The Experts below are selected from a list of 147 Experts worldwide ranked by ideXlab platform
Graham M. Nicholson - One of the best experts on this subject based on the ideXlab platform.
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The omega-atracotoxins: selective blockers of insect M-LVA and HVA calcium channels
Elsevier, 2007Co-Authors: Chong Youmie, King, Glenn F., Hayes, Jessica L., Sollod Brianna, Wen Suping, Wilson, David T., Hains, Peter G., Hodgson, Wayne C., Broady, Kevin W., Graham M. NicholsonAbstract:The omega-atracotoxins (omega-ACTX) are a family of arthropod-selective peptide neurotoxins from Australian funnel-web spider venoms (Hexathelidae: Atracinae) that are candidates for development as biopesticides. We isolated a 37-residue insect-selective neurotoxin, omega-ACTX-Ar1a, from the venom of the Sydney funnel-web spider Atrax robustus, with high homology to several previously characterized members of the omega-ACTX-1 family. The peptide induced potent excitatory symptoms, followed by flaccid paralysis leading to death, in acute toxicity tests in house crickets. Using isolated smooth and skeletal nerve-muscle preparations, the toxin was shown to lack overt vertebrate toxicity at concentrations up to 1 microM. To further characterize the target of the omega-ACTXs, voltage-clamp analysis using the whole-cell patch-clamp technique was undertaken using cockroach dorsal unpaired median neurons. It is shown here for the first time that omega-ACTX-Ar1a, and its homolog omega-ACTX-Hv1a from Hadronyche versuta, reversibly block both mid-low- (M-LVA) and high-voltage-activated (HVA) insect calcium channel (Ca(v)) currents. This block occurred in the absence of alterations in the voltage-dependence of Ca(v) channel activation, and was voltage-independent, suggesting that omega-ACTX-1 family toxins are pore blockers rather than gating modifiers. At a concentration of 1 microM omega-ACTX-Ar1a failed to significantly affect global K(v) channel currents. However, 1 microM omega-ACTX-Ar1a caused a modest 18% block of insect Na(v) channel currents, similar to the minor block of Na(v) channels reported for other insect Ca(v) channel blockers such as omega-agatoxin IVA. These findings validate both M-LVA and HVA Ca(v) channels as potential targets for insecticides
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The ω-atracotoxins: Selective blockers of insect M-LVA and HVA calcium channels
Biochemical pharmacology, 2007Co-Authors: Youmie Chong, David Wilson, Glenn F. King, Kevin W. Broady, Peter G Hains, Jessica L Hayes, Brianna L. Sollod, Suping Wen, Wayne C. Hodgson, Graham M. NicholsonAbstract:The ω-atracotoxins (ω-ACTX) are a family of arthropod-selective peptide neurotoxins from Australian funnel-web spider venoms (Hexathelidae: Atracinae) that are candidates for development as biopesticides. We isolated a 37-residue insect-selective neurotoxin, ω-ACTX-Ar1a, from the venom of the Sydney funnel-web spider Atrax robustus, with high homology to several previously characterized members of the ω-ACTX-1 family. The peptide induced potent excitatory symptoms, followed by flaccid paralysis leading to death, in acute toxicity tests in house crickets. Using isolated smooth and skeletal nerve-muscle preparations, the toxin was shown to lack overt vertebrate toxicity at concentrations up to 1 μM. To further characterize the target of the ω-ACTXs, voltage-clamp analysis using the whole-cell patch-clamp technique was undertaken using cockroach dorsal unpaired median neurons. It is shown here for the first time that ω-ACTX-Ar1a, and its homolog ω-ACTX-Hv1a from Hadronyche versuta, reversibly block both mid–low- (M-LVA) and high-voltage-activated (HVA) insect calcium channel (Cav) currents. This block occurred in the absence of alterations in the voltage-dependence of Cav channel activation, and was voltage-independent, suggesting that ω-ACTX-1 family toxins are pore blockers rather than gating modifiers. At a concentration of 1 μM ω-ACTX-Ar1a failed to significantly affect global Kv channel currents. However, 1 μM ω-ACTX-Ar1a caused a modest 18% block of insect Nav channel currents, similar to the minor block of Nav channels reported for other insect Cav channel blockers such as ω-agatoxin IVA. These findings validate both M-LVA and HVA Cav channels as potential targets for insecticides.
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Synthesis and Characterization of δ-Atracotoxin-Ar1a, the Lethal Neurotoxin from Venom of the Sydney Funnel-Web Spider (Atrax robustus)
Biochemistry, 2003Co-Authors: Dianne Alewood, Paul K Pallaghy, Raymond S. Norton, Liesl C. Birinyi-strachan, Graham M. Nicholson, Paul Francis AlewoodAbstract:δ-Atracotoxin-Ar1a (δ-ACTX-Ar1a) is the major polypeptide neurotoxin isolated from the venom of the male Sydney funnel-web spider, Atrax robustus. This neurotoxin targets both insect and mammalian voltage-gated sodium channels, where it competes with scorpion α-toxins for neurotoxin receptor site-3 to slow sodium-channel inactivation. Progress in characterizing the structure and mechanism of action of this toxin has been hampered by the limited supply of pure toxin from natural sources. In this paper, we describe the first successful chemical synthesis and oxidative refolding of the four-disulfide bond containing δ-ACTX-Ar1a. This synthesis involved solid-phase Boc chemistry using double coupling, followed by oxidative folding of purified peptide using a buffer of 2 M GdnHCl and glutathione/glutathiol in a 1:1 mixture of 2-propanol (pH 8.5). Successful oxidation and refolding was confirmed using both chemical and pharmacological characterization. Ion spray mass spectrometry was employed to confirm the mol...
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isolation of δ missulenatoxin mb1a the major vertebrate active spider δ toxin from the venom of missulena bradleyi actinopodidae 1
FEBS Letters, 2003Co-Authors: Simon Joseph Gunning, Kevin W. Broady, Youmie Chong, Ali A Khalife, Peter G Hains, Graham M. NicholsonAbstract:Abstract The present study describes the isolation and pharmacological characterisation of the neurotoxin δ-missulenatoxin-Mb1a (δ-MSTX-Mb1a) from the venom of the male Australian eastern mouse spider, Missulena bradleyi. This toxin was isolated using reverse-phase high-performance liquid chromatography and was subsequently shown to cause an increase in resting tension, muscle fasciculation and a decrease in indirect twitch tension in a chick biventer cervicis nerve-muscle bioassay. Interestingly, these effects were neutralised by antivenom raised against the venom of the Sydney funnel-web spider Atrax robustus. Subsequent whole-cell patch-clamp electrophysiology on rat dorsal root ganglion neurones revealed that δ-MSTX-Mb1a caused a reduction in peak tetrodotoxin (TTX)-sensitive sodium current, a slowing of sodium current inactivation and a hyperpolarising shift in the voltage at half-maximal activation. In addition, δ-MSTX-Mb1a failed to affect TTX-resistant sodium currents. Subsequent Edman degradation revealed a 42-residue peptide with unusual N- and C-terminal cysteines and a cysteine triplet (Cys14-16). This toxin was highly homologous to a family of δ-atracotoxins (δ-ACTX) from Australian funnel-web spiders including conservation of all eight cysteine residues. In addition to actions on sodium channel gating and kinetics to δ-ACTX, δ-MSTX-Mb1a caused significant insect toxicity at doses up to 2000 pmol/g. δ-MSTX-Mb1a therefore provides evidence of a highly conserved spider δ-toxin from a phylogenetically distinct spider family that has not undergone significant modification.
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Isolation of delta-missulenatoxin-Mb1a, the major vertebrate-active spider delta-toxin from the venom of Missulena bradleyi (Actinopodidae).
FEBS letters, 2003Co-Authors: Simon Joseph Gunning, Kevin W. Broady, Youmie Chong, Ali A Khalife, Peter G Hains, Graham M. NicholsonAbstract:The present study describes the isolation and pharmacological characterisation of the neurotoxin delta-missulenatoxin-Mb1a (delta-MSTX-Mb1a) from the venom of the male Australian eastern mouse spider, Missulena bradleyi. This toxin was isolated using reverse-phase high-performance liquid chromatography and was subsequently shown to cause an increase in resting tension, muscle fasciculation and a decrease in indirect twitch tension in a chick biventer cervicis nerve-muscle bioassay. Interestingly, these effects were neutralised by antivenom raised against the venom of the Sydney funnel-web spider Atrax robustus. Subsequent whole-cell patch-clamp electrophysiology on rat dorsal root ganglion neurones revealed that delta-MSTX-Mb1a caused a reduction in peak tetrodotoxin (TTX)-sensitive sodium current, a slowing of sodium current inactivation and a hyperpolarising shift in the voltage at half-maximal activation. In addition, delta-MSTX-Mb1a failed to affect TTX-resistant sodium currents. Subsequent Edman degradation revealed a 42-residue peptide with unusual N- and C-terminal cysteines and a cysteine triplet (Cys(14-16)). This toxin was highly homologous to a family of delta-atracotoxins (delta-ACTX) from Australian funnel-web spiders including conservation of all eight cysteine residues. In addition to actions on sodium channel gating and kinetics to delta-ACTX, delta-MSTX-Mb1a caused significant insect toxicity at doses up to 2000 pmol/g. Delta-MSTX-Mb1a therefore provides evidence of a highly conserved spider delta-toxin from a phylogenetically distinct spider family that has not undergone significant modification.
Raymond S. Norton - One of the best experts on this subject based on the ideXlab platform.
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Synthesis and Characterization of δ-Atracotoxin-Ar1a, the Lethal Neurotoxin from Venom of the Sydney Funnel-Web Spider (Atrax robustus)
Biochemistry, 2003Co-Authors: Dianne Alewood, Paul K Pallaghy, Raymond S. Norton, Liesl C. Birinyi-strachan, Graham M. Nicholson, Paul Francis AlewoodAbstract:δ-Atracotoxin-Ar1a (δ-ACTX-Ar1a) is the major polypeptide neurotoxin isolated from the venom of the male Sydney funnel-web spider, Atrax robustus. This neurotoxin targets both insect and mammalian voltage-gated sodium channels, where it competes with scorpion α-toxins for neurotoxin receptor site-3 to slow sodium-channel inactivation. Progress in characterizing the structure and mechanism of action of this toxin has been hampered by the limited supply of pure toxin from natural sources. In this paper, we describe the first successful chemical synthesis and oxidative refolding of the four-disulfide bond containing δ-ACTX-Ar1a. This synthesis involved solid-phase Boc chemistry using double coupling, followed by oxidative folding of purified peptide using a buffer of 2 M GdnHCl and glutathione/glutathiol in a 1:1 mixture of 2-propanol (pH 8.5). Successful oxidation and refolding was confirmed using both chemical and pharmacological characterization. Ion spray mass spectrometry was employed to confirm the mol...
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1H NMR study of robustoxin, the lethal neurotoxin from the funnel web spider Atrax robustus
Toxicon : official journal of the International Society on Toxinology, 1999Co-Authors: Mark D. Temple, Merlin E.h. Howden, D.d. Sheumack, Mark G. Hinds, Raymond S. NortonAbstract:Robustoxin, the lethal neurotoxin from the Sydney funnel web spider Atrax robustus, is a polypeptide of 42 residues cross-linked by four disulfide bonds. This paper describes the sequence-specific assignment of resonances in the 1H nuclear magnetic resonance spectrum of robustoxin in aqueous solution. Several broad backbone amide resonances were encountered in spectra recorded at 27 degrees C, making the assignments at that temperature incomplete. In spectra recorded at lower temperatures these amide resonances became sharper, but others that were sharp at 27 degrees C became broad, indicative of conformational averaging on the millisecond timescale for certain regions of the structure. Nevertheless, it was possible to establish that robustoxin contains a small, triple-stranded, antiparallel beta-sheet and several reverse turns, but no alpha-helix. These observations indicate that this toxin may adopt the inhibitor cystine knot structure found in polypeptides from a diverse range of species, including a number of spiders. Analysis of the pH dependence of the spectrum yielded pKa values for Tyr22 and Tyr25, one of the three carboxyl groups, and the Lys residues.
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Solution structure of robustoxin, the lethal neurotoxin from the funnel-web spider Atrax robustus.
FEBS Letters, 1997Co-Authors: Paul K Pallaghy, Dianne Alewood, Paul Francis Alewood, Raymond S. NortonAbstract:The solution structure of robustoxin, the lethal neurotoxin from the Sydney funnel-web spider Atrax robustus, has been determined from 2D 1H NMR data. Robustoxin is a polypeptide of 42 residues cross-linked by four disulphide bonds, the connectivities of which were determined from NMR data and trial structure calculations to be 1–15, 8–20, 14–31 and 16–42 (a 1–4/2–6/3–7/5–8 pattern). The structure consists of a small three-stranded, anti-parallel β-sheet and a series of interlocking γ-turns at the C-terminus. It also contains a cystine knot, thus placing it in the inhibitor cystine knot motif family of structures, which includes the ω-conotoxins and a number of plant and animal toxins and protease inhibitors. Robustoxin contains three distinct charged patches on its surface, and an extended loop that includes several aromatic and non-polar residues. Both of these structural features may play a role in its binding to the voltage-gated sodium channel.
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Solution structure of robustoxin, the lethal neurotoxin from the funnel-web spider Atrax robustus.
FEBS letters, 1997Co-Authors: Paul K Pallaghy, Dianne Alewood, Paul Francis Alewood, Raymond S. NortonAbstract:The solution structure of robustoxin, the lethal neurotoxin from the Sydney funnel-web spider Atrax robustus, has been determined from 2D 1H NMR data. Robustoxin is a polypeptide of 42 residues cross-linked by four disulphide bonds, the connectivities of which were determined from NMR data and trial structure calculations to be 1-15, 8-20, 14-31 and 16-42 (a 1-4/2-6/3-7/5-8 pattern). The structure consists of a small three-stranded, anti-parallel beta-sheet and a series of interlocking gamma-turns at the C-terminus. It also contains a cystine knot, thus placing it in the inhibitor cystine knot motif family of structures, which includes the omega-conotoxins and a number of plant and animal toxins and protease inhibitors. Robustoxin contains three distinct charged patches on its surface, and an extended loop that includes several aromatic and non-polar residues. Both of these structural features may play a role in its binding to the voltage-gated sodium channel.
Paul Francis Alewood - One of the best experts on this subject based on the ideXlab platform.
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Synthesis and Characterization of δ-Atracotoxin-Ar1a, the Lethal Neurotoxin from Venom of the Sydney Funnel-Web Spider (Atrax robustus)
Biochemistry, 2003Co-Authors: Dianne Alewood, Paul K Pallaghy, Raymond S. Norton, Liesl C. Birinyi-strachan, Graham M. Nicholson, Paul Francis AlewoodAbstract:δ-Atracotoxin-Ar1a (δ-ACTX-Ar1a) is the major polypeptide neurotoxin isolated from the venom of the male Sydney funnel-web spider, Atrax robustus. This neurotoxin targets both insect and mammalian voltage-gated sodium channels, where it competes with scorpion α-toxins for neurotoxin receptor site-3 to slow sodium-channel inactivation. Progress in characterizing the structure and mechanism of action of this toxin has been hampered by the limited supply of pure toxin from natural sources. In this paper, we describe the first successful chemical synthesis and oxidative refolding of the four-disulfide bond containing δ-ACTX-Ar1a. This synthesis involved solid-phase Boc chemistry using double coupling, followed by oxidative folding of purified peptide using a buffer of 2 M GdnHCl and glutathione/glutathiol in a 1:1 mixture of 2-propanol (pH 8.5). Successful oxidation and refolding was confirmed using both chemical and pharmacological characterization. Ion spray mass spectrometry was employed to confirm the mol...
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Cross-reactivity of Sydney funnel-web spider antivenom: neutralization of the in vitro toxicity of other Australian funnel-web (Atrax and Hadronyche) spider venoms
Toxicon : official journal of the International Society on Toxinology, 2002Co-Authors: Andis Graudins, Paul Francis Alewood, David Wilson, Kevin W. Broady, Graham M. NicholsonAbstract:Australian funnel-web spiders are recognized as one of the most venomous spiders to humans world-wide. Funnel-web spider antivenom (FWS AV) reverses clinical effects of envenomation from the bite of Atrax robustus and a small number of related Hadronyche species. This study assessed the in vitro efficacy of FWS AV in neutralization of the effects of funnel-web spider venoms, collected from various locations along the eastern seaboard of Australia, in an isolated chick biventer cervicis nerve–muscle preparation. Venoms were separated by SDS-PAGE electrophoresis to compare protein composition and transblotted for Western blotting and incubation with FWS AV. SDS-PAGE of venoms revealed similar low and high molecular weight protein bands. Western blotting with FWS AV showed similar antivenom binding with protein bands in all the venoms tested. Male funnel-web spider venoms (7/7) and female venoms (5/10) produced muscle contracture and fasciculation when applied to the nerve–muscle preparation. Venom effects were reversed by subsequent application of FWS AV or prevented by pretreatment of the preparation with antivenom. FWS AV appears to reverse the in vitro toxicity of a number of funnel-web spider venoms from the eastern seaboard of Australia. FWS AV should be effective in the treatment of envenomation from most, if not all, species of Australian funnel-web spiders.
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Solution structure of robustoxin, the lethal neurotoxin from the funnel-web spider Atrax robustus.
FEBS Letters, 1997Co-Authors: Paul K Pallaghy, Dianne Alewood, Paul Francis Alewood, Raymond S. NortonAbstract:The solution structure of robustoxin, the lethal neurotoxin from the Sydney funnel-web spider Atrax robustus, has been determined from 2D 1H NMR data. Robustoxin is a polypeptide of 42 residues cross-linked by four disulphide bonds, the connectivities of which were determined from NMR data and trial structure calculations to be 1–15, 8–20, 14–31 and 16–42 (a 1–4/2–6/3–7/5–8 pattern). The structure consists of a small three-stranded, anti-parallel β-sheet and a series of interlocking γ-turns at the C-terminus. It also contains a cystine knot, thus placing it in the inhibitor cystine knot motif family of structures, which includes the ω-conotoxins and a number of plant and animal toxins and protease inhibitors. Robustoxin contains three distinct charged patches on its surface, and an extended loop that includes several aromatic and non-polar residues. Both of these structural features may play a role in its binding to the voltage-gated sodium channel.
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Solution structure of robustoxin, the lethal neurotoxin from the funnel-web spider Atrax robustus.
FEBS letters, 1997Co-Authors: Paul K Pallaghy, Dianne Alewood, Paul Francis Alewood, Raymond S. NortonAbstract:The solution structure of robustoxin, the lethal neurotoxin from the Sydney funnel-web spider Atrax robustus, has been determined from 2D 1H NMR data. Robustoxin is a polypeptide of 42 residues cross-linked by four disulphide bonds, the connectivities of which were determined from NMR data and trial structure calculations to be 1-15, 8-20, 14-31 and 16-42 (a 1-4/2-6/3-7/5-8 pattern). The structure consists of a small three-stranded, anti-parallel beta-sheet and a series of interlocking gamma-turns at the C-terminus. It also contains a cystine knot, thus placing it in the inhibitor cystine knot motif family of structures, which includes the omega-conotoxins and a number of plant and animal toxins and protease inhibitors. Robustoxin contains three distinct charged patches on its surface, and an extended loop that includes several aromatic and non-polar residues. Both of these structural features may play a role in its binding to the voltage-gated sodium channel.
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Solution structure of robustoxin, the lethal neurotoxin from the funnel-web spider Atrax robustus
'Elsevier BV', 1997Co-Authors: Paul K Pallaghy, Paul Francis Alewood, Alewood D, Rs NortonAbstract:The solution structure of robustoxin, the lethal neurotoxin from the Sydney funnel-web spider Atrax robustus, has been determined from 2D H-1 NMR data, Robustoxin is a polypeptide of 42 residues cross-linked by four disulphide bonds, the connectivities of which were determined from NMR data and trial structure calculations to be 1-15, 8-20, 14-31 and 16-42 (a 1-4/2-6/3-7/5-8 pattern), The structure consists of a small three-stranded, anti-parallel beta-sheet and a series of interlocking gamma-turns at the C-terminus. It also contains a cystine knot, thus placing it in the inhibitor cystine knot motif family of structures, which includes the omega-conotoxins and a number of plant and animal toxins and protease inhibitors. Robustoxin contains three distinct charged patches on its surface, and an extended loop that includes several aromatic and non-polar residues, Both of these structural features may play a role in its binding to the voltage-gated sodium channel. (C) 1997 Federation of European Biochemical Societies
Paul K Pallaghy - One of the best experts on this subject based on the ideXlab platform.
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Synthesis and Characterization of δ-Atracotoxin-Ar1a, the Lethal Neurotoxin from Venom of the Sydney Funnel-Web Spider (Atrax robustus)
Biochemistry, 2003Co-Authors: Dianne Alewood, Paul K Pallaghy, Raymond S. Norton, Liesl C. Birinyi-strachan, Graham M. Nicholson, Paul Francis AlewoodAbstract:δ-Atracotoxin-Ar1a (δ-ACTX-Ar1a) is the major polypeptide neurotoxin isolated from the venom of the male Sydney funnel-web spider, Atrax robustus. This neurotoxin targets both insect and mammalian voltage-gated sodium channels, where it competes with scorpion α-toxins for neurotoxin receptor site-3 to slow sodium-channel inactivation. Progress in characterizing the structure and mechanism of action of this toxin has been hampered by the limited supply of pure toxin from natural sources. In this paper, we describe the first successful chemical synthesis and oxidative refolding of the four-disulfide bond containing δ-ACTX-Ar1a. This synthesis involved solid-phase Boc chemistry using double coupling, followed by oxidative folding of purified peptide using a buffer of 2 M GdnHCl and glutathione/glutathiol in a 1:1 mixture of 2-propanol (pH 8.5). Successful oxidation and refolding was confirmed using both chemical and pharmacological characterization. Ion spray mass spectrometry was employed to confirm the mol...
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Solution structure of robustoxin, the lethal neurotoxin from the funnel-web spider Atrax robustus.
FEBS Letters, 1997Co-Authors: Paul K Pallaghy, Dianne Alewood, Paul Francis Alewood, Raymond S. NortonAbstract:The solution structure of robustoxin, the lethal neurotoxin from the Sydney funnel-web spider Atrax robustus, has been determined from 2D 1H NMR data. Robustoxin is a polypeptide of 42 residues cross-linked by four disulphide bonds, the connectivities of which were determined from NMR data and trial structure calculations to be 1–15, 8–20, 14–31 and 16–42 (a 1–4/2–6/3–7/5–8 pattern). The structure consists of a small three-stranded, anti-parallel β-sheet and a series of interlocking γ-turns at the C-terminus. It also contains a cystine knot, thus placing it in the inhibitor cystine knot motif family of structures, which includes the ω-conotoxins and a number of plant and animal toxins and protease inhibitors. Robustoxin contains three distinct charged patches on its surface, and an extended loop that includes several aromatic and non-polar residues. Both of these structural features may play a role in its binding to the voltage-gated sodium channel.
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Solution structure of robustoxin, the lethal neurotoxin from the funnel-web spider Atrax robustus.
FEBS letters, 1997Co-Authors: Paul K Pallaghy, Dianne Alewood, Paul Francis Alewood, Raymond S. NortonAbstract:The solution structure of robustoxin, the lethal neurotoxin from the Sydney funnel-web spider Atrax robustus, has been determined from 2D 1H NMR data. Robustoxin is a polypeptide of 42 residues cross-linked by four disulphide bonds, the connectivities of which were determined from NMR data and trial structure calculations to be 1-15, 8-20, 14-31 and 16-42 (a 1-4/2-6/3-7/5-8 pattern). The structure consists of a small three-stranded, anti-parallel beta-sheet and a series of interlocking gamma-turns at the C-terminus. It also contains a cystine knot, thus placing it in the inhibitor cystine knot motif family of structures, which includes the omega-conotoxins and a number of plant and animal toxins and protease inhibitors. Robustoxin contains three distinct charged patches on its surface, and an extended loop that includes several aromatic and non-polar residues. Both of these structural features may play a role in its binding to the voltage-gated sodium channel.
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Solution structure of robustoxin, the lethal neurotoxin from the funnel-web spider Atrax robustus
'Elsevier BV', 1997Co-Authors: Paul K Pallaghy, Paul Francis Alewood, Alewood D, Rs NortonAbstract:The solution structure of robustoxin, the lethal neurotoxin from the Sydney funnel-web spider Atrax robustus, has been determined from 2D H-1 NMR data, Robustoxin is a polypeptide of 42 residues cross-linked by four disulphide bonds, the connectivities of which were determined from NMR data and trial structure calculations to be 1-15, 8-20, 14-31 and 16-42 (a 1-4/2-6/3-7/5-8 pattern), The structure consists of a small three-stranded, anti-parallel beta-sheet and a series of interlocking gamma-turns at the C-terminus. It also contains a cystine knot, thus placing it in the inhibitor cystine knot motif family of structures, which includes the omega-conotoxins and a number of plant and animal toxins and protease inhibitors. Robustoxin contains three distinct charged patches on its surface, and an extended loop that includes several aromatic and non-polar residues, Both of these structural features may play a role in its binding to the voltage-gated sodium channel. (C) 1997 Federation of European Biochemical Societies
Joachim Haupt - One of the best experts on this subject based on the ideXlab platform.
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Distinct primary structures of the major peptide toxins from the venom of the spider Macrothele gigas that bind to sites 3 and 4 in the sodium channel.
FEBS letters, 2003Co-Authors: Gerardo Corzo, Nicolas Gilles, Honoo Satake, Elba Villegas, Li Dai, Terumi Nakajima, Joachim HauptAbstract:Six peptide toxins (Magi 1-6) were isolated from the Hexathelidae spider Macrothele gigas. The amino acid sequences of Magi 1, 2, 5 and 6 have low similarities to the amino acid sequences of known spider toxins. The primary structure of Magi 3 is similar to the structure of the palmitoylated peptide named PlTx-II from the North American spider Plectreurys tristis (Plectreuridae). Moreover, the amino acid sequence of Magi 4, which was revealed by cloning of its cDNA, displays similarities to the Na+ channel modifier delta-atracotoxin from the Australian spider Atrax robustus (Hexathelidae). Competitive binding assays using several 125I-labelled peptide toxins clearly demonstrated the specific binding affinity of Magi 1-5 to site 3 of the insect sodium channel and also that of Magi 5 to site 4 of the rat sodium channel. Only Magi 6 did not compete with the scorpion toxin LqhalphaIT in binding to site 3 despite high toxicity on lepidoptera larvae of 3.1 nmol/g. The K(i)s of other toxins were between 50 pM for Magi 4 and 1747 nM for Magi 1. In addition, only Magi 5 binds to both site 3 in insects (K(i)=267 nM) and site 4 in rat brain synaptosomes (K(i)=1.2 nM), whereas it showed no affinities for either mammal binding site 3 or insect binding site 4. Magi 5 is the first spider toxin with binding affinity to site 4 of a mammalian sodium channel.
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Distinct primary structures of the major peptide toxins from the venom of the spider Macrothele gigas that bind to sites 3 and 4 in the sodium channel1
FEBS Letters, 2003Co-Authors: Gerardo Corzo, Nicolas Gilles, Honoo Satake, Elba Villegas, Li Dai, Terumi Nakajima, Joachim HauptAbstract:Six peptide toxins (Magi 1–6) were isolated from the Hexathelidae spider Macrothele gigas. The amino acid sequences of Magi 1, 2, 5 and 6 have low similarities to the amino acid sequences of known spider toxins. The primary structure of Magi 3 is similar to the structure of the palmitoylated peptide named PlTx-II from the North American spider Plectreurys tristis (Plectreuridae). Moreover, the amino acid sequence of Magi 4, which was revealed by cloning of its cDNA, displays similarities to the Na+ channel modifier δ-atracotoxin from the Australian spider Atrax robustus (Hexathelidae). Competitive binding assays using several 125I-labelled peptide toxins clearly demonstrated the specific binding affinity of Magi 1–5 to site 3 of the insect sodium channel and also that of Magi 5 to site 4 of the rat sodium channel. Only Magi 6 did not compete with the scorpion toxin LqhαIT in binding to site 3 despite high toxicity on lepidoptera larvae of 3.1 nmol/g. The Kis of other toxins were between 50 pM for Magi 4 and 1747 nM for Magi 1. In addition, only Magi 5 binds to both site 3 in insects (Ki=267 nM) and site 4 in rat brain synaptosomes (Ki=1.2 nM), whereas it showed no affinities for either mammal binding site 3 or insect binding site 4. Magi 5 is the first spider toxin with binding affinity to site 4 of a mammalian sodium channel.