101
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Wang Y, Shao X, Li M, Wang S, Chi C, Wang C. mr1e, a conotoxin from Conus marmoreus with a novel disulfide pattern. Acta Biochim Biophys Sin (Shanghai) 2008; 40:391-6. [PMID: 18465024 DOI: 10.1111/j.1745-7270.2008.00414.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Conotoxins are well known for their highly variable structures and functions. Here we report the identification of a novel conotoxin named mr1e from Conus marmoreus. mr1e is composed of 11 amino acid residues cross-linked by two disulfide bonds (CCHSSWCKHLC). The spacing of intercysteine loops in mr1e is exactly the same as that in alpha4/3 conotoxins. However, the native mr1e peptide co-eluted on reverse-phase HPLC with the regioselectively synthesized ribbon disulfide linkage isomer (C1-C4, C2-C3) but not the globular linkage isomer (C1-C3, C2-C4). Although this peptide has the same disulfide connectivity as the chi-conotoxins, their sequences do not share significant homology. Thus, mr1e could be defined as a novel conotoxin family. By intracranial injection into mice, mr1e showed an excitatory effect. The characterization of mr1e certainly enriches our understanding of conotoxins, and also opens an avenue for further structural and functional investigation.
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Affiliation(s)
- Yanfang Wang
- Institute of Protein Research, Tongji University, Shanghai 200092, China
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102
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Identification of a novel S-superfamily conotoxin from vermivorous Conus caracteristicus. Toxicon 2008; 51:1331-7. [PMID: 18423793 DOI: 10.1016/j.toxicon.2008.03.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2007] [Revised: 02/27/2008] [Accepted: 03/03/2008] [Indexed: 11/21/2022]
Abstract
Conotoxins have been classified into several different superfamilies based on the highly conserved signal peptide sequences of their precursors. However, little is known about the five disulfide bonds containing S-superfamily conotoxins. Only two S-superfamily conotoxins have been identified but their cDNAs are not reported. In this work, we identified a novel S-superfamily conotoxin ca8a from vermivorous Conus caracteristicus. Its sequence shares no homology with those of two other previously reported toxins of the same superfamily, but they have the same cysteine framework, in particular the CX(3)CXC-CXC-CXCXC pattern at the C-terminal part. This implies that these toxins might have the same spatial scaffold, but different local conformation or residue side chains may be the cause of their different biological functions. Furthermore, the cDNA of ca8a was cloned with the RACE method. ca8a has a signal peptide sequence different from those of other conotoxins. This gives a defining feature of S-superfamily conotoxins and led to the cloning of more S-superfamily conotoxins from cone snails of different prey types, which indicates that S-superfamily conotoxins widely exist. These results will certainly enrich our understanding of the highly diversified S-superfamily conotoxins.
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103
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Escoubas P, Quinton L, Nicholson GM. Venomics: unravelling the complexity of animal venoms with mass spectrometry. JOURNAL OF MASS SPECTROMETRY : JMS 2008; 43:279-295. [PMID: 18302316 DOI: 10.1002/jms.1389] [Citation(s) in RCA: 117] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Animal venoms and toxins are now recognized as major sources of bioactive molecules that may be tomorrow's new drug leads. Their complexity and their potential as drug sources have been demonstrated by application of modern analytical technologies, which have revealed venoms to be vast peptide combinatorial libraries. Structural as well as pharmacological diversity is immense, and mass spectrometry is now one of the major investigative tools for the structural investigation of venom components. Recent advances in its use in the study of venom and toxins are reviewed. The application of mass spectrometry techniques to peptide toxin sequence determination by de novo sequencing is discussed in detail, in the light of the search for novel analgesic drugs. We also present the combined application of LC-MALDI separation with mass fingerprinting and ISD fragmentation for the determination of structural and pharmacological classes of peptides in complex spider venoms. This approach now serves as the basis for the full investigation of complex spider venom proteomes, in combination with cDNA analysis.
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Affiliation(s)
- P Escoubas
- Université de Nice-Sophia Antipolis, Institut de Pharmacologie Moléculaire et Cellulaire, CNRS UMR6097, 06560 Valbonne, France.
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104
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Bulaj G, Olivera BM. Folding of conotoxins: formation of the native disulfide bridges during chemical synthesis and biosynthesis of Conus peptides. Antioxid Redox Signal 2008; 10:141-55. [PMID: 17961068 DOI: 10.1089/ars.2007.1856] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Conopeptides from >700 species of predatory marine Conus snails provide an impressive molecular diversity of cysteine-rich peptides. Most of the estimated 50,000-100,000 distinct conopeptides range in size from 10 to 50 amino acid residues, often with multiple posttranslational modifications. The great majority contain from two to four disulfide bridges. As the biosynthetic and chemical production of this impressive repertoire of disulfide-rich peptides has been investigated, particularly the formation of native disulfide bridges, differences between in vivo and in vitro oxidative folding have become increasingly evident. In this article, we provide an overview of the molecular diversity of conotoxins with an emphasis on the cysteine patterns and disulfide frameworks. The conotoxin folding studies reviewed include regioselective and direct oxidation strategies, recombinant expression, optimization of folding methods, mechanisms of in vitro folding, and preliminary data on the biosynthesis of conotoxins in venom ducts. Despite these studies, how the cone snails efficiently produce properly folded conotoxins remains unanswered. As chemists continue to master oxidative folding techniques, insights gleaned from how conotoxins are folded in vivo will likely lead to the development of the new folding methods, as well as shed some light on fundamental mechanisms relevant to the protein folding problem.
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Affiliation(s)
- Grzegorz Bulaj
- Department of Medicinal Chemistry, College of Pharmacy, Salt Lake City, Utah 84108, USA.
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105
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Kaas Q, Westermann JC, Halai R, Wang CKL, Craik DJ. ConoServer, a database for conopeptide sequences and structures. Bioinformatics 2007; 24:445-6. [PMID: 18065428 DOI: 10.1093/bioinformatics/btm596] [Citation(s) in RCA: 168] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
SUMMARY ConoServer is a new database dedicated to conopeptides, a large family of peptides found in the venom of marine snails of the genus Conus. These peptides have an exceptional diversity of sequences and chemical modifications and their ability to block ion channels makes them important as drug leads and tools for physiological studies. ConoServer uses standardized names and a genetic and structural classification scheme to present data retrieved from SwissProt, GenBank, the Protein DataBank and the literature. The ConoServer web site incorporates specialized features like the graphic display of post-translational modifications that are extensively present in conopeptides. Currently, ConoServer manages 1214 nucleic sequences (from 54 Conus species), 2258 proteic sequences (from 66 Conus species) and 99 3D structures. AVAILABILITY http://research1t.imb.uq.edu.au/conoserver/.
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Affiliation(s)
- Quentin Kaas
- Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland, 4072, Australia
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106
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Balamurgan K, Dey A, Sivakumar G. Some neuropharamacological effects of the crude extract of Conus parvatus in mice. Pak J Biol Sci 2007; 10:4136-4139. [PMID: 19090294 DOI: 10.3923/pjbs.2007.4136.4139] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The present study was aimed to characterize the type of conotoxin present in Conus parvatus. (CP) belongs to family conidae, through neuro-pharmacological activities of the crude venom extract on some of the CNS animal experiment using mice as animal model. The effects of CP on CNS were studied, by using spontaneous motor activity, gross behavior, rota-rod performance, analgesic activity and potentiation of pentobarbitone sleeping time in mice. Preliminary evaluation of acute toxicity was also carried out; The LD50 value was found to be 425.20 mcg kg(-1) by i.p. route. The extract (200 mcg kg(-1) i.p.) was found to produce, reduction in spontaneous motor activity, potent analgesic activity, reduction in motor coordination and prolonged pentobarbitone-sleeping time. From the above all pharmacological activities, it may concluded that, the conotoxin present in CP is most likely to be a alpha-conotoxin and also it will be more suitable to continue the studies in the areas of analgesic and other CNS depressant therapeutic areas after isolation of the pure cono-peptide from CP.
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Affiliation(s)
- K Balamurgan
- Department of Pharmacy, Annamalai University, Annamalai Nagar, Tamil Nadu, India
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107
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Peng C, Wu X, Han Y, Yuan D, Chi C, Wang C. Identification of six novel T-1 conotoxins from Conus pulicarius by molecular cloning. Peptides 2007; 28:2116-24. [PMID: 17933431 DOI: 10.1016/j.peptides.2007.08.026] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2007] [Revised: 08/30/2007] [Accepted: 08/31/2007] [Indexed: 10/22/2022]
Abstract
Cone snails are a group of ancient marine gastropods with highly sophisticated defense and prey strategies using conotoxins in their venom. Conotoxins are a diverse array of small peptides, mostly with multiple disulfide bridges. Using a 3' RACE approach, we identified six novel peptides from the venom ducts of a worm-hunting cone snail Conus pulicarius. These peptides are named Pu5.1-Pu5.6 as their primary structures show the typical pattern of T-1 conotoxin family, a large and diverse group of peptides widely distributed in venom ducts of all major feeding types of Conus. Except for the conserved signal peptide sequences in the precursors and unique arrangement of Cys residues (CC-CC) in mature domains, the six novel T-1 conotoxins show remarkable sequence diversity in their pro and mature regions and are, thus, likely to be functionally diversified. Here, we present a simple and fast strategy of gaining novel disulfide-rich conotoxins via molecular cloning and our detailed sequence analysis will pave the way for the future functional characterization of toxin-receptor interaction.
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Affiliation(s)
- Can Peng
- Institute of Protein Research, College of Life Science and Technology, Tongji University, 1239 Siping Road, Shanghai, China
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108
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I(1)-superfamily conotoxins and prediction of single D-amino acid occurrence. Toxicon 2007; 51:218-29. [PMID: 17996262 DOI: 10.1016/j.toxicon.2007.09.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2007] [Revised: 09/06/2007] [Accepted: 09/25/2007] [Indexed: 11/22/2022]
Abstract
The considerable diversity of Conus peptides in the I(1)-superfamily provides a rare opportunity to define parameters important for the post-translational l- to d-isomerization of amino acids. This subtlest of post-translational modifications is not readily detectable by most techniques, and it would be a considerable advance if one could predict its potential occurrence purely from gene sequences. We previously described three I(1)-conotoxins, iota-RXIA (formerly designated r11a), r11b and r11c, each containing a d-amino acid at the third position from the C-terminus. In this work, we investigated two novel I(1)-superfamily members, r11d and ar11a, which we show have only l-amino acids. Based on these observations and an analysis of cDNA sequences of other group members, we suggest that there is a rule to predict d-amino acids in I(1)-superfamily peptides. Two factors are important: the residue to be modified should be three amino acids from the C-terminus of the precursor sequence, and it should be in a suitable sequence context. We apply the rule to other members of the I(1)-superfamily, to determine a priori which are probably modified.
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109
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Buczek O, Wei D, Babon JJ, Yang X, Fiedler B, Chen P, Yoshikami D, Olivera BM, Bulaj G, Norton RS. Structure and sodium channel activity of an excitatory I1-superfamily conotoxin. Biochemistry 2007; 46:9929-40. [PMID: 17696362 PMCID: PMC2566796 DOI: 10.1021/bi700797f] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Conotoxin iota-RXIA, from the fish-hunting species Conus radiatus, is a member of the recently characterized I1-superfamily, which contains eight cysteine residues arranged in a -C-C-CC-CC-C-C- pattern. iota-RXIA (formerly designated r11a) is one of three characterized I1 peptides in which the third last residue is posttranslationally isomerized to the d configuration. Naturally occurring iota-RXIA with d-Phe44 is significantly more active as an excitotoxin than the l-Phe analogue both in vitro and in vivo. We have determined the solution structures of both forms by NMR spectroscopy, the first for an I1-superfamily member. The disulfide connectivities were determined from structure calculations and confirmed chemically as 5-19, 12-22, 18-27, and 21-38, suggesting that iota-RXIA has an ICK structural motif with one additional disulfide (21-38). Indeed, apart from the first few residues, the structure is well defined up to around residue 35 and does adopt an ICK structure. The C-terminal region, including Phe44, is disordered. Comparison of the d-Phe44 and l-Phe44 forms indicates that the switch from one enantiomer to the other has very little effect on the structure, even though it is clearly important for receptor interaction based on activity data. Finally, we identify the target of iota-RXIA as a voltage-gated sodium channel; iota-RXIA is an agonist, shifting the voltage dependence of activation of mouse NaV1.6 expressed in Xenopus oocytes to more hyperpolarized potentials. Thus, there is a convergence of structure and function in iota-RXIA, as its disulfide pairing and structure resemble those of funnel web spider toxins that also target sodium channels.
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Affiliation(s)
- Olga Buczek
- Department of Biology, University of Utah, Salt Lake City, Utah, 84112, USA
| | - Daxiu Wei
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville 3050 Australia
| | - Jeffrey J. Babon
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville 3050 Australia
| | - Xiaodong Yang
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville 3050 Australia
| | - Brian Fiedler
- Department of Biology, University of Utah, Salt Lake City, Utah, 84112, USA
| | - Ping Chen
- Department of Biology, University of Utah, Salt Lake City, Utah, 84112, USA
| | - Doju Yoshikami
- Department of Biology, University of Utah, Salt Lake City, Utah, 84112, USA
| | | | - Grzegorz Bulaj
- Department of Medicinal Chemistry, University of Utah, Salt Lake City, Utah, 84108, USA
| | - Raymond S. Norton
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville 3050 Australia
- To whom correspondence should be addressed: Phone: +61 3 9345 2306. Fax: +61 3 9345 2686
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110
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López-Vera E, Aguilar MB, Schiavon E, Marinzi C, Ortiz E, Restano Cassulini R, Batista CVF, Possani LD, Heimer de la Cotera EP, Peri F, Becerril B, Wanke E. Novel alpha-conotoxins from Conus spurius and the alpha-conotoxin EI share high-affinity potentiation and low-affinity inhibition of nicotinic acetylcholine receptors. FEBS J 2007; 274:3972-85. [PMID: 17635581 DOI: 10.1111/j.1742-4658.2007.05931.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
alpha-Conotoxins from marine snails are known to be selective and potent competitive antagonists of nicotinic acetylcholine receptors. Here we describe the purification, structural features and activity of two novel toxins, SrIA and SrIB, isolated from Conus spurius collected in the Yucatan Channel, Mexico. As determined by direct amino acid and cDNA nucleotide sequencing, the toxins are peptides containing 18 amino acid residues with the typical 4/7-type framework but with completely novel sequences. Therefore, their actions (and that of a synthetic analog, [gamma15E]SrIB) were compared to those exerted by the alpha4/7-conotoxin EI from Conus ermineus, used as a control. Their target specificity was evaluated by the patch-clamp technique in mammalian cells expressing alpha(1)beta(1)gammadelta, alpha(4)beta(2) and alpha(3)beta(4) nicotinic acetylcholine receptors. At high concentrations (10 microm), the peptides SrIA, SrIB and [gamma15E]SrIB showed weak blocking effects only on alpha(4)beta(2) and alpha(1)beta(1)gammadelta subtypes, but EI also strongly blocked alpha(3)beta(4) receptors. In contrast to this blocking effect, the new peptides and EI showed a remarkable potentiation of alpha(1)beta(1)gammadelta and alpha(4)beta(2) nicotinic acetylcholine receptors if briefly (2-15 s) applied at concentrations several orders of magnitude lower (EC(50), 1.78 and 0.37 nm, respectively). These results suggest not only that the novel alpha-conotoxins and EI can operate as nicotinic acetylcholine receptor inhibitors, but also that they bind both alpha(1)beta(1)gammadelta and alpha(4)beta(2) nicotinic acetylcholine receptors with very high affinity and increase their intrinsic cholinergic response. Their unique properties make them excellent tools for studying the toxin-receptor interaction, as well as models with which to design highly specific therapeutic drugs.
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Affiliation(s)
- Estuardo López-Vera
- Laboratorio de Neurofarmacología Marina, Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Queretaro, México
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111
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Liu L, Chew G, Hawrot E, Chi C, Wang C. Two potent alpha3/5 conotoxins from piscivorous Conus achatinus. Acta Biochim Biophys Sin (Shanghai) 2007; 39:438-44. [PMID: 17558449 DOI: 10.1111/j.1745-7270.2007.00301.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Every cone snail produces a mixture of different conotoxins and secretes them to immobilize their prey and predators. alpha3/5 Conotoxins, isolated from fish-hunting cone snails, target muscle nicotinic acetylcholine receptors. The structure and function of alpha3/5 conotoxin from the piscivorous Conus achatinus have not been studied. We synthesized two pentadecamer peptides, Ac1.1a and Ac1.1b, with appropriate disulfide bonding, based on cDNA sequences of alpha3/5 conotoxins from C. achatinus. Ac1.1a and Ac1.1b differ by only one amino acid residue. They have similar potency on blocking recombinant mouse muscle acetylcholine receptor expressed in Xenopus laevis oocytes, with IC50 values of 36 nM and 26 nM, respectively. For Ac1.1b, deletion of the first three N-terminal amino acids did not change its activity, indicating that the N-terminus is not involved in the interaction with its receptor. Furthermore, our experiments indicate that both toxins strongly prefer the alpha1-delta subunit interface instead of the alpha1-gamma binding site on the mouse muscle nicotinic acetylcholine receptor. These peptides provide additional tools for the study of the structure and function of nicotinic receptor.
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Affiliation(s)
- Li Liu
- Institute of Protein Research, Tongji University, Shanghai 200092, China
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112
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Wang X, Xie LP, Li QA, Zhang RQ, Zhou XW, Huang PT. Effect of O-superfamily conotoxin SO3 on synchronized spontaneous calcium spikes in cultured hippocampal networks. Cell Biol Toxicol 2007; 24:11-7. [PMID: 17522958 DOI: 10.1007/s10565-007-9011-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2006] [Accepted: 03/16/2007] [Indexed: 10/23/2022]
Abstract
SO3 belongs to the O-superfamily of conotoxins and is known to have analgesic effects in experimental animals. In order to explore the mechanism of its potential pharmacological actions, the effect of SO3 on synchronized spontaneous calcium spikes was examined in cultured hippocampal networks by calcium imaging. Spontaneous oscillations of intracellular concentrations of calcium (Ca(2+)) in the form of waves and spikes are found in cultured hippocampal networks. Exposure to increasing concentrations of SO3 resulted in a progressive decrease in synchronized spontaneous calcium spikes. The higher concentrations (0.1 micromol/L and 1 micromol/L) of SO3 showed the strongest inhibition. The rank order of inhibition was 1 micromol/L > 0.1 micromol/L > 10 micromol/L > 0.01 micromol/L. This action of SO3 in reducing synchronized calcium spikes suggests a possible application for therapeutic treatment of epilepsy.
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Affiliation(s)
- Xue Wang
- Department of Biological Sciences and Biotechnology, Institute of Marine Biotechnology, Tsinghua University, Beijing, PR China
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113
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Aguilar MB, López-Vera E, Heimer de la Cotera EP, Falcón A, Olivera BM, Maillo M. I-conotoxins in vermivorous species of the West Atlantic: peptide sr11a from Conus spurius. Peptides 2007; 28:18-23. [PMID: 17166627 DOI: 10.1016/j.peptides.2006.08.024] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2006] [Revised: 08/22/2006] [Accepted: 08/22/2006] [Indexed: 11/28/2022]
Abstract
Peptide sr11a was purified from the venom of Conus spurius, a vermivorous cone snail collected in the Yucatan Channel, in the Western Atlantic. Its primary structure was determined by automatic Edman degradation after reduction and alkylation. Its molecular mass, as determined by MALDI-TOF mass spectrometry (average mass 3650.77 Da), confirmed the chemical data (calculated average mass, 3651.13 Da). The sequence of peptide sr11a (CRTEGMSCgamma gamma NQQCCWRSCCRGECEAPCRFGP&; gamma, gamma-carboxy-Glu; &, amidated C-terminus) shows eight Cys residues arranged in the pattern that defines the I-superfamily of conotoxins. Peptide sr11a contains two gamma-carboxy-Glu residues, a post-translational modification that has been found in other I-conotoxins from species that live in the West Pacific: r11e from the piscivorous Conus radiatus, and kappa-BtX from the vermivorous Conus betulinus. Peptide sr11a is the eighth I-conotoxin isolated from a Conus venom and the first I-conotoxin from a species from the Western Atlantic. Peptide sr11a produced stiffening of body, limbs and tail when injected intracranially into mice.
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Affiliation(s)
- Manuel B Aguilar
- Laboratorio de Neurofarmacología Marina, Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro 76230, México.
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114
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Luna-Ramírez KS, Aguilar MB, Falcón A, Heimer de la Cotera EP, Olivera BM, Maillo M. An O-conotoxin from the vermivorous Conus spurius active on mice and mollusks. Peptides 2007; 28:24-30. [PMID: 17166626 DOI: 10.1016/j.peptides.2006.08.025] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2006] [Revised: 08/22/2006] [Accepted: 08/22/2006] [Indexed: 11/30/2022]
Abstract
Here, we report the purification, amino acid sequence and a preliminary biological characterization of a peptide, sr7a, from the venom of Conus spurius, a vermivorous species collected in the Yucatan Channel, Mexico. The peptide consists of 32 amino acid residues (CLQFGSTCFLGDDDICCSGECFYSGGTFGICS&; &, amidated C-terminus) and contains six cysteines arranged in the pattern (C-C-CC-C-C) that characterizes the O-superfamily of conotoxins. This superfamily includes several pharmacological families (omega-, kappa-, muO-, delta- and gamma-conotoxins) that target Ca(2+), K(+), Na(+) and pacemaker voltage-gated ion channels. Compared with other O-conotoxins that were purified from venoms, this peptide displays sequence similarity with omega-SVIA (from Conus striatus), delta-TxVIA/B (from Conus textile), omega-CVID (from Conus catus) and kappa-PVIIA (from Conus purpurascens). At a dose of 250 pmol, peptide sr7a elicited hyperactivity when injected intracranially into mice and produced paralysis when injected into the pedal muscle of freshwater snails, Pomacea paludosa, but it had no apparent effect after intramuscular injection into the limpet Patella opea or the freshwater fish Lebistes reticulatus.
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Affiliation(s)
- Karen S Luna-Ramírez
- Laboratorio de Neurofarmacología Marina, Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro 76230, México
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115
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Brust A, Tickle AE. High-throughput synthesis of conopeptides: a safety-catch linker approach enabling disulfide formation in 96-well format. J Pept Sci 2007; 13:133-41. [PMID: 17160973 DOI: 10.1002/psc.825] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Conotoxins exhibit a high degree of selectivity and potency for a range of pharmacologically relevant targets. The rapid access to libraries of conotoxin analogues, containing multiple intramolecular disulfide bridges for use in drug development, can be a very labor intensive, multi-step task. This work describes a high-throughput method for the synthesis of cystine-bridged conopeptides. Peptides were assembled on a peptide synthesizer employing the Fmoc solid-phase strategy using a safety-catch amide linker (SCAL). Side-chain protecting groups were removed on solid phase before SCAL activation with ammonium iodide in TFA, finally releasing the peptide into the TFA solution. Disulfide bond formation was performed in the cleavage mixture employing DMSO. This improved method allows mixtures of oxidized peptides to be obtained in parallel directly from a peptide synthesizer. A single HPLC purification of the resulting crude oxidized material produced peptides of > 95% purity.
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Affiliation(s)
- Andreas Brust
- Xenome Ltd, 120 Meiers Road, Indooroopilly 4068, Australia.
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116
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Luo S, Zhangsun D, Wu Y, Zhu X, Xie L, Hu Y, Zhang J, Zhao X. Identification and molecular diversity of T-superfamily conotoxins from Conus lividus and Conus litteratus. Chem Biol Drug Des 2006; 68:97-106. [PMID: 16999774 DOI: 10.1111/j.1747-0285.2006.00422.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The T-superfamily conotoxins comprise a large and diverse group of biologically active peptides and are widely distributed in venom ducts of all major feeding types of Conus. Six novel T-superfamily peptides from the two worm-hunting cone snail species of Conus lividus andConus. litteratus native to Hainan were identified and determined to share a common signal sequence as well as a conserved arrangement of cysteine residues (CC-CC). The predicted mature peptides consist of 11-15 amino acids only. Phylogenetic analyses of new conotoxins from C. lividus andC. litteratus in present study and published homologue T-superfamily sequences from the other Conus species was systematically performed. Phylogenetic trees, residue substitutions to view evolutionary relationships of the precursors' signal, propeptide, and mature toxin regions were explored, as well as residue frequency component and cystine codon usage. Percent divergence of the amino acid sequences of the signal-region exhibited high conservation, whereas the sequences of the mature peptides ranged from high similarity to high divergence between inter- and intro-species. Notably, diversity of pro-peptide region was also high with intermediate percent divergence between that observed in signal and toxin-regions. Consensus hydrophobic residues Leu, Val, Ala, Ile and Pro of signal regions were abundant, whereas among propeptides, basic residues Arg and Lys and acidic residue Asp, addition of hydrophilic residues Thr and Ser were abundant. Residue frequency components were hypervariable in mature toxin region except for highly conservative cystine frame residues. The T-superfamily conotoxins have been previously found mainly in piscivorous and molluscivorous cone snails. The newly identified six T-superfamily peptides described in this investigation exemplify the first to be found from vermivorousC. lividus andC. litteratus. The elucidated cDNAs of the six toxins will facilitate a better understanding of the relationship between structure and function as well as provide a framework for their further research and development.
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Affiliation(s)
- Sulan Luo
- Key Laboratory for Tropical Biological Resources (MOE), Ocean College, Center for Experimental Biotechnology, Hainan University, Haikou, Hainan 570228, China.
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Abstract
Bob Endean was a dedicated marine biologist with an extensive knowledge of coral reef communities in the Great Barrier Reef and fauna in subtropical Queensland waters. He commenced a study of venomous and poisonous marine animals dangerous to man at a time when the field was new, employing a variety of techniques to investigate the venom apparatus, mode of delivery of venom or toxin, mode of toxic action on excitable tissues, and biochemistry of venom or toxin. Determination of the pharmacological properties of crude venom from Conus marine snails advanced characterization of conotoxins by later workers. A study of four types of nematocysts from the box-jellyfish Chironex fleckeri provided information as to their structure, function, and mechanism of discharge; myotoxins T1 and T2 were isolated from microbasic mastigophores. Endean studied poisonous stonefish (Synanceia trachynis) and, with Ann Cameron, scorpionfish (Notesthes robusta); investigations of ciguatera and of paralytic shellfish poisoning were initiated. He organized the collection of Australian frogs which led to the isolation of caerulein by Erspamer in Italy. Endean highlighted the ecological danger of the population explosion of the crown-of-thorns starfish (Acanthaster planci) and provided the impetus for the creation of the Great Barrier Reef Marine Park.
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118
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Cecchini AL, Vasconcelos F, Amara SG, Giglio JR, Arantes EC. Effects of Tityus serrulatus scorpion venom and its toxin TsTX-V on neurotransmitter uptake in vitro. Toxicol Appl Pharmacol 2006; 217:196-203. [PMID: 17049577 DOI: 10.1016/j.taap.2006.09.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2006] [Revised: 08/31/2006] [Accepted: 09/04/2006] [Indexed: 11/29/2022]
Abstract
Scorpion neurotoxins targeting the Na(v) channel can be classified into two classes: alpha- and beta-neurotoxins and are reported as highly active in mammalian brain. In this work, we evaluate the effects of Tityus serrulatus venom (Ts venom) and its alpha-neurotoxin TsTX-V on gamma-aminobutyric acid (GABA), dopamine (DA) and glutamate (Glu) uptake in isolated rat brain synaptosomes. TsTX-V was isolated from Ts venom by ion exchange chromatography followed by reverse-phase (C18) high-performance liquid chromatography. Neither Ts venom nor TsTX-V was able to affect (3)H-Glu uptake. On the other hand, Ts venom (0.13 microg/mg) significantly inhibited both (3)H-GABA and (3)H-DA uptake ( approximately 50%). TsTX-V showed IC(50) values of 9.37 microM and 22.2 microM for the inhibition of (3)H-GABA and (3)H-DA uptake, respectively. These effects were abolished by pre-treatment with tetrodotoxin (TTX, 1 microM), indicating the involvement of voltage-gated Na(+) channels in this process. In the absence of Ca(2+), and at low Ts venom concentrations, the reduction of (3)H-GABA uptake was not as marked as in the presence of Ca(2+). TsTX-V did not reduce (3)H-GABA uptake in COS-7 cells expressing the GABA transporters GAT-1 and GAT-3, suggesting that this toxin indirectly reduces the transport. The reduced (3)H-GABA uptake by synaptosomes might be due to rapid cell depolarization as revealed by confocal microscopy of C6 glioma cells. Thus, TsTX-V causes a reduction of (3)H-GABA and (3)H-DA uptake in a Ca(2+)-dependent manner, not directly affecting GABA transporters, but, in consequence of depolarization, involving voltage-gated Na(+) channels.
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Affiliation(s)
- Alessandra L Cecchini
- Departamento de Física e Química, Faculdade de Ciências Farmacêuticas de Ribeirão Preto-USP, Av. do Café, s/n, 14040-903, Ribeirão Preto-SP, Brazil
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119
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Luo S, Zhangsun D, Lin Q, Xie L, Wu Y, Zhu X. Sequence diversity of O-superfamily conopetides from Conus marmoreus native to Hainan. Peptides 2006; 27:3058-68. [PMID: 17011667 DOI: 10.1016/j.peptides.2006.08.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2006] [Revised: 08/18/2006] [Accepted: 08/22/2006] [Indexed: 10/24/2022]
Abstract
The full-length cDNAs of six new O-superfamily conotoxins (CTX) were cloned and sequenced from Conus marmoreus native to Hainan in China South Sea using RT-PCR and 3'-RACE. Six novel conotoxin precursors encoded by these cDNAs consist of three typical regions of signal, pro-peptide and mature peptide. All the six toxin regions share a common O-superfamily cysteine pattern (C-C-CC-C-C, with three disulfide bridges). The predicted precursors are composed of 73-88 amino acids, and the predicted mature peptides consist of 26-34 amino acids. Phylogenetic analysis of new conotoxins from C. marmoreus from the present study and published homologue T-superfamily sequences from other Conus species was performed systematically. Patterns of sequence divergence for three regions of signal, pro-region and mature peptides, as well as Cys codon usage define the major O-superfamily branches and suggest how these separate branches arose. Percent identities of the amino acid sequences of the signal region exhibited high conservation, whereas the sequences of the mature peptides ranged from almost identical to highly divergent between inter- and intra-species. Notably, the diversity of the pro-region was also high with intermediate divergence between that observed in signal and toxin regions. Amino acid sequences and their mode of action (target) of previously identified conotoxins from molluscivorous C. marmoreus for the known conotoxins classes are discussed in detail. The data presented are new and should pave the way for chemical synthesis of these unique conotoxins for to allow determination of the molecular targets of these peptides, and also to provide clues for a better understanding of the phylogeny of these peptides.
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Affiliation(s)
- Sulan Luo
- Key Laboratory for Tropical Biology Resources, Ministry of Education, Ocean College, Center for Experimental Biotechnology, Hainan University, Haikou, Hainan 570228, China. luosulan@
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120
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Escoubas P. Molecular diversification in spider venoms: a web of combinatorial peptide libraries. Mol Divers 2006; 10:545-54. [PMID: 17096075 DOI: 10.1007/s11030-006-9050-4] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2004] [Accepted: 03/28/2006] [Indexed: 01/19/2023]
Abstract
Spider venoms are a rich source of novel pharmacologically and agrochemically interesting compounds that have received increased attention from pharmacologists and biochemists in recent years. The application of technologies derived from genomics and proteomics have led to the discovery of the enormous molecular diversity of those venoms, which consist mainly of peptides and proteins. The molecular diversity of spider peptides has been revealed by mass spectrometry and appears to be based on a limited set of structural scaffolds. Genetic analysis has led to a further understanding of the molecular evolution mechanisms presiding over the generation of these combinatorial peptide libraries. Gene duplication and focal hypermutation, which has been described in cone snails, appear to be common mechanisms to venomous mollusks and spiders. Post-translational modifications, fine structural variations and new molecular scaffolds are other potential mechanisms of toxin diversification, leading to the pharmacologically complex cocktails used for predation and defense.
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Affiliation(s)
- Pierre Escoubas
- Institut de Pharmacologie Moléculaire et Cellulaire (IPMC) CNRS UMR 6097, 660 Route des Lucioles, Valbonne, France.
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121
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Zhangsun D, Luo S, Wu Y, Zhu X, Hu Y, Xie L. Novel O-superfamily Conotoxins Identified by cDNA Cloning From Three Vermivorous Conus Species. Chem Biol Drug Des 2006; 68:256-65. [PMID: 17177885 DOI: 10.1111/j.1747-0285.2006.00443.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The O-superfamily of conotoxins includes several subfamilies with different pharmacological targets, all of which are voltage-gated ion channels and distributed widely in varied Conus species. The venom components from any Conus species are quite distinct from those of other species. Seven novel O-superfamily peptides were identified by cDNA cloning from the three vermivorous Conus species of C. betulinus, C. lividus and C. caracteristicus native to Hainan. They share three common signal sequences, and a conserved arrangement of cysteine residues (C-C-CC-C-C). Phylogenetic analysis of newly found conotoxins in this study and known homologue O-superfamily sequences from the other Conus species was performed systematically. Divergence and percentage identity of the amino acid sequences of the signal regions suggest that the novel conotoxins described in this investigation belong to the three broad clades: MSGL, ME-QK and MKLT, each of which has its own characteristic signature signal sequence and cysteine codon conservation. Relative to this work, it is noted that O-superfamily conotoxins are not well represented from vermivorous species. The elucidated cDNAs of these newly found vermivorous toxins would facilitate a better understanding for basic research and drug discovery.
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Affiliation(s)
- Dongting Zhangsun
- Key Laboratory for Tropical Biology Resources (MOE), Ocean College, Center for Experimental Biotechnology, Hainan University, Haikou Hainan 570228, China
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122
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Luo S, Zhangsun D, Zhang B, Chen X, Feng J. Direct cDNA cloning of novel conotoxins of the T-superfamily from Conus textile. Peptides 2006; 27:2640-6. [PMID: 16765485 DOI: 10.1016/j.peptides.2006.05.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2006] [Revised: 04/30/2006] [Accepted: 05/02/2006] [Indexed: 10/24/2022]
Abstract
The T-superfamily is a large and diverse group of peptides, widely distributed in venom ducts of all major feeding types of Conus. These peptides are likely to be functionally diverse. A directed PCR-based approach using primers based on the conserved signal sequence was applied to investigate new conotoxins of the T-superfamily from Conus textile native to Hainan. Using RT-PCR and 3'-RACE, four novel cDNA sequences encoding precursor peptides were identified in C. textile. They share a common T-superfamily cysteine pattern (CC-CC, with two disulfide bridges). The predicted peptides are small (9-12 amino acids). TeAr193 composed of nine amino acid residues is one of the shortest T-superfamily conotoxins ever found. Patterns of sequence divergence and Cys codon usage define the major T-superfamily branches and suggest how these separate branches arose. The sequences of the signal regions exhibited highest conservation, whereas the sequences of the mature peptides were either almost identical or highly divergent; and conservation of the pro-region was intermediate between that observed in signal and toxin regions. The elucidated cDNAs of the four toxins will facilitate a better understanding of the relationship between structure and function.
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Affiliation(s)
- Sulan Luo
- Key Laboratory for Tropical Biological Resources (MOE), Ocean College, Center for Experimental Biotechnology, Hainan University, Haikou Hainan 570228, China.
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123
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Sabareesh V, Gowd KH, Ramasamy P, Sudarslal S, Krishnan KS, Sikdar SK, Balaram P. Characterization of contryphans from Conus loroisii and Conus amadis that target calcium channels. Peptides 2006; 27:2647-54. [PMID: 16945451 DOI: 10.1016/j.peptides.2006.07.009] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2006] [Revised: 07/13/2006] [Accepted: 07/14/2006] [Indexed: 11/26/2022]
Abstract
Distinctly different effects of two closely related contryphans have been demonstrated on voltage-activated Ca(2+) channels. The peptides Lo959 and Am975 were isolated from Conus loroisii, a vermivorous marine snail and Conus amadis, a molluscivore, respectively. The sequences of Lo959 and Am975 were deduced by mass spectrometric sequencing (MALDI-MS/MS) and confirmed by chemical synthesis. The sequences of Lo959, GCP(D)WDPWC-NH(2) and Am975, GCO(D)WDPWC-NH(2) (O: 4-trans-hydroxyproline: Hyp), differ only at residue 3; Pro in Lo959, Hyp in Am975, which is identical to contryphan-P, previously isolated from Conus purpurascens, a piscivore; while Lo959 is a novel peptide. Both Lo959 and Am975 undergo slow conformational interconversion under reverse-phase chromatographic conditions, a characteristic feature of all contryphans reported thus far. Electrophysiological studies performed using dorsal root ganglion neurons reveal that both peptides target high voltage-activated Ca(2+) channels. While Lo959 increases the Ca(2+) current, Am975 causes inhibition. The results establish that subtle sequence effects, which accompany post-translational modifications in Conus peptides, can have dramatic effects on target ion channels.
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Affiliation(s)
- V Sabareesh
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India
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124
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Lovelace ES, Armishaw CJ, Colgrave ML, Wahlstrom ME, Alewood PF, Daly NL, Craik DJ. Cyclic MrIA: A Stable and Potent Cyclic Conotoxin with a Novel Topological Fold that Targets the Norepinephrine Transporter. J Med Chem 2006; 49:6561-8. [PMID: 17064074 DOI: 10.1021/jm060299h] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Conotoxins, disulfide-rich peptides from the venom of cone snails, have created much excitement over recent years due to their potency and specificity for ion channels and their therapeutic potential. One recently identified conotoxin, MrIA, a 13-residue member of the chi-conotoxin family, inhibits the human norepinephrine transporter (NET) and has potential applications in the treatment of pain. In the current study, we show that the beta-hairpin structure of native MrIA is retained in a synthetic cyclic version, as is biological activity at the NET. Furthermore, the cyclic version has increased resistance to trypsin digestion relative to the native peptide, an intriguing result because the cleavage site for the trypsin is not close to the cyclization site. The use of peptides as drugs is generally hampered by susceptibility to proteolysis, and so, the increase in enzymatic stability against trypsin observed in the current study may be useful in improving the therapeutic potential of MrIA. Furthermore, the structure reported here for cyclic MrIA represents a new topology among a growing number of circular disulfide-rich peptides.
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Affiliation(s)
- Erica S Lovelace
- Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland 4072, Australia
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125
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Peng C, Tang S, Pi C, Liu J, Wang F, Wang L, Zhou W, Xu A. Discovery of a novel class of conotoxin from Conus litteratus, lt14a, with a unique cysteine pattern. Peptides 2006; 27:2174-81. [PMID: 16797781 DOI: 10.1016/j.peptides.2006.04.016] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2006] [Revised: 04/02/2006] [Accepted: 04/04/2006] [Indexed: 10/24/2022]
Abstract
Conus litteratus is a worm-hunting cone snail with a highly sophisticated neuropharmacological defense strategy using small peptides in its venom. By analyzing different clones in the cDNA library of venom ducts from C. litteratus, we identified the peptide lt14a which displays a characteristic signal peptide sequence in its precursor and a unique arrangement of Cys residues (-C-C-C-C-) in its mature peptide region. RT-PCR analysis suggested that lt14a is abundantly expressed throughout the whole venom duct. An intensive analysis in sequence suggested that lt14a is similar to alpha-conotoxin qc1.1 cloned from Conus quercinus. We conducted the chemical synthesis of lt14a. The synthetic lt14a has a remarkable biological activity to suppress pain and inhibits the neuronal-type nicotinic acetylcholine receptors.
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Affiliation(s)
- Can Peng
- State Key Laboratory of Biocontrol, Guangdong Key Laboratory of Pharmaceutic Functional Genes, The Open Laboratory for Marine Functional Genomics of State High-Tech Development Program, College of Life Sciences, Sun Yat-Sen University, Guangzhou, PR China
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126
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Abstract
In the four decades since toxinologists in Australia and elsewhere started to investigate the active constituents of venomous cone snails, a wealth of information has emerged on the various classes of peptides and proteins that make their venoms such potent bioactive cocktails. This article provides an overview of the current state of knowledge of these venom constituents, several of which are of interest as potential human therapeutics as a consequence of their high potency and exquisite target specificity. With the promise of as many as 50,000 venom components across the entire Conus genus, many more interesting peptides can be anticipated.
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Affiliation(s)
- Raymond S Norton
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville 3050, Victoria, Australia.
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127
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Livett BG, Sandall DW, Keays D, Down J, Gayler KR, Satkunanathan N, Khalil Z. Therapeutic applications of conotoxins that target the neuronal nicotinic acetylcholine receptor. Toxicon 2006; 48:810-29. [PMID: 16979678 DOI: 10.1016/j.toxicon.2006.07.023] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Pain therapeutics discovered by molecular mining of the expressed genome of Australian predatory cone snails are providing lead compounds for the treatment of neurological diseases such as multiple sclerosis, shingles, diabetic neuropathy and other painful neurological conditions. The high specificity exhibited by these novel compounds for neuronal receptors and ion channels in the brain and nervous system indicates the high degree of selectivity that this class of neuropeptides can be expected to show when used therapeutically in humans. A lead compound, ACV1 (conotoxin Vc1.1 from Conus victoriae), has entered Phase II clinical trials and is being developed for the treatment for neuropathic pain. ACV1 will be targeted initially for the treatment of sciatica, shingles and diabetic neuropathy. The compound is a 16 amino acid peptide [Sandall et al., 2003. A novel alpha-conotoxin identified by gene sequencing is active in suppressing the vascular response to selective stimulation of sensory nerves in vivo. Biochemistry 42, 6904-6911], an antagonist of neuronal nicotinic acetylcholine receptors. It has potent analgesic activity following subcutaneous or intramuscular administration in several preclinical animal models of human neuropathic pain [Satkunanathan et al., 2005. Alpha conotoxin Vc1.1 alleviates neuropathic pain and accelerates functional recovery of injured neurons. Brain. Res. 1059, 149-158]. ACV1 may act as an analgesic by decreasing ectopic excitation in sensory nerves. In addition ACV1 appears to accelerate the recovery of injured nerves and tissues.
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Affiliation(s)
- Bruce G Livett
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Victoria 3010, Australia.
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128
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Marx UC, Daly NL, Craik DJ. NMR of conotoxins: structural features and an analysis of chemical shifts of post-translationally modified amino acids. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2006; 44 Spec No:S41-50. [PMID: 16826542 DOI: 10.1002/mrc.1821] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Conotoxins are small conformationally constrained peptides found in the venom of marine snails of the genus Conus. They are usually cysteine rich and frequently contain a high degree of post-translational modifications such as C-terminal amidation, hydroxylation, carboxylation, bromination, epimerisation and glycosylation. Here we review the role of NMR in determining the three-dimensional structures of conotoxins and also provide a compilation and analysis of 1H and 13C chemical shifts of post-translationally modified amino acids and compare them with data from common amino acids. This analysis provides a reference source for chemical shifts of post-translationally modified amino acids.
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Affiliation(s)
- Ute C Marx
- Institute for Molecular Bioscience and Australian Research Council Special Research Centre for Functional and Applied Genomics, University of Queensland, Brisbane QLD 4072, Australia
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129
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Judge SIV, Bever CT. Potassium channel blockers in multiple sclerosis: Neuronal Kv channels and effects of symptomatic treatment. Pharmacol Ther 2006; 111:224-59. [PMID: 16472864 DOI: 10.1016/j.pharmthera.2005.10.006] [Citation(s) in RCA: 200] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2005] [Accepted: 10/12/2005] [Indexed: 02/07/2023]
Abstract
Multiple sclerosis (MS) is an inflammatory disease of the central nervous system (CNS) characterized by demyelination, with a relative sparing of axons. In MS patients, many neurologic signs and symptoms have been attributed to the underlying conduction deficits. The idea that neurologic function might be improved if conduction could be restored in CNS demyelinated axons led to the testing of potassium (K(+)) channel blockers as a symptomatic treatment. To date, only 2 broad-spectrum K(+) channel blockers, 4-aminopyridine (4-AP) and 3,4-diaminopyridine (3,4-DAP), have been tested in MS patients. Although both 4-AP and 3,4-DAP produce clear neurologic benefits, their use has been limited by toxicity. Here we review the current status of basic science and clinical research related to the therapeutic targeting of voltage-gated K(+) channels (K(v)) in MS. By bringing together 3 distinct but interrelated disciplines, we aim to provide perspective on a vast body of work highlighting the lengthy and ongoing process entailed in translating fundamental K(v) channel knowledge into new clinical treatments for patients with MS and other demyelinating diseases. Covered are (1) K(v) channel nomenclature, structure, function, and pharmacology; (2) classic and current experimental morphology and neurophysiology studies of demyelination and conduction deficits; and (3) a comprehensive overview of clinical trials utilizing 4-AP and 3,4-DAP in MS patients.
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Affiliation(s)
- Susan I V Judge
- MS Center of Excellence-East, Research and Neurology Services, VA Maryland Health Care System, USA.
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130
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Takada K, Hamada T, Hirota H, Nakao Y, Matsunaga S, van Soest RWM, Fusetani N. Asteropine A, a Sialidase-Inhibiting Conotoxin-like Peptide from the Marine Sponge Asteropus simplex. ACTA ACUST UNITED AC 2006; 13:569-74. [PMID: 16793514 DOI: 10.1016/j.chembiol.2006.05.010] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2006] [Revised: 04/05/2006] [Accepted: 05/09/2006] [Indexed: 11/30/2022]
Abstract
Marine sponges contain structurally intriguing and biologically active peptides of nonribosomal peptide synthase origin, often containing amino acids with novel structures. Here we report the discovery of asteropine A (APA), a cystine knot to be isolated from marine sponges. The solution structure of APA as determined by NMR belongs to the four-loop class of cystine knots similar to those of some conotoxins and spider toxins. However, the highly negatively charged surface of APA is uncommon among other cystine knots. APA competitively inhibits bacterial sialidases, but not a viral sialidase. APA was inactive against all other enzymes tested and did not have any apparent antitumor activity. Our data suggest that APA and other knotting peptides may be important leads for antibacterial and even antiviral drug development.
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Affiliation(s)
- Kentaro Takada
- Laboratory of Aquatic Natural Products Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Japan
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131
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132
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Chen WH, Han YH, Wang Q, Miao XW, Ou L, Shao XX. cDNA cloning of two novel T-superfamily conotoxins from Conus leopardus. Acta Biochim Biophys Sin (Shanghai) 2006; 38:287-91. [PMID: 16604269 DOI: 10.1111/j.1745-7270.2006.00159.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
The full-length cDNAs of two novel T-superfamily conotoxins, Lp5.1 and Lp5.2, were cloned from a vermivorous cone snail Conus leopardus using 3'/5'-rapid amplification of cDNA ends. The cDNA of Lp5.1 encodes a precursor of 65 residues, including a 22-residue signal peptide, a 28-residue propeptide and a 15-residue mature peptide. Lp5.1 is processed at the common signal site-X-Arg- immediately before the mature peptide sequences. In the case of Lp5.2, the precursor includes a 25-residue signal peptide and a 43-residue sequence comprising the propeptide and mature peptide, which is probably cleaved to yield a 29-residue propeptide and a 14-residue mature toxin. Although these two conotoxins share a similar signal sequence and a conserved disulfide pattern with the known T-superfamily, the pro-region and mature peptides are of low identity, especially Lp5.2 with an identity as low as 10.7% compared with the reference Mr5.1a. The elucidated cDNAs of these two toxins will facilitate a better understanding of the species distribution, the sequence diversity of T-superfamily conotoxins, the special gene structure and the evolution of these peptides.
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Affiliation(s)
- Wei-Hua Chen
- Institute of Protein Research, Tongji University, Shanghai 200092, China
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133
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Jiang H, Wang CZ, Xu CQ, Fan CX, Dai XD, Chen JS, Chi CW. A novel M-superfamily conotoxin with a unique motif from Conus vexillum. Peptides 2006; 27:682-9. [PMID: 16181706 DOI: 10.1016/j.peptides.2005.08.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2005] [Revised: 08/10/2005] [Accepted: 08/11/2005] [Indexed: 11/17/2022]
Abstract
Cone snails are tropical marine mollusks that envenomate prey with a complex mixture of neuropharmacologically active compounds for the purpose of feeding and defence, each evolved to act in a highly specific manner on different parts of the nervous system. Here, we report the peptide purification, molecular cloning, chemical synthesis, and functional characterization of a structurally unique toxin isolated from the venom of Conus vexillum. The novel peptide, designated Vx2, was composed of 21 amino acid residues cross-linked by 3 disulfide bonds (WIDPSHYCCCGGGCTDDCVNC). Intriguingly, its mature peptide sequence shows low level of similarity with other identified conotoxins, and its unique motif (-CCCGGGC-) was not reported in other Conus peptides. However, its signal peptide sequence shares high similarity with those of the M-superfamily conotoxins. Hence, Vx2 could be classified into a new family of the M-superfamily.
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Affiliation(s)
- Hui Jiang
- Shanghai Institute of Biochemistry and Cell Biology, Shanghai Institute of Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
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134
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Escoubas P, Sollod B, King GF. Venom landscapes: mining the complexity of spider venoms via a combined cDNA and mass spectrometric approach. Toxicon 2006; 47:650-63. [PMID: 16574177 DOI: 10.1016/j.toxicon.2006.01.018] [Citation(s) in RCA: 141] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The complexity of Australian funnel-web spider venoms has been explored via the combined use of MALDI-TOF mass spectrometry coupled with chromatographic separation and the analysis of venom-gland cDNA libraries. The results show that these venoms are far more complex than previously realized. We show that the venoms of Australian funnel-web spiders contain many hundreds of peptides that follow a bimodal distribution, with about 75% of the peptides having a mass of 3000-5000 Da. The mass spectral data were validated by matching the experimentally observed masses with those predicted from peptide sequences derived from analysis of venom-gland cDNA libraries. We show that multiple isoforms of these peptides are found in small chromatographic windows, which suggests that the wide distribution of close molecular weights among the chromatographic fractions probably reflects a diversity of structures and physicochemical properties. The combination of all predicted and measured parameters permits the interpretation of three-dimensional 'venom landscapes' derived from LC-MALDI analysis. We propose that these venom landscapes might have predictive value for the discovery of various groups of pharmacologically distinct toxins in complex venoms.
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Affiliation(s)
- Pierre Escoubas
- Institut de Pharmacologie Moléculaire et Cellulaire-CNRS, 660 Route des Lucioles, Valbonne 06560, France.
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135
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Jakubowski JA, Kelley WP, Sweedler JV. Screening for post-translational modifications in conotoxins using liquid chromatography/mass spectrometry: an important component of conotoxin discovery. Toxicon 2006; 47:688-99. [PMID: 16574181 DOI: 10.1016/j.toxicon.2006.01.021] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Mass spectrometry has emerged as an important technique for conotoxin analysis due to its capacity for selective, sensitive, information-rich analyses. Using liquid chromatography/mass spectrometry, Conus venom can be fractionated and the peptides surveyed for specific post-translational modifications, indicating those toxin components likely to have an important biological function. With Conus striatus and Conus victoriae venom as models, bromination, carboxylation and glycosylation modifications are identified through characteristics such as isotopic distribution and labile losses observed during mass spectrometric analysis. This modification screening approach enables the identification of a C. victoriae bromo-carboxy-conotoxin, designated vc5c, as a candidate for detailed mass spectrometric analysis. Using a cDNA sequence coupled with liquid chromatography/mass spectrometry and nanoelectrospray ionization-ion trap-mass spectrometry, the sequence of vc5c is determined to be ICCYPNXWCCD, where W is 6-bromotryptophan, X is gamma-carboxy glutamate and C is disulfide-linked cysteine. This represents the ninth T-superfamily (-CC-CC- scaffold) toxin that has been isolated from venom and characterized.
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Affiliation(s)
- Jennifer A Jakubowski
- Department of Chemistry and the Beckman Institute, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue 63-5, Urbana, IL 61801, USA
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136
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Aguilar MB, Lezama-Monfil L, Maillo M, Pedraza-Lara H, López-Vera E, Heimer de la Cotera EP. A biologically active hydrophobic T-1-conotoxin from the venom of Conus spurius. Peptides 2006; 27:500-5. [PMID: 16297502 DOI: 10.1016/j.peptides.2005.07.020] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2005] [Accepted: 07/20/2005] [Indexed: 11/16/2022]
Abstract
A major, very hydrophobic peptide, sr5a, was purified from the venom duct of Conus spurius specimens collected in the Yucatan Channel, Mexico. Its amino acid sequence (IINWCCLIFYQCC; calculated monoisotopic mass assuming two disulfide bridges 1616.68 Da) was determined by automatic Edman degradation after reduction and alkylation, and confirmed by mass spectrometry (ESI monoisotopic mass, 1616.60; MALDI monoisotopic mass 1616.42 Da). The primary structure of sr5a showed the pattern that characterizes the family of the T-1-conotoxins, which belong to the T-superfamily of conotoxins. The disulfide bonds were determined by partial reduction and alkylation with N-ethylmaleimide, followed by total reduction and alkylation with 4-vinylpyridine, and automatic Edman sequencing. The connectivity of the Cys residues (I-III, II-IV) is the same as that found in the T-1-conotoxin family. When injected intracranially (2.0 nmol) into mice, peptide sr5a caused depressed behavioral activity.
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Affiliation(s)
- Manuel B Aguilar
- Laboratory of Marine Neuropharmacology, Institute of Neurobiology, Universidad Nacional Autónoma de México, Campus UNAM-UAQ Juriquilla, Km 15 Carr. Querétaro-S.L.P., Juriquilla, Qro. 76230, México.
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137
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Zugasti-Cruz A, Maillo M, López-Vera E, Falcón A, Heimer de la Cotera EP, Olivera BM, Aguilar MB. Amino acid sequence and biological activity of a gamma-conotoxin-like peptide from the worm-hunting snail Conus austini. Peptides 2006; 27:506-11. [PMID: 16325964 DOI: 10.1016/j.peptides.2005.07.021] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2005] [Accepted: 07/20/2005] [Indexed: 11/19/2022]
Abstract
A novel 31-residue toxin, named as7a, was isolated and characterized from the venom of Conus austini, a vermivorous cone snail collected in the western Gulf of Mexico. The complete amino acid sequence, TCKQKGEGCSLDVgammaCCSSSCKPGGPLFDFDC, was determined by automatic Edman sequencing after reduction and alkylation. The sequence shows six Cys residues arranged in the pattern that defines the O-superfamily of conotoxins, and the sequence motif -gammaCCS-, which has only been found in the gamma-conotoxin family. The molecular mass of the native peptide was determined by matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry, which confirmed the chemical analyses and suggested a free C-terminus. The purified peptide elicited toxic effects in the freshwater snail Pomacea paludosa after intramuscular injection, but it had no effect when injected intracerebrally into mice. The structural similarity of peptide as7a to other gamma-conotoxins suggests that modulation of pacemaker channels could be responsible for its biological activity.
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Affiliation(s)
- Alejandro Zugasti-Cruz
- Posgrado en Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Ciudad Universitaria, México D.F. 04510, Mexico
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138
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Jiang H, Xu CQ, Wang CZ, Fan CX, Zhao TY, Chen JS, Chi CW. Two novel O-superfamily conotoxins from Conus vexillum. Toxicon 2006; 47:425-36. [PMID: 16457862 DOI: 10.1016/j.toxicon.2005.12.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2005] [Revised: 12/13/2005] [Accepted: 12/16/2005] [Indexed: 11/24/2022]
Abstract
O-superfamily conotoxins include several families that have diverse pharmacological activity on Na+, K+ or Ca2+ channels. These superfamily toxins have been mainly found in fish-hunting and mollusk-hunting Conus species. Here, we reported two novel O-superfamily conotoxins, vx6a and vx6b, purified from a worm-hunting cone snail, Conus vexillum. Though their cysteine framework and signal peptides share high similarity with those of other members of O-superfamily, the mature vx6a and vx6b both have a low sequence homology with others. To test the biological function of vx6a, the toxin was chemically synthesized and then tested on the locust dorsal unpaired median (DUM) neuron system which containing various ion channels. Although no any activity on ion channels was found on the DUM neuron system, vx6a could clearly elicit a series of symptoms in mouse via intracranial injection, such as quivering, climbing, scratching, barrel rolling and paralysis of limbs at different dose.
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Affiliation(s)
- Hui Jiang
- Key Laboratory of Proteomics, Shanghai Institute of Biochemistry and Cell Biology, Shanghai Institute of Biological Sciences, Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai 200031, China
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139
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Wang F, Chen G, Zhu Y, Guo Z, Zheng S, Zhan J. Development of antibody-based assays for omega-conotoxin MVIIA. ACTA ACUST UNITED AC 2006; 67:49-56. [PMID: 16503054 DOI: 10.1016/j.jbbm.2006.01.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2005] [Revised: 01/06/2006] [Accepted: 01/09/2006] [Indexed: 11/26/2022]
Abstract
Omega-conotoxin MVIIA (CTX MVIIA) is a specific peptide blocker of the N-type voltage-sensitive calcium channel in neurons. The synthetic version of CTX MVIIA, Ziconotide, has been recently approved by FDA for management of severe and chronic pains. Currently, the chemical synthetic CTX MVIIA has been analyzed by RP-HPLC, and there are no chemical or immunological assays available for determination of the peptide. In this article, we report a novel method for preparation of polyclonal antibody against CTX MVIIA, and the antibody-based assays for the analysis of CTX MVIIA. The DNA sequences encoding the conotoxin were chemically synthesized and then cloned into the expression vector pGEX-2T. The GST fusion protein of CTX MVIIA was expressed in E. coli BL21 (DE3) with induction of IPTG. The purified fusion protein was used to immunize the male rabbits with standard protocols. The produced antiserum was purified through anion-exchange chromatography. Another thioredoxin (Trx) fusion protein of CTX MVIIA was employed to cross-examine the antibody against the conotoxin. Our Western blot and ELISA results show that the polyclonal antibody was capable of binding the conotoxin parts of both GST and Trx fusion proteins, and the antibody titer is 1:8192. Thus, the assays based on this antibody are useful for the conotoxin analysis.
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Affiliation(s)
- Feng Wang
- Department of Biochemistry, Zhejiang University Medical School, Hangzhou 310006, China
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140
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Pi C, Liu Y, Peng C, Jiang X, Liu J, Xu B, Yu X, Yu Y, Jiang X, Wang L, Dong M, Chen S, Xu AL. Analysis of expressed sequence tags from the venom ducts of Conus striatus: focusing on the expression profile of conotoxins. Biochimie 2006; 88:131-40. [PMID: 16183187 DOI: 10.1016/j.biochi.2005.08.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2005] [Accepted: 08/16/2005] [Indexed: 11/19/2022]
Abstract
Cone snails (genus Conus) are predatory marine gastropods that use venom peptides for interacting with prey, predators and competitors. A majority of these peptides, generally known as conotoxins demonstrate striking selectivity in targeting specific subtypes of ion channels and neurotransmitter receptors. So they are not only useful tools in neuroscience to characterize receptors and receptor subtypes, but offer great potential in new drug research and development as well. Here, a cDNA library from the venom ducts of a fish-hunting cone snail species, Conus striatus is described for the generation of expressed sequence tags (ESTs). A total of 429 ESTs were grouped into 137 clusters or singletons. Among these sequences, 221 were toxin sequences, accounting for 52.1% (corresponding to 19 clusters) of all transcripts. A-superfamily (132 ESTs) and O-superfamily conotoxins (80 ESTs) constitute the predominant toxin components. Some non-disulfide-rich Conus peptides were also found. The expression profile of conotoxins also explained to some extent the pharmacological and physiological reactions elicited by this typical piscivorous species. For the first time, a nonstop transcript of conotoxin was identified, which is suggestive that alternative polyadenylation may be a means of post-transcriptional regulation of conotoxin production. A comparison analysis of these conotoxins reveals the different variation and divergence patterns in these two superfamilies. Our investigations indicate that focal hyper-mutation, block substitution and exon shuffling are three main mechanisms leading to the conotoxin diversity in a species. The comprehensive set of Conus gene sequences allowed the identification of the representative classes of conotoxins and related components, which may lay the foundation for further research and development of conotoxins.
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Affiliation(s)
- Canhui Pi
- State Key Laboratory of Biocontrol, Guangdong Province Key Laboratory of Therapeutic Functional Genes, Department of Biochemistry, College of Life Sciences, Sun Yat-sen (Zhongshan) University, 135 Xingangxi Road, 510275 Guangzhou, China
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141
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Xia Z, Chen Y, Zhu Y, Wang F, Xu X, Zhan J. Recombinant ??-Conotoxin MVIIA Possesses Strong Analgesic Activity. BioDrugs 2006; 20:275-81. [PMID: 17025374 DOI: 10.2165/00063030-200620050-00003] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
BACKGROUND omega-Conotoxin (CTX) MVIIA is a specific antagonist of N-type voltage-sensitive calcium channels. A synthetic peptide version of CTX MVIIA (ziconotide) has been approved by the US FDA for severe and chronic pain. Given the high cost and complexity of the synthetic process of the disulfide-rich peptide, the genetic recombinant approach may simplify the development of this potent therapeutic agent. AIM In this study, we report a new method for production of the recombinant CTX MVIIA. METHOD A novel DNA fragment encoding CTX MVIIA was designed using Escherichia coli-preferred codons, and the fragment was cloned into the expression vector pGEX(2T). The fusion protein, CTX MVIIA and glutathione-S-transferase (GST) [GST-CTX MVIIA], was expressed in E. coli and purified by affinity chromatography on a glutathione-agarose column. After digestion with thrombin, the CTX MVIIA fragment was purified on a Sephacryl S-100 HR column and identified by mass spectrometry. The bioactivity of the peptide was evaluated by the hot tail-flick assay, in which the CTX MVIIA was intracerebroventricularly administered into Sprague-Dawley rats and its antinociceptive effect measured. RESULTS The analgesic activity of the conotoxin was about 800 times stronger than that of morphine. CONCLUSION The recombinant CTX MVIIA expressed in E. coli has shown marked analgesic activity, which may have potential in clinical application.
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Affiliation(s)
- Zheng Xia
- Department of Biochemistry and Molecular Biology, Zhejiang University Medical School, 353 Yan-An Road, Hangzhou 310006, People's Republic of China
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142
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Luo S, Zhangsun D, Zhang B, Quan Y, Wu Y. Novel α-conotoxins identified by gene sequencing from cone snails native to Hainan, and their sequence diversity. J Pept Sci 2006; 12:693-704. [PMID: 16981242 DOI: 10.1002/psc.781] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Conotoxins (CTX) from the venom of marine cone snails (genus Conus) represent large families of proteins, which show a similar precursor organization with surprisingly conserved signal sequence of the precursor peptides, but highly diverse pharmacological activities. By using the conserved sequences found within the genes that encode the alpha-conotoxin precursors, a technique based on RT-PCR was used to identify, respectively, two novel peptides (LiC22, LeD2) from the two worm-hunting Conus species Conus lividus, and Conus litteratus, and one novel peptide (TeA21) from the snail-hunting Conus species Conus textile, all native to Hainan in China. The three peptides share an alpha4/7 subfamily alpha-conotoxins common cysteine pattern (CCX(4)CX(7)C, two disulfide bonds), which are competitive antagonists of nicotinic acetylcholine receptor (nAChRs). The cDNA of LiC22N encodes a precursor of 40 residues, including a propeptide of 19 residues and a mature peptide of 21 residues. The cDNA of LeD2N encodes a precursor of 41 residues, including a propeptide of 21 residues and a mature peptide of 16 residues with three additional Gly residues. The cDNA of TeA21N encodes a precursor of 38 residues, including a propeptide of 20 residues and a mature peptide of 17 residues with an additional residue Gly. The additional residue Gly of LeD2N and TeA21N is a prerequisite for the amidation of the preceding C-terminal Cys. All three sequences are processed at the common signal site -X-Arg- immediately before the mature peptide sequences. The properties of the alpha4/7 conotoxins known so far were discussed in detail. Phylogenetic analysis of the new conotoxins in the present study and the published homologue of alpha4/7 conotoxins from the other Conus species were performed systematically. Patterns of sequence divergence for the three regions of signal, proregion, and mature peptides, both nucleotide acids and residue substitutions in DNA and peptide levels, as well as Cys codon usage were analyzed, which suggest how these separate branches originated. Percent identities of the DNA and amino acid sequences of the signal region exhibited high conservation, whereas the sequences of the mature peptides ranged from almost identical to highly divergent between inter- and intra-species. Notably, the diversity of the proregion was also high, with an intermediate percentage of divergence between that observed in the signal and in the toxin regions. The data presented are new and are of importance, and should attract the interest of researchers in this field. The elucidated cDNAs of these toxins will facilitate a better understanding of the relationship of their structure and function, as well as the process of their evolutionary relationships.
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Affiliation(s)
- Sulan Luo
- Key Laboratory for Tropical Aquatic and Terrestrial Biological Resources (MOE), Ocean College, Center for Experimental Biotechnology, Hainan University, Haikou Hainan, 570228 China.
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143
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Moore EL, Haspel G, Libersat F, Adams ME. Parasitoid wasp sting: A cocktail of GABA, taurine, and β-alanine opens chloride channels for central synaptic block and transient paralysis of a cockroach host. ACTA ACUST UNITED AC 2006; 66:811-20. [PMID: 16673394 DOI: 10.1002/neu.20254] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The wasp Ampulex compressa injects venom directly into the prothoracic ganglion of its cockroach host to induce a transient paralysis of the front legs. To identify the biochemical basis for this paralysis, we separated venom components according to molecular size and tested fractions for inhibition of synaptic transmission at the cockroach cercal-giant synapse. Only fractions in the low molecular weight range (<2 kDa) caused synaptic block. Dabsylation of venom components and analysis by HPLC and MALDI-TOF-MS revealed high levels of GABA (25 mM), and its receptor agonists beta-alanine (18 mM), and taurine (9 mM) in the active fractions. Each component produces transient block of synaptic transmission at the cercal-giant synapse and block of efferent motor output from the prothoracic ganglion, which mimics effects produced by injection of whole venom. Whole venom evokes picrotoxin-sensitive chloride currents in cockroach central neurons, consistent with a GABAergic action. Together these data demonstrate that Ampulex utilizes GABAergic chloride channel activation as a strategy for central synaptic block to induce transient and focal leg paralysis in its host.
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Affiliation(s)
- Eugene L Moore
- Department of Entomology, University of California, Riverside, 92521, USA
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144
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Avila C. Molluscan Natural Products as Biological Models: Chemical Ecology, Histology, and Laboratory Culture. MOLLUSCS 2006; 43:1-23. [PMID: 17153336 DOI: 10.1007/978-3-540-30880-5_1] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The utility of some natural products from molluscs has been known for centuries. However, only recently have modern technologies and advances in the fields of chemistry, chemical ecology, anatomy, histology, and laboratory culture allowed the exploitation of new, unprecedented applications of natural products. Recent studies have dealt with (a) the role that these compounds have in the sea in protecting the animals (e.g., chemical defense), or in mediating their intraspecific communication (e.g., pheromones), (b) the geographical differences in similar or related species (and the implications of this in chemical ecology and phylogeny), and (c) the localization of these metabolites in molluscan tissues (by means of the most modern technologies), among others. The methodology for the laboratory culture of some species has also been established, thus offering new insights into this interesting field. Further applications of all these challenging studies are currently being developed.
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Affiliation(s)
- C Avila
- Centre d'Estudis Advançats de Blanes (CEAB-CSIC), C/Accés a la Cala Sant Francesc 14 17300 Blanes (Girona), Catalunya, Spain
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145
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Saminathan R, Babuji S, Sethupathy S, Viswanathan P, Balasubramanian T, Gopalakrishanakone P. Clinico-toxinological characterization of the acute effects of the venom of the marine snail, Conus loroisii. Acta Trop 2006; 97:75-87. [PMID: 16216213 DOI: 10.1016/j.actatropica.2005.09.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2004] [Revised: 07/15/2005] [Accepted: 09/07/2005] [Indexed: 11/22/2022]
Abstract
The venom of the marine snail, Conus loroisii, was studied to assess its risk and lethal factors in regard of human welfare. The lethality of the crude venom (LD50-5.0 mg/kg via i.p.) in mice was associated with reduced motor activity, asphyxiation, followed by respiratory failure. The effects on vital tissues revealed vascular congestion and inflammatory cell infiltration around the portal triad of the liver, spongiosis of the brain, hemorrhages/congested blood vessels in lung and endothelial cells of the renal tubule. Repeated measures of hematological profiles indicated that the venom significantly reduced erythrocytes (P<0.001, GLM repeated measures), followed associated with depletion of hemoglobin, hematocrit, mean corpuscular volume, mean corpuscular hemoglobin and platelet count. Serum enzymes such as, glutamic-oxaloacetic transaminase, glutamic-pyruvic transaminase, lactate dehydrogenase and alkaline and acid phosphatases were altered significantly (P<0.05, Friedman test), which in turn confirmed the damage of vital organ tissues. Dual effect of the venom on the activity of mouse brain acetylcholinesterase stand for concentration specific, whereas maximal inhibition (60.41%, P<0.05, Wilcoxon signed rank test) in erythrocyte acetylcholinesterase did not show the dual activity observed in brain. The Ciphergen ProteinChip analysis of the envenomed serum further revealed that the venom causes changes in definite molecules involved in inflammatory process and ionic transport. In all, the venom of C. loroisii is potentially lethal to mammals, through its rapid action on the central and peripheral nervous systems by blocking neurotransmission with selective interference of ionic channels/receptors.
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Affiliation(s)
- R Saminathan
- Venom and Toxin Research Programme, Faculty of Medicine, Department of Anatomy, National University of Singapore, Singapore 117597, Singapore
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146
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Kozlov S, Grishin E. Classification of spider neurotoxins using structural motifs by primary structure features. Single residue distribution analysis and pattern analysis techniques. Toxicon 2005; 46:672-86. [PMID: 16169031 DOI: 10.1016/j.toxicon.2005.07.009] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2005] [Revised: 07/12/2005] [Accepted: 07/13/2005] [Indexed: 11/20/2022]
Abstract
In recent years the data on the novel structures of spider toxins have been greatly increasing. The sequence data should be classified. We introduced two primary structure analysis techniques-single residue distribution analysis (SRDA) and pattern analysis for classifying spider polypeptide toxins with molecular weight less than 10kDa. For multiple sequence alignment, we also introduced three novel sequence representation formats named as a simple record, motif record and a pattern record, which can be useful for large-scale analysis of structures. About 300 sequences of spider toxins were analyzed and nine primary structure motifs were identified. New classification of spider toxins was proposed on the basis of previously described principal structural motif (PSM) and extra structural motif (ESM) [Kozlov, S.A., Malyavka, A.A., McCutchen, B., Lu, A., Schepers, E., Herrmann, R., Grishin, E.V., 2005. A novel strategy for the identification of toxin-like structures in spider venom. Proteins 59 (1), 131-140]. Five main structural classes were revealed, and for putative ion channel inhibitors from the most numerous classes 1, 2, and 3, five-digital personal ID numbers were introduced. A reference table with simple, motif and pattern representation sequence formats was created for all analyzed structures.
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Affiliation(s)
- Sergey Kozlov
- Neuroreceptors and Neuroregulators Department, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, ul. Miklukho-Maklaya, 16/10, 117997 Moscow, Russian Federation.
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147
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Wen L, Yang S, Qiao H, Liu Z, Zhou W, Zhang Y, Huang P. SO-3, a new O-superfamily conopeptide derived from Conus striatus, selectively inhibits N-type calcium currents in cultured hippocampal neurons. Br J Pharmacol 2005; 145:728-39. [PMID: 15880145 PMCID: PMC1576188 DOI: 10.1038/sj.bjp.0706223] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Whole-cell currents in cultured hippocampal neurons were recorded to investigate the effects of SO-3, a new O-superfamily conopeptide derived from Conus striatus, on voltage-sensitive channels. SO-3 had no effect on voltage-sensitive sodium currents, delayed rectifier potassium currents, and transient outward potassium currents. Similar to the selective N-type calcium channel blocker omega-conotoxin MVIIA (MVIIA), SO-3 could concentration-dependently inhibit the high voltage-activated (HVA) calcium currents (I(Ca)). MVIIA(3 microM), 10 microM nimodipine, and 0.5 microM omega-agatoxin IVA (Aga) could selectively block the N-, L-, and P/Q-type I(Ca), which contributed approximately 32, approximately 38, and approximately 21% of the HVA currents in hippocampal neurons, respectively. About 31% of the total HVA currents were inhibited by 3 microM SO-3. SO-3 (3 microM) and 3 microM MVIIA inhibited the overlapping components of HVA currents, whereas no overlapping component was inhibited by 3 microM SO-3 and 10 microM nimodipine, or by 3 microM SO-3 and 0.5 microM Aga. Also, 3 microM SO-3 had no effect on R-type currents. SO-3 had less inhibitory effects on non-N-type HVA currents than MVIIA at higher concentrations (30 and 100 microM). The inhibitory effects of SO-3 and MVIIA on HVA currents were almost fully reversible. However, the recovery from block by MVIIA was more rapid than recovery from block by SO-3. It is concluded that SO-3 is a new omega-conotoxin selectively targeting N-type voltage-sensitive calcium channels. Considering the significance of N-type calcium channels for pain transduction, SO-3 may have therapeutic potential as a novel analgesic agent.
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Affiliation(s)
- Lei Wen
- Beijing Institute of Pharmacology and Toxicology, 27 Tai-Ping Road, Haidian District, Beijing 100850, China
| | - Sheng Yang
- Beijing Institute of Pharmacology and Toxicology, 27 Tai-Ping Road, Haidian District, Beijing 100850, China
| | - Haifa Qiao
- Beijing Institute of Pharmacology and Toxicology, 27 Tai-Ping Road, Haidian District, Beijing 100850, China
| | - Zhenwei Liu
- Beijing Institute of Pharmacology and Toxicology, 27 Tai-Ping Road, Haidian District, Beijing 100850, China
| | - Wenxia Zhou
- Beijing Institute of Pharmacology and Toxicology, 27 Tai-Ping Road, Haidian District, Beijing 100850, China
| | - Yongxiang Zhang
- Beijing Institute of Pharmacology and Toxicology, 27 Tai-Ping Road, Haidian District, Beijing 100850, China
- Author for correspondence:
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148
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Abstract
Ligand-gated ion channels, or ionotropic receptors, constitute a group of membrane-bound proteins that regulate the flux of ions across the cell membrane. In the brain, ligand-gated ion channels mediate fast neurotransmission. They are crucial for normal brain function and involved in many diseases in the brain. Historically, natural products have been used extensively in biomedical studies and ultimately as drugs or leads for drug design. In studies of ligand-gated ion channels, natural products have been essential for the understanding of their structure and function. In the following a short survey of natural products and their use in studies of ligand-gated ion channels is given.
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Affiliation(s)
- Kristian Strømgaard
- Department of Medicinal Chemistry, The Danish University of Pharmaceutical Sciences, DK-2100 Copenhagen, Denmark.
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149
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Mebs D, Kauferstein S. Ichthyotoxicity caused by marine cone snail venoms? Toxicon 2005; 46:355-6. [PMID: 15990144 DOI: 10.1016/j.toxicon.2005.04.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2005] [Accepted: 04/27/2005] [Indexed: 11/18/2022]
Abstract
Ten venoms from marine cone snails were tested for ichthyotoxic effects on zebra fish (Brachydanio rerio) when added to the water. Only two venoms, from Conus capitaneus and Conus episcopatus, produced lethal effects at high concentrations (50-300 microg/ml) within 20-90 min. No sedative or hypnotic symptoms were observed. The experiments confirm that Conus venoms exert a quick and prompt activity only by parenteral injection into the prey as it is performed by the snail.
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Affiliation(s)
- Dietrich Mebs
- Zentrum der Rechtsmedizin, University of Frankfurt, Kennedyallee 104, D-69596 Frankfurt am Main, Germany.
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150
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Brown MA, Begley GS, Czerwiec E, Stenberg LM, Jacobs M, Kalume DE, Roepstorff P, Stenflo J, Furie BC, Furie B. Precursors of Novel Gla-Containing Conotoxins Contain a Carboxy-Terminal Recognition Site That Directs γ-Carboxylation,. Biochemistry 2005; 44:9150-9. [PMID: 15966739 DOI: 10.1021/bi0503293] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Vitamin K-dependent gamma-glutamyl carboxylase catalyzes the conversion of glutamyl residues to gamma-carboxyglutamate. Its substrates include vertebrate proteins involved in blood coagulation, bone mineralization, and signal transduction and invertebrate ion channel blockers known as conotoxins. Substrate recognition involves a recognition element, the gamma-carboxylation recognition site, typically located within a cleavable propeptide preceding the targeted glutamyl residues. We have purified two novel gamma-carboxyglutamate-containing conotoxins, Gla-TxX and Gla-TxXI, from the venom of Conus textile. Their cDNA-deduced precursors have a signal peptide but no apparent propeptide. Instead, they contain a C-terminal extension that directs gamma-carboxylation but is not found on the mature conotoxin. A synthetic 13-residue "postpeptide" from the Gla-TxXI precursor reduced the K(m) for the reaction of the Conus gamma-carboxylase with peptide substrates, including FLEEL and conantokin-G, by up to 440-fold, regardless of whether it was positioned at the N- or C-terminal end of the mature toxin. Comparison of the postpeptides to propeptides from other conotoxins suggested some common elements, and amino acid substitutions of these residues perturbed gamma-carboxylation of the Gla-TxXI peptide. The demonstration of a functional and transferable C-terminal postpeptide in these conotoxins indicates the presence of the gamma-carboxylation recognition site within the postpeptide and defines a novel precursor structure for vitamin K-dependent polypeptides. It also provides the first formal evidence to prove that gamma-carboxylation occurs as a post-translational rather than a cotranslational process.
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Affiliation(s)
- Mark A Brown
- Marine Biological Laboratory, Woods Hole, Massachusetts 02543, USA
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