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Studies on sea snake venom.

Tamiya N, Yagi T - Proc. Jpn. Acad., Ser. B, Phys. Biol. Sci. (2011)

Bottom Line: Erabutoxins a and b are neurotoxins isolated from venom of a sea snake Laticauda semifasciata (erabu-umihebi).The sequence comparison and the location of essential residues on the protein suggested the mechanism of binding of the toxin to the acetylcholine receptor.Classification of snakes by means of sequence comparison and that based on different morphological features were inconsistent, which led the authors to propose a hypothesis "Evolution without divergence."

View Article: PubMed Central - PubMed

Affiliation: Tohoku University, Miyagi, Japan.

ABSTRACT
Erabutoxins a and b are neurotoxins isolated from venom of a sea snake Laticauda semifasciata (erabu-umihebi). Amino acid sequences of the toxins indicated that the toxins are members of a superfamily consisting of short and long neurotoxins and cytotoxins found in sea snakes and terrestrial snakes. The short neurotoxins to which erabutoxins belong act by blocking the nicotinic acetylcholine receptor on the post synaptic membrane in a manner similar to that of curare. X-ray crystallography and NMR analyses showed that the toxins have a three-finger structure, in which three fingers made of three loops emerging from a dense core make a gently concave surface of the protein. The sequence comparison and the location of essential residues on the protein suggested the mechanism of binding of the toxin to the acetylcholine receptor. Classification of snakes by means of sequence comparison and that based on different morphological features were inconsistent, which led the authors to propose a hypothesis "Evolution without divergence."

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Sequence alignment of some short, long and longN neurotoxins of sea and terrestrial snakes. The sequences above the dotted line are those of the short neurotoxins, the sequences Nos. 20, 21 and 22, the longN neurotoxins, and the others, the long neurotoxins. The structurally essential residues are boldfaced. The disulfide bonds are Cys3/24, Cys17/41, Cys43/54, and Cys55/60 for the short neurotoxins (No. 1), Cys10/34, Cys13/21, Cys27/53, Cys57/68 and Cys69/74 for the longN neurotoxins (No. 21), and Cys3/20, Cys14/41, Cys26/30, Cys45/56, and Cys57/62 for the long neurotoxins (No. 28). Astrotia toxins (Nos. 24 and 25) are unique among neurotoxins in having C-terminal amide. The toxins from terrestrial snakes have sequence numbers asterisked. In the column, Accession (for NCBI Protein sequence database), those for Protein Data Bank (PDB), which deposits three-dimensional structures, are boldfaced. One-letter codes for amino acids: A, alanine; C, cysteine; D, aspartate; E, glutamate; F, phenylalanine; G, glycine; H, histidine; I, isoleucine; K, lysine; L, leucine; M, methionine; N, asparagine; P, proline; Q, glutamine; R, arginine; S, serine; T, threonine; V, valine; W, tryptophan; Y, tyrosine.
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fig03: Sequence alignment of some short, long and longN neurotoxins of sea and terrestrial snakes. The sequences above the dotted line are those of the short neurotoxins, the sequences Nos. 20, 21 and 22, the longN neurotoxins, and the others, the long neurotoxins. The structurally essential residues are boldfaced. The disulfide bonds are Cys3/24, Cys17/41, Cys43/54, and Cys55/60 for the short neurotoxins (No. 1), Cys10/34, Cys13/21, Cys27/53, Cys57/68 and Cys69/74 for the longN neurotoxins (No. 21), and Cys3/20, Cys14/41, Cys26/30, Cys45/56, and Cys57/62 for the long neurotoxins (No. 28). Astrotia toxins (Nos. 24 and 25) are unique among neurotoxins in having C-terminal amide. The toxins from terrestrial snakes have sequence numbers asterisked. In the column, Accession (for NCBI Protein sequence database), those for Protein Data Bank (PDB), which deposits three-dimensional structures, are boldfaced. One-letter codes for amino acids: A, alanine; C, cysteine; D, aspartate; E, glutamate; F, phenylalanine; G, glycine; H, histidine; I, isoleucine; K, lysine; L, leucine; M, methionine; N, asparagine; P, proline; Q, glutamine; R, arginine; S, serine; T, threonine; V, valine; W, tryptophan; Y, tyrosine.

Mentions: Sequence alignment of selected snake toxins are shown in Fig. 3. Four disulfide bridges are found in common in short, long and longN neurotoxins and cytotoxins. An additional disulfide bridge is present in long and longN neurotoxins, whose positions are different in the two groups. General features of protein folding and disulfide bridges of representative short and long neurotoxins are schematically illustrated in Fig. 4. There are medium-sized neurotoxins (around 65 residues), one of which (No. 19 in Fig. 3) belongs to the short toxins having four disulfide bridges, and the other (No. 23) belongs to the long toxins having five disulfide bridges. Sequence alignments composed of more short and long neurotoxins, as well as cytotoxins, can be found elsewhere.7,22)


Studies on sea snake venom.

Tamiya N, Yagi T - Proc. Jpn. Acad., Ser. B, Phys. Biol. Sci. (2011)

Sequence alignment of some short, long and longN neurotoxins of sea and terrestrial snakes. The sequences above the dotted line are those of the short neurotoxins, the sequences Nos. 20, 21 and 22, the longN neurotoxins, and the others, the long neurotoxins. The structurally essential residues are boldfaced. The disulfide bonds are Cys3/24, Cys17/41, Cys43/54, and Cys55/60 for the short neurotoxins (No. 1), Cys10/34, Cys13/21, Cys27/53, Cys57/68 and Cys69/74 for the longN neurotoxins (No. 21), and Cys3/20, Cys14/41, Cys26/30, Cys45/56, and Cys57/62 for the long neurotoxins (No. 28). Astrotia toxins (Nos. 24 and 25) are unique among neurotoxins in having C-terminal amide. The toxins from terrestrial snakes have sequence numbers asterisked. In the column, Accession (for NCBI Protein sequence database), those for Protein Data Bank (PDB), which deposits three-dimensional structures, are boldfaced. One-letter codes for amino acids: A, alanine; C, cysteine; D, aspartate; E, glutamate; F, phenylalanine; G, glycine; H, histidine; I, isoleucine; K, lysine; L, leucine; M, methionine; N, asparagine; P, proline; Q, glutamine; R, arginine; S, serine; T, threonine; V, valine; W, tryptophan; Y, tyrosine.
© Copyright Policy - open-access
Related In: Results  -  Collection

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fig03: Sequence alignment of some short, long and longN neurotoxins of sea and terrestrial snakes. The sequences above the dotted line are those of the short neurotoxins, the sequences Nos. 20, 21 and 22, the longN neurotoxins, and the others, the long neurotoxins. The structurally essential residues are boldfaced. The disulfide bonds are Cys3/24, Cys17/41, Cys43/54, and Cys55/60 for the short neurotoxins (No. 1), Cys10/34, Cys13/21, Cys27/53, Cys57/68 and Cys69/74 for the longN neurotoxins (No. 21), and Cys3/20, Cys14/41, Cys26/30, Cys45/56, and Cys57/62 for the long neurotoxins (No. 28). Astrotia toxins (Nos. 24 and 25) are unique among neurotoxins in having C-terminal amide. The toxins from terrestrial snakes have sequence numbers asterisked. In the column, Accession (for NCBI Protein sequence database), those for Protein Data Bank (PDB), which deposits three-dimensional structures, are boldfaced. One-letter codes for amino acids: A, alanine; C, cysteine; D, aspartate; E, glutamate; F, phenylalanine; G, glycine; H, histidine; I, isoleucine; K, lysine; L, leucine; M, methionine; N, asparagine; P, proline; Q, glutamine; R, arginine; S, serine; T, threonine; V, valine; W, tryptophan; Y, tyrosine.
Mentions: Sequence alignment of selected snake toxins are shown in Fig. 3. Four disulfide bridges are found in common in short, long and longN neurotoxins and cytotoxins. An additional disulfide bridge is present in long and longN neurotoxins, whose positions are different in the two groups. General features of protein folding and disulfide bridges of representative short and long neurotoxins are schematically illustrated in Fig. 4. There are medium-sized neurotoxins (around 65 residues), one of which (No. 19 in Fig. 3) belongs to the short toxins having four disulfide bridges, and the other (No. 23) belongs to the long toxins having five disulfide bridges. Sequence alignments composed of more short and long neurotoxins, as well as cytotoxins, can be found elsewhere.7,22)

Bottom Line: Erabutoxins a and b are neurotoxins isolated from venom of a sea snake Laticauda semifasciata (erabu-umihebi).The sequence comparison and the location of essential residues on the protein suggested the mechanism of binding of the toxin to the acetylcholine receptor.Classification of snakes by means of sequence comparison and that based on different morphological features were inconsistent, which led the authors to propose a hypothesis "Evolution without divergence."

View Article: PubMed Central - PubMed

Affiliation: Tohoku University, Miyagi, Japan.

ABSTRACT
Erabutoxins a and b are neurotoxins isolated from venom of a sea snake Laticauda semifasciata (erabu-umihebi). Amino acid sequences of the toxins indicated that the toxins are members of a superfamily consisting of short and long neurotoxins and cytotoxins found in sea snakes and terrestrial snakes. The short neurotoxins to which erabutoxins belong act by blocking the nicotinic acetylcholine receptor on the post synaptic membrane in a manner similar to that of curare. X-ray crystallography and NMR analyses showed that the toxins have a three-finger structure, in which three fingers made of three loops emerging from a dense core make a gently concave surface of the protein. The sequence comparison and the location of essential residues on the protein suggested the mechanism of binding of the toxin to the acetylcholine receptor. Classification of snakes by means of sequence comparison and that based on different morphological features were inconsistent, which led the authors to propose a hypothesis "Evolution without divergence."

Show MeSH
Related in: MedlinePlus