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Nirthanan S. Snake three-finger α-neurotoxins and nicotinic acetylcholine receptors: molecules, mechanisms and medicine. Biochem Pharmacol 2020; 181:114168. [PMID: 32710970 DOI: 10.1016/j.bcp.2020.114168] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 07/20/2020] [Accepted: 07/20/2020] [Indexed: 12/13/2022]
Abstract
Snake venom three-finger α-neurotoxins (α-3FNTx) act on postsynaptic nicotinic acetylcholine receptors (nAChRs) at the neuromuscular junction (NMJ) to produce skeletal muscle paralysis. The discovery of the archetypal α-bungarotoxin (α-BgTx), almost six decades ago, exponentially expanded our knowledge of membrane receptors and ion channels. This included the localisation, isolation and characterization of the first receptor (nAChR); and by extension, the pathophysiology and pharmacology of neuromuscular transmission and associated pathologies such as myasthenia gravis, as well as our understanding of the role of α-3FNTxs in snakebite envenomation leading to novel concepts of targeted treatment. Subsequent studies on a variety of animal venoms have yielded a plethora of novel toxins that have revolutionized molecular biomedicine and advanced drug discovery from bench to bedside. This review provides an overview of nAChRs and their subtypes, classification of α-3FNTxs and the challenges of typifying an increasing arsenal of structurally and functionally unique toxins, and the three-finger protein (3FP) fold in the context of the uPAR/Ly6/CD59/snake toxin superfamily. The pharmacology of snake α-3FNTxs including their mechanisms of neuromuscular blockade, variations in reversibility of nAChR interactions, specificity for nAChR subtypes or for distinct ligand-binding interfaces within a subtype and the role of α-3FNTxs in neurotoxic envenomation are also detailed. Lastly, a reconciliation of structure-function relationships between α-3FNTx and nAChRs, derived from historical mutational and biochemical studies and emerging atomic level structures of nAChR models in complex with α-3FNTxs is discussed.
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Affiliation(s)
- Selvanayagam Nirthanan
- School of Medical Science, Griffith Health Group, Griffith University, Gold Coast, Queensland, Australia.
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2
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Dutertre S, Nicke A, Tsetlin VI. Nicotinic acetylcholine receptor inhibitors derived from snake and snail venoms. Neuropharmacology 2017. [PMID: 28623170 DOI: 10.1016/j.neuropharm.2017.06.011] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The nicotinic acetylcholine receptor (nAChR) represents the prototype of ligand-gated ion channels. It is vital for neuromuscular transmission and an important regulator of neurotransmission. A variety of toxic compounds derived from diverse species target this receptor and have been of elemental importance in basic and applied research. They enabled milestone discoveries in pharmacology and biochemistry ranging from the original formulation of the receptor concept, the first isolation and structural analysis of a receptor protein (the nAChR) to the identification, localization, and differentiation of its diverse subtypes and their validation as a target for therapeutic intervention. Among the venom-derived compounds, α-neurotoxins and α-conotoxins provide the largest families and still represent indispensable pharmacological tools. Application of modified α-neurotoxins provided substantial structural and functional details of the nAChR long before high resolution structures were available. α-bungarotoxin represents not only a standard pharmacological tool and label in nAChR research but also for unrelated proteins tagged with a minimal α-bungarotoxin binding motif. A major advantage of α-conotoxins is their smaller size, as well as superior selectivity for diverse nAChR subtypes that allows their development into ligands with optimized pharmacological and chemical properties and potentially novel drugs. In the following, these two groups of nAChR antagonists will be described focusing on their respective roles in the structural and functional characterization of nAChRs and their development into research tools. In addition, we provide a comparative overview of the diverse α-conotoxin selectivities that can serve as a practical guide for both structure activity studies and subtype classification. This article is part of the Special Issue entitled 'Venom-derived Peptides as Pharmacological Tools.'
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Affiliation(s)
- Sébastien Dutertre
- Institut des Biomolécules Max Mousseron, UMR 5247, Université Montpellier - CNRS, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France
| | - Annette Nicke
- Walther Straub Institute for Pharmacology and Toxicology, Ludwig-Maximilians-Universität, Nußbaumstr. 26, 80336 Munich, Germany.
| | - Victor I Tsetlin
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya str.16/10, Moscow 117999, Russian Federation
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3
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Toxin Fused with SUMO Tag: A New Expression Vector Strategy to Obtain Recombinant Venom Toxins with Easy Tag Removal inside the Bacteria. Toxins (Basel) 2017; 9:toxins9030082. [PMID: 28264436 PMCID: PMC5371837 DOI: 10.3390/toxins9030082] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Revised: 02/16/2017] [Accepted: 02/22/2017] [Indexed: 01/19/2023] Open
Abstract
Many animal toxins may target the same molecules that need to be controlled in certain pathologies; therefore, some toxins have led to the formulation of drugs that are presently used, and many other drugs are still under development. Nevertheless, collecting sufficient toxins from the original source might be a limiting factor in studying their biological activities. Thus, molecular biology techniques have been applied in order to obtain large amounts of recombinant toxins into Escherichia coli. However, most animal toxins are difficult to express in this system, which results in insoluble, misfolded, or unstable proteins. To solve these issues, toxins have been fused with tags that may improve protein expression, solubility, and stability. Among these tags, the SUMO (small ubiquitin-related modifier) has been shown to be very efficient and can be removed by the Ulp1 protease. However, removing SUMO is a labor- and time-consuming process. To enhance this system, here we show the construction of a bicistronic vector that allows the expression of any protein fused to both the SUMO and Ulp1 protease. In this way, after expression, Ulp1 is able to cleave SUMO and leave the protein interest-free and ready for purification. This strategy was validated through the expression of a new phospholipase D from the spider Loxosceles gaucho and a disintegrin from the Bothrops insularis snake. Both recombinant toxins showed good yield and preserved biological activities, indicating that the bicistronic vector may be a viable method to produce proteins that are difficult to express.
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4
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Development of a single-chain variable fragment-alkaline phosphatase fusion protein and a sensitive direct competitive chemiluminescent enzyme immunoassay for detection of ractopamine in pork. Anal Chim Acta 2012; 736:85-91. [DOI: 10.1016/j.aca.2012.05.033] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Revised: 04/08/2012] [Accepted: 05/17/2012] [Indexed: 11/24/2022]
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5
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Vetter I, Davis JL, Rash LD, Anangi R, Mobli M, Alewood PF, Lewis RJ, King GF. Venomics: a new paradigm for natural products-based drug discovery. Amino Acids 2010; 40:15-28. [DOI: 10.1007/s00726-010-0516-4] [Citation(s) in RCA: 128] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2010] [Accepted: 02/04/2010] [Indexed: 10/19/2022]
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6
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Dokmetjian JC, Del Canto S, Vinzón S, de Jiménez Bonino MB. Biochemical characterization of the Micrurus pyrrhocryptus venom. Toxicon 2008; 53:375-82. [PMID: 19135468 DOI: 10.1016/j.toxicon.2008.12.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2008] [Revised: 12/02/2008] [Accepted: 12/04/2008] [Indexed: 10/21/2022]
Abstract
Snake venom toxicity is the consequence of a combination of peptides and proteins whose identification and characterization are of great importance to understand envenomation and develop new clinical treatments. The Elapinae subfamily includes coral snakes whose bite causes mainly neurotoxic effects which disable muscle contraction and paralyse the heart as well as inhibit respiration. However, the structure-function relationship of venom toxins has been investigated only for a few species. We herein study biological aspects of the Micrurus pyrrhocryptus venom such as LD(50), hemorrhagic, necrotic, coagulant, myotoxic and hemolytic activity as well as the ability of venom components to compete with alpha-Bungarotoxin for the ligand-binding site of the nicotinic acetylcholine receptor. Besides, we report the determination of the molecular mass and N-terminal sequence of toxins including PLA2s, short, long and weak neurotoxins. The complete sequence of one of the short neurotoxins has also been obtained, this being the first sequence of an alpha-neurotoxin determined in the M. pyrrhocryptus venom and one of the few fully determined in members of the Micrurus genus.
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Affiliation(s)
- José Christian Dokmetjian
- Instituto Nacional de Producción de Biológicos, ANLIS - Dr. Carlos G. Malbran, Av. Velez Sarsfield 563, (1282) Buenos Aires, Argentina
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7
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Toxins from cone snails: properties, applications and biotechnological production. Appl Microbiol Biotechnol 2008; 79:1-9. [PMID: 18340446 PMCID: PMC2755758 DOI: 10.1007/s00253-008-1385-6] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2007] [Revised: 01/24/2008] [Accepted: 01/25/2008] [Indexed: 11/12/2022]
Abstract
Cone snails are marine predators that use venoms to immobilize their prey. The venoms of these mollusks contain a cocktail of peptides that mainly target different voltage- and ligand-gated ion channels. Typically, conopeptides consist of ten to 30 amino acids but conopeptides with more than 60 amino acids have also been described. Due to their extraordinary pharmacological properties, conopeptides gained increasing interest in recent years. There are several conopeptides used in clinical trials and one peptide has received approval for the treatment of pain. Accordingly, there is an increasing need for the production of these peptides. So far, most individual conopeptides are synthesized using solid phase peptide synthesis. Here, we describe that at least some of these peptides can be obtained using prokaryotic or eukaryotic expression systems. This opens the possibility for biotechnological production of also larger amounts of long chain conopeptides for the use of these peptides in research and medical applications.
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de Melo FHM, Butera D, Medeiros RS, Andrade LNDS, Nonogaki S, Soares FA, Alvarez RA, Moura da Silva AM, Chammas R. Biological applications of a chimeric probe for the assessment of galectin-3 ligands. J Histochem Cytochem 2007; 55:1015-26. [PMID: 17565118 DOI: 10.1369/jhc.7a7174.2007] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Beta1-6 branching of N-linked oligosaccharides has been correlated with the progression of different cancers. The leukoagglutinins of Phaseolus vulgaris (L-PHA) have been used to study this pattern of glycosylation whose biological significance is incompletely understood. The animal lectin, galectin-3, also binds to structures recognized by L-PHA. To develop a functional tool for the in situ identification of this pattern of glycosylation, human galectin-3 was fused to bacterial alkaline phosphatase (gal3/AP). Gal3/AP recognized both A and B blood group saccharides (B>A) and lactosamine derivatives. Gal3/AP recognition depended at least in part on the N-linked oligosaccharides of different glycoproteins. The presence and distribution of galectin-3 ligands were analyzed in both murine and human normal and tumor samples. Loss of apical expression of galectin-3 ligands was commonly found in carcinomas. Endothelial and inflammatory cells were enriched in galectin-3 ligands as compared with tumor cells; thus, gal3/AP is a suitable tool for studying tumor microenvironments. Comparative analysis of both gal3/AP and L-PHA binding patterns indicated that although similar, these patterns are not identical. The probe developed was useful for several immunoenzymatic assays and will allow the physiological and clinical significance of the expression pattern of galectin-3 ligands to be established. This manuscript contains online supplemental material at http://www.jhc.org. Please visit this article online to view these materials.
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Affiliation(s)
- Fabiana H M de Melo
- Faculdade de Medicina da Universidade de São Paulo, Avenida Dr. Arnaldo 455, 01246-903 São Paulo SP, Brazil
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9
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Tucker JB, Hooper C. Protein engineering: security implications. The increasing ability to manipulate protein toxins for hostile purposes has prompted calls for regulation. EMBO Rep 2006; 7 Spec No:S14-7. [PMID: 16819442 PMCID: PMC1490303 DOI: 10.1038/sj.embor.7400677] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- Jonathan B Tucker
- Center for Nonproliferation Studies, Monterey Institute of International Studies, CA, USA.
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10
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Carneiro SM, Zablith MB, Kerchove CM, Moura-da-Silva AM, Quissell DO, Markus RP, Yamanouye N. Venom production in long-term primary culture of secretory cells of the Bothrops jararaca venom gland. Toxicon 2006; 47:87-94. [PMID: 16310237 DOI: 10.1016/j.toxicon.2005.10.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2005] [Revised: 10/06/2005] [Accepted: 10/08/2005] [Indexed: 11/19/2022]
Abstract
There is an increasing interest of obtaining venom by other ways than from extracting it from snakes captured in the wild. A readily available source of this venom will be useful for all pharmacological and biotechnological studies, as well as providing an improved avenue for treatments of snakebites. Here, we show that secretory cells of venom gland can be a good in vitro apparatus to produce venom. We have maintained and morphologically characterized the secretory cells of the Bothrops jararaca venom gland cultured up to 21 days. The isolated cells assemble into acini that growth in size up to 21st day, instead of adhering to the substrate. Bothropasin, a venom metalloprotease, was localized in secretory vesicles by immunoelectron microscopy and venom was also detected in culture medium in a concentration as high as 63 microg/ml. These data show that the acini formed in culture are functionally viable; they can produce and secrete venom.
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Affiliation(s)
- S M Carneiro
- Laboratório de Biologia Celular, Instituto Butantan, Av. Vital Brazil, 1500, 05503-900 São Paulo, SP, Brazil
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Bel Haj Rhouma R, Cérutti-Duonor M, Benkhadir K, Goudey-Perrière F, El Ayeb M, Lopez-Ferber M, Karoui H. Insecticidal effects of Buthus occitanus tunetanus BotIT6 toxin expressed in Escherichia coli and baculovirus/insect cells. JOURNAL OF INSECT PHYSIOLOGY 2005; 51:1376-83. [PMID: 16216259 DOI: 10.1016/j.jinsphys.2005.08.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2005] [Revised: 08/24/2005] [Accepted: 08/26/2005] [Indexed: 05/04/2023]
Abstract
BotIT6 is a neurotoxin polypeptide derived from the venom of the scorpion Buthus occitanus tunetanus (Bot). Its mature form is composed of 62 amino acids. BotIT6 has been reported to be the most potent toxin from Bot venom that has a strict selectivity for insects. Such toxin may have potential as a potent animal-harmless tool against insects. Using RT-PCR, we isolated and sequenced a cDNA encoding 62 amino acid residues corresponding to the known amino acid sequence of BotIT6. We have expressed a recombinant active form of BotIT6 in significantly high amounts in Escherichia coli. We have also engineered the cDNA into the Autographa californica Nuclear Polyhedrosis Virus (AcMNPV) genome and expressed the protein under control of the polyhedrin promoter. Supernatants of AcIT6-virus infected Sf9 insect cells exhibit a typical intoxication effect when injected to Spodoptera littoralis larvae. Moreover, injection of the recombinant virus showed enhanced insecticidal potency against S. littoralis larvae compared with wild type AcMNPV.
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Affiliation(s)
- Rahima Bel Haj Rhouma
- Laboratoire des Venins et Toxines, Institut Pasteur de Tunis, Tunis-Belvedère, Tunisia
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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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13
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Butera D, Skielka K, McLane MA, Paquette-Straub C, Ducancel F, da Silva AMM. Cloning, expression, and characterization of a bi-functional disintegrin/alkaline phosphatase hybrid protein. Protein Expr Purif 2003; 31:286-91. [PMID: 14550649 DOI: 10.1016/s1046-5928(03)00169-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Integrins are transmembrane heterodimeric glycoproteins responsible for cellular communication; therefore, they play an essential role in many physiological events. Viper snake venoms contain integrin antagonists called disintegrins which bind and inhibit integrin function. They present a loop containing an RGD motif responsible for integrin binding. The engineering of disintegrins fused to a reporter enzyme will be an interesting approach to build integrin markers. Even more, the disintegrin scaffold could be used to present other protein binding motifs. In this work, we have obtained alkaline phosphatase (APv) tagged eristostatin (Er) by cloning and expressing eristostatin DNA into the pLIP6-GN vector. Eristostatin, a 49 residue disintegrin, binds selectively to alphaIIbbeta3 integrin, inhibiting its binding to fibrinogen. The resulting fusion protein Er/APv was identified by SDS-PAGE and by Western blotting using both anti-Er and anti-AP antibodies. This fusion protein showed enzymatic AP activity similar to that of wild APv and its potential use for an alphaIIbbeta3 integrin assay was tested in a one-step dot blot using immobilized cells incubated with the marker and developed by AP substrate. Er/APv showed selectivity towards platelets and alphaIIbbeta3 integrin transfected cells and reacted with the same region as unlabeled Er, as analyzed in competition assays. Our data present a novel tool, Er/APv, with potential use as molecular marker in processes where the alphaIIbbeta3 integrin is involved.
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Affiliation(s)
- Diego Butera
- Laboratório de Imunopatologia, Instituto Butantan, Av Vital Brasil 1500, 05503-900 São Paulo, Brazil
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Bouhaouala-Zahar B, Benkhalifa R, Srairi N, Zenouaki I, Ligny-Lemaire C, Drevet P, Sampieri F, Pelhate M, El Ayeb M, Ménez A, Karoui H, Ducancel F. A chimeric scorpion alpha-toxin displays de novo electrophysiological properties similar to those of alpha-like toxins. EUROPEAN JOURNAL OF BIOCHEMISTRY 2002; 269:2831-41. [PMID: 12071945 DOI: 10.1046/j.1432-1033.2002.02918.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BotXIV and LqhalphaIT are two structurally related long chain scorpion alpha-toxins that inhibit sodium current inactivation in excitable cells. However, while LqhalphaIT from Leiurus quinquestriatus hebraeus is classified as a true and strong insect alpha-toxin, BotXIV from Buthus occitanus tunetanus is characterized by moderate biological activities. To assess the possibility that structural differences between these two molecules could reflect the localization of particular functional topographies, we compared their sequences. Three structurally deviating segments located in three distinct and exposed loops were identified. They correspond to residues 8-10, 19-22, and 38-43. To evaluate their functional role, three BotXIV/LqhalphaIT chimeras were designed by transferring the corresponding LqhalphaIT sequences into BotXIV. Structural and antigenic characterizations of the resulting recombinant chimera show that BotXIV can accommodate the imposed modifications, confirming the structural flexibility of that particular alpha/beta fold. Interestingly, substitution of residues 8-10 yields to a new electrophysiological profile of the corresponding variant, partially comparable to that one of alpha-like scorpion toxins. Taken together, these results suggest that even limited structural deviations can reflect functional diversity, and also that the structure-function relationships between insect alpha-toxins and alpha-like scorpion toxins are probably more complex than expected.
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Huys I, Dyason K, Waelkens E, Verdonck F, van Zyl J, du Plessis J, Müller GJ, van der Walt J, Clynen E, Schoofs L, Tytgat J. Purification, characterization and biosynthesis of parabutoxin 3, a component of Parabuthus transvaalicus venom. EUROPEAN JOURNAL OF BIOCHEMISTRY 2002; 269:1854-65. [PMID: 11952787 DOI: 10.1046/j.1432-1033.2002.02833.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A novel peptidyl inhibitor of voltage-gated K+ channels, named parabutoxin 3 (PBTx3), has been purified to homogeneity from the venom of Parabuthus transvaalicus. This scorpion toxin contains 37 residues, has a mass of 4274 Da and displays 41% identity with charybdotoxin (ChTx, also called 'alpha-KTx1.1'). PBTx3 is the tenth member (called 'alpha-KTx1.10') of subfamily 1 of K+ channel-blocking peptides known thus far. Electrophysiological experiments using Xenopus laevis oocytes indicate that PBTx3 is an inhibitor of Kv1 channels (Kv1.1, Kv1.2, Kv1.3), but has no detectable effects on Kir-type and ERG-type channels. The dissociation constants (Kd) for Kv1.1, Kv1.2 and Kv1.3 channels are, respectively, 79 microm, 547 nm and 492 nm. A synthetic gene encoding a PBTx3 homologue was designed and expressed as a fusion protein with the maltose-binding protein (MBP) in Escherichia coli. The recombinant protein was purified from the bacterial periplasm compartment using an amylose affinity resin column, followed by a gel filtration purification step and cleavage by factor Xa (fXa) to release the recombinant toxin peptide (rPBTx3). After final purification and refolding, rPBTx3 was shown to be identical to the native PBTx3 with respect to HPLC retention time, mass spectrometric analysis and functional properties. The three-dimensional structure of PBTx3 is proposed by homology modelling to contain a double-stranded antiparallel beta sheet and a single alpha-helix, connected by three disulfide bridges. The scaffold of PBTx3 is homologous to most other alpha-KTx scorpion toxins.
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Affiliation(s)
- Isabelle Huys
- Laboratory of Toxicology, University of Leuven, Leuven, Belgium
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16
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Papineni RV, Sanchez JU, Baksi K, Willcockson IU, Pedersen SE. Site-specific charge interactions of alpha-conotoxin MI with the nicotinic acetylcholine receptor. J Biol Chem 2001; 276:23589-98. [PMID: 11323431 DOI: 10.1074/jbc.m102350200] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have tested the importance of charge interactions for alpha-conotoxin MI binding to the nicotinic acetylcholine receptor (AChR). Ionic residues on alpha-conotoxin MI were altered by site-directed mutagenesis or by chemical modification. In physiological buffer, removal of charges at the N terminus, His-5, and Lys-10 had small (2-4-fold) effects on binding affinity to the mouse muscle AChR and the Torpedo AChR. It was also demonstrated that conotoxin had no effect on the conformational equilibrium of either receptor, as assessed by the effects of the noncompetitive antagonist proadifen on conotoxin binding and, conversely, the effect of conotoxin on the affinity of phencyclidine, proadifen, and ethidium. Conotoxin displayed higher binding affinity in low ionic strength buffer; neutralization of Lys-10 and the N terminus by acetylation blocked this affinity shift at the alphadelta site but not at the alphagamma site. It is concluded that Ctx residues Lys-10 and the N terminal interact with oppositely charged receptor residues only at the alphadelta site, and the two sites have distinct arrangements of charged residues. Ethidium fluorescence experiments demonstrated that conotoxin is formally competitive with a small cholinergic ligand, tetramethylammonium. Thus, alpha-conotoxin MI appears to interact with the portion of the binding site responsible for stabilizing agonist cations but does not do so with a cationic residue and is, consequently, incapable of inducing a conformational change.
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Affiliation(s)
- R V Papineni
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas 77030, USA
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Ricciardi A, le Du MH, Khayati M, Dajas F, Boulain JC, Menez A, Ducancel F. Do structural deviations between toxins adopting the same fold reflect functional differences? J Biol Chem 2000; 275:18302-10. [PMID: 10849442 DOI: 10.1074/jbc.275.24.18302] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Three-finger proteins form a structurally related family of compounds that exhibit a great variety of biological properties. To address the question of the prediction of functional areas on their surfaces, we tentatively conferred the acetylcholinesterase inhibitory activity of fasciculins on a short-chain curaremimetic toxin. For this purpose, we assimilated the three-dimensional structure of fasciculin 2 with the one of toxin alpha. This comparison revealed that the tips of the first and second loops, together with the C terminus residue, deviated most. A first recombinant fasciculin/toxin alpha chimera was designed by transferring loop 1 in its entirety together with the tip of loop 2 of fasciculin 2 into the toxin alpha scaffold. A second chimera (rChII) was obtained by adding the point Asn-61 --> Tyr substitution. Comparison of functional and structural properties of both chimeras show that rChII can accommodate the imposed modifications and displays nearly all the acetylcholinesterase-blocking activities of fasciculins. The three-dimensional structure of rChII demonstrates that rChII adopts a typical three-fingered fold with structural features of both parent toxins. Taken together, these results emphasize the great structural flexibility and functional adaptability of that fold and confirm that structural deviations between fasciculins and short-chain neurotoxins do indeed reflect functional diversity.
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Affiliation(s)
- A Ricciardi
- Instituto de Investigaciones Biologicas, Clemente Estable, Montevideo, Uruguay 11600, France
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18
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Abstract
The regulation of crystal morphology by proteins is often observed in biology. It is a central feature in the formation of hard tissues such as bones, teeth and mollusc shells. We have developed a genetic system in the bacterium Escherichia coli to study the protein-mediated control of crystal growth. We have used the crystallization of gold as a model system and found polypeptides that control the morphology of the resulting gold crystals. Analysis of the crystallization process influenced by these polypeptides indicates they act catalytically by an acid mechanism. Our results suggest that the concepts and methods of microbial genetics are general and can be applied to substances not commonly found in biological systems.
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Affiliation(s)
- S Brown
- Department of Molecular Cell Biology, University of Copenhagen, Oster Farimagsgade 2A, Copenhagen K, DK-1353, Denmark.
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19
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Singh SB, Armugam A, Kini RM, Jeyaseelan K. Phospholipase A(2) with platelet aggregation inhibitor activity from Austrelaps superbus venom: protein purification and cDNA cloning. Arch Biochem Biophys 2000; 375:289-303. [PMID: 10700385 DOI: 10.1006/abbi.1999.1672] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Four phospholipase A(2) (PLA(2)) enzymes (Superbins a, b, c, and d) with varying platelet aggregation inhibitor activities have been purified from Austrelaps superbus by a combination of gel filtration, ion-exchange, and reversed-phase high-pressure liquid chromatography. Purity and homogeneity of the superbins have been confirmed by high-performance capillary zone electrophoresis and mass spectrometry. The electron spray ionization mass spectrometry data showed that their molecular masses range from 13,140 to 13,236 Da. Each of the proteins has been found to be basic and exhibit varying degrees of PLA(2) activity. They also displayed different platelet aggregation inhibitory activities. Superbin a was found to possess the most potent inhibitory activity with an IC(50) of 9.0 nM, whereas Superbin d was found to be least effective with an IC(50) of 3.0 microM. Superbins b and c were moderately effective with IC(50) values of 0.05 and 0.5 microM, respectively. The amino-terminal sequencing confirmed the identity of these superbins. cDNA cloning resulted in the identification of 17 more PLA(2) isoforms in A. superbus venom. It has also provided complete information on the precursor PLA(2). The precursor PLA(2) contained a 27-amino-acid signal peptide and 117- to 125-amino-acid PLA(2) (molecular mass ranging from 13,000 to 14,000 Da). Two of these PLA(2) enzymes resembled more closely (87%) Superbin a in structure. Two unique PLA(2) enzymes containing an extra pancreatic loop also have been identified among the isoforms.
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Affiliation(s)
- S B Singh
- Department of Biochemistry, National University of Singapore, 10 Medical Drive, Singapore, 119260
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20
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Gaucher JF, Ménez R, Arnoux B, Pusset J, Ducruix A. High resolution x-ray analysis of two mutants of a curaremimetic snake toxin. EUROPEAN JOURNAL OF BIOCHEMISTRY 2000; 267:1323-9. [PMID: 10691969 DOI: 10.1046/j.1432-1327.2000.01099.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A previous mutational analysis of erabutoxin a (Ea), a curaremimetic toxin from sea snake venom, showed that the substitutions S8G and S8T caused, respectively, 176-fold and 780-fold affinity decreases for the nicotinic acetylcholine receptor (AchR). In view of the fact that the side-chain of Ser8 is buried in the wild-type toxin, we wondered whether these affinity changes reflect a direct binding contribution of S8 to the receptor and/or conformational changes that could have occurred in Ea as a result of the introduced mutations. To approach this question, we solved X-ray structures of the two mutants S8G and S8T at high resolution (0.18 nm and 0.17 nm, with R factors of 18.0% and 17.9%, respectively). The data show that none of the mutations significantly modified the toxin structure. Even within the site where the toxin binds to the receptor the backbone conformation remained unchanged. Therefore, the low affinities of the mutants S8T and S8G cannot be explained by a large conformational change of the toxin structure. Although we cannot exclude the possibility that undetectable structural changes have occurred in the toxin mutants, our data support the view that, although buried between loop I and II, S8 is part of the functional epitope of the toxin.
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Affiliation(s)
- J F Gaucher
- Laboratoire d'Enzymologie et de Biochimie Structurales, UPR 9063 CNRS, 91198 Gif-sur-Yvette, France
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21
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Reily MD, Bokman AM, Offord J, McConnell P. Nuclear magnetic resonance spectroscopy of peptide ion channel ligands: cloning and expression as aid to evaluation of structural and dynamic properties. Methods Enzymol 1999; 294:92-117. [PMID: 9916224 DOI: 10.1016/s0076-6879(99)94008-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Affiliation(s)
- M D Reily
- Department of Chemistry, Parke-Davis Pharmaceutical Research, Division of Warner Lambert Company, Ann Arbor, Michigan 48105, USA
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22
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Woodbury RG, Wendin C, Clendenning J, Melendez J, Elkind J, Bartholomew D, Brown S, Furlong CE. Construction of biosensors using a gold-binding polypeptide and a miniature integrated surface plasmon resonance sensor. Biosens Bioelectron 1998; 13:1117-26. [PMID: 9842707 DOI: 10.1016/s0956-5663(98)00060-8] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Surface plasmon resonance (SPR) biosensors were constructed on miniature integrated sensors. Recognition elements were attached to the sensor surface using a gold-binding repeating polypeptide. Biosensors with fluorescyl groups attached to their surfaces were functional for at least 1 month of daily use with little decrease in response to the binding of an anti-fluorescyl monoclonal antibody. The coupling of protein A to the gold-binding polypeptide on the sensor surface enabled the biosensor to detect the binding of antibodies to the protein A and provided a sensor with convertible specificity. The system described herein provides a simple and rapid approach for the fabrication of highly specific, durable, portable and low cost SPR-based biosensors.
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Affiliation(s)
- R G Woodbury
- Department of Medicine, University of Washington, Seattle 98195, USA
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23
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Léonetti M, Thai R, Cotton J, Leroy S, Drevet P, Ducancel F, Boulain JC, Ménez A. Increasing Immunogenicity of Antigens Fused to Ig-Binding Proteins by Cell Surface Targeting. THE JOURNAL OF IMMUNOLOGY 1998. [DOI: 10.4049/jimmunol.160.8.3820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
Fusion of antigenic proteins to Ig-binding proteins such as protein A from Staphylococcus aureus and its derived ZZ fragment is known to increase immunogenicity of the fused Ag in vivo. To shed light on the origin of this effect, we used snake toxins as Ags and observed that 1) fusion of toxins to ZZ enhanced their presentation to a toxin-specific T cell hybridoma (T1B2), using A20 B lymphoma cells, splenocytes, or peritoneal exudate cells as APCs; 2) this enhancement further increased when the number of fused Ig-binding domains varied from two with ZZ to five with protein A; and 3) the phenomenon vanished when the fusion protein was preincubated with an excess of free ZZ or when P388D1 monocytes cells were used as APCs. Therefore, ZZ-fused toxins are likely to be targeted to surface Igs of APCs by their ZZ moiety. Furthermore, ZZ-α and toxin α stimulated similar profiles of toxin-specific T cells in BALB/c mice, suggesting a comparable processing and presentation in vivo for both toxin forms. To improve the targeting efficiency, ZZ-α was noncovalently complexed to various Igs directed to different cell surface components of APCs. The resulting complexes were up to 103-fold more potent than the free toxin at stimulating T1B2. Also, they elicited both a T cell and an Ab response in BALB/c mice, without the need of any adjuvant. This simple approach may find practical applications by increasing the immunogenicity of recombinant proteins without the use of adjuvant.
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Affiliation(s)
- Michel Léonetti
- Département d’Ingéniérie et d’Études des Protéines (DIEP) C. E. Saclay, Gif-Sur-Yvette, France
| | - Robert Thai
- Département d’Ingéniérie et d’Études des Protéines (DIEP) C. E. Saclay, Gif-Sur-Yvette, France
| | - Joël Cotton
- Département d’Ingéniérie et d’Études des Protéines (DIEP) C. E. Saclay, Gif-Sur-Yvette, France
| | - Sandrine Leroy
- Département d’Ingéniérie et d’Études des Protéines (DIEP) C. E. Saclay, Gif-Sur-Yvette, France
| | - Pascal Drevet
- Département d’Ingéniérie et d’Études des Protéines (DIEP) C. E. Saclay, Gif-Sur-Yvette, France
| | - Frédéric Ducancel
- Département d’Ingéniérie et d’Études des Protéines (DIEP) C. E. Saclay, Gif-Sur-Yvette, France
| | - Jean Claude Boulain
- Département d’Ingéniérie et d’Études des Protéines (DIEP) C. E. Saclay, Gif-Sur-Yvette, France
| | - André Ménez
- Département d’Ingéniérie et d’Études des Protéines (DIEP) C. E. Saclay, Gif-Sur-Yvette, France
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24
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Lobeck K, Drevet P, Léonetti M, Fromen-Romano C, Ducancel F, Lajeunesse E, Lemaire C, Ménez A. Towards a recombinant vaccine against diphtheria toxin. Infect Immun 1998; 66:418-23. [PMID: 9453589 PMCID: PMC107921 DOI: 10.1128/iai.66.2.418-423.1998] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/1997] [Accepted: 11/04/1997] [Indexed: 02/06/2023] Open
Abstract
Two recombinant fragments of diphtheria toxin (DT) were fused to an engineered tandem repeat of the immunoglobulin (Ig) binding domain of protein A, called ZZ. These fragments are (i) the receptor binding domain (DTR), which comprises amino acids 382 to 535 of DT, and (ii) a linear peptide (DT(168-220)) which comprises residues 168 to 220 of the loop between fragment A and fragment B of DT. The fusion proteins were produced in Escherichia coli and purified by affinity chromatography. In vitro experiments showed that the DTR domain is responsible for the capacity of ZZ-DTR to bind to Vero cells and is capable of inhibiting the cytotoxicity of DT for these cells. These findings suggest that DTR binds to the cell surface receptors of DT and hence adopts a conformation that is similar to that of the receptor binding domain of DT. We compared the capacities of ZZ-DTR, ZZ-DT(168-220), and a chemically detoxified form of DT currently used for vaccination to elicit antibodies in rabbits. The toxoid was more immunogenic than ZZ-DT(168-220), which in turn was more immunogenic than ZZ-DTR. However, ZZ-DT(168-220) antiserum was poorly efficient at neutralizing DT cytotoxicity on Vero cells, whereas ZZ-DTR antiserum was only 15-fold less potent than anti-DT antisera.
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Affiliation(s)
- K Lobeck
- CEA, Départment d'Ingénierie et d'Etudes des Protéines, Centre d'Etudes de Saclay, Gif-sur-Yvette, France
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25
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Drevet P, Lemaire C, Gasparini S, Zinn-Justin S, Lajeunesse E, Ducancel F, Pinkasfeld S, Courçon M, Tremeau O, Boulain JC, Ménez A. High-level production and isotope labeling of snake neurotoxins, disulfide-rich proteins. Protein Expr Purif 1997; 10:293-300. [PMID: 9268675 DOI: 10.1006/prep.1997.0740] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The aim of this work was to produce and to label snake neurotoxins, disulfide-rich proteins. A mutant of a snake toxin, erabutoxin a, was used as a model. Its N-terminal part was fused to ZZ, a synthetic IgG-binding domain of protein A (B. Nilsson et al., 1987, Protein Eng. 1, 107-113), thus preventing degradation in the bacterial cytoplasm and providing a simple affinity-purification method on IgG Sepharose. A soluble fusion protein was obtained with a yield of 60 mg/L, corresponding to 20 mg/L toxin. The toxin moiety was folded on the column while the hybrid was still bound. The oxidoreducing conditions for the refolding were optimized and were found to be oxidative but with a need for reducing molecules. The concentration of the hybrid bound to the column could be increased up to 3.3 mg/ml without significantly altering the folding process. CNBr cleavage of the fusion protein followed by a purification step yielded about 2 mg of biologically active toxin mutant per gram of dry cell weight. This procedure was applied to produce 55 mg of a toxin uniformly labeled with 15N.
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Affiliation(s)
- P Drevet
- Département d'Ingénierie et d'Etudes des Protéines, DSV, Saclay, CEA, Gif-sur-Yvette, France
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26
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Turkov M, Rashi S, Noam Z, Gordon D, Ben Khalifa R, Stankiewicz M, Pelhate M, Gurevitz M. In vitro folding and functional analysis of an anti-insect selective scorpion depressant neurotoxin produced in Escherichia coli. Protein Expr Purif 1997; 10:123-31. [PMID: 9179299 DOI: 10.1006/prep.1997.0724] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The selective toxicity of depressant scorpion neurotoxins to insects is useful in studying insect sodium channel gating and has an applied potential. In order to establish a genetic system enabling a structure-activity approach, the functional expression of such polypeptides is required. By engineering the cDNA encoding the depressant scorpion neurotoxin, LahIT2, behind the T7 promoter, large amounts of recombinant insoluble and nonactive toxin were obtained in Escherichia coli. Following denaturation and reduction, the recombinant protein, constructed with an additional N-terminal methionine residue, was subjected to renaturation. Optimal conditions for reconstitution of a functional toxin, having a dominant fold over many other possible isoforms, were established. The recombinant active toxin was purified by RP-HPLC and characterized. Toxicity (ED50) to insects, binding affinity (IC50) to an insect receptor site, and electrophysiological effect on an insect axonal preparation were found to be similar to those of the native toxin. Substitution of the C-terminal glycine by a Gly-Lys-Lys triplet did not abolish folding but affected toxicity (3.5-fold decrease) of LqhIT2. Apparently, this efficient bacterial expression system (500 micrograms HPLC-purified toxin/1 liter E. coli culture) provides the means for studying structure/ activity relationship and the molecular basis for the phylogenetic selectivity of scorpion depressant neurotoxins.
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Affiliation(s)
- M Turkov
- Department of Plant Sciences, Faculty of Life Sciences, Tel-Aviv University, Ramat-Aviv, Israel
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27
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Abstract
Attachment of proteins to metal surfaces has the potential to improve our understanding of protein adhesion and has applications in sensor technology. Repeating polypeptides able to bind to metallic gold or chromium were selected from a population of approximately 5 million different polypeptides. Each polypeptide contained several direct repeats of identical peptide units 14 or 28 amino acids long. The metal-recognizing polypeptides were found to retain their binding properties when freed from the protein used to select them. One gold-binding polypeptide's avidity for gold was found to be dependent on the number of repeats and the presence of salt.
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Affiliation(s)
- S Brown
- Department of Molecular Cell Biology, University of Copenhagen, Denmark.
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28
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Marchot P, Prowse CN, Kanter J, Camp S, Ackermann EJ, Radić Z, Bougis PE, Taylor P. Expression and activity of mutants of fasciculin, a peptidic acetylcholinesterase inhibitor from mamba venom. J Biol Chem 1997; 272:3502-10. [PMID: 9013597 DOI: 10.1074/jbc.272.6.3502] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Fasciculin, a selective peptidic inhibitor of acetylcholinesterase, is a member of the three-fingered peptide toxin superfamily isolated from snake venoms. The availability of a crystal structure of a fasciculin 2 (Fas2)-acetylcholinesterase complex affords an opportunity to examine in detail the interaction of this toxin with its target site. To this end, we constructed a synthetic fasciculin gene with an appropriate leader peptide for expression and secretion from mammalian cells. Recombinant wild-type Fas2, expressed and amplified in Chinese hamster ovary cells, was purified to homogeneity and found to be identical in composition and biological activities to the venom-derived toxin. Sixteen mutations at positions where the crystal structure of the complex indicates a significant interfacial contact point or determinant of conformation were generated. Two mutants of loop I, T8A/T9A and R11Q, ten mutants of the longest loop II, R24T, K25L, R27W, R28D, H29D, DeltaPro30, P31R, K32G, M33A, and V34A/L35A, and two mutants of loop III, D45K and K51S, were expressed transiently in human embryonic kidney cells. Inhibitory potencies of the Fas2 mutants toward mouse AChE were established, based on titration of the mutants with a polyclonal anti-Fas2 serum. The Arg27, Pro30, and Pro31 mutants each lost two or more orders of magnitude in Fas2 activity, suggesting that this subset of three residues, at the tip of loop II, dominates the loop conformation and interaction of Fas2 with the enzyme. The Arg24, Lys32, and Met33 mutants lost about one order of magnitude, suggesting that these residues make moderate contributions to the strength of the complex, whereas the Lys25, Arg28, Val34-Leu35, Asp45, and Lys51 mutants appeared as active as Fas2. The Thr8-Thr9, Arg11, and His29 mutants showed greater ratios of inhibitory activity to immunochemical titer than Fas2. This may reflect immunodominant determinants in these regions or intramolecular rearrangements in conformation that enhance the interaction. Of the many Fas2 residues that lie at the interface with acetylcholinesterase, only a few appear to provide substantial energetic contributions to the high affinity of the complex.
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Affiliation(s)
- P Marchot
- Department of Pharmacology, University of California at San Diego, La Jolla, California 92093-0636, USA
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29
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Ducancel F, Mérienne K, Fromen-Romano C, Trémeau O, Pillet L, Drevet P, Zinn-Justin S, Boulain JC, Ménez A. Mimicry between receptors and antibodies. Identification of snake toxin determinants recognized by the acetylcholine receptor and an acetylcholine receptor-mimicking monoclonal antibody. J Biol Chem 1996; 271:31345-53. [PMID: 8940141 DOI: 10.1074/jbc.271.49.31345] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
In several instances, a monoclonal antibody raised against a receptor ligand has been claimed to mimic the ligand receptor. Thus, a specific monoclonal antibody (Malpha2-3) raised against a short-chain toxin from snake was proposed to mimic the nicotinic acetylcholine receptor (AChR) (). Further confirming this mimicry, we show that (i) like AChR, Malpha2-3 elicits anti-AChR antibodies, which in turn elicit anti-toxin antibodies; and (ii) the region 106-122 of the alpha-chain of AChR shares 66% primary structure identity with complementarity-determining regions of Malpha2-3. Also, a mutational analysis of erabutoxin a reveals that the epitope recognized by Malpha2-3 consists of 10 residues, distributed within the three toxin loops. Eight of these residues also belong to the 10-residue epitope recognized by AChR, a result that offers an explanation as to the functional similarities between the receptor and the antibody. Strikingly, however, most of the residues common to the two epitopes contribute differentially to the energetic formation of the antibody-toxin and the receptor-toxin complexes. Together, the data suggest that the mimicry between AChR and Malpha2-3 is partial only.
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Affiliation(s)
- F Ducancel
- Département d'Ingénierie et d'Etudes des Protéines, DSV, CEA, Saclay, 91191 Gif-sur-Yvette, France
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30
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Ghadessy FJ, Chen D, Kini RM, Chung MC, Jeyaseelan K, Khoo HE, Yuen R. Stonustoxin is a novel lethal factor from stonefish (Synanceja horrida) venom. cDNA cloning and characterization. J Biol Chem 1996; 271:25575-81. [PMID: 8810331 DOI: 10.1074/jbc.271.41.25575] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Stonustoxin (SNTX) is a multifunctional lethal protein isolated from venom elaborated by the stonefish, Synanceja horrida. It comprises two subunits, termed alpha and beta, which have respective molecular masses of 71 and 79 kDa. SNTX elicits an array of biological responses both in vitro and in vivo, particularly a potent hypotension that appears to be mediated by the nitric oxide pathway. As a prelude to structure-function studies, we have isolated and sequenced cDNA clones encoding the alpha- and beta-subunits of SNTX from a venom gland cDNA library. The deduced amino acid sequence of neither subunit shows significant homology with any known protein. Protein sequence alignment does, however, show the subunits to be 50% homologous to each other and implies that they may have arisen from a common ancestor. The subunits of this novel toxin lack typical N-terminal signal sequences commonly found in proteins that are secreted via the endoplasmic reticulum-Golgi apparatus pathway, indicating the possibility of its being secreted by a non-classical pathway, which is not clearly understood. The SNTX subunits have been expressed in Escherichia coli as cleavable fusion proteins that cross-react with antibodies raised against the native toxin. To the best of our knowledge, this is the first complete sequence of a fish-derived protein toxin to be reported.
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Affiliation(s)
- F J Ghadessy
- Department of Biochemistry, Faculty of Medicine, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260, USA
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31
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Bouhaouala-Zahar B, Ducancel F, Zenouaki I, Ben Khalifa R, Borchani L, Pelhate M, Boulain JC, El Ayeb M, Ménez A, Karoui H. A recombinant insect-specific alpha-toxin of Buthus occitanus tunetanus scorpion confers protection against homologous mammal toxins. EUROPEAN JOURNAL OF BIOCHEMISTRY 1996; 238:653-60. [PMID: 8706664 DOI: 10.1111/j.1432-1033.1996.0653w.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
We have constructed a cDNA library from venom glands of the scorpion Buthus occitanus tunetanus and cloned a DNA sequence that encodes an alpha-toxin. This clone was efficiently expressed in Escherichia coli as a fusion protein with two Ig-binding (Z) domains of protein A from Staphylococcus aureus. After CNBr treatment of the fusion protein and HPLC purification, we obtained approximately 1 mg recombinant apha-toxin/l bacterial culture. The toxin, called Bot XIV, displays no toxicity towards mammals but is active towards insects as shown by its paralytic activity against Blatella germanica cockroach and by electrophysiological studies on Periplaneta americana cockroaches. The Bot XIV protein fused to two Z domains is highly immunogenic in mice and induces production of antisera that specifically recognize and neutralize highly toxic components that had been injected into mice. This fusion protein could be very useful for development of potent protective antisera against scorpion venoms.
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32
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Fiordalisi JJ, James PL, Zhang Y, Grant GA. Facile production of native-like kappa-bungarotoxin in yeast: an enhanced system for the production of a neuronal nicotinic acetylcholine receptor probe. Toxicon 1996; 34:213-24. [PMID: 8711755 DOI: 10.1016/0041-0101(95)00135-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Research on the mammalian central nervous system had been hindered by the limited number and meager supply of naturally occurring toxins that can be used as pharmacological reagents. The kappa-neurotoxins in particular are not found abundantly in nature and are difficult to obtain and isolate in quantities sufficient for research purposes. Here we report the expression and isolation of relatively large quantities of the kappa-neurotoxin, kappa-bungarotoxin, in an active form using a yeast, Pichia pastoris, expression system. The resultant product of the expression system has a short amino-terminal amino acid extension relative to venom-derived kappa-bungarotoxin, but is equivalent to the native toxin in physical and biological properties, as judged by the CD spectra, the ability to form dimers in solution, and the activity on chick ciliary ganglia. The yeast system produces approximately 0.2 mg from a 2 liter culture and the purification takes approximately 2 days. In contrast, E. coli, the only other available expression system for this toxin, produces one-fifth to one-half as much active material from a 5 liter high-density fermentation and the resulting protein takes over a week to purify. No high mol. wt disulfide-bonded aggregates were found in the yeast expression system product, indicating that the product is that of a biologically assisted folding process. This has significant implications not only for the efficient production of native toxin but also for the production of mutant proteins to study the structure-function relationship in these proteins.
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Affiliation(s)
- J J Fiordalisi
- Department of Molecular Biology and Pharmacology, Washington University School of Medicine, St Louis, MO 63110, USA
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33
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Affiliation(s)
- A T Tu
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins 80523-1870, USA
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34
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Trémeau O, Lemaire C, Drevet P, Pinkasfeld S, Ducancel F, Boulain JC, Ménez A. Genetic engineering of snake toxins. The functional site of Erabutoxin a, as delineated by site-directed mutagenesis, includes variant residues. J Biol Chem 1995; 270:9362-9. [PMID: 7721859 DOI: 10.1074/jbc.270.16.9362] [Citation(s) in RCA: 120] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Using site-directed mutagenesis, we previously identified some residues that probably belong to the site by which Erabutoxin a (Ea), a sea snake toxin, recognizes the nicotinic acetylcholine receptor (AcChoR) (Pillet, L., Trémeau, O., Ducancel, F. Drevet, P., Zinn-Justin, S., Pinkasfeld, S., Boulain, J.-C., and Ménez, A. (1993) J. Biol. Chem. 268, 909-916). We have now studied the effect of mutating 26 new positions on the affinity of Ea for AcChoR. The mutations are F4A, N5V, H6A, Q7L, S9G, Q10A, P11N, Q12A, T13V, T14A, K15A, T16A, delta S18, E21A, Y25F, Q28A, S30A, T35A, I36R, P44V, T45A, V46A, K47A, P48Q, I50Q, and S53A. Binding affinity decreases upon mutation at Gln-7, Gln-10 and to a lesser extent at His-6, Ser-9 and Tyr-25 whereas it increases upon mutation at Ile-36. Other mutations have no effect on Ea affinity. In addition, new mutations of the previously explored Ser-8, Asp-31, Arg-33, and Glu-38 better explain the functional role of these residues in Ea. The previous and present mutational analysis suggest that the "functional" site of Ea covers a homogeneous surface of at least 680 A2, encompassing the three toxin loops, and includes both conserved and variant residues. The variable residues might contribute to the selectivity of Ea for some AcChoRs, including those from fish, the prey of sea snakes.
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Affiliation(s)
- O Trémeau
- Département d'Ingénierie et d'Etudes des Protéines, DSV, CEA, Saclay, Gif-sur-Yvette, France
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35
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Evidence for the presence of α-bungarotoxin in venom-derived κ-bungarotoxin. ACTA ACUST UNITED AC 1995. [DOI: 10.1016/s1080-8914(06)80037-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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36
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Danse JM, Rowan EG, Gasparini S, Ducancel F, Vatanpour H, Young LC, Poorheidari G, Lajeunesse E, Drevet P, Ménez R. On the site by which alpha-dendrotoxin binds to voltage-dependent potassium channels: site-directed mutagenesis reveals that the lysine triplet 28-30 is not essential for binding. FEBS Lett 1994; 356:153-8. [PMID: 7805827 DOI: 10.1016/0014-5793(94)01235-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
We constructed a synthetic gene encoding the published amino acid sequence of DTx from Dendroaspis angusticeps, a ligand of voltage-dependent postassium channels that facilitates neurotransmitter release. We expressed it in Escherichia coli as a fusion protein secreted in the culture medium. The recombinant DTx was generated in vitro by chemical treatment and recovered as two isoforms. One of them (rDTx), like the venom toxin, has an N-terminal pyroglutamate whereas the other (rQDTx) has a free N-terminal glutamine. Chromatographic differences between rDTx and natural DTx led us to re-examine the amino acid sequence of natural DTx. In contrast to what was previously published, position 12 was an Asp and not Asn. Despite this difference, rDTx and DTx had similar toxicity in mice and binding affinity to synaptosomes, suggesting that residue 12 is not important for DTx function. Nor is the N-terminal residue implicated in DTx function since rDTx and rQDTx also had similar biological activities. We also synthesized and expressed a mutant of the DTx gene in which the lysine triplet 28-30 was changed into Ala-Ala-Gly. The two resulting recombinant isoforms exhibited only small decreases in biological activity, excluding the possibility that the positively charged lysine triplet 28-30 of DTx is directly involved in the toxin functional site.
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Affiliation(s)
- J M Danse
- Département d'Ingénierie et d'Etudes des Protéines (DIEP), CEA, Saclay, Gif-sur-Yvette, France
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37
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Chi LM, Vyas AA, Rule GS, Wu WG. Expression of glutathione S-transferase-cardiotoxin fusion protein in Escherichia coli. Toxicon 1994; 32:1679-83. [PMID: 7725337 DOI: 10.1016/0041-0101(94)90328-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
We report here the construction of cardiotoxin V gene, from cobra snake venom (Naja naja atra), by chemically synthesized oligonucleotides and its expression as a glutathione S-transferase-cardiotoxin fusion protein in the inclusion bodies of Escherichia coli. The expression of cardiotoxin fusion protein in protein with a yield of about 35 mg/liter culture was confirmed by highly specific anti-peptide antibodies generated against the unique amino acid residues located at the tip of loop II of cardiotoxin V. Since the fusion protein can be easily treated by CNBr to free the toxin moiety, as revealed by immunoblotting of the cleaved protein, the results provide an avenue for future structural and functional studies of cardiotoxin molecules.
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Affiliation(s)
- L M Chi
- Institute of Life Sciences, National Tsing Hua University, Hsinchu, Taiwan, Republic of China
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38
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Gasparini S, Kiyatkin N, Drevet P, Boulain J, Tacnet F, Ripoche P, Forest E, Grishin E, Ménez A. The low molecular weight protein which co-purifies with alpha-latrotoxin is structurally related to crustacean hyperglycemic hormones. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)32091-4] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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39
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Martin-Eauclaire MF, Søgaard M, Ramos C, Cestèle S, Bougis PE, Svensson B. Production of active, insect-specific scorpion neurotoxin in yeast. EUROPEAN JOURNAL OF BIOCHEMISTRY 1994; 223:637-45. [PMID: 8055934 DOI: 10.1111/j.1432-1033.1994.tb19036.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
A cDNA encoding the Androctonus australis Hector insect toxin 1 (AaH IT1) was expressed in yeast leading to secretion of fully biologically active protein. Three different multicopy plasmids were constructed using PCR. Expression was directed by the strong PGK1 promoter of the yeast vector pMA 91. Plasmid pMA 91-AaH IT1 encodes AaH IT1 and its own signal peptide. In the two other constructions, the cDNA encoding the mature part of AaH IT1 is fused to the prepro-signal sequence of the yeast alpha-mating-factor precursor; the pBAL 7-alpha-KREAEA-AaH IT1 includes the cDNA sequence encoding the KR(EAEA) processing sequence of the alpha-mating factor, and pBAL 7-alpha-KR-AaH IT1 encodes the KR fused directly to the AaH IT1 gene. The yeast alpha-mating-factor signal peptide launched the pro-alpha-mating-factor-AaH IT1 fusion protein into the secretory pathway. The fusion proteins are expected to be cleaved in the Golgi by the KEX2 endopeptidase and the STE13 dipeptidyl aminopeptidase, leading to release of mature AaH IT1. Pulse/chase labelling of transformed yeast protoplasts, followed by SDS/PAGE analysis of proteins immunoprecipitated from either the lysate or the extracellular fluid, showed that AaH IT1 was produced. The highest concentration of recombinant AaH IT1 in the culture medium, as determined using a 125I-AaH IT1 specific radioimmunoassay, was 4 micrograms/l (0.5 nM). The recombinant toxin was fully biologically active against cockroaches as assessed by injection and comparison to native AaH IT1. Moreover, it competed with radiolabelled native toxin for its receptor on the voltage-sensitive Na+ channel with a dissociation constant of 0.5 nM.
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40
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Rosenthal J, Hsu S, Schneider D, Gentile L, Messier N, Vaslet C, Hawrot E. Functional expression and site-directed mutagenesis of a synthetic gene for alpha-bungarotoxin. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(19)78107-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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41
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Arnoux B, Ménez R, Drevet P, Boulain JC, Ducruix A, Ménez A. Three-dimensional crystal structure of recombinant erabutoxin a at 2.0 A resolution. FEBS Lett 1994; 342:12-4. [PMID: 8143841 DOI: 10.1016/0014-5793(94)80574-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Recombinant erabutoxin a (Ea(r)) has been crystallized by vapour diffusion in hanging drops. The crystals belong to space group P2(1)2(1)2(1) with cell dimensions a = 55.8 A, b = 53.4 A, c = 40.8 A. Diffraction data have been recorded on a FAST detector up to 2.0 A. The atomic crystal structure of Ea(r) has been determined by initial refinement of the structure of the isotoxin erabutoxin b (Eb) the crystals of which were grown under identical conditions. The R-factor was 23% at 2.0 A resolution. The secondary and tertiary structures of Ea(r) are shown to be identical with that of wild-type Eb, within the experimental error.
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Affiliation(s)
- B Arnoux
- Laboratoire de Biologie Structurale, CNRS, Gif-sur-Yvette, France
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42
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Ezan E, Ducancel F, Gillet D, Drevet P, Ménez A, Grognet JM, Boulain JC. Recombinant technology in the preparation of immunogen and enzymatic tracer. Application to the development of an enzyme immunoassay for rat prolactin. J Immunol Methods 1994; 169:205-11. [PMID: 8133080 DOI: 10.1016/0022-1759(94)90264-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
A competitive enzyme immunoassay for rat prolactin using an immunogen and a tracer obtained by recombinant DNA technology is described. Polyclonal antibodies were raised in rabbits immunized with a purified chimeric protein consisting of rat prolactin fused with two synthetic immunoglobulin G binding domains derived from staphylococcal Protein A. The enzymatic tracer was obtained using an expression system which permits insertion of rPRL DNA sequence in the alkaline phosphatase gene. Antibodies and tracer were used to develop a solid-phase competitive immunoassay for the measurement of rat prolactin in plasma with a minimal detectable concentration of 0.5 ng/ml. The mean intra- and inter-assay coefficients of variation were 7.8 and 13.2%, respectively. Rat plasma concentrations measured with this assay correlated well with those obtained with a conventional enzyme immunoassay (r = 0.993, slope = 1.037, n = 24).
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Affiliation(s)
- E Ezan
- Service de Pharmacologie et d'Immunologie, DRIPP Bât 136, Commissariat à l'Energie Atomique, CE/Saclay, Gif-sur-Yvette, France
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43
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Belin P, Quéméneur E, Boquet PL. A pleîotropic acid phosphatase-deficient mutant of Escherichia coli shows premature termination in the dsbA gene. Use of dsbA::phoA fusions to localize a structurally important domain in DsbA. MOLECULAR & GENERAL GENETICS : MGG 1994; 242:23-32. [PMID: 8277944 DOI: 10.1007/bf00277344] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
A one-step mutant of Escherichia coli K-12 lacking both glucose-1-phosphatase (Agp) and pH 2.5 acid phosphatase (AppA) activities in the periplasmic space was isolated. The mutation which mapped close to chlB, at 87 min on the E. coli linkage map, also caused the loss of alkaline phosphatase (PhoA) activity, even when this activity was expressed from TnphoA fusions to genes encoding periplasmic or membrane proteins. A DNA fragment that complements the mutation was cloned and shown to carry the dsbA gene, which encodes a periplasmic disulphide bond-forming factor. The mutant had an ochre triplet in dsbA, truncating the protein at amino acid 70. Introduction of TnphoA fusions into a plasmid-borne dsbA gene resulted in DsbA-PhoA hybrid proteins that were all exported to the periplasmic space in both dsbA+ and dsbA strains. They belong to three different classes, depending on the length of the DsbA fragment fused to PhoA. When PhoA was fused to an amino-terminal DsbA heptapeptide, the protein was only seen in the periplasm of a dsbA+ strain, as in the case of wild-type PhoA. Hybrid proteins missing up to 29 amino acids at the carboxy-terminus of DsbA were stable and retained both the DsbA and PhoA activities. Those with shorter DsbA fragments that still carried the -Cys-Pro-His-Cys- motif were rapidly degraded (no DsbA activity). The presence is discussed of a structural domain lying around amino acid 170 of DsbA and which is probably essential for its folding into a proteolytic-resistant and enzymatically active form.
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Affiliation(s)
- P Belin
- Département d'Ingénierie et d'Etudes des Protéines, C.E. Saclay, CEA, Gif-sur-Yvette, France
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44
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Hodgson D, Gasparini S, Drevet P, Ducancel F, Bouet F, Boulain JC, Harris JB, Menez A. Production of recombinant notechis 11'2L, an enzymatically active mutant of a phospholipase A2 from Notechis scutatus scutatus venom, as directly generated by cleavage of a fusion protein produced in Escherichia coli. EUROPEAN JOURNAL OF BIOCHEMISTRY 1993; 212:441-6. [PMID: 8444182 DOI: 10.1111/j.1432-1033.1993.tb17680.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
We have constructed an expression vector to produce, in Escherichia coli, a fusion protein containing successively two IgG binding domains from staphyloccocal protein A, a nine-amino-acid linker peptide terminating in a methionine residue and the phospholipase A2 notechis 11'2L, an isoform of notexin of Notechis scutatus scutatus venom. Notechis 11'2L is a mutant of the naturally occurring notechis 11'2 [Bouchier, C., Boyot, P., Tesson, F., Trémeau, O., Bouet, F., Hodgson, D., Boulain, J. C. & Ménez, A. (1991) Eur. J. Biochem. 202, 493-500] in which Met8 has been replaced by Leu. The fusion protein was recovered in the periplasmic extract with a yield of 0.25 mg/l culture. It was hydrolyzed with cyanogen bromide, yielding a protein having the molecular mass, amino acid composition and N-terminal sequence of notechis 11'2L. Notechis 11'2L and the wild notechis 11'2 displayed identical circular dichroic spectra and shared similar enzymatic, myotoxic and antigenic properties, suggesting that the recombinant notechis 11'2L was directly generated in a correctly folded form.
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Affiliation(s)
- D Hodgson
- Département d'Ingéniérie et d'Etudes des Protéines, CE Saclay, Gif-sur-Yvette, France
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45
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Genetic engineering of snake toxins. Role of invariant residues in the structural and functional properties of a curaremimetic toxin, as probed by site-directed mutagenesis. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(18)54020-5] [Citation(s) in RCA: 125] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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46
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McEuen AR, Edwards B, Koepke KA, Ball AE, Jennings BA, Wolstenholme AJ, Danson MJ, Hough DW. Zinc binding by retroviral integrase. Biochem Biophys Res Commun 1992; 189:813-8. [PMID: 1472053 DOI: 10.1016/0006-291x(92)92275-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Zinc binding by integrase from Moloney murine leukaemia virus and a protein A fusion protein containing integrase from human immunodeficiency virus type 1 was demonstrated by a zinc blotting technique using 65ZnCl2. Autoradiography revealed a clear band that was absent from the appropriate controls. This band co-migrated with the major band in Coomassie-stained gels and in immunoblots. This binding activity was retained in the presence of competing divalent cations and was sensitive to oxidation. This is the first demonstration of zinc binding by intact retroviral integrase.
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Affiliation(s)
- A R McEuen
- Biochemistry Dept., University of Bath, U.K
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47
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Hervé M, Pillet L, Humbert P, Trémeau O, Ducancel F, Hirth C, Ménez A. Role and environment of the conserved Lys27 of snake curaremimetic toxins as probed by chemical modifications, site-directed mutagenesis and photolabelling experiments. EUROPEAN JOURNAL OF BIOCHEMISTRY 1992; 208:125-31. [PMID: 1511681 DOI: 10.1111/j.1432-1033.1992.tb17165.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The positive charge of Lys27 was suppressed by chemical means in two short-chain curaremimetic toxins, namely erabutoxin a (Ea) from Laticauda semifasciata and toxin alpha from Naja nigricollis. This modification leads to a decrease in the binding affinity of the toxins for the nicotinic acetylcholine receptor, which range 6-15-fold, as judged from both the data reported here and those previously described in the literature. A negatively charged glutamate residue has been introduced at position 27 of erabutoxin a by site-directed mutagenesis. This change provokes a 120-fold decrease in the affinity, which reflects a major alteration of toxin-receptor cognate events. Using toxin-alpha derivative harbouring a photoactive group at Lys27, we probed the toxin local environment in a receptor-bound state by photocoupling experiments. The delta chain was the predominant coupling target, in contrast to previous observations indicating that a photoactive probe on Lys47 predominantly labelled the alpha chain. The toxin derivative weakly labelled the alpha and gamma chains but not the beta chain. The toxin may therefore interact with subunits other than the alpha chain, at least in the vicinity of Lys27.
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Affiliation(s)
- M Hervé
- Département d'Ingénierie et d'Etudes des Protéines, Centre d'Etudes de Saclay, Gif-sur Yvette, France
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48
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Bouchier C, Boyot P, Tesson F, Trémeau O, Bouet F, Hodgson D, Boulain JC, Ménez A. Notechis 11'2, a non-toxic phospholipase A2 from the venom of Notechis scutatus scutatus. EUROPEAN JOURNAL OF BIOCHEMISTRY 1991; 202:493-500. [PMID: 1761049 DOI: 10.1111/j.1432-1033.1991.tb16399.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Previously, we deduced the amino acid sequence of a novel phospholipase-A2-like protein (PLA2) from the nucleotide sequence of a cDNA isolated from a library prepared from the venom gland of the Australian elapid Notechis scutatus scutatus. The corresponding protein has now been identified, purified from the venom and named Notechis 11'2. Its complete amino acid sequence has been determined by automated Edman degradation of both the whole protein and peptides generated by Staphylococcus aureus protease digestion and chemical cleavage at a tryptophan residue. As predicted from its sequence which contains all the residues putatively required for PLA2 activity, Notechis 11'2 exhibits an esterase activity, preferentially against neutral phospholipids. However, despite its sequence homology with other highly toxic PLA2 present in the venom of Notechis scutatus scutatus, notechis 11'2 has no lethal activity. This observation further supports the view that the lethal activity of PLA2 from Notechis scutatus scutatus is not due to the esterasic activity only.
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Affiliation(s)
- C Bouchier
- Service de Biochimie des Protéines, Laboratoire d'Ingénierie des Protéines, CEN Saclay, Gif-sur-Yvette, France
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49
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Boyot P, Pillet L, Ducancel F, Boulain JC, Tremeau O, Ménez A. A recombinant snake neurotoxin generated by chemical cleavage of a hybrid protein recovers full biological properties. FEBS Lett 1990; 266:87-90. [PMID: 2365072 DOI: 10.1016/0014-5793(90)81513-n] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
We previously reported the production of a fused snake neurotoxin composed of protein A and erabutoxin a in E. coli. The hybrid had much lower toxicity and affinity for the acetylcholine nicotinic receptor than natural erabutoxin. By treating the hybrid with cyanogen bromide we generated a toxin which was purified in a single step by RP-HPLC. This compound, produced in a good yield, recovered all properties of native erabutoxin a, implying that the lower toxic activities of the hybrid were due to the bulky protein A and not to an incorrect folding of the toxin. This work serves as a basis for future studies of toxin-receptor interactions using engineered toxin mutants.
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Affiliation(s)
- P Boyot
- Département de Biologie, Laboratoire d'Ingénierie des Protéines, C.E.N., Gif-sur-Yvette, France
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50
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Charpentier I, Pillet L, Karlsson E, Couderc J, Ménez A. Recognition of the acetylcholine receptor binding site of a long-chain neurotoxin by toxin-specific monoclonal antibodies. J Mol Recognit 1990; 3:74-81. [PMID: 1694448 DOI: 10.1002/jmr.300030204] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The present paper reports the preparation and characterization of two neutralizing monoclonal antibodies (Mabs), called MST1 and MST2, which bind at the central loop of a long-chain neurotoxin from cobra venom. The central loop is a critical region for the binding of the toxin to the nicotinic acetylcholine receptor. Some of the residues incorporated in the epitopes recognized by MST1 and MST2 have been identified on the basis of competition experiments using a set of 'chemical mutants' of the toxin. We show that MST1 and MST2 bind at the base and at the tip of the central loop of the toxin, respectively, however, only MST2 actually overlaps the acetylcholine receptor binding site. Accordingly, only MST2 is capable of recognizing all homologous toxins so far examined. MST2, therefore, mimicks, at least partially, the site by which the nicotinic acetylcholine receptor recognizes a long-chain neurotoxin.
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Affiliation(s)
- I Charpentier
- Département de Biologie, Protéines CEN Saclay, Gif-sur Yvette, France
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