Agelenin

Agelenin, also called U1-agatoxin-Aop1a,[1] is an antagonist of the presynaptic P-type calcium channel in insects. This neurotoxic peptide consists of 35 amino acids and can be isolated from the venom of the spider Allagelena opulenta.

Agelenin
Names
Other names
U1-agatoxin-Aop1a, U1-AGTX-Aop1a
Identifiers
ChemSpider
  • none
KEGG
Properties
Molar mass 3500 g/mol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Sources

Agelenin - toxicologically named as U1-agatoxin-Aop1a and abbreviated as U1-AGTX-Aop1a - is an insecticidal toxin of the venom of the species Allagelena opulenta.[2] It was first discovered in 1990.[3]

Chemistry

Agelenin consists of a polypeptide chain of 35 amino acid residues.[3] It has a short anti-parallel β-sheet connected by three disulfide bonds and four β-turns that form the compact core structure. The three amino acid residues that are thought to be essential for the inhibiting activity of agelenin are Phe9, Ser28 and Arg33.[4]

The structure of agelenin is similar to the structure of ICK toxins like ω-Aga-IVA and ω-ACTXHv1a in that they all consist of three disulfide bonds with the same bonding pattern. An important difference between agelenin and ω-Aga-IVA and ω-ACTXHv1a is that ω-Aga-IVA and ω-ACTXHv1a have functional C-terminal tails.[4]

Agelenin belongs to toxin group of Agatoxins.[2] The amino acid structure of agelenin is Gly-Gly-Cys-Leu-Pro-His-Asn-Arg-Phe-Cys-Asn-Ala-Leu-Ser-Gly-Pro-Arg-Cys-Cys-Ser-Gly-Leu-Lis-Cys-Lis-Glu-Leu-Ser-Ile-Trp-Asp-Ser-Arg-Cys-Leu.[4]

Target

Agelenin is directed against P-subtype calcium channels in insects.[5]

Toxicity

Agelenin is not toxic in mammals, but has a PD50 of 291 pmol/g in crickets where it causes rapid, reversible paralysis.[4] In preparations of neuromuscular junctions of lobsters agelenin causes a non-reversible paralysis due to the suppression of excitatory postsynaptic potentials, presumably by inhibition of the presynaptic calcium influx.[3]

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References
  1. Institute for Molecular Bioscience. (2010) “U2-agatoxin-Aop1a”, Arachnoserver. Accessed on: 11 October 2015.
  2. Institute for Molecular Bioscience. (2010) “U2-agatoxin-Ao1a”, Arachnoserver. Accessed on: 11 October 2015.
  3. Hagiwara, K., Sakai, T., Miwa, A., Kawai, N. and Nakajima, T. (1990) “Complete amino acid sequence of a new type of neurotoxin from the venom of the spider, Agelena opulenta”, BioMed Research International, vol. 11, pp. 181-186.
  4. Yamaji, N., Sugase, K., Nakajima, T., Miki, T., Wakamori, M., More, Y. and Iwashita, T. (2007) “Solution structure of agelenin, an intisecticidal peptide isolated from the spider Agelena opulenta, and its structural similarities to insect-specific calcium channel inhibitors”, FEBS Letters, vol. 20, pp. 3789-3794.
  5. Rash, L.D. and Hodgson, W.C. (2002) “Pharmacology and biochemistry of spider venoms”, Toxicon, vol. 40, pp. 225-254.
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