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Martin-Eauclaire MF, Marchot P. Obituary - Hervé Paul Marie Antoine ROCHAT 1937-2023. Toxicon 2023; 233:107249. [PMID: 37659118 DOI: 10.1016/j.toxicon.2023.107249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/04/2023]
Affiliation(s)
- Marie-France Martin-Eauclaire
- Lab. "Architecture et Fonction des Macromolécules Biologiques" (AFMB), Centre National de La Recherche Scientifique (CNRS), Aix-Marseille Univ. (AMU), Faculté des Sciences - Campus Luminy, Marseille, France.
| | - Pascale Marchot
- Lab. "Architecture et Fonction des Macromolécules Biologiques" (AFMB), Centre National de La Recherche Scientifique (CNRS), Aix-Marseille Univ. (AMU), Faculté des Sciences - Campus Luminy, Marseille, France.
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PnPP-19 Peptide Restores Erectile Function in Hypertensive and Diabetic Animals Through Intravenous and Topical Administration. J Sex Med 2019; 16:365-374. [PMID: 30773502 DOI: 10.1016/j.jsxm.2019.01.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2018] [Revised: 01/02/2019] [Accepted: 01/04/2019] [Indexed: 01/18/2023]
Abstract
INTRODUCTION With the aim of overcoming the high toxicity of PnTx2-6 (or δ-CNTX-Pn2a), a toxin from the venom of the armed spider (Phoneutria nigriventer), the 19-aminoacid peptide, PnPP-19 (P nigriventer potentiator peptide), was synthesized based on molecular modeling studies of PnTx2-6. PnPP-19 improved the erectile function of normotensive rats and mice, without eliciting side effects, and no signs of toxicity were observed. In addition, PnPP-19 was able to potentiate the effect of sildenafil. AIM To evaluate the efficacy of PnPP-19 in hypertensive and diabetic mouse/rat models in restoring erectile function, after topical administration; verify the biodistribution of PnPP-19 administration (topical and intravenous), permeation, and cyclic guanosine monophosphate (cGMP)/nitric oxide via implication. METHODS Corpus cavernosum relaxation was evaluated using cavernous strips from male spontaneous hypertensive rats (SHR) and from streptozotocin (STZ)-diabetic mice contracted with phenylephrine and submitted to electrical field stimulation before and after incubation with PnPP-19 (10-8 mol/L, 10 minutes) or vehicle. This procedure was also used to determine cGMP/nitric oxide levels, at 8 Hz and to check the effect of PnPP-19 with sildenafil citrate. Biodistribution assays were performed using iodine 123-radiolabeled PnPP-19. In vivo erectile function was evaluated using intracavernosal pressure/main arterial pressure ratio in STZ-diabetic rats after PnPP-19 topical administration. MAIN OUTCOME MEASURES PnPP-19 may become a new drug able to fill the gap in the pharmacologic treatment of erectile dysfunction, especially for hypertensive and diabetic individuals RESULTS: PnPP-19 potentiated corpus cavernosum relaxation, in both control and SHR rats. SHR-cavernosal tissue treated with PnPP-19 (1-32 Hz) reached the same relaxation levels as control Wistar rats (16 and 32 Hz). PnPP-19 treatment improved cavernosal tissue relaxation in STZ-diabetic mice and rats. PnPP-19 enhanced cGMP levels in STZ-diabetic mice corpus cavernosum strips. After topical or intravenous administration in rats, 123I-PnPP-19 was mainly recruited to the penis. When topically administered (400 μg/rat), PnPP-19 restores erectile function in STZ-diabetic rats, also improving it in healthy rats by increasing the intracavernosal pressure/main arterial pressure ratio. PnPP-19 exhibited an additive effect when co-administered with sildenafil, showing a novel mode of action regardless of phosphodiesterase type 5 inhibition. CLINICAL IMPLICATIONS PnPP-19 seems to be an indicated drug to be tested to treat ED in diabetic and hypertensive patients. STRENGTH & LIMITATIONS PnPP-19, although active by topical application and showing safety to human beings (not shown), has low permeability, about 10% of the applied dose. CONCLUSION Our results showed that PnPP-19 may emerge as a potent new drug that can be topically administered, becoming a promising alternative for erectile dysfunction treatment. Nunes da Silva C, Pedrosa Nunes K, De Marco Almeida F, et al. PnPP-19 Peptide Restores Erectile Function In Hypertensive And Diabetic Animals Through Intravenous And Topical Administration. J Sex Med 2019;16:365-374.
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β/δ-PrIT1, a highly insecticidal toxin from the venom of the Brazilian spider Phoneutria reidyi (F.O. Pickard-Cambridge, 1897). Toxicon 2015. [DOI: 10.1016/j.toxicon.2015.07.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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Matavel A, Fleury C, Oliveira LC, Molina F, de Lima ME, Cruz JS, Cordeiro MN, Richardson M, Ramos CHI, Beirão PSL. Structure and activity analysis of two spider toxins that alter sodium channel inactivation kinetics. Biochemistry 2009; 48:3078-88. [PMID: 19231838 DOI: 10.1021/bi802158p] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this work, Phoneutria nigriventer toxins PnTx2-5 and PnTx2-6 were shown to markedly delay the fast inactivation kinetics of neuronal-type sodium channels. Furthermore, our data show that they have significant differences in their interaction with the channel. PnTx2-6 has an affinity 6 times higher than that of PnTx2-5, and its effects are not reversible within 10-15 min of washing. PnTx2-6 partially (59%) competes with the scorpion alpha-toxin AaHII, but not with the scorpion beta-toxin CssIV, thus suggesting a mode of action similar to that of site 3 toxins. However, PnTx2-6 is not removed by strong depolarizing pulses, as in the known site 3 toxins. We have also established the correct PnTx2-5 amino acid sequence and confirmed the sequence of PnTx2-6, in both cases establishing that the cysteines are in their oxidized form. A structural model of each toxin is proposed. They show structures with poor alpha-helix content. The model is supported by experimental and theoretical tests. A likely binding region on PnTx2-5 and PnTx2-6 is proposed on the basis of their different affinities and sequence differences.
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Affiliation(s)
- Alessandra Matavel
- Department of Biochemistry and Immunology, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
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Borges A, De Sousa L, Espinoza J, Santos RG, Kalapothakis E, Valadares D, Chávez-Olórtegui C. Characterization of Tityus scorpion venoms using synaptosome binding assays and reactivity towards Venezuelan and Brazilian Antivenoms. Toxicon 2008; 51:66-79. [DOI: 10.1016/j.toxicon.2007.08.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2007] [Revised: 08/13/2007] [Accepted: 08/14/2007] [Indexed: 10/22/2022]
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Moran Y, Kahn R, Cohen L, Gur M, Karbat I, Gordon D, Gurevitz M. Molecular analysis of the sea anemone toxin Av3 reveals selectivity to insects and demonstrates the heterogeneity of receptor site-3 on voltage-gated Na+ channels. Biochem J 2007; 406:41-8. [PMID: 17492942 PMCID: PMC1948988 DOI: 10.1042/bj20070233] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Av3 is a short peptide toxin from the sea anemone Anemonia viridis shown to be active on crustaceans and inactive on mammals. It inhibits inactivation of Na(v)s (voltage-gated Na+ channels) like the structurally dissimilar scorpion alpha-toxins and type I sea anemone toxins that bind to receptor site-3. To examine the potency and mode of interaction of Av3 with insect Na(v)s, we established a system for its expression, mutagenized it throughout, and analysed it in toxicity, binding and electrophysiological assays. The recombinant Av3 was found to be highly toxic to blowfly larvae (ED50=2.65+/-0.46 pmol/100 mg), to compete well with the site-3 toxin LqhalphaIT (from the scorpion Leiurus quinquestriatus) on binding to cockroach neuronal membranes (K(i)=21.4+/-7.1 nM), and to inhibit the inactivation of Drosophila melanogaster channel, DmNa(v)1, but not that of mammalian Na(v)s expressed in Xenopus oocytes. Moreover, like other site-3 toxins, the activity of Av3 was synergically enhanced by ligands of receptor site-4 (e.g. scorpion beta-toxins). The bioactive surface of Av3 was found to consist mainly of aromatic residues and did not resemble any of the bioactive surfaces of other site-3 toxins. These analyses have portrayed a toxin that might interact with receptor site-3 in a different fashion compared with other ligands of this site. This assumption was corroborated by a D1701R mutation in DmNa(v)1, which has been shown to abolish the activity of all other site-3 ligands, except Av3. All in all, the present study provides further evidence for the heterogeneity of receptor site-3, and raises Av3 as a unique model for design of selective anti-insect compounds.
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Affiliation(s)
- Yehu Moran
- Department of Plant Sciences, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Ramat-Aviv 69978, Tel-Aviv, Israel
| | - Roy Kahn
- Department of Plant Sciences, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Ramat-Aviv 69978, Tel-Aviv, Israel
| | - Lior Cohen
- Department of Plant Sciences, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Ramat-Aviv 69978, Tel-Aviv, Israel
| | - Maya Gur
- Department of Plant Sciences, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Ramat-Aviv 69978, Tel-Aviv, Israel
| | - Izhar Karbat
- Department of Plant Sciences, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Ramat-Aviv 69978, Tel-Aviv, Israel
| | - Dalia Gordon
- Department of Plant Sciences, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Ramat-Aviv 69978, Tel-Aviv, Israel
- Correspondence may be addressed to either of these authors (email or )
| | - Michael Gurevitz
- Department of Plant Sciences, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Ramat-Aviv 69978, Tel-Aviv, Israel
- Correspondence may be addressed to either of these authors (email or )
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Karbat I, Kahn R, Cohen L, Ilan N, Gilles N, Corzo G, Froy O, Gur M, Albrecht G, Heinemann SH, Gordon D, Gurevitz M. The unique pharmacology of the scorpion α-like toxin Lqh3 is associated with its flexible C-tail. FEBS J 2007; 274:1918-31. [PMID: 17355257 DOI: 10.1111/j.1742-4658.2007.05737.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The affinity of scorpion alpha-toxins for various voltage-gated sodium channels (Na(v)s) differs considerably despite similar structures and activities. It has been proposed that key bioactive residues of the five-residue-turn (residues 8-12) and the C-tail form the NC domain, whose topology is dictated by a cis or trans peptide-bond conformation between residues 9 and 10, which correlates with the potency on insect or mammalian Na(v)s. We examined this hypothesis using Lqh3, an alpha-like toxin from Leiurus quinquestriatus hebraeus that is highly active in insects and mammalian brain. Lqh3 exhibits slower association kinetics to Na(v)s compared with other alpha-toxins and its binding to insect Na(v)s is pH-dependent. Mutagenesis of Lqh3 revealed a bi-partite bioactive surface, composed of the Core and NC domains, as found in other alpha-toxins. Yet, substitutions at the five-residue turn and stabilization of the 9-10 bond in the cis conformation did not affect the activity. However, substitution of hydrogen-bond donors/acceptors at the NC domain reduced the pH-dependency of toxin binding, while retaining its high potency at Drosophila Na(v)s expressed in Xenopus oocytes. Based on these results and the conformational flexibility and rearrangement of intramolecular hydrogen-bonds at the NC domain, evident from the known solution structure, we suggest that acidic pH or specific mutations at the NC domain favor toxin conformations with high affinity for the receptor by stabilizing the bound toxin-receptor complex. Moreover, the C-tail flexibility may account for the slower association rates and suggests a novel mechanism of dynamic conformer selection during toxin binding, enabling alpha-like toxins to affect a broad range of Na(v)s.
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Affiliation(s)
- Izhar Karbat
- Department of Plant Sciences, George S.Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv, Tel Aviv, Israel
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Hammoudi-Triki D, Lefort J, Rougeot C, Robbe-Vincent A, Bon C, Laraba-Djebari F, Choumet V. Toxicokinetic and toxicodynamic analyses of Androctonus australis hector venom in rats: optimization of antivenom therapy. Toxicol Appl Pharmacol 2006; 218:205-14. [PMID: 17198719 DOI: 10.1016/j.taap.2006.11.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2006] [Revised: 10/31/2006] [Accepted: 11/04/2006] [Indexed: 10/23/2022]
Abstract
This paper reports the simultaneous determination of toxicokinetic and toxicodynamic properties of Androctonus australis hector venom, in the absence and presence of antivenom (F(ab')(2) and Fab), in envenomed rats. After subcutaneous injection of the venom, toxins showed a complete absorption phase from the site of injection associated with a distribution into a large extravascular compartment. The injection of Fab and F(ab')(2) induced the neutralization of venom antigens in the blood compartment, as well as the redistribution of venom components from the extravascular compartment to the blood compartment. Interestingly, F(ab')(2) and Fab showed distinct efficiencies depending on their route of injection. F(ab')(2) induced a faster venom neutralization and redistribution than Fab when injected intravenously. Fab was more effective than F(ab')(2) by the intramuscular route. The hemodynamic effects of Aah venom were further investigated. Changes in mean arterial pressure and heart rate were observed in parallel with an upper airway obstruction. Fab was more effective than F(ab')(2) for preventing early symptoms of envenomation, whatever their route of administration. Intraperitoneal injection of F(ab')(2) and Fab was similar for the prevention of the delayed symptoms, even after a late administration. Fab was more effective than F(ab')(2) in the inhibition of airway resistance, independent of the route and time of administration. These results show that the treatment for scorpion stings might be improved by the intravascular injection of a mixture of Fab and F(ab')(2). If antivenom cannot be administered intravenously, Fab might be an alternative as they are more effective than F(ab')(2) when injected intramuscularly.
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Diniz MRV, Theakston RDG, Crampton JM, Nascimento Cordeiro MD, Pimenta AMC, De Lima ME, Diniz CR. Functional expression and purification of recombinant Tx1, a sodium channel blocker neurotoxin from the venom of the Brazilian “armed” spider, Phoneutria nigriventer. Protein Expr Purif 2006; 50:18-24. [PMID: 16908187 DOI: 10.1016/j.pep.2006.06.012] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2006] [Revised: 06/05/2006] [Accepted: 06/10/2006] [Indexed: 11/21/2022]
Abstract
Tx1 from the venom of the Brazilian spider, Phoneutria nigriventer, is a lethal neurotoxic polypeptide of M(r) 8600 Da with 14 cysteine residues. It is a novel sodium channel blocker which reversibly inhibits sodium currents in CHO cells expressing recombinant sodium (Nav1.2) channels. We cloned and expressed the Tx1 toxin as a thioredoxin fusion product in the cytoplasm of Escherichia coli. After semipurification by immobilized Ni-ion affinity chromatography, the recombinant Tx1 was purified by reverse phase chromatography and characterized. It displayed similar biochemical and pharmacological properties to the native toxin, and it should be useful for further investigation of structure-function relationship of Na channels.
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Affiliation(s)
- Marcelo R V Diniz
- Centro de Pesquisa e Desenvolvimento, Fundação Ezequiel Dias, Rua Conde Pereira Carneiro, 80, 30 510-010 Belo Horizonte (MG), Brazil.
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Cohen L, Lipstein N, Gordon D. Allosteric interactions between scorpion toxin receptor sites on voltage‐gated Na channels imply a novel role for weakly active components in arthropod venom. FASEB J 2006; 20:1933-5. [PMID: 16877526 DOI: 10.1096/fj.05-5545fje] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Scorpion beta and alpha-toxins modify the activation and inactivation of voltage-gated sodium channels. Although the two types of toxin bind at two distinct receptor sites on the same sodium channel, they exhibit synergic effects when coinjected into insects. To clarify the basis of this synergism we examined the mutual effects of alpha and beta toxin representatives in radio-ligand binding assays. We found positive allosteric interactions between receptor site-4 of the excitatory Bj-xtrIT and the depressant LqhIT2 beta toxins and receptor site-3 of the alpha toxin LqhalphaIT, on locust neuronal membranes. Unexpectedly, a nontoxic mutant Bj-xtrIT-E15R, which binds with high affinity to receptor site-4, was able to enhance LqhalphaIT binding and toxicity similarly to the unmodified Bj-xtrIT. This result indicates that mere binding of a nontoxic ligand to receptor site-4 ("silent binding") induces a conformational change that does not alter channel gating, but influences toxin binding at receptor site-3 leading to enhanced toxicity. This finding suggests a new functional role for weakly toxic polypeptides in that they enhance the effect of other active neurotoxins in the arthropod venom. Such silent binding may have also valuable implications in attempts to improve drug efficacy by combining potent drugs with nonactive allosteric enhancers.
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Affiliation(s)
- Lior Cohen
- Department of Plant Sciences, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Ramat-Aviv, Tel-Aviv 69978, Israel
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Cohen L, Gilles N, Karbat I, Ilan N, Gordon D, Gurevitz M. Direct evidence that receptor site-4 of sodium channel gating modifiers is not dipped in the phospholipid bilayer of neuronal membranes. J Biol Chem 2006; 281:20673-20679. [PMID: 16720570 DOI: 10.1074/jbc.m603212200] [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: 11/06/2022] Open
Abstract
In a recent note to Nature, R. MacKinnon has raised the possibility that potassium channel gating modifiers are able to partition in the phospholipid bilayer of neuronal membranes and that by increasing their partial concentration adjacent to their receptor, they affect channel function with apparent high affinity (Lee and MacKinnon (2004) Nature 430, 232-235). This suggestion was adopted by Smith et al. (Smith, J. J., Alphy, S., Seibert, A. L., and Blumenthal, K. M. (2005) J. Biol. Chem. 280, 11127-11133), who analyzed the partitioning of sodium channel modifiers in liposomes. They found that certain modifiers were able to partition in these artificial membranes, and on this basis, they have extrapolated that scorpion beta-toxins interact with their channel receptor in a similar mechanism as that proposed by MacKinnon. Since this hypothesis has actually raised a new conception, we examined it in binding assays using a number of pharmacologically distinct scorpion beta-toxins and insect and mammalian neuronal membrane preparations, as well as by analyzing the rate by which the toxin effect on gating of Drosophila DmNa(v)1 and rat brain rNa(v)1.2a develops. We show that in general, scorpion beta-toxins do not partition in neuronal membranes and that in the case in which a depressant beta-toxin partitions in insect neuronal membranes, this partitioning is unrelated to its interaction with the receptor site and the effect on the gating properties of the sodium channel. These results negate the hypothesis that the high affinity of beta-toxins for sodium channels is gained by their ability to partition in the phospholipid bilayer and clearly indicate that the receptor site for scorpion beta-toxins is accessible to the extracellular solvent.
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Affiliation(s)
- Lior Cohen
- Department of Plant Sciences, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Ramat-Aviv 69978, Tel-Aviv, Israel
| | - Nicolas Gilles
- Commissariat à l'Energie Atomique, Department d'Ingenierie et d'Etudes des Proteines, C.E. Saclay, F-91191 Gif Sur Yvette Cedex, France
| | - Izhar Karbat
- Department of Plant Sciences, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Ramat-Aviv 69978, Tel-Aviv, Israel
| | - Nitza Ilan
- Department of Plant Sciences, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Ramat-Aviv 69978, Tel-Aviv, Israel
| | - Dalia Gordon
- Department of Plant Sciences, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Ramat-Aviv 69978, Tel-Aviv, Israel.
| | - Michael Gurevitz
- Department of Plant Sciences, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Ramat-Aviv 69978, Tel-Aviv, Israel.
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Krifi MN, Savin S, Debray M, Bon C, El Ayeb M, Choumet V. Pharmacokinetic studies of scorpion venom before and after antivenom immunotherapy. Toxicon 2005; 45:187-98. [PMID: 15626368 DOI: 10.1016/j.toxicon.2004.10.007] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2004] [Accepted: 10/07/2004] [Indexed: 11/22/2022]
Abstract
The improvement of the immunotherapeutic treatment of envenomations requires a better knowledge of the pharmacological actions of the scorpion venom and of the mechanism of its in vivo neutralization by antivenom. In the present work, we determined the toxicokinetic parameters of the toxic fraction of Androctonus australis garzonii venom in the absence and after antivenom immunotherapy, in experimentally envenomed rabbits. After subcutaneous injection of the scorpion venom, toxins showed a fast and complete resorption from the site of injection associated with a simultaneous distribution in a large extracellular compartment and with an important body clearance. The precocious intravenous injection of an appropriate antivenom dose was shown to induce an immediate, complete and durable neutralization of toxins, as well as their rapid redistribution from the peripheric compartment to the vascular one. On the contrary, the intramuscular injection of the same antivenom dose produced a slower and partial redistribution of toxins, leading to a delayed neutralization of the venom. The intravenous injection of smaller antivenom doses induced transient decreases of circulating toxins, indicating that a minimal antivenom dose has to be administered to allow an efficient and durable neutralization of the venom. We concluded also that this minimal effective dose of antivenom has to be injected precociously, by intravenous route, to achieve an efficient immunotherapy.
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Affiliation(s)
- Mohamed Naceur Krifi
- Laboratoire d'Immunobiotechnologie et de Biovalorisation, Institut Supérieur des Technologies Médicales de Tunis, 9 rue Prof. Zouhaïr Essafi, 1006 Tunis, Tunisia.
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Cohen L, Karbat I, Gilles N, Ilan N, Benveniste M, Gordon D, Gurevitz M. Common features in the functional surface of scorpion beta-toxins and elements that confer specificity for insect and mammalian voltage-gated sodium channels. J Biol Chem 2004; 280:5045-53. [PMID: 15569679 DOI: 10.1074/jbc.m408427200] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Scorpion beta-toxins that affect the activation of mammalian voltage-gated sodium channels (Navs) have been studied extensively, but little is known about their functional surface and mode of interaction with the channel receptor. To enable a molecular approach to this question, we have established a successful expression system for the anti-mammalian scorpion beta-toxin, Css4, whose effects on rat brain Navs have been well characterized. A recombinant toxin, His-Css4, was obtained when fused to a His tag and a thrombin cleavage site and had similar binding affinity for and effect on Na currents of rat brain sodium channels as those of the native toxin isolated from the scorpion venom. Molecular dissection of His-Css4 elucidated a functional surface of 1245 A2 composed of the following: 1) a cluster of residues associated with the alpha-helix, which includes a putative "hot spot" (this cluster is conserved among scorpion beta-toxins and contains their "pharmacophore"); 2) a hydrophobic cluster associated mainly with the beta2 and beta3 strands, which is likely to confer the specificity for mammalian Navs; 3) a single bioactive residue (Trp-58) in the C-tail; and 4) a negatively charged residue (Glu-15) involved in voltage sensor trapping as inferred from our ability to uncouple toxin binding from activity upon its substitution. This study expands our understanding about the mode of action of scorpion beta-toxins and illuminates differences in the functional surfaces that may dictate their specificities for mammalian versus insect sodium channels.
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Affiliation(s)
- Lior Cohen
- Department of Plant Sciences, George S. Wise Faculty of Life Sciences, Sackler School of Medicine, Tel-Aviv University, Ramat-Aviv 69978, Tel-Aviv, Israel
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Devaux C, Jouirou B, Naceur Krifi M, Clot-Faybesse O, El Ayeb M, Rochat H. Quantitative variability in the biodistribution and in toxinokinetic studies of the three main alpha toxins from the Androctonus australis hector scorpion venom. Toxicon 2004; 43:661-9. [PMID: 15109887 DOI: 10.1016/j.toxicon.2004.02.021] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2003] [Revised: 02/17/2004] [Accepted: 02/25/2004] [Indexed: 10/26/2022]
Abstract
Scorpion stings represent a medical problem in numerous countries. The scorpion Androctonus australis hector produces three alpha toxins (Aah I to III), which are responsible for most of the lethality in mammals. These toxins act on sodium channel and do not cross-react immunologically. We used RIA and ELISA to measure the concentrations of these three toxins in plasma, urine and different organs after i.v. and s.c. injections of water extracts of venoms in rabbits or mice. In both animals, the toxins rapidly appeared in plasma after s.c. injection as it was previously described for the whole venom. However, the toxins disappeared from the blood more quickly than did other main components of the venom. Thus, serotherapy must be initiated immediately to prevent the toxin from reaching its target. We also detected the toxins in urine, kidneys, heart and lungs, but not in the brain. However, the concentration of Aah II was always lower than that of Aah I. Analysis of five samples of venom collected in different areas of southern Tunisia showed that a large polymorphism exists for the three toxins. This is yet another difficulty for serotherapy as there is no cross-antigenicity between them.
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Affiliation(s)
- Christiane Devaux
- CNRS UMR 6560, Faculté de Médecine-Nord, Boulevard Dramard, 13916 Marseille Cedex 20, France.
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Aubrey N, Muzard J, Christophe Peter J, Rochat H, Goyffon M, Devaux C, Billiald P. Engineering of a recombinant Fab from a neutralizing IgG directed against scorpion neurotoxin AahI, and functional evaluation versus other antibody fragments. Toxicon 2004; 43:233-41. [PMID: 15033320 DOI: 10.1016/j.toxicon.2003.11.024] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2003] [Revised: 10/15/2003] [Accepted: 11/25/2003] [Indexed: 11/16/2022]
Abstract
Antibody-based therapy is the only specific treatment for scorpion envenomation. However, there are still major drawbacks associated with its use; mainly because antivenoms are still prepared from immune equine serum raised against crude venoms, whereas only a limited number of neurotoxins are responsible for the lethality of the venom. Using a murine hybridoma that secretes a well-characterized neutralizing IgG directed to neurotoxins AahI and AahIII from the venom of the scorpion Androctonus australis, we constructed a recombinant Fab (rFab) fragment, which was produced and purified from transformed bacteria. It recognized toxin AahI with a high affinity (KD = 8.2 x 10(-11)) equivalent to the homologous pFab prepared by papain digestion of whole IgG. Although the AahI-neutralizing capacity of protein L-purified rFab was low compared to other recombinant antibody formats (scFv and diabody) investigated in parallel, the antibody engineering approach presented here provides an innovative way to synthesize novel toxin-neutralizing molecules. It may serve as a strategy for designing a new generation of antivenoms.
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Affiliation(s)
- Nicolas Aubrey
- Muséum National d'Histoire Naturelle, USM 0505-Lerai, 57 rue Cuvier, F75231 Paris cedex 05, France
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16
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M'Barek S, Fajloun Z, Cestèle S, Devaux C, Mansuelle P, Mosbah A, Jouirou B, Mantegazza M, Van Rietschoten J, El Ayeb M, Rochat H, Sabatier JM, Sampieri F. First chemical synthesis of a scorpion α-toxin affecting sodium channels: The Aah I toxin ofAndroctonus australis hector. J Pept Sci 2004; 10:666-77. [PMID: 15568681 DOI: 10.1002/psc.582] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Aah I is a 63-residue alpha-toxin isolated from the venom of the Buthidae scorpion Androctonus australis hector, which is considered to be the most dangerous species. We report here the first chemical synthesis of Aah I by the solid-phase method, using a Fmoc strategy. The synthetic toxin I (sAah I) was renatured in DMSO-Tris buffer, purified and subjected to thorough analysis and comparison with the natural toxin. The sAah I showed physico-chemical (CD spectrum, molecular mass, HPLC elution), biochemical (amino-acid composition, sequence), immunochemical and pharmacological properties similar to those of the natural toxin. The synthetic toxin was recognized by a conformation-dependent monoclonal anti-Aah I antibody, with an IC50 value close to that for the natural toxin. Following intracerebroventricular injection, the synthetic and the natural toxins were similarly lethal to mice. In voltage-clamp experiments, Na(v) 1.2 sodium channel inactivation was inhibited by the application of sAah I or of the natural toxin in a similar way. This work describes a simple protocol for the chemical synthesis of a scorpion alpha-toxin, making it possible to produce structural analogues in time.
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Affiliation(s)
- Sarrah M'Barek
- FRE 2738 CNRS-Université de la Méditerranée, Laboratoire de Biochimie and Laboratoire International Associé d'lngénierie Biomoleculaire, IFR Jean Roche, Faculté de Médecine Nord, Bd Pierre Dramard, 13916 Marseille, France
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17
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Benkhadir K, Kharrat R, Cestèle S, Mosbah A, Rochat H, El Ayeb M, Karoui H. Molecular cloning and functional expression of the alpha-scorpion toxin BotIII: pivotal role of the C-terminal region for its interaction with voltage-dependent sodium channels. Peptides 2004; 25:151-61. [PMID: 15062995 DOI: 10.1016/j.peptides.2004.01.009] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2003] [Revised: 01/05/2004] [Accepted: 01/06/2004] [Indexed: 11/26/2022]
Abstract
Alpha scorpion toxins bind to receptor site 3 on voltage-dependent sodium channels and inhibit their inactivation. The alpha-scorpion toxin BotIII is the most toxic protein of Buthus occitanus tunetanus. Its sequence differs only by three amino acid residues from that of AahII, the most active alpha-toxin. Due to their high affinity and selectivity for mammalian sodium channels, BotIII and AahII represent powerful tools for studying the molecular determinants of specificity for voltage-dependent sodium channels. Sequence analysis of BotIII gene has revealed two exons separated by a 381-bp intron and a signal peptide of 19 amino acids. We succeeded in expressing BotIII in significantly higher amounts than AahII the only expressed strict alpha anti-mammalian scorpion toxin reported in the literature. We have also modified specific amino acid residues of BotIII. The recombinant and the natural toxins differ by the amidation of the C-terminal residue. Toxicity and binding experiments indicated: (a) the affinity of rBotIII-OH and rAahII-OH (rBotIII-OH with the 3 mutations R10V, V51L, N64H) for the voltage-dependent sodium channels is reduced compared to the natural toxins. This data revealed the important role of the C-terminal amidation for the biological activity of BotIII and AahII; (b) the single mutation N64H is responsible for the difference of toxicity and affinity between rBotIII-OH and rAahII-OH; (c) the addition of the sequence GR to rBotIII-OH leads to the loss of biological activity. This study is in agreement with the important role attributed to the C-terminal sequence of alpha-toxins in their interaction with sodium channels receptors.
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Affiliation(s)
- Khadija Benkhadir
- Laboratoire des Venins et Toxines, Institut Pasteur de Tunis, B. P 74, 1002 Tunis-Belvédère, Tunisia
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18
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Devaux C, Clot-Faybesse O, Pugnière M, Mani JC, Rochat H, Granier C. A strategy for inducing an immune response against Androctonus australis scorpion venom toxin I in mice. Production of high-affinity monoclonal antibodies and their use in a sensitive two-site immunometric assay. J Immunol Methods 2002; 271:37-46. [PMID: 12445727 DOI: 10.1016/s0022-1759(02)00338-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Scorpion neurotoxins acting on ion channels share some structural features but differ in antigenic and immunogenic properties. They are highly structured peptides, 60-70 amino acids long. Monoclonal antibodies have been obtained for Androctonus australis hector scorpion venom neurotoxin II (AahII) and a nontoxic synthetic analog ((Abu)(8) AahII). In this study, no antibody response was elicited in mice of various strains injected with AahI, the other important toxin of the venom, in a native or an inactive ((Abu)(8) AahI) form. We found that AahI was only immunogenic in BALB/c or C57BL/6 mice if it was coupled to a carrier protein. The helper protein molecule could be BSA, KLH, or the nontoxic analog of AahII. We obtained a panel of high-affinity mAbs with these immunogens. Two of these mAbs, including the very high-affinity antibody 9C2 (K(D)=0.11x10(-11) M), were used to set up a two-site ELISA, sensitive enough for the quantification of AahI in the biological fluids of envenomed animals. The detection limit of the assay was 75 pg/ml.
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Affiliation(s)
- Christiane Devaux
- Laboratoire de Biochimie-Ingénierie des Protéines, CNRS UMR 6560, Faculté de Médecine-Nord, Bd P. Dramard, 13916 Marseille Cedex 20, France.
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19
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de Lima ME, Stankiewicz M, Hamon A, de Figueiredo SG, Cordeiro MN, Diniz CR, Martin-Eauclaire MF, Pelhate M. The toxin Tx4(6-1) from the spider Phoneutria nigriventer slows down Na(+) current inactivation in insect CNS via binding to receptor site 3. JOURNAL OF INSECT PHYSIOLOGY 2002; 48:53-61. [PMID: 12770132 DOI: 10.1016/s0022-1910(01)00143-3] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Tx4(6-1) a neurotoxic peptide from the venom of the aggressive South American 'armed' spider Phoneutria nigriventer, has been previously isolated and sequenced. It shows no detectable activity in mice but affects the peripheral nervous system of insects by stimulating glutamate release at the neuromuscular junction. Here we investigate possible interactions of the toxin with voltage-activated sodium channels (Na(v)). We confirm that it is ineffective on mammalian Na(v) channels, and establish that it competes with the alpha-like toxin 125I-Bom IV, for binding on the site 3 of insect Na(v) channel (IC(50) value around 25nM). The physiological consequences of this binding to the insect Na(v) channel are shown by electrophysiology: Tx4(6-1) prolongs evoked axonal action potentials (APs) (<500&mgr;s duration in control). Prolonged 8-10ms or 'plateau' 500-800ms APs accompanied by repetitive firing at 80-150Hz are recorded after 4-8min of toxin action. This modification of evoked activity is due to a slowing down of sodium current inactivation. Effects of Tx4(6-1) on sodium current are compared with those of a typical scorpion alpha-toxin and of some other spider toxins active on insect Na(v) channels. At the end of long voltage pulses, the maintained inward sodium current may represent 50% of the peak current after scorpion alpha-toxin but only about 8-10% after spider toxins. To understand the slight differences in the effects of alpha-scorpion and spider toxins on the insect Na(v) channel, structural studies of toxin-channels interactions would be necessary.
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Affiliation(s)
- M E. de Lima
- Departamento de Bioquimica e Imunologia, Universidade Federal de Minas Gerais, Av. Antonio Carlos 6627, 31270-901, MG, Belo Horizonte, Brazil
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20
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Kopeyan C, Martinez G, Rochat H. Primary structure of toxin IV of Leiurus quinquestriatus quinquestriatus. FEBS Lett 2001. [DOI: 10.1016/0014-5793(85)80262-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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21
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Aubrey N, Devaux C, di Luccio E, Goyffon M, Rochat H, Billiald P. A recombinant scFv/streptavidin-binding peptide fusion protein for the quantitative determination of the scorpion venom neurotoxin AahI. Biol Chem 2001; 382:1621-8. [PMID: 11767952 DOI: 10.1515/bc.2001.197] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
We created a construct encoding a peptide known to mimic the binding properties of biotin fused to the carboxy-terminus of a scFv fragment that binds a scorpion toxin (AahI). This fusion protein was produced in the periplasm of bacteria and purified to homogeneity by single-step affinity chromatography on streptavidin-agarose with a yield close to 1 mg/l. DNA sequencing, dot blot and mass spectrometric analyses demonstrated the integrity of the soluble immunoconjugate. Fusion to the streptavidin-binding peptide did not affect the ability of the scFv to recognize its antigen with a high affinity (Kd = 2.3 x 10(-10) M). Similarly, the streptavidin-binding property was not impaired in the fusion protein. Thus, the immunoconjugate was bifunctional and had a low molecular mass of 28 kDa. This enabled us to develop rapid and sensitive immunoassays for the specific detection of the toxin AahI accurately to 0.6 ng/ml, opening up new perspectives for the diagnosis of envenomations.
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Affiliation(s)
- N Aubrey
- Muséum National d'Histoire Naturelle, LERAI, Paris, France
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22
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Devaux C, Moreau E, Goyffon M, Rochat H, Billiald P. Construction and functional evaluation of a single-chain antibody fragment that neutralizes toxin AahI from the venom of the scorpion Androctonus australis hector. EUROPEAN JOURNAL OF BIOCHEMISTRY 2001; 268:694-702. [PMID: 11168408 DOI: 10.1046/j.1432-1327.2001.01923.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
9C2 is a murine monoclonal IgG that participates in the neutralization of Androctonus australis hector scorpion venom. It recognizes AahI and AahIII, two of the three main neurotoxins responsible for almost all the toxicity of the venom when injected into mammals. Using PCR we cloned the antibody variable region coding genes from 9C2 hybridoma cells and constructed a gene encoding a single-chain antibody variable fragment molecule (scFv). This scFv was produced in the periplasm of Escherichia coli in a soluble and functional form and purified in a single step using protein L-agarose beads yielding 1-2 mg.L(-1) of bacterial culture. scFv9C2 was predominantly monomeric but also tended to form dimeric and oligomeric structures, all capable of binding toxin AahI. The affinity of scFv and the parental mAb for toxin AahI and homologous toxin AahIII was of the same magnitude, in the nanomolar range. Similarly, purified forms of scFv9C2 completely inhibited the binding of toxin AahI to rat brain synaptosomes. Finally, scFv9C2 was efficient in protecting mice against the toxic effects of AahI after injection of the toxin and scFv to mice by the intracerebroventricular route in a molar ratio as low as 0.36 : 1. Thus, we produced a recombinant scFv that reproduces the recognition properties of the parent antibody and neutralizes the scorpion neurotoxin AahI, thereby opening new prospects for the treatment of envenomation.
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Affiliation(s)
- C Devaux
- CNRS UMR 6560, University of Méditerranée, Marseille, France.
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23
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Clot-Faybesse O, Guieu R, Rochat H, Devaux C. Toxicity during early development of the mouse nervous system of a scorpion neurotoxin active on sodium channels. Life Sci 2000; 66:185-92. [PMID: 10665992 DOI: 10.1016/s0024-3205(99)00579-2] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The lethal effects of scorpion envenomation is due to neurotoxins active on voltage-sensitive sodium channels. Dysfunctions of the peripheral and central nervous systems with neurological manifestations are commonly observed after scorpion stings, specially in young children. Since the neurotoxicity of venom fraction is greatly higher by intracerebroventricular than by subcutaneous injections, a direct effect of venom on CNS cannot be excluded specially in infants where the blood-brain barrier is not fully functional. We investigated the activity of a neurotoxin from the scorpion Androctonus australis hector (AahII) in newborn mice at 3, 7 and 14 days after birth and in adults. Young mice (P3, P7) were more sensitive to AahII injected subcutaneously than were adults, but were less sensitive to intracerebroventricular injection. The affinity of AahII for its receptor site on brain synaptosomes from P3 and P7 mice was slightly higher and the density of the binding sites was half that of adult mice. After subcutaneous injection of [125I]-AahII it was also observed that a small amount of radioactivity was found in brains of neonate mice but not in that of adults. This amount is however extremely lower than the value of the LD50 determined by intracerebroventricular injection. Results are consistent with a peripheral action of AahII and show that its toxic activity changes during the mouse nervous system development.
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Affiliation(s)
- O Clot-Faybesse
- Ingénierie des Protéines, CNRS UMR 6560, IFR Jean Roche, Faculté de Médecine-Nord, Univ Mediterranee, Marseille, France
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24
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Santos RG, Diniz CR, Cordeiro MN, De Lima ME. Binding sites and actions of Tx1, a neurotoxin from the venom of the spider Phoneutria nigriventer, in guinea pig ileum. Braz J Med Biol Res 1999; 32:1565-9. [PMID: 10585642 DOI: 10.1590/s0100-879x1999001200019] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Tx1, a neurotoxin isolated from the venom of the South American spider Phoneutria nigriventer, produces tail elevation, behavioral excitation and spastic paralysis of the hind limbs after intracerebroventricular injection in mice. Since Tx1 contracts isolated guinea pig ileum, we have investigated the effect of this toxin on acetylcholine release, as well as its binding to myenteric plexus-longitudinal muscle membranes from the guinea pig ileum. [125I]-Tx1 binds specifically and with high affinity (Kd = 0.36 +/- 0.02 nM) to a single, non-interacting (nH = 1.1), low capacity (Bmax 1.1 pmol/mg protein) binding site. In competition experiments using several compounds (including ion channel ligands), only PhTx2 and PhTx3 competed with [125I]-Tx1 for specific binding sites (K0.5 apparent = 7.50 x 10(-4) g/l and 1.85 x 10(-5) g/l, respectively). PhTx2 and PhTx3, fractions from P. nigriventer venom, contain toxins acting on sodium and calcium channels, respectively. However, the neurotoxin PhTx2-6, one of the isoforms found in the PhTx2 pool, did not affect [125I]-Tx1 binding. Tx1 reduced the [3H]-ACh release evoked by the PhTx2 pool by 33%, but did not affect basal or KCl-induced [3H]-ACh release. Based on these results, as well as on the homology of Tx1 with toxins acting on calcium channels (omega-Aga IA and IB) and its competition with [125I]-omega-Cono GVIA in the central nervous system, we suggest that the target site for Tx1 may be calcium channels.
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Affiliation(s)
- R G Santos
- Laboratório de Radiobiologia, Centro de Desenvolvimento da Tecnologia Nuclear, Belo Horizonte, MG, Brasil
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25
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Clot-Faybesse O, Juin M, Rochat H, Devaux C. Monoclonal antibodies against the Androctonus australis hector scorpion neurotoxin I: characterisation and use for venom neutralisation. FEBS Lett 1999; 458:313-8. [PMID: 10570931 DOI: 10.1016/s0014-5793(99)01179-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A series of monoclonal antibodies (mAbs) specific for the alpha-neurotoxin I (Aah I) from the venom of the dangerous Androctonus australis hector scorpion were obtained using carrier protein-coupled toxin. Competitive RIA, receptor assays and mouse toxicity tests were performed to characterise mAbs in terms of affinity and neutralisation. Cross-reactivity studies and two-site ELISA results allowed some classification of mAbs into three groups. One mAb, 9C2, was particularly interesting since it recognised the parent toxin I with a K(D) of 0.15 nM and was also reactive with toxins of the same immunological group. Its ability to neutralise the toxic effect of the parent toxin and the venom fraction has been investigated. This anti-Aah I mAb 9C2, associated with anti-Aah II mAb 4C1, provides a valuable tool to neutralise the toxicity of the venom.
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Affiliation(s)
- O Clot-Faybesse
- CNRS UMR 6560, Ingénierie des Protéines, IFR Jean Roche, Université Méditerranée, Faculté de Médecine-Nord, BD P. Dramard, Marseille, France
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26
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Mousli M, Devaux C, Rochat H, Goyffon M, Billiald P. A recombinant single-chain antibody fragment that neutralizes toxin II from the venom of the scorpion Androctonus australis hector. FEBS Lett 1999; 442:183-8. [PMID: 9928998 DOI: 10.1016/s0014-5793(98)01647-0] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Monoclonal antibody 4C1 specifically binds to and neutralizes the most potent neurotoxin (AahII) of the scorpion Androctonus australis. The cDNAs encoding the variable regions of this antibody were isolated by PCR-mediated cloning. A single-chain Fv gene was engineered and expressed in Escherichia coli. The recombinant protein had neutralizing activity similar to that of the intact antibody in vitro and in vivo. We have thus neutralized the pharmacological and biological properties of a scorpion neurotoxin with a single-chain Fv, which opens new perspectives for the treatment of envenomizations.
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Affiliation(s)
- M Mousli
- Muséum national d'Histoire naturelle, Paris, France
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27
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Little MJ, Wilson H, Zappia C, Cestèle S, Tyler MI, Martin-Eauclaire MF, Gordon D, Nicholson GM. Delta-atracotoxins from Australian funnel-web spiders compete with scorpion alpha-toxin binding on both rat brain and insect sodium channels. FEBS Lett 1998; 439:246-52. [PMID: 9845331 DOI: 10.1016/s0014-5793(98)01378-7] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Atracotoxins are novel peptide toxins from the venom of Australian funnel-web spiders that slow sodium current inactivation in a similar manner to scorpion alpha-toxins. To analyse their interaction with known sodium channel neurotoxin receptor sites we determined their effect on scorpion toxin, batrachotoxin and saxitoxin binding. Nanomolar concentrations of delta-atracotoxin-Hv1 and delta-atracotoxin-Ar1 completely inhibited the binding of the scorpion alpha-toxin AaH II to rat brain synaptosomes as well as the binding of LqhalphaIT, a scorpion alpha-toxin highly active on insects, to cockroach neuronal membranes. Moreover, delta-atracotoxin-Hv1 cooperatively enhanced batrachotoxin binding to rat brain synaptosomes in an analogous fashion to scorpion alpha-toxins. Thus the delta-atracotoxins represent a new class of toxins which bind to both mammalian and insect sodium channels at sites similar to, or partially overlapping with, the receptor binding sites of scorpion alpha-toxins.
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Affiliation(s)
- M J Little
- Department of Health Sciences, University of Technology, Broadway, NSW, Australia
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28
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Sautière P, Cestèle S, Kopeyan C, Martinage A, Drobecq H, Doljansky Y, Gordon D. New toxins acting on sodium channels from the scorpion Leiurus quinquestriatus hebraeus suggest a clue to mammalian vs insect selectivity. Toxicon 1998; 36:1141-54. [PMID: 9690781 DOI: 10.1016/s0041-0101(98)00080-4] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Two new toxins were purified from Leiurus quinquestriatus hebraeus (Lqh) scorpion venom, Lqh II and Lqh III. Lqh II sequence reveals only two substitutions, as compared to AaH II, the most active scorpion alpha-toxin on mammals from Androctounus australis Hector. Lqh III shares 80% sequence identity with the alpha-like toxin Bom III from Buthus occitanus mardochei. Using bioassays on mice and cockroach coupled with competitive binding studies with 125I-labeled scorpion alpha-toxins on rat brain and cockroach synaptosomes, the animal selectivity was examined. Lqh II has comparable activity to mammals as AaH II, but reveals significantly higher activity to insects attributed to its C-terminal substitution, and competes at low concentration for binding on both mammalian and cockroach sodium channels. Lqh II thus binds to receptor site 3 on sodium channels. Lqh III is active on both insects and mammals but competes for binding only on cockroach. The latter indicates that Lqh III binds to a distinct receptor site. Thus, Lqh II and Lqh III represent two different scorpion toxin groups, the alpha- and alpha-like toxins, respectively, according to the structural and pharmacological criteria. These new toxins may serve as a lead for clarification of the structural basis for insect vs mammal selectivity of scorpion toxins.
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Affiliation(s)
- P Sautière
- Laboratoire de Chimie des Biomolecules, URA 1309 CNRS, Institut Pasteur de Lille, France
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29
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Devaux C, Clot-Faybesse O, Juin M, Mabrouk K, Sabatier JM, Rochat H. Monoclonal antibodies neutralizing the toxin II from Androctonus australis hector scorpion venom: usefulness of a synthetic, non-toxic analog. FEBS Lett 1997; 412:456-60. [PMID: 9276446 DOI: 10.1016/s0014-5793(97)00826-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Scorpion venom contains toxins that act on ion channels. Some are responsible for the noxious effects observed when people are stung by scorpions. The study of the neutralization of these molecules and the production of monoclonal antibodies (mAbs) should prove valuable. Toxin II from Androctonus australis hector scorpion (AahII) is one of the most potent toxins and has been well-characterized and studied. Producing mAbs against such molecules is often difficult due to their toxicity. We used a synthetic, non-toxic analog, (Abu)8-AahII, to obtain mAbs which recognize and neutralize the native toxin AahII. Sets of peptides spanning the entire sequence of AahII were assayed to identify the binding sites of the mAbs. The various mAbs recognized only the largest peptides (12-17 residues). They recognized peptides corresponding to different parts of the AahII sequence, suggesting that several regions of the (Abu)8-AahII sequence mimic AahII epitopes and then elicit mAbs directed against toxin.
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MESH Headings
- Amino Acid Sequence
- Animals
- Antibodies, Monoclonal/administration & dosage
- Antibodies, Monoclonal/biosynthesis
- Antibodies, Monoclonal/chemistry
- Binding Sites, Antibody
- Binding, Competitive/immunology
- Epitope Mapping
- Female
- Hybridomas/metabolism
- Injections, Intraperitoneal
- Injections, Intraventricular
- Injections, Subcutaneous
- Mice
- Mice, Inbred BALB C
- Mice, Inbred C57BL
- Molecular Sequence Data
- Neurotoxins/chemical synthesis
- Neurotoxins/immunology
- Neurotoxins/toxicity
- Peptides/chemical synthesis
- Peptides/immunology
- Rats
- Reptilian Proteins
- Scorpion Venoms/chemical synthesis
- Scorpion Venoms/immunology
- Scorpion Venoms/toxicity
- Synaptosomes/immunology
- Synaptosomes/metabolism
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Affiliation(s)
- C Devaux
- CNRS UMR 6560, Laboratoire d'Ingénierie des Protéines, Faculté de Médecine-Nord, Marseille, France.
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30
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Kharrat R, Zenouaki I, Ben Lasfar Z, Miled K, el Ayeb M. Molecular characterization, antigenicity and immunogenicity of anatoxic polymeric forms conferring protection against scorpion venoms. Toxicon 1997; 35:915-30. [PMID: 9241785 DOI: 10.1016/s0041-0101(96)00187-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Two polymeric forms of Buthus occitamus tunetanus (Bot) G-50 and Androctonus australis hector (Aah) G-50 were obtained by controlled polymerization with glutaraldehyde. Their mol. wts, determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and exclusion high-performance liquid chromatography using radiolabelled toxin, ranged from 14,000 to 90,000 and 90,000 to 100,000 for Aah G-50 and Bot G-50, respectively. Modification of about 20% of the lysine residues yielded completely detoxified Bot G-50 fractions which retained the antigenic cross-reactivity with the native G-50 fraction, venom and toxins. High levels of specific antibodies against venoms and toxins were generated by immunization with prepared polymeric forms because absorbance values higher than 3 units were regularly observed by enzyme-linked immunosorbent assay with immune sera dilutions of 1/10,000. In vitro protection experiments demonstrated that immune sera from mice, horse and monkeys efficiently neutralized either Aah or Bot venom. Depending on the adjuvant and animal model species used, the neutralizing titre estimated by subcutaneous injection in mice varied between 20 and 40 LD50/ml. The in vivo protection assays showed that immunized mice could resist the challenge by six times the LD50 amounts of the toxic fraction. This protection was found to be long-lived. It was concluded that G-50 polymeric forms are highly detoxified and immunogenic, and should be useful for the production of potent polyvalent antivenom against scorpion toxins. They could also be considered for further studies towards the development of vaccine candidates.
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Affiliation(s)
- R Kharrat
- Laboratoire des Venins et Toxines, Institut Pasteur de Tunis, Tunisia
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31
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Borchani L, Stankiewicz M, Kopeyan C, Mansuelle P, Kharrat R, Cestèle S, Karoui H, Rochat H, Pelhate M, el Ayeb M. Purification, structure and activity of three insect toxins from Buthus occitanus tunetanus venom. Toxicon 1997; 35:365-82. [PMID: 9080593 DOI: 10.1016/s0041-0101(96)00173-0] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
One contractive and two depressant toxins active on insect were purified by high-performance liquid chromatography from the venom of Buthus occitanus tunetanus (Bot). The two depressant toxins, BotIT4 and BotIT5, differ only at position 6 (Arg for Lys) and are equally toxic to insects (LD50 to Blatella germanica = 110 ng/100 mg body weight). They show a strong antigenic cross-reaction with a depressive toxin from Leiurus quinquestriatus quinquestriatus (LqqIT2). The two toxins are able to inhibit with high affinity (K0.5 between 2 and 3 nM) the specific binding of the radioiodinated excitatory insect toxin (125I-AaHIT) on its receptor site on Periplaneta americana synaptosomal membranes. These toxins depolarize the cockroach axon, irreversibly block the action potential, and slow down and very progressively block the transmembrane transient Na+ current. The contracturant toxin BotIT1 is highly toxic to B. germanica (LD50 = 60 ng/ 100 mg body weight) and barely toxic to mice (LD50 = 1 microgram/20 g body weight) when injected intracerebroventricularly. It does not compete with 125I-AaHIT for its receptor site on P. americana synaptosomal membranes. On cockroach axon, BotIT1 develops plateau potentials and slows down the inactivation mechanism of the Na+ channels. Thus, BotIT1 belongs to the group of alpha insect-selective toxins and shows a strong sequence identity (> 90%) with Lqh alpha IT and LqqIII, two insect alpha-toxins previously purified from the venom of L. q. hebraeus and L. q. quinquestriatus. respectively.
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Affiliation(s)
- L Borchani
- Laboratoire des Venins et Toxines, Institut Pasteur de Tunis, Belvédère, Tunisia
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32
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Zenouaki I, Kharrat R, Sabatier JM, Devaux C, Karoui H, Van Rietschoten J, el Ayeb M, Rochat H. In vivo protection against Androctonus australis hector scorpion toxin and venom by immunization with a synthetic analog of toxin II. Vaccine 1997; 15:187-94. [PMID: 9066037 DOI: 10.1016/s0264-410x(97)00144-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
A synthetic peptide mimicking the North African scorpion Androctonus australis hector toxin II was designed and produced by chemical solid-phase synthesis. It contains the entire sequence of toxin II (64 amino acid residues), with each half-cystine being replaced by the isosteric residue a-aminobutyric acid, and was thus devoid of disulfide bridges. This construct was totally nontoxic in mice even if large amounts, equivalent to 1000 times the LD50 of the original toxin, were injected by the intracerebroventricular route. The synthetic peptide, either as a monomer or polymerized by means of glutaraldehyde, induced the production of antitoxin neutralizing antibodies in immunized mice and rabbits. After three injections with either the monomeric or polymerized synthetic peptide, the immunized mice were protected against several lethal doses of the corresponding native toxin or scorpion venom. Six months after immunization, the mice were completely protected against challenge with eight LD50 of the original toxin. The protection was better when the polymerized synthetic peptide was used. One month after the start of the immunization program, it showed a good correlation between antibody titer and protection. However, antibody titer decreased with time but protection remained high. This suggests that additional factors other than circulating antibodies play a role in protective activity.
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Affiliation(s)
- I Zenouaki
- Laboratoire des Venins et Toxines, Institut Pasteur de Tunis, Tunisia
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33
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Devaux C, Fourquet P, Granier C. A conserved sequence region of scorpion toxins rendered immunogenic induces broadly cross-reactive, neutralizing antibodies. EUROPEAN JOURNAL OF BIOCHEMISTRY 1996; 242:727-35. [PMID: 9022703 DOI: 10.1111/j.1432-1033.1996.0727r.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Scorpion toxins constitute a family of proteins with a high degree of sequence diversity but a common mode of action. Neutralization of the toxic effects of scorpion stings by serotherapy is limited due to the various serotypes expressed by these proteins. We explored the possibility of raising antibodies to conserved parts of the toxins which could recognize several members of the family. We established the variability profile of a set of 25 scorpion toxin sequences, then evaluated systematically by peptide-scanning methods the antigenicity of one scorpion toxin. The most conserved regions were generally very poorly antigenic. One exception was the N-terminal region, which is both conserved and antigenic. Antibodies were raised in rabbits against an eight-residue synthetic peptide mimicking the N-terminal region. These peptide antibodies were cross-reactive with several scorpion toxins belonging to different serotypes and neutralized both the pharmacological effects (binding to rat brain synaptosomes) and the biological activity (toxicity in mice) of the parent toxin. The molecular model of the toxin indicates that antibody binding to residues 1-8 probably either masks some residue(s) of the N-terminus critical for the biological activity or overlaps with the epitope previously defined by neutralizing monoclonal antibody. These findings could open the way for new therapeutic strategies for the medical care of envenomations.
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Affiliation(s)
- C Devaux
- CNRS URA 1455, Laboratoire de Biochimie, IFR Jean Roche, Faculté de Médecine Nord, Marseille, France
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34
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Borchani L, Mansuelle P, Stankiewicz M, Grolleau F, Cestèle S, Karoui H, Lapied B, Rochat H, Pelhate M, el Ayeb M. A new scorpion venom toxin paralytic to insects that affects Na+ channel activation. Purification, structure, antigenicity and mode of action. EUROPEAN JOURNAL OF BIOCHEMISTRY 1996; 241:525-32. [PMID: 8917451 DOI: 10.1111/j.1432-1033.1996.00525.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
A new toxin, BotIT2, with a unique mode of action on the isolated giant axon of the cockroach Periplaneta americana and DUM (dorsal unpaired median) neurons, has been purified from the venom of the scorpion Buthus occitanus tunetanus. Its structural, antigenic and pharmacological properties are compared to those of three other groups of neurotoxins found in Buthidae scorpion venoms. Like excitatory, depressant and alpha-type insect-selective neurotoxins, BotIT2 is toxic to insects, but shows the following common and distinctive characteristics. (a) As alpha-type toxins, BotIT2 lack strict selectivity to insects; they have measurable but low toxicity to mice. (b) As depressant toxins and unlike alpha-type toxins, BotIT2 is able to displace iodinated AaHIT from its binding sites in insect neuronal membranes. This indicates that the binding site for BotIT2 is identical, contiguous or in allosteric interaction with that of AaHIT and depressant toxins. (c) The BotIT2 amino acid sequence shows strong similarity to depressant toxins. However, unexpectedly, despite this high sequence similarity, BotIT2 shares moderate cross-antigenic reactivity with depressant toxins. (d) Voltage and current-clamp studies show that BotIT2 induces limited depolarization concomitantly with the development of depolarizing after potential, repetitive activity and later plateau potentials terminated by bursts. Under voltage-clamp conditions, BotIT2 specifically acts on Na+ channels by decreasing the peak Na+ current and by simultaneously inducing a new current with very slow activation/deactivation kinetics. The voltage dependence of this slow current is not significantly different from that of the control current. These observations indicate that BotIT2 chiefly modifies the kinetics of axonal and DUM neuronal membrane Na(+)-channel activation.
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Affiliation(s)
- L Borchani
- Laboratoire des Venins et Toxins, Institut Pasteur de Tunis, Belvédère, Tunisia
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35
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Rosso JP, Vargas-Rosso O, Gutiérrez JM, Rochat H, Bougis PE. Characterization of alpha-neurotoxin and phospholipase A2 activities from Micrurus venoms. Determination of the amino acid sequence and receptor-binding ability of the major alpha-neurotoxin from Micrurus nigrocinctus nigrocinctus. EUROPEAN JOURNAL OF BIOCHEMISTRY 1996; 238:231-9. [PMID: 8665942 DOI: 10.1111/j.1432-1033.1996.0231q.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
New World elapids are coral snakes that belong to the genus Micrurus, and for which the venom biochemistry is mostly unknown. Analysis has been difficult because the coral snakes produce small quantities of venom. Clinical observations following bites show mainly neurotoxic effects. Experimentally, cardiotoxic, haemolytic and myotoxic activities are also reported. An experimental approach, using reverse-phase high-performance liquid chromatography and specific assays for alpha-neurotoxin and phospholipase A2 activities, was conducted on milligram quantities of venoms from three Micrurus species from Costa Rica; M. nigrocinctus nigrocinctus, M. alleni yatesi and M. multifasciatus. Neurotoxicity was determined by competition binding experiments with the Torpedo marmorata acetylcholine receptor. Phospholipase A2 activity was measured by fluorimetry using a pyrene lipid substrate. In this way, we purified and characterized seven alpha-neurotoxins, five phospholipases A2 and four toxin homologs. The amino acid sequence of the major alpha-neurotoxin from M. nigrocinctus nigrocinctus venom was fully determined and compared to Old Word representatives. Distance matrix data were generated to set up phylogeny relationships among elapid short-chain alpha-neurotoxins, which proved to be in accordance with the taxonomic classification and geographical distribution of snake species.
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Affiliation(s)
- J P Rosso
- Laboratoire de Biochimie, Unité de Recherche Associée 1455 du Centre National de la Recherche Scientifique, Institut Fédératif Jean Roche, Université de la Méditérranée, Faculté de Médecine Secteur Nord, Marseille, France
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36
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Gordon D, Martin-Eauclaire MF, Cestèle S, Kopeyan C, Carlier E, Khalifa RB, Pelhate M, Rochat H. Scorpion toxins affecting sodium current inactivation bind to distinct homologous receptor sites on rat brain and insect sodium channels. J Biol Chem 1996; 271:8034-45. [PMID: 8626486 DOI: 10.1074/jbc.271.14.8034] [Citation(s) in RCA: 153] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Sodium channels posses receptor sites for many neurotoxins, of which several groups were shown to inhibit sodium current inactivation. Receptor sites that bind alpha- and alpha-like scorpion toxins are of particular interest since neurotoxin binding at these extracellular regions can affect the inactivation process at intramembranal segments of the channel. We examined, for the first time, the interaction of different scorpion neurotoxins, all affecting sodium current inactivation and toxic to mammals, with alpha-scorpion toxin receptor sites on both mammalian and insect sodium channels. As specific probes for rat and insect sodium channels, we used the radiolabeled alpha-scorpion toxins AaH II and LqhalphaIT, the most active alpha-toxins on mammals and insect, respectively. We demonstrate that the different scorpion toxins may be classified to several groups, according to their in vivo and in vitro activity on mammalian and insect sodium channels. Analysis of competitive binding interaction reveal that each group may occupy a distinct receptor site on sodium channels. The alpha-mammal scorpion toxins and the anti-insect Lqh alphaIT bind to homologous but not identical receptor sites on both rat brain and insect sodium channels. Sea anemone toxin ATX II, previously considered to share receptor site 3 with alpha-scorpion toxins, is suggested to bind to a partially overlapping receptor site with both AaH II and Lqh alphaIT. Competitive binding interactions with other scorpion toxins suggest the presence of a putative additional receptor site on sodium channels, which may bind a unique group of these scorpion toxins (Bom III and IV), active on both mammals and insects. We suggest the presence of a cluster of receptor sites for scorpion toxins that inhibit sodium current inactivation, which is very similar on insect and rat brain sodium channels, in spite of the structural and pharmacological differences between them. The sea anemone toxin ATX II is also suggested to bind within this cluster.
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Affiliation(s)
- D Gordon
- Laboratory of Biochemistry, CNRS URA 1455, INSERM U 374, Faculty of Medicine Nord, Jean Roche Institute, Bd. Pierre Dramard, 13916 Marseille Cedex 20, France
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37
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Cestèle S, Ben Khalifa RB, Pelhate M, Rochat H, Gordon D. Alpha-scorpion toxins binding on rat brain and insect sodium channels reveal divergent allosteric modulations by brevetoxin and veratridine. J Biol Chem 1995; 270:15153-61. [PMID: 7797499 DOI: 10.1074/jbc.270.25.15153] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
At least six topologically separated neurotoxin receptor sites have been identified on sodium channels that reveal strong allosteric interactions among them. We have studied the allosteric modulation induced by veratridine, binding to receptor site 2, and brevetoxin PbTx-1, occupying receptor site 5, on the binding of alpha-scorpion toxins at receptor site 3, on three different neuronal sodium channels: rat brain, locust, and cockroach synaptosomes. We used 125I-AaH II, the most active alpha-scorpion toxin on vertebrates, and 125I-Lqh alpha IT, shown to have high activity on insects, as specific probes for receptor site 3 in rat brain and insect sodium channels. Our results reveal that brevetoxin PbTx-1 generates three types of effects at receptor site 3:1) negative allosteric modulation in rat brain sodium channels, 2) positive modulation in locust sodium channels, and 3) no effect on cockroach sodium channel. However, PbTx-1 activates sodium channels in cockroach axon similarly to its activity in other preparation. Veratridine positively modulates both rat brain and locust sodium channels but had no effect on alpha-toxin binding in cockroach. The dramatic differences in allosteric modulations in each sodium channel subtype suggest structural differences in receptor sites for PbTx-1 and/or at the coupling regions with alpha-scorpion toxin receptor sites in the different sodium channels, which can be detected by combined application of specific channel modifiers and may elucidate the dynamic gating activity and the mechanism of allosteric interactions among various neurotoxin receptors.
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Affiliation(s)
- S Cestèle
- Faculty of Medicine Nord, Institut Féderatif de Recherche Jean Roche, Laboratory of Biochemistry, URA CNRS 1455, Marseille, France
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38
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De Lima ME, Martin-Eauclaire MF, Chavez-Olortegui C, Diniz CR, Granier C. Tityus serrulatus scorpion venom toxins display a complex pattern of antigenic reactivity. Toxicon 1993; 31:223-7. [PMID: 8456451 DOI: 10.1016/0041-0101(93)90290-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The antigenic properties of alpha-type and beta-type toxins purified from Tityus serrulatus (Ts) venom were analysed by radioimmunoassay, using rabbit antibodies raised against Ts VII, the main beta-type toxin in the venom, and against Ts IV, an alpha-type toxin. The anti-Ts VII serum did not recognize either the other beta-toxins Ts I and Ts II or the alpha-toxin Ts IV; the anti-Ts IV serum did not bind any of the three beta-toxins Ts I, Ts II or Ts VII. Thus, Tityus toxins display at least three distinct antigenic reactivity patterns.
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Affiliation(s)
- M E De Lima
- Departamento de Bioquimica e Immunologia, Instituto de Ciencias Biologicas, Belo Horizonte, M.G, Brazil
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39
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Ait-Amara D, Chavez-Olortegui C, Romi R, Mery J, Brugidou J, Albericio F, Devaux C, Granier C. Antibodies cross-reactive with the scorpion-toxin II from Androctonus australis Hector elicited in mice by a synthetic peptide. NATURAL TOXINS 1993; 1:255-62. [PMID: 8167944 DOI: 10.1002/nt.2620010410] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
With the aim of developing active protection against the noxious effects provoked in humans by scorpion stings, the possibility of eliciting toxin reactive antibodies by immunization with a short peptide was assessed in mice. The amino acid sequence of residues 50 to 59 of Androctonus australis Hector toxin II was chosen, on the basis of previous results indicating that rabbit anti-(50-59) antibodies neutralize the biological effects of the parent toxin. The peptide was prepared by solid-phase synthesis procedures and used in different forms (free, linearly polymerized, coupled to KLH, coupled to a low-molecular weight B-lymphocyte activator) in order to immunize groups of non-congenic NMRI or congenic C57BL/6 mice. The reactivities of each serum with the peptide and with the toxin were assessed in ELISA. Strong reactivities with both the peptide (mean titer over 1:52,600) and the toxin (mean titer 1:800) were observed in all mice from the group that received the KLH-coupled peptide. However, mouse immune sera failed either to recognize the toxin in a liquid-phase radioimmunoassay or to neutralize the lethal effects of the toxin. The requirements, in terms of affinity and recognition of native conformation, for anti-peptide antibodies to display neutralizing properties are discussed.
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Affiliation(s)
- D Ait-Amara
- Laboratoire de Biochimie, CNRS 1455 Faculté de Médecine Secteur Nord, Marseille, France
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40
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Kopeyan C, Mansuelle P, Martin-Eauclaire MF, Rochat H, Miranda F. Characterization of toxin III of the scorpion Leiurus quinquestriatus quinquestriatus: a new type of alpha-toxin highly toxic both to mammals and insects. NATURAL TOXINS 1993; 1:308-12. [PMID: 8167952 DOI: 10.1002/nt.2620010510] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The primary structure of toxin III of Leiurus quinquestriatus quinquestriatus (Lqq III) was elucidated by automatic Edman degradation of the reduced and S-carboxymethylated protein and derived tryptic peptides. Like other scorpion toxins that are active on sodium channels, Lqq III, consisting of 64 amino acids, is a 7 kDa single-chain polypeptide crosslinked by four disulfide bridges. It belongs to the alpha-toxin group, as judged by competition experiments with 125I AaH II for binding to rat brain synaptosomes (K0.5 = 7 x 10(-7) M). Lqq III is the first alpha-toxin to be characterized that is highly toxic to mice [LD50 = 50 micrograms (7.1 nmol)/kg body wt], by subcutaneous injection, insects Blatella germanica [LD50 = 60 ng (8.5 pmol)/g body wt.] and Musca domestica [LD50 = 120 ng (17 pmol)/g body wt]. When tested via the intracerebroventricular route, the toxicity for mice [55 micrograms (8 nmol)/kg] was of the same order as that found by subcutaneous injection, indicating that Lqq III has a higher affinity for peripheral sodium channels that for those of the central nervous system. There are three differences between the sequences of Lqq III and Lqh alpha IT, an alpha-toxin isolated from the venom of Leiurus quinquestriatus hebraeus. These substitutions are found at positions 20, 24, and 64 (Ser-->Ala,Asp-->Glu and His-->Arg, respectively). Surprisingly Lqh alpha IT is only weakly active in mice [LD50 = 5 mg (0.7 mumol)/kg], while in insects its toxicity is similar to that of Lqq III [140 ng (20 pmol)/g body wt blowfly larvae]. These observations are relevant to the definition of scorpion toxin structure-activity relationships.
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Affiliation(s)
- C Kopeyan
- Laboratoire de Biochime, Centre National de la Recherche Scientifique URA 1455, Faculté de Médecine, Secteur Nord, Marseille, France
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41
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Yahi N, Devaux C, Mansuelle P, Defendini ML, Granier C. Monoclonal antibodies to toxin II from the scorpion Androctonus australis Hector: further characterization of epitope specificities and neutralizing capacities. Toxicon 1992; 30:723-31. [PMID: 1380740 DOI: 10.1016/0041-0101(92)90006-q] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The epitope specificities of two previously prepared monoclonal antibodies (mAb) to the toxin II from Androctonus australis Hector were characterized. Neither mAb 4C1 nor mAb 3C5 was able to recognize any of the 58 overlapping synthetic heptapeptides which cover the whole sequence of toxin II. Thus, both mAbs probably recognize conformation-dependent epitopes at the surface of the toxin. Experiments were designed to check whether or not the two mAbs, or their Fab fragments, were able to bind simultaneously to the toxin. The results indicated that the epitopes recognized by the two antibodies are probably close together at the surface of the toxin, thus preventing the simultaneous binding of both mAbs to a single toxin molecule. Given the proximity of the two epitopes and the fact that mAb 4C1 is known to be a neutralizing antibody, the capacity of mAb 3C5 to inhibit the toxic effects of the toxin was re-evaluated in C57BL/6 mice. A clear, but weak, neutralizing effect was found, consistent with the low affinity binding of the mAb in the proximity of a neutralizing site of the toxin.
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Affiliation(s)
- N Yahi
- CNRS URA 1455, Laboratoire de Biochimie, Faculté de Médecine Secteur Nord, Marseille, France
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42
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Céard B, De Lima ME, Bougis PE, Martin-Eauclaire MF. Purification of the main beta-toxin from Tityus serrulatus scorpion venom using high-performance liquid chromatography. Toxicon 1992; 30:105-10. [PMID: 1595074 DOI: 10.1016/0041-0101(92)90506-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The venom of the Brazilian scorpion Tityus serrulatus was fractionated using high-performance liquid chromatography which allowed us to purify in two steps the main beta-type toxin of the venom. The toxin constituted about 15% of the absorbance at 280 nm and 50% of the toxicity of the venom. According to its amino acid content, its electrophoretic migration on Phast-Gel homogenous 20 and its biological properties both in vivo by intracerebroventricular injection to the mouse (LD50 = 30 ng/kg mouse) and in vitro by competition receptor assay on rat brain synaptosomes (K0.5 = 80 pM), the toxin was identified as toxin Ts VII already purified from the same venom using low-pressure liquid chromatography (BECHIS et al., 1984 Biochem. biophys. Res. Commun. 122, 1146). The high-performance liquid chromatographic technique used improved by a factor of four the amount of toxin purified.
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Affiliation(s)
- B Céard
- Laboratoir de Biochimie, U.R.A. 1455 du C.N.R.S., Faculté de Médecine Secteur Nord, Marseille, France
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43
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Mansuelle P, Martin-Eauclaire MF, Chavez-Olortegui C, de Lima ME, Rochat H, Granier C. The β-type toxin Ts II from the scorpionTityus serrulatus: Amino acid sequence determination and assessment of biological and antigenic properties. ACTA ACUST UNITED AC 1992; 1:119-25. [PMID: 1344906 DOI: 10.1002/nt.2620010211] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The toxin Ts II from the venom of the Brazilian scorpion Tityus serrulatus was purified in two successive chromatographic steps. The amino acid sequence was then determined by automated Edman degradation of the reduced and S-carboxymethylated protein and of proteolytic peptides derived from it. This sequence appears to differ from that of previously characterized toxins found in this venom. However, it is identical to the recently published sequence of protein III-8 from the same venom [Possani et al., J Biol Chem 266:3178-3185, 1991], except that the C-terminus was found to be amidated. Homologies were found between the sequence of Ts II and that of other toxins from Tityus; in particular, the amino acid sequence of Ts II displays 72% sequence identity with Ts VII (also called Titx gamma). Consistent with this structural similarity, some biological properties of Ts II were found to be similar to those of Ts VII: Ts II has an intracerebroventricular LD50 of 6 ng, as compared to 0.6 ng for Ts VII; in a receptor binding assay Ts II, like Ts VII, was found to behave as a beta-type toxin and to inhibit the binding of the reference labelled toxin with a K0.5 of 5 x 10(-9) M, as compared to 7 x 10(-11) M for Ts VII. Nevertheless, Ts II is unable to bind to anti-Ts VII antibodies in radioimmunoassay experiments, indicating the non-conservation between the two toxins of at least some antigenically important residues.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- P Mansuelle
- Centre National de la Recherche Scientifique, URA 1455, Laboratoire de Biochimie, Faculté de Médecine Nord, Marseille, France
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44
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Mansuelle P, Martin MF, Rochat H, Granier C. The amino acid sequence of toxin IV from theAndroctonus australis scorpion: Differing effects of natural mutations in scorpion α-toxins on their antigenic and toxic properties. ACTA ACUST UNITED AC 1992; 1:61-9. [PMID: 1344902 DOI: 10.1002/nt.2620010112] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The complete amino acid sequence (64 residues) of the AaH IV toxin from the scorpion Androctonus australis Hector was determined by automated Edman degradation and was compared with the sequences of other Androctonus toxins. AaH IV was also tested by radioimmunoassay for binding to antisera raised against other toxins of the same species. The results indicated that AaH IV shares some of the antigenic properties of AaH I and AaH III toxins, but does not cross-react with anti-AaH II antibodies. The structural basis for the observed antigenic relationships can be found in the high degree of homology displayed by AaH IV with regard to AaH I and III, the changes in amino acid residues equally affecting regions included or excluded from the main predicted antigenic sites of AaH IV. The lower biological potency of AaH IV is presumably the result of some of the sequence differences. In particular, substitution affecting the charge and bulkiness of residue 61 could account for the poor receptor binding and consequential weak toxic properties of this molecule.
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Affiliation(s)
- P Mansuelle
- Centre National de la Recherche Scientifique UA 1455, Faculté de Médecine, Secteur Nord, Marseille, France
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Fishman L, Kagan ML, Zlotkin E. Accessibility of the insect nervous system to a neurotoxic polypeptide. ACTA ACUST UNITED AC 1991. [DOI: 10.1002/jez.1402570103] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Zerrouk H, Bougis PE, Céard B, Benslimane A, Martin-Eauclaire MF. Analysis by high-performance liquid chromatography of Androctonus mauretanicus mauretanicus (black scorpion) venom. Toxicon 1991; 29:951-60. [PMID: 1949066 DOI: 10.1016/0041-0101(91)90078-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The venom of the black scorpion, Androctonus mauretanicus mauretanicus, was obtained by means of manual stimulation and was analyzed using high-performance liquid chromatography. Starting from 20 mg of venom and using only two chromatographic steps, six toxins were purified to homogeneity. They have been characterized by their amino acid content and compared to those already isolated from a pool of venoms obtained using electric stimulation (Rosso and Rochat, Toxicon 23, 113-125, 1985). The toxins Amm I and Amm II were not found, suggesting either different levels of toxin expression or the existence of Androctonus mauretanicus mauretanicus subspecies. Using rat brain synaptosomes, it was demonstrated that the toxins Amm III, Amm IV and Amm V were alpha-toxins. The toxin Amm VI was neither alpha- or beta-toxin. Unexpectedly, the toxin Amm VII was found to be a beta-toxin, the first one identified in a north African scorpion venom. In addition, some toxins active on mammals exhibited different levels of specificity towards phylogenetically related groups of arthropods.
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Affiliation(s)
- H Zerrouk
- Centre National de la Recherche Scientifique, URA 1179, Laboratoire de Biochimie, Faculté de Médecine, Marseille, France
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Kharrat R, Darbon H, Granier C, Rochat H. Structure-activity relationships of scorpion alpha-neurotoxins: contribution of arginine residues. Toxicon 1990; 28:509-23. [PMID: 2389252 DOI: 10.1016/0041-0101(90)90295-i] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The role of arginine residues in the structure-activity relationships of alpha-scorpion neurotoxins was studied. Toxins I and II from Androctonus australis Hector (north African scorpion), containing respectively 2 and 3 arginines, were modified by phenylglyoxal or p-hydroxyphenylglyoxal. Modified derivatives were purified by reverse-phase HPLC and/or ion exchange HPLC. Subsequent bioassays showed that toxin I (AaH I) derivatives with single modifications on Arg 2 and Arg 60 had low activity (25 and 14% of residual activity, assessed in receptor binding experiments). Doubly modified (Arg 2, Arg 60) AaH I had 7% residual activity while further derivatization of the alpha-amino group led to an almost inactive derivative. These results agree with the involvement of arginines 2 and 60, as well as the alpha-amino group, of AaH I in the toxin/receptor interaction, probably via electrostatic interactions. Consistent with the role of N-terminal residues, the selective removal of the N-terminal dipeptide Val-Arg of toxin III from the same scorpion resulted in low activity (7% residual activity). The arginine residue in position 56 of toxin II was important for bioactivity since the derivative modified by phenylglyoxal on Arg 56 exhibited low residual activity (20%). Arg 62 and Arg 18, on the other hand, can be modified without any great effect on the pharmacological activity of AaH II. These results furnish a more precise picture of those residues involved in the "toxic region", which appears to be composed of residues belonging to the conserved hydrophobic surface and to the C-terminal and N-terminal sequences.
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Affiliation(s)
- R Kharrat
- CNRS URA 37-INSERM U 172 Laboratoire de Biochimie, Faculté de Médecine-Secteur Nord, Marseille, France
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Kharrat R, Darbon H, Rochat H, Granier C. Structure/activity relationships of scorpion alpha-toxins. Multiple residues contribute to the interaction with receptors. EUROPEAN JOURNAL OF BIOCHEMISTRY 1989; 181:381-90. [PMID: 2714290 DOI: 10.1111/j.1432-1033.1989.tb14735.x] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Chemical modifications of tyrosine and tryptophan residues of scorpion alpha-neurotoxins II and III from Androctonus australis Hector were performed as well as modification of the two arginines and the alpha-amino group of toxin I. The pharmacological potencies of each derivative were assessed in vivo by LD50 measurement and in vitro by competition experiments with 125I-toxin for synaptosomal receptors. Arginine residues in positions 2 and 60 and the alpha-amino group of Androctonus toxin I were derivatized by p-hydroxyphenylglyoxal; the corresponding modified toxins exhibit low pharmacological potencies. Tryptophan 38 of toxin II and tryptophan 45 of toxin III were modified by nitrophenylsulfenyl chloride, leading respectively to a poorly and a fully active derivative. The tetranitromethane modification of tyrosine residues in positions 60, 5 and 14 of toxin III induced respectively 60%, 40% and 30% of loss of biological activity. Circular dichroic analysis indicated that for every derivative, except the nitrophenylsulfenyl derivative of Trp-45 of AaH III, the conformation of the toxin was not altered by derivatization. Conformational integrity was also confirmed by full activity of the derivatives in radioimmunoassays. Taken together, the results suggest that aromatic residues belonging to the conserved hydrophobic surface, to the C-terminal and to the loop region 37-44 are involved in the molecular mechanisms by which scorpion alpha-toxins act. Charged residues in the N-terminal and C-terminal also contribute to the high efficacy of the binding process. It appears that all important residues are clustered on one face of the toxin, suggesting a multipoint interaction with the proteins of the sodium channel.
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Affiliation(s)
- R Kharrat
- CNRS URA 37, INSERUM U. 172, Faculté de Médecine Secteur Nord, Marseille, France
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