterized. The physicochemical properties of the synthetic toxin (sWntx-5) agree with those anticipated for the natural toxin. We show that this toxin interacts with relatively low affinity (K(d) = 180 nm) with the muscular-type acetylcholine receptor of the electric organ of T. marmorata, and with an even weaker affinity (90 microm) with the neuronal alpha7 receptor of chicken. Electrophysiological recordings using isolated mouse hemidiaphragm and frog cutaneous pectoris nerve-muscle preparations revealed no blocking activity of sWntx-5 at microm concentrations. Our data confirm previous observations that natural weak neurotoxins from cobras have poor affinity for nicotinic acetylcholine receptors.
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Affiliation(s)
- Siew Lay Poh
- Département d'Ingénierie et d'Etudes des Protéines, CEA, Saclay, 91191 Gif-sur-Yvette Cedex, France
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Gong N, Armugam A, Mirtschin P, Jeyaseelan K. Cloning and characterization of the pseudonajatoxin b precursor. Biochem J 2001; 358:647-56. [PMID: 11535126 PMCID: PMC1222099 DOI: 10.1042/0264-6021:3580647] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
An Australian common brown snake, Pseudonaja textilis, is known to contain highly lethal neurotoxins. Among them, a long-chain alpha-neurotoxin, pseudonajatoxin b, has been identified. In this report, while presenting evidence for the presence of at least four such long-chain alpha-neurotoxins in the venom of P. textilis, we describe the characteristics of both the mRNA and the gene responsible for the synthesis of these neurotoxins. A precursor toxin synthesized from the gene has been identified as being capable of producing the isoforms possibly by post-translational modifications at its C-terminal end. Recombinant toxins corresponding to the precursor and its product have been found to possess similar binding affinities for muscular acetylcholine receptors (IC(50)=3x10(-8) M) and a lethality, LD(50), of 0.15 microg/g in mice.
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Affiliation(s)
- N Gong
- Department of Biochemistry, Faculty of Medicine, National University of Singapore, 10 Medical Drive, Singapore 119260
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Vulfius CA, Krasts IV, Utkin YN, Tsetlin VI. Nicotinic receptors in Lymnaea stagnalis neurons are blocked by alpha-neurotoxins from cobra venoms. Neurosci Lett 2001; 309:189-92. [PMID: 11514073 DOI: 10.1016/s0304-3940(01)02081-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The influence of cobra neurotoxins on the Cl-dependent responses to acetylcholine (ACh) of Lymnaea neurons was studied by the voltage-clamp technique. It was found that a short chain neurotoxin II (NT II), a long chain cobratoxin (CTX) and weak neurotoxin (WTX) diminished the ACh-induced currents, the block being concentration-dependent and competitive. The IC(50) values of 130 nM for CTX, 11 microM for NT II, and 67 microM for WTX were determined. The block induced by NT II was quickly reversible upon toxin washout, whereas the action of CTX and WTX was only partially reversible even after an hour of intensive washing. The data obtained suggest that acetylcholine receptors (AChRs) in Lymnaea neurons have common features with cation-selective alpha 7 AChRs of vertebrates and one type of Aplysia Cl-conducting AChRs.
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Affiliation(s)
- C A Vulfius
- lnstitute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia.
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Michalet S, Teixeira F, Gilquin B, Mourier G, Servent D, Drevet P, Binder P, Tzartos S, Ménez A, Kessler P. Relative spatial position of a snake neurotoxin and the reduced disulfide bond alpha (Cys192-Cys193) at the alpha gamma interface of the nicotinic acetylcholine receptor. J Biol Chem 2000; 275:25608-15. [PMID: 10807914 DOI: 10.1074/jbc.m002362200] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We determined the distances separating five functionally important residues (Gln(10), Lys(27), Trp(29), Arg(33), and Lys(47)) of a three-fingered snake neurotoxin from the reduced disulfide bond alpha(Cys(192)-Cys(193)) located at the alphagamma interface of the Torpedo nicotinic acetylcholine receptor. Each toxin position was substituted individually for a cysteine, which was then linked to a maleimido moiety through three different spacers, varying in length from 10 to 22 A. We estimated the coupling efficiency between the 15 toxin derivatives and the reduced cystine alpha(192-193) by gel densitometry of Coomassie Blue-stained gels. A nearly quantitative coupling was observed between alphaCys(192) and/or alphaCys(193) and all probes introduced at the tip of the first (position 10) and second (position 33) loops of Naja nigricollis alpha-neurotoxin. These data sufficed to locate the reactive thiolate in a "croissant-shaped" volume comprised between the first two loops of the toxin. The volume was further restrained by taking into account the absence or partial coupling of the other derivatives. Altogether, the data suggest that alphaCys(192) and/or alphaCys(193), at the alphagamma interface of a muscular-type acetylcholine receptor, is (are) located in a volume located between 11.5 and 15.5 A from the alpha-carbons at positions 10 and 33 of the toxin, under the tip of the toxin first loop and close to the second one.
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Affiliation(s)
- S Michalet
- CEA/Saclay, Département d'Ingénierie et d'Etudes des Protéines, Gif-sur-Yvette, France
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