Scorpion toxin

Scorpion long-chain toxin
Crystal structure of toxin II from the scorpion Androctonus australis Hector.[1]
Identifiers
Symbol Toxin_3
Pfam PF00537
InterPro IPR002061
SCOP 2sn3
SUPERFAMILY 2sn3
OPM superfamily 58
OPM protein 1djt
Scorpion short toxin
Agitoxin-2. Disulphide bonds are highlighted. PDB 1agt [2]
Identifiers
Symbol Toxin_2
Pfam PF00451
Pfam clan CL0054
InterPro IPR001947
PROSITE PDOC00875

Scorpion toxins are proteins found in the venom of scorpions. Their toxic effect may be mammal- or insect-specific and acts by binding to sodium channels, inhibiting the inactivation of activated channels and blocking neuronal transmission.

The family includes related short- and long-chain scorpion toxins. It also contains a group of proteinase inhibitors from the plants Arabidopsis thaliana and Brassica spp.

The Brassica napus (Oil seed rape) and Sinapis alba (White mustard) inhibitors,[3][4] inhibit the catalytic activity of bovine beta-trypsin and bovine alpha-chymotrypsin, which belong to MEROPS peptidase family S1 (InterPro: IPR001254).[5]

This group of proteins is now used in the creation of insecticides, vaccines, and protein engineering scaffolds.

Structure

The complete covalent structure of several such toxins has been deduced: They comprise around 66 amino acid residues forming a three stranded anti-parallel beta sheet over which lies an alpha helix of approximately three turns. Four disulfide bridges cross-link the structure of the long-chain toxins whereas the short toxins contain only three.[6][7] BmKAEP, an anti-epilepsy peptide isolated from the venom of the Manchurian scorpion,[8] shows similarity to both scorpion neurotoxins and anti-insect toxins.

Function

The toxin's molecular function is to inhibit ion channels. Scorpion toxins are used in insecticides, vaccines, and protein engineering scaffolds. The toxins are now used to treat cancer patients by injecting fluorescent scorpion toxin into cancerous tissue to show tumor boundaries. Scorpion toxin genes are also used to kill insect pests by creating hypervirulent fungus in the insect through gene insertion.

Subfamilies

References

  1. ↑ PDB: 1PTX​; Housset D, Habersetzer-Rochat C, Astier JP, Fontecilla-Camps JC (April 1994). "Crystal structure of toxin II from the scorpion Androctonus australis Hector refined at 1.3 A resolution". Journal of Molecular Biology. 238 (1): 88–103. doi:10.1006/jmbi.1994.1270. PMID 8145259.
  2. ↑ Krezel AM, Kasibhatla C, Hidalgo P, MacKinnon R, Wagner G (August 1995). "Solution structure of the potassium channel inhibitor agitoxin 2: caliper for probing channel geometry". Protein Science. 4 (8): 1478–89. doi:10.1002/pro.5560040805. PMC 2143198. PMID 8520473.
  3. ↑ Ceciliani F, Bortolotti F, Menegatti E, Ronchi S, Ascenzi P, Palmieri S (April 1994). "Purification, inhibitory properties, amino acid sequence and identification of the reactive site of a new serine proteinase inhibitor from oil-rape (Brassica napus) seed". FEBS Letters. 342 (2): 221–4. doi:10.1016/0014-5793(94)80505-9. PMID 8143882.
  4. ↑ Menegatti E, Tedeschi G, Ronchi S, Bortolotti F, Ascenzi P, Thomas RM, Bolognesi M, Palmieri S (April 1992). "Purification, inhibitory properties and amino acid sequence of a new serine proteinase inhibitor from white mustard (Sinapis alba L.) seed". FEBS Letters. 301 (1): 10–4. doi:10.1016/0014-5793(92)80199-Q. PMID 1451776.
  5. ↑ Rawlings ND, Tolle DP, Barrett AJ (March 2004). "Evolutionary families of peptidase inhibitors". The Biochemical Journal. 378 (Pt 3): 705–16. doi:10.1042/BJ20031825. PMC 1224039. PMID 14705960.
  6. ↑ Kopeyan C, Mansuelle P, Sampieri F, Brando T, Bahraoui EM, Rochat H, Granier C (February 1990). "Primary structure of scorpion anti-insect toxins isolated from the venom of Leiurus quinquestriatus quinquestriatus". FEBS Letters. 261 (2): 423–6. doi:10.1016/0014-5793(90)80607-K. PMID 2311768.
  7. ↑ Gregoire J, Rochat H (1983). "Covalent structure of toxins I and II from the scorpion Buthus occitanus tunetanus". Toxicon. 21 (1): 153–62. doi:10.1016/0041-0101(83)90058-2. PMID 6845379.
  8. ↑ Zhou XH, Yang D, Zhang JH, Liu CM, Lei KJ (January 1989). "Purification and N-terminal partial sequence of anti-epilepsy peptide from venom of the scorpion Buthus martensii Karsch". The Biochemical Journal. 257 (2): 509–17. doi:10.1042/bj2570509. PMC 1135608. PMID 2930463.
This article incorporates text from the public domain Pfam and InterPro: IPR002061
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