Snake Venom Three Finger Toxins (3FTx), An Overview

Snake Venom Three Finger Toxins (3FTx), An Overview

Snake venom three finger toxins (3FTx), 51 to 83 amino acids in length, are non-enzymatic members of the superfamily of three-finger protein domains^1,2. The group name for the superfamily derives from a common structural motif resembling a hand with three fingers^1,2. The three “fingers” are β-strands connected to a central core. Typically the core contains four conserved disulfide linkages. Snake venom three finger toxins may exist as monomers and as covalently or non-covalently linked homodimers or heterodimers^1,2. Although 3TFx’s do not possess enzymatic activity, they do possess a wide range of toxic and/or pharmacological properties. They include α-neurotoxins, β-cardiotoxins, γ-neurotoxins, κ-neurotoxins, cytotoxins, fasiculins, mambalgins and hannalgesin^1,2.

κ-Bungarotoxin^1-4

Illustrated above is the ribbon structure of κ-Bungarotoxin, a 3TFx from the many banded krait (Bungarus multicinctus). κ-Bungarotoxin is somewhat unique among 3FTx’s in that it possess 5 (instead of 4) disulfide linkages and exists as a dimer^1-3. 

References

1)      Ferraz, C. R., Arrahman, A., Xie, C., Casewell, N. R., Lewis, R. J., Kool, J., & Cardoso, F. C., (2019). Multifunctional toxins in snake venoms and therapeutic implications: from pain to hemorrhage and necrosis. Frontiers in Ecology and Evolution, 7, 218.

2)      Kappa-bungarotoxin  https://en.wikipedia.org/wiki/Kappa-bungarotoxin

3)      Dewan, J. C., Grant, G. A., & Sacchettini, J. C. (1994). Crystal structure of. kappa.-Bungarotoxin at 2.3-. ANG. resolution. Biochemistry, 33(44), 13147-13154.

4)      https://www.rcsb.org/structure/1KBA