The Experts below are selected from a list of 11964 Experts worldwide ranked by ideXlab platform
Michel Lazdunski - One of the best experts on this subject based on the ideXlab platform.
-
binding of Sea Anemone toxin to rec system of sodium channel in synapti scorpion neurotoxin synaptosomes
2016Co-Authors: J P Vincent, M Balerna, Jacques Barhanin, M Fosset, Michel LazdunskiAbstract:Iodination of toxin II from the Sea Anemone Anemonia sulcata gives a labeled monoiododerivative that re- tains 80% of the original neurotoxicity. This derivative binds specifically to rat brain synaptosomes at 20?C and pH 7.4 with a second-order rate constant of association ka = 4.6 X 104 M-1 seec- and a first-order rate constant of dissociation kd = 1.1 X 10-2 sec1. The binding occurs on the Na+ channel at a binding site distinct from that of other gating system toxins like batra- chotoxin, veratridine, grayanotoxin, aconitine, and pyrethroids. The maximal binding capacity Bmax is 3.2 pmol/mg of protein (i.e., about two Sea Anemone toxin binding sites per tetrodotoxin binding site) and the Kd is 240 nM for the monoiododerivative and 150 nM for the native toxin. Corresponding binding pa- rameters for the association of a 125I-labeled derivative of toxin II from the scorpion Androctonus australis Hector are Bmax = 0.3 pmol/mg of protein and Kd = 1 nM, whereas the Kd of the unmodified scorpion toxin is 0.6 nM. Competition experiments involving scorpion toxins, Sea Anemone toxins, and synapto- somes demonstrate that, although the Sea Anemone toxin is able to displace the scorpion toxin bound to synaptosomes, the scorpion toxin does not displace the Sea Anemone toxin. The Sea Anemone toxin but not the scorpion toxin binds to depolarized synaptosomes. Differences between binding properties of the two polypeptide toxins are analyzed in the discussion. A number of toxic molecules are now available for the analysis of the structural organization and function of the voltage- dependent Na+ channel in excitable membranes. These toxins
-
Binding of Sea Anemone toxin to rec system of sodium channel in synapti (scorpion neurotoxin/synaptosomes)
2016Co-Authors: J P Vincent, M Balerna, Jacques Barhanin, M Fosset, Michel LazdunskiAbstract:Iodination of toxin II from the Sea Anemone Anemonia sulcata gives a labeled monoiododerivative that re- tains 80% of the original neurotoxicity. This derivative binds specifically to rat brain synaptosomes at 20?C and pH 7.4 with a second-order rate constant of association ka = 4.6 X 104 M-1 seec- and a first-order rate constant of dissociation kd = 1.1 X 10-2 sec1. The binding occurs on the Na+ channel at a binding site distinct from that of other gating system toxins like batra- chotoxin, veratridine, grayanotoxin, aconitine, and pyrethroids. The maximal binding capacity Bmax is 3.2 pmol/mg of protein (i.e., about two Sea Anemone toxin binding sites per tetrodotoxin binding site) and the Kd is 240 nM for the monoiododerivative and 150 nM for the native toxin. Corresponding binding pa- rameters for the association of a 125I-labeled derivative of toxin II from the scorpion Androctonus australis Hector are Bmax = 0.3 pmol/mg of protein and Kd = 1 nM, whereas the Kd of the unmodified scorpion toxin is 0.6 nM. Competition experiments involving scorpion toxins, Sea Anemone toxins, and synapto- somes demonstrate that, although the Sea Anemone toxin is able to displace the scorpion toxin bound to synaptosomes, the scorpion toxin does not displace the Sea Anemone toxin. The Sea Anemone toxin but not the scorpion toxin binds to depolarized synaptosomes. Differences between binding properties of the two polypeptide toxins are analyzed in the discussion. A number of toxic molecules are now available for the analysis of the structural organization and function of the voltage- dependent Na+ channel in excitable membranes. These toxins
-
a new Sea Anemone peptide apetx2 inhibits asic3 a major acid sensitive channel in sensory neurons
The EMBO Journal, 2004Co-Authors: Sylvie Diochot, Lachlan D Rash, Anne Baron, Emmanuel Deval, Pierre Escoubas, Sabine Scarzello, Miguel Salinas, Michel LazdunskiAbstract:From a systematic screening of animal venoms, we isolated a new toxin (APETx2) from the Sea Anemone Anthopleura elegantissima, which inhibits ASIC3 homomeric channels and ASIC3-containing heteromeric channels both in heterologous expression systems and in primary cultures of rat sensory neurons. APETx2 is a 42 amino-acid peptide crosslinked by three disulfide bridges, with a structural organization similar to that of other Sea Anemone toxins that inhibit voltage-sensitive Na+ and K+ channels. APETx2 reversibly inhibits rat ASIC3 (IC50=63 nM), without any effect on ASIC1a, ASIC1b, and ASIC2a. APETx2 directly inhibits the ASIC3 channel by acting at its external side, and it does not modify the channel unitary conductance. APETx2 also inhibits heteromeric ASIC2b+3 current (IC50=117 nM), while it has less affinity for ASIC1b+3 (IC50=0.9 μM), ASIC1a+3 (IC50=2 μM), and no effect on the ASIC2a+3 current. The ASIC3-like current in primary cultured sensory neurons is partly and reversibly inhibited by APETx2 with an IC50 of 216 nM, probably due to the mixed inhibitions of various co-expressed ASIC3-containing channels.
-
apetx1 a new toxin from the Sea Anemone anthopleura elegantissima blocks voltage gated human ether a go go related gene potassium channels
Molecular Pharmacology, 2003Co-Authors: Sylvie Diochot, Lászlo Béress, Thomas Bruhn, Erwann Loret, Michel LazdunskiAbstract:A new peptide, APETx1, which specifically inhibits human ether-a-go-go–related gene (HERG) channels, was purified from venom of the Sea Anemone Anthopleura elegantissima. APETx1 is a 42-amino acid peptide cross-linked by three disulfide bridges and shares 54% homology with BDS-I, another Sea Anemone K+ channel inhibitor. Although they differ in their specific targets, circular dichroism spectra and molecular modeling indicate that APETx1 and BDS-I have a common molecular scaffold and belong to the same structural family of K+ channel blocking peptides. APETx1 inhibits HERG currents in a heterologous system with an IC50 value of 34 nM by modifying the voltage dependence of the channel gating. Central injections in mice failed to induce any neurotoxic symptoms. APETx1, which has no sequence homologies with scorpion toxins acting on HERG, defines a new structural group of HERG gating modifiers isolated from a Sea Anemone.
-
apetx1 a new toxin from the Sea Anemone anthopleura elegantissima blocks voltage gated human ether a go go related gene potassium channels
Molecular Pharmacology, 2003Co-Authors: Sylvie Diochot, Lászlo Béress, Thomas Bruhn, Erwann Loret, Michel LazdunskiAbstract:A new peptide, APETx1, which specifically inhibits human ether-a-go-go-related gene (HERG) channels, was purified from venom of the Sea Anemone Anthopleura elegantissima. APETx1 is a 42-amino acid peptide cross-linked by three disulfide bridges and shares 54% homology with BDS-I, another Sea Anemone K+ channel inhibitor. Although they differ in their specific targets, circular dichroism spectra and molecular modeling indicate that APETx1 and BDS-I have a common molecular scaffold and belong to the same structural family of K+ channel blocking peptides. APETx1 inhibits HERG currents in a heterologous system with an IC50 value of 34 nM by modifying the voltage dependence of the channel gating. Central injections in mice failed to induce any neurotoxic symptoms. APETx1, which has no sequence homologies with scorpion toxins acting on HERG, defines a new structural group of HERG gating modifiers isolated from a Sea Anemone.
Jan Tytgat - One of the best experts on this subject based on the ideXlab platform.
-
bcstx3 is a founder of a novel Sea Anemone toxin family of potassium channel blocker
FEBS Journal, 2013Co-Authors: Diego J B Orts, Yehu Moran, Camila Takeno Cologna, Bruno Madio, Daniela Praher, Loic Quinton, Jose Eduardo P W Bicudo, Steve Peigneur, Edwin De Pauw, Jan TytgatAbstract:Sea Anemone venoms have become a rich source of peptide toxins which are invaluable tools for studying the structure and functions of ion channels. In this work, BcsTx3, a toxin found in the venom of a Bunodosoma caissarum (population captured at the Saint Peter and Saint Paul Archipelago, Brazil) was purified and biochemically and pharmacologically characterized. The pharmacological effects were studied on 12 different subtypes of voltage-gated potassium channels (KV1.1–KV1.6; KV2.1; KV3.1; KV4.2; KV4.3; hERG and Shaker IR) and three cloned voltage-gated sodium channel isoforms (NaV1.2, NaV1.4 and BgNaV1.1) expressed in Xenopus laevis oocytes. BcsTx3 shows a high affinity for Drosophila Shaker IR channels over rKv1.2, hKv1.3 and rKv1.6, and is not active on NaV channels. Biochemical characterization reveals that BcsTx3 is a 50 amino acid peptide crosslinked by four disulfide bridges, and sequence comparison allowed BcsTx3 to be classified as a novel type of Sea Anemone toxin acting on KV channels. Moreover, putative toxins homologous to BcsTx3 from two additional actiniarian species suggest an ancient origin of this newly discovered toxin family.
-
A Natural Point Mutation Reveals Target Promiscuity of Toxins Isolated from the Sea Anemone Anthopleura Elegantissima
Biophysical Journal, 2012Co-Authors: Steve Peigneur, Evelien Lescrinier, Carolina Möller, Frank Marí, Lászlo Béress, Jan TytgatAbstract:Sea Anemone venom is a known source of interesting bioactive compounds, including peptide toxins which are invaluable tools for studying structure and function of voltage-gated potassium channels. APETx3 is a novel peptide isolated from the Sea Anemone Anthopleura elegantissima, containing 42 amino acids cross-linked by 3 disulfide bridges. Sequence alignment reveals that APETx3 is a natural occurring mutant from APETx1, only differing in 1 amino acid at position 3. APETx1 is believed to be a selective modulator of human ether-a-go-go related (hERG) potassium channels. In this study, APETx1, 2 and 3 have been subjected to an electrophysiological screening on a wide range of 21 ion channels expressed in Xenopus leavis oocytes: 10 cloned voltage-gated sodium channels (NaV1.2-NaV1.8, the insect channels DmNaV1, BgNaV1-1a and the arachnid channel VdNaV1) and 11 cloned voltage-gated potassium channels (KV2.1, KV3.1, KV4.2, KV4.3, KV7.1, KV7.2, KV7.3, KV7.4, KV7.5, hERG, the insect channel Shaker IR). Surprisingly, the Thr3Pro substitution results in a complete abolishment of APETx3 modulation on hERG channels. However, the same substitution provides this toxin the ability to become a potent modulator of voltage-gated sodium channels (NaVs). APETx3 slows down the inactivation of mammalian and insect channels similar to site 3 toxins such as α-scorpion toxins and Sea Anemone NaVs toxins. Our screening reveals that the homologous toxins APETx1 and APETx2 display promiscuous properties as they are also capable of recognizing NaV channels, causing an inhibition of the sodium conductance.All together, these data provide new insights in key residues which allow these toxins to recognize distinct ion channels with similar potency but with different modulatory effects. Furthermore, we describe for the first time the target promiscuity of a family of Sea Anemone toxins believed to be highly selective.
-
a bifunctional Sea Anemone peptide with kunitz type protease and potassium channel inhibiting properties
Biochemical Pharmacology, 2011Co-Authors: Steve Peigneur, Lászlo Béress, Bert Billen, Rita Derua, Etienne Waelkens, Sarah Debaveye, Jan TytgatAbstract:Abstract Sea Anemone venom is a known source of interesting bioactive compounds, including peptide toxins which are invaluable tools for studying structure and function of voltage-gated potassium channels. APEKTx1 is a novel peptide isolated from the Sea Anemone Anthopleura elegantissima , containing 63 amino acids cross-linked by 3 disulfide bridges. Sequence alignment reveals that APEKTx1 is a new member of the type 2 Sea Anemone peptides targeting voltage-gated potassium channels (K V s), which also include the kalicludines from Anemonia sulcata . Similar to the kalicludines, APEKTx1 shares structural homology with both the basic pancreatic trypsin inhibitor (BPTI), a very potent Kunitz-type protease inhibitor, and dendrotoxins which are powerful blockers of voltage-gated potassium channels. In this study, APEKTx1 has been subjected to a screening on a wide range of 23 ion channels expressed in Xenopus laevis oocytes: 13 cloned voltage-gated potassium channels (K V 1.1–K V 1.6, K V 1.1 triple mutant, K V 2.1, K V 3.1, K V 4.2, K V 4.3, hERG, the insect channel Shaker IR), 2 cloned hyperpolarization-activated cyclic nucleotide-sensitive cation non-selective channels (HCN1 and HCN2) and 8 cloned voltage-gated sodium channels (Na V 1.2–Na V 1.8 and the insect channel DmNa V 1). Our data show that APEKTx1 selectively blocks K V 1.1 channels in a very potent manner with an IC 50 value of 0.9 nM. Furthermore, we compared the trypsin inhibitory activity of this toxin with BPTI. APEKTx1 inhibits trypsin with a dissociation constant of 124 nM. In conclusion, this study demonstrates that APEKTx1 has the unique feature to combine the dual functionality of a potent and selective blocker of K V 1.1 channels with that of a competitive inhibitor of trypsin.
-
A bifunctional Sea Anemone peptide with Kunitz type protease and potassium channel inhibiting properties.
Biochemical Pharmacology, 2011Co-Authors: Steve Peigneur, Lászlo Béress, Bert Billen, Rita Derua, Etienne Waelkens, Sarah Debaveye, Jan TytgatAbstract:Sea Anemone venom is a known source of interesting bioactive compounds, including peptide toxins which are invaluable tools for studying structure and function of voltage-gated potassium channels. APEKTx1 is a novel peptide isolated from the Sea Anemone , containing 63 amino acids cross-linked by 3 disulfide bridges. Sequence alignment reveals that APEKTx1 is a new member of the type 2 Sea Anemone peptides targeting voltage-gated potassium channels (K's), which also include the kalicludines from . Similar to the kalicludines, APEKTx1 shares structural homology with both the basic pancreatic trypsin inhibitor (BPTI), a very potent Kunitz-type protease inhibitor, and dendrotoxins which are powerful blockers of voltage-gated potassium channels. In this study, APEKTx1 has been subjected to a screening on a wide range of 23 ion channels expressed in oocytes: 13 cloned voltage-gated potassium channels (K1.1-K1.6, K1.1 triple mutant, K2.1, K3.1, K4.2, K4.3, hERG, the insect channel IR), 2 cloned hyperpolarization-activated cyclic nucleotide-sensitive cation non-selective channels (HCN1 and HCN2) and 8 cloned voltage-gated sodium channels (Na1.2-Na1.8 and the insect channel DmNa1). Our data shows that APEKTx1 selectively blocks K1.1 channels in a very potent manner with an IC value of 0.9nM. Furthermore, we compared the trypsin inhibitory activity of this toxin with BPTI. APEKTx1 inhibits trypsin with a dissociation constant of 124nM. In conclusion, this study demonstrates that APEKTx1 has the unique feature to combine the dual functionality of a potent and selective blocker of K1.1 channels with that of a competitive inhibitor of trypsin.
-
Sea Anemone venom as a source of insecticidal peptides acting on voltage gated na channels
Toxicon, 2007Co-Authors: Frank Bosmans, Jan TytgatAbstract:Sea Anemones produce a myriad of toxic peptides and proteins of which a large group acts on voltage-gated Na+ channels. However, in comparison to other organisms, their venoms and toxins are poorly studied. Most of the known voltage-gated Na+ channel toxins isolated from Sea Anemone venoms act on neurotoxin receptor site 3 and inhibit the inactivation of these channels. Furthermore, it seems that most of these toxins have a distinct preference for crustaceans. Given the close evolutionary relationship between crustaceans and insects, it is not surprising that Sea Anemone toxins also profoundly affect insect voltage-gated Na+ channels, which constitutes the scope of this review. For this reason, these peptides can be considered as insecticidal lead compounds in the development of insecticides.
Kazuo Shiomi - One of the best experts on this subject based on the ideXlab platform.
-
novel peptide toxins from the Sea Anemone stichodactyla haddoni
Peptides, 2008Co-Authors: T Honma, Shino Kawahata, Masami Ishida, Hiroshi Nagai, Yuji Nagashima, Kazuo ShiomiAbstract:Abstract Four peptide toxins, SHTX I–III with crab-paralyzing activity and SHTX IV with crab lethality, were isolated from the Sea Anemone Stichodactyla haddoni and their primary structures elucidated by protein sequencing and cDNA cloning. SHTX I (new toxin, 28 residues), II (analogue of SHTX I, 28 residues) and III (Kunitz-type protease inhibitor, 62 residues) are potassium channel toxins and SHTX IV (48 residues) is a member of the type 2 Sea Anemone sodium channel toxins. The precursor protein of SHTX IV is composed of a signal peptide, propart and mature peptide, while the propart is missing in that of SHTX III. In addition to these four toxins, an epidermal growth factor-like peptide was detected in S. haddoni by RT-PCR.
-
an epidermal growth factor like toxin and two sodium channel toxins from the Sea Anemone stichodactyla gigantea
Toxicon, 2003Co-Authors: Kazuo Shiomi, T Honma, Masami Ishida, Yuji Nagashima, Makoto ChinoAbstract:Abstract Three peptide toxins (gigantoxins I–III) with crab toxicity were isolated from the Sea Anemone Stichodactyla gigantea by gel filtration on Sephadex G-50 and reverse-phase HPLC on TSKgel ODS-120T and their complete amino acid sequences were determined. Gigantoxins II (44 residues) and III (48 residues) have LD 50 (against crabs) of 70 and 120 μg/kg, respectively, and are analogous to the known type 1 and 2 Sea Anemone sodium channel toxins, respectively. On the other hand, gigantoxin I (48 residues) is potently paralytic to crabs (ED 50 215 μg/kg), although its lethality is very weak (LD 50 >1000 μg/kg). Interestingly, gigantoxin I has 31–33% homologies with mammalian epidermal growth factors (EGFs), with the same location of six cysteine residues. In accordance with the sequence similarity, gigantoxin I exhibits EGF activity as evidenced by rounding of A431 cells and tyrosine phosphorylation of the EGF receptor in the cells, although much less potently than human EGF. Gigantoxin I is the first example of EGF-like toxins of natural origin.
-
a polypeptide toxin in the Sea Anemone actinia equina homologous with other Sea Anemone sodium channel toxins isolation and amino acid sequence
Toxicon, 1996Co-Authors: Masami Ishida, Yuji Nagashima, Kazuo ShiomiAbstract:Abstract The Sea Anemone (Actinia equina) was newly established to contain a polypeptide toxin (named Ae I) having lethal activity to crabs, besides the well-known cytolytic toxins (equinatoxins) of proteinic nature. Ae I, with a minimum lethal dose against crabs of 25 μg/kg, was easily isolated by gel filtration on Sephadex G-50 and reverse-phase HPLC on Nucleosil 300-7C18. Its amino acid composition is characterized by the abundance of Gly, the absence of Ala and the presence of Met. The complete amino acid sequence of Ae I was determined. Ae I has high sequence homology with type 1 Sea Anemone neurotoxins. Interestingly, the polypeptide chain of Ae I comprises 54 amino acid residues, being 5–8 residues longer than the known type 1 toxins having 46–49 residues.
Lászlo Béress - One of the best experts on this subject based on the ideXlab platform.
-
A Natural Point Mutation Reveals Target Promiscuity of Toxins Isolated from the Sea Anemone Anthopleura Elegantissima
Biophysical Journal, 2012Co-Authors: Steve Peigneur, Evelien Lescrinier, Carolina Möller, Frank Marí, Lászlo Béress, Jan TytgatAbstract:Sea Anemone venom is a known source of interesting bioactive compounds, including peptide toxins which are invaluable tools for studying structure and function of voltage-gated potassium channels. APETx3 is a novel peptide isolated from the Sea Anemone Anthopleura elegantissima, containing 42 amino acids cross-linked by 3 disulfide bridges. Sequence alignment reveals that APETx3 is a natural occurring mutant from APETx1, only differing in 1 amino acid at position 3. APETx1 is believed to be a selective modulator of human ether-a-go-go related (hERG) potassium channels. In this study, APETx1, 2 and 3 have been subjected to an electrophysiological screening on a wide range of 21 ion channels expressed in Xenopus leavis oocytes: 10 cloned voltage-gated sodium channels (NaV1.2-NaV1.8, the insect channels DmNaV1, BgNaV1-1a and the arachnid channel VdNaV1) and 11 cloned voltage-gated potassium channels (KV2.1, KV3.1, KV4.2, KV4.3, KV7.1, KV7.2, KV7.3, KV7.4, KV7.5, hERG, the insect channel Shaker IR). Surprisingly, the Thr3Pro substitution results in a complete abolishment of APETx3 modulation on hERG channels. However, the same substitution provides this toxin the ability to become a potent modulator of voltage-gated sodium channels (NaVs). APETx3 slows down the inactivation of mammalian and insect channels similar to site 3 toxins such as α-scorpion toxins and Sea Anemone NaVs toxins. Our screening reveals that the homologous toxins APETx1 and APETx2 display promiscuous properties as they are also capable of recognizing NaV channels, causing an inhibition of the sodium conductance.All together, these data provide new insights in key residues which allow these toxins to recognize distinct ion channels with similar potency but with different modulatory effects. Furthermore, we describe for the first time the target promiscuity of a family of Sea Anemone toxins believed to be highly selective.
-
a bifunctional Sea Anemone peptide with kunitz type protease and potassium channel inhibiting properties
Biochemical Pharmacology, 2011Co-Authors: Steve Peigneur, Lászlo Béress, Bert Billen, Rita Derua, Etienne Waelkens, Sarah Debaveye, Jan TytgatAbstract:Abstract Sea Anemone venom is a known source of interesting bioactive compounds, including peptide toxins which are invaluable tools for studying structure and function of voltage-gated potassium channels. APEKTx1 is a novel peptide isolated from the Sea Anemone Anthopleura elegantissima , containing 63 amino acids cross-linked by 3 disulfide bridges. Sequence alignment reveals that APEKTx1 is a new member of the type 2 Sea Anemone peptides targeting voltage-gated potassium channels (K V s), which also include the kalicludines from Anemonia sulcata . Similar to the kalicludines, APEKTx1 shares structural homology with both the basic pancreatic trypsin inhibitor (BPTI), a very potent Kunitz-type protease inhibitor, and dendrotoxins which are powerful blockers of voltage-gated potassium channels. In this study, APEKTx1 has been subjected to a screening on a wide range of 23 ion channels expressed in Xenopus laevis oocytes: 13 cloned voltage-gated potassium channels (K V 1.1–K V 1.6, K V 1.1 triple mutant, K V 2.1, K V 3.1, K V 4.2, K V 4.3, hERG, the insect channel Shaker IR), 2 cloned hyperpolarization-activated cyclic nucleotide-sensitive cation non-selective channels (HCN1 and HCN2) and 8 cloned voltage-gated sodium channels (Na V 1.2–Na V 1.8 and the insect channel DmNa V 1). Our data show that APEKTx1 selectively blocks K V 1.1 channels in a very potent manner with an IC 50 value of 0.9 nM. Furthermore, we compared the trypsin inhibitory activity of this toxin with BPTI. APEKTx1 inhibits trypsin with a dissociation constant of 124 nM. In conclusion, this study demonstrates that APEKTx1 has the unique feature to combine the dual functionality of a potent and selective blocker of K V 1.1 channels with that of a competitive inhibitor of trypsin.
-
A bifunctional Sea Anemone peptide with Kunitz type protease and potassium channel inhibiting properties.
Biochemical Pharmacology, 2011Co-Authors: Steve Peigneur, Lászlo Béress, Bert Billen, Rita Derua, Etienne Waelkens, Sarah Debaveye, Jan TytgatAbstract:Sea Anemone venom is a known source of interesting bioactive compounds, including peptide toxins which are invaluable tools for studying structure and function of voltage-gated potassium channels. APEKTx1 is a novel peptide isolated from the Sea Anemone , containing 63 amino acids cross-linked by 3 disulfide bridges. Sequence alignment reveals that APEKTx1 is a new member of the type 2 Sea Anemone peptides targeting voltage-gated potassium channels (K's), which also include the kalicludines from . Similar to the kalicludines, APEKTx1 shares structural homology with both the basic pancreatic trypsin inhibitor (BPTI), a very potent Kunitz-type protease inhibitor, and dendrotoxins which are powerful blockers of voltage-gated potassium channels. In this study, APEKTx1 has been subjected to a screening on a wide range of 23 ion channels expressed in oocytes: 13 cloned voltage-gated potassium channels (K1.1-K1.6, K1.1 triple mutant, K2.1, K3.1, K4.2, K4.3, hERG, the insect channel IR), 2 cloned hyperpolarization-activated cyclic nucleotide-sensitive cation non-selective channels (HCN1 and HCN2) and 8 cloned voltage-gated sodium channels (Na1.2-Na1.8 and the insect channel DmNa1). Our data shows that APEKTx1 selectively blocks K1.1 channels in a very potent manner with an IC value of 0.9nM. Furthermore, we compared the trypsin inhibitory activity of this toxin with BPTI. APEKTx1 inhibits trypsin with a dissociation constant of 124nM. In conclusion, this study demonstrates that APEKTx1 has the unique feature to combine the dual functionality of a potent and selective blocker of K1.1 channels with that of a competitive inhibitor of trypsin.
-
a new toxin from the Sea Anemone condylactis gigantea with effect on sodium channel inactivation
Toxicon, 2006Co-Authors: Ludger Standker, Lászlo Béress, Anoland Garateix, Torsten Christ, Ursula Ravens, Emilio Salceda, Enrique Soto, Harald John, Wolfgeorg Forssmann, Abel AneirosAbstract:Abstract A new peptide toxin exhibiting a molecular weight of 5043 Da (av.) and comprising 47 amino acid residues was isolated from the Sea Anemone Condylactis gigantea. Purification of the peptide was achieved by a multistep chromatographic procedure monitoring its strong paralytic activity on crustacea (LD50 approx. 1 μg/kg). Complete sequence analysis of the toxic peptide revealed the isolation of a new member of type I Sea Anemone sodium channel toxins containing the typical pattern of the six cysteine residues. From 11 kg of wet starting material, approximately 1 g of the peptide toxin was isolated. The physiological action of the new toxin from C. gigantea CgNa was investigated on sodium currents of rat dorsal root ganglion neurons in culture using whole-cell patch clamp technique ( n = 60 ). Under current clamp condition (CgNa) increased action potential duration. This effect is due to slowing down of the TTX-S sodium current inactivation, without modifying the activation process. CgNa prolonged the cardiac action potential duration and enhanced contractile force albeit at 100-fold higher concentrations than the Anemonia sulcata toxin ATXII. The action on sodium channel inactivation and on cardiac excitation-contraction coupling resemble previous results with compounds obtained from this and other Sea Anemones [Shapiro, B.I., 1968. Purification of a toxin from tentacles of the Anemone C. gigantea. Toxicon 5, 253–259; Pelhate, M., Zlotkin, E., 1982. Actions of insect toxin and other toxins derived from the venom of scorpion Androtonus australis on isolated giant axons of the cockroach Periplaneta americana. J. Exp. Biol. 97, 67–77; Salgado, V., Kem, W., 1992. Actions of three structurally distinct Sea Anemone toxins on crustacean and insect sodium channels. Toxicon 30, 1365–1381; Bruhn, T., Schaller, C., Schulze, C., Sanchez-Rodriquez, J., Dannmeier, C., Ravens, U., Heubach, J.F., Eckhardt, K., Schmidtmayer, J., Schmidt, H., Aneiros, A., Wachter, E., Beress, L., 2001. Isolation and characterization of 5 neurotoxic and cardiotoxic polypeptides from the Sea Anemone Anthopleura elegantissima. Toxicon, 39, 693–702]. Comprehensive analysis of the purified active fractions suggests that CgNa may represent the main peptide toxin of this Sea Anemone species.
-
apetx1 a new toxin from the Sea Anemone anthopleura elegantissima blocks voltage gated human ether a go go related gene potassium channels
Molecular Pharmacology, 2003Co-Authors: Sylvie Diochot, Lászlo Béress, Thomas Bruhn, Erwann Loret, Michel LazdunskiAbstract:A new peptide, APETx1, which specifically inhibits human ether-a-go-go–related gene (HERG) channels, was purified from venom of the Sea Anemone Anthopleura elegantissima. APETx1 is a 42-amino acid peptide cross-linked by three disulfide bridges and shares 54% homology with BDS-I, another Sea Anemone K+ channel inhibitor. Although they differ in their specific targets, circular dichroism spectra and molecular modeling indicate that APETx1 and BDS-I have a common molecular scaffold and belong to the same structural family of K+ channel blocking peptides. APETx1 inhibits HERG currents in a heterologous system with an IC50 value of 34 nM by modifying the voltage dependence of the channel gating. Central injections in mice failed to induce any neurotoxic symptoms. APETx1, which has no sequence homologies with scorpion toxins acting on HERG, defines a new structural group of HERG gating modifiers isolated from a Sea Anemone.
Steve Peigneur - One of the best experts on this subject based on the ideXlab platform.
-
a novel Sea Anemone peptide that inhibits acid sensing ion channels
Peptides, 2014Co-Authors: Armando Rodriguez, Steve Peigneur, Andre Junqueira Zaharenko, Michael K Richardson, Anoland Garateix, Emilio Salceda, Omar Lopez, Tirso Pons, Maylin Diaz, Yasnay HernandezAbstract:Abstract Sea Anemones produce ion channels peptide toxins of pharmacological and biomedical interest. However, peptides acting on ligand-gated ion channels, including acid-sensing ion channel (ASIC) toxins, remain poorly explored. PhcrTx1 is the first compound characterized from the Sea Anemone Phymanthus crucifer , and it constitutes a novel ASIC inhibitor. This peptide was purified by gel filtration, ion-exchange and reversed-phase chromatography followed by biological evaluation on ion channels of isolated rat dorsal root ganglia (DRG) neurons using patch clamp techniques. PhcrTx1 partially inhibited ASIC currents (IC 50 ∼ 100 nM), and also voltage-gated K + currents but the effects on the peak and on the steady state currents were lower than 20% in DRG neurons, at concentrations in the micromolar range. No significant effect was observed on Na + voltage-gated currents in DRG neurons. The N-terminal sequencing yielded 32 amino acid residues, with a molecular mass of 3477 Da by mass spectrometry. No sequence identity to other Sea Anemone peptides was found. Interestingly, the bioinformatic analysis of Cys-pattern and secondary structure arrangement suggested that this peptide presents an Inhibitor Cystine Knot (ICK) scaffold, which has been found in other venomous organisms such as spider, scorpions and cone snails. Our results show that PhcrTx1 represents the first member of a new structural group of Sea Anemones toxins acting on ASIC and, with much lower potency, on K v channels. Moreover, this is the first report of an ICK peptide in cnidarians, suggesting that the occurrence of this motif in venomous animals is more ancient than expected.
-
bcstx3 is a founder of a novel Sea Anemone toxin family of potassium channel blocker
FEBS Journal, 2013Co-Authors: Diego J B Orts, Yehu Moran, Camila Takeno Cologna, Bruno Madio, Daniela Praher, Loic Quinton, Jose Eduardo P W Bicudo, Steve Peigneur, Edwin De Pauw, Jan TytgatAbstract:Sea Anemone venoms have become a rich source of peptide toxins which are invaluable tools for studying the structure and functions of ion channels. In this work, BcsTx3, a toxin found in the venom of a Bunodosoma caissarum (population captured at the Saint Peter and Saint Paul Archipelago, Brazil) was purified and biochemically and pharmacologically characterized. The pharmacological effects were studied on 12 different subtypes of voltage-gated potassium channels (KV1.1–KV1.6; KV2.1; KV3.1; KV4.2; KV4.3; hERG and Shaker IR) and three cloned voltage-gated sodium channel isoforms (NaV1.2, NaV1.4 and BgNaV1.1) expressed in Xenopus laevis oocytes. BcsTx3 shows a high affinity for Drosophila Shaker IR channels over rKv1.2, hKv1.3 and rKv1.6, and is not active on NaV channels. Biochemical characterization reveals that BcsTx3 is a 50 amino acid peptide crosslinked by four disulfide bridges, and sequence comparison allowed BcsTx3 to be classified as a novel type of Sea Anemone toxin acting on KV channels. Moreover, putative toxins homologous to BcsTx3 from two additional actiniarian species suggest an ancient origin of this newly discovered toxin family.
-
A Natural Point Mutation Reveals Target Promiscuity of Toxins Isolated from the Sea Anemone Anthopleura Elegantissima
Biophysical Journal, 2012Co-Authors: Steve Peigneur, Evelien Lescrinier, Carolina Möller, Frank Marí, Lászlo Béress, Jan TytgatAbstract:Sea Anemone venom is a known source of interesting bioactive compounds, including peptide toxins which are invaluable tools for studying structure and function of voltage-gated potassium channels. APETx3 is a novel peptide isolated from the Sea Anemone Anthopleura elegantissima, containing 42 amino acids cross-linked by 3 disulfide bridges. Sequence alignment reveals that APETx3 is a natural occurring mutant from APETx1, only differing in 1 amino acid at position 3. APETx1 is believed to be a selective modulator of human ether-a-go-go related (hERG) potassium channels. In this study, APETx1, 2 and 3 have been subjected to an electrophysiological screening on a wide range of 21 ion channels expressed in Xenopus leavis oocytes: 10 cloned voltage-gated sodium channels (NaV1.2-NaV1.8, the insect channels DmNaV1, BgNaV1-1a and the arachnid channel VdNaV1) and 11 cloned voltage-gated potassium channels (KV2.1, KV3.1, KV4.2, KV4.3, KV7.1, KV7.2, KV7.3, KV7.4, KV7.5, hERG, the insect channel Shaker IR). Surprisingly, the Thr3Pro substitution results in a complete abolishment of APETx3 modulation on hERG channels. However, the same substitution provides this toxin the ability to become a potent modulator of voltage-gated sodium channels (NaVs). APETx3 slows down the inactivation of mammalian and insect channels similar to site 3 toxins such as α-scorpion toxins and Sea Anemone NaVs toxins. Our screening reveals that the homologous toxins APETx1 and APETx2 display promiscuous properties as they are also capable of recognizing NaV channels, causing an inhibition of the sodium conductance.All together, these data provide new insights in key residues which allow these toxins to recognize distinct ion channels with similar potency but with different modulatory effects. Furthermore, we describe for the first time the target promiscuity of a family of Sea Anemone toxins believed to be highly selective.
-
a bifunctional Sea Anemone peptide with kunitz type protease and potassium channel inhibiting properties
Biochemical Pharmacology, 2011Co-Authors: Steve Peigneur, Lászlo Béress, Bert Billen, Rita Derua, Etienne Waelkens, Sarah Debaveye, Jan TytgatAbstract:Abstract Sea Anemone venom is a known source of interesting bioactive compounds, including peptide toxins which are invaluable tools for studying structure and function of voltage-gated potassium channels. APEKTx1 is a novel peptide isolated from the Sea Anemone Anthopleura elegantissima , containing 63 amino acids cross-linked by 3 disulfide bridges. Sequence alignment reveals that APEKTx1 is a new member of the type 2 Sea Anemone peptides targeting voltage-gated potassium channels (K V s), which also include the kalicludines from Anemonia sulcata . Similar to the kalicludines, APEKTx1 shares structural homology with both the basic pancreatic trypsin inhibitor (BPTI), a very potent Kunitz-type protease inhibitor, and dendrotoxins which are powerful blockers of voltage-gated potassium channels. In this study, APEKTx1 has been subjected to a screening on a wide range of 23 ion channels expressed in Xenopus laevis oocytes: 13 cloned voltage-gated potassium channels (K V 1.1–K V 1.6, K V 1.1 triple mutant, K V 2.1, K V 3.1, K V 4.2, K V 4.3, hERG, the insect channel Shaker IR), 2 cloned hyperpolarization-activated cyclic nucleotide-sensitive cation non-selective channels (HCN1 and HCN2) and 8 cloned voltage-gated sodium channels (Na V 1.2–Na V 1.8 and the insect channel DmNa V 1). Our data show that APEKTx1 selectively blocks K V 1.1 channels in a very potent manner with an IC 50 value of 0.9 nM. Furthermore, we compared the trypsin inhibitory activity of this toxin with BPTI. APEKTx1 inhibits trypsin with a dissociation constant of 124 nM. In conclusion, this study demonstrates that APEKTx1 has the unique feature to combine the dual functionality of a potent and selective blocker of K V 1.1 channels with that of a competitive inhibitor of trypsin.
-
A bifunctional Sea Anemone peptide with Kunitz type protease and potassium channel inhibiting properties.
Biochemical Pharmacology, 2011Co-Authors: Steve Peigneur, Lászlo Béress, Bert Billen, Rita Derua, Etienne Waelkens, Sarah Debaveye, Jan TytgatAbstract:Sea Anemone venom is a known source of interesting bioactive compounds, including peptide toxins which are invaluable tools for studying structure and function of voltage-gated potassium channels. APEKTx1 is a novel peptide isolated from the Sea Anemone , containing 63 amino acids cross-linked by 3 disulfide bridges. Sequence alignment reveals that APEKTx1 is a new member of the type 2 Sea Anemone peptides targeting voltage-gated potassium channels (K's), which also include the kalicludines from . Similar to the kalicludines, APEKTx1 shares structural homology with both the basic pancreatic trypsin inhibitor (BPTI), a very potent Kunitz-type protease inhibitor, and dendrotoxins which are powerful blockers of voltage-gated potassium channels. In this study, APEKTx1 has been subjected to a screening on a wide range of 23 ion channels expressed in oocytes: 13 cloned voltage-gated potassium channels (K1.1-K1.6, K1.1 triple mutant, K2.1, K3.1, K4.2, K4.3, hERG, the insect channel IR), 2 cloned hyperpolarization-activated cyclic nucleotide-sensitive cation non-selective channels (HCN1 and HCN2) and 8 cloned voltage-gated sodium channels (Na1.2-Na1.8 and the insect channel DmNa1). Our data shows that APEKTx1 selectively blocks K1.1 channels in a very potent manner with an IC value of 0.9nM. Furthermore, we compared the trypsin inhibitory activity of this toxin with BPTI. APEKTx1 inhibits trypsin with a dissociation constant of 124nM. In conclusion, this study demonstrates that APEKTx1 has the unique feature to combine the dual functionality of a potent and selective blocker of K1.1 channels with that of a competitive inhibitor of trypsin.
