Symbol ? SUPERFAMILY 1G92 OPM protein 1g92 | SCOP 1G92 OPM superfamily 160 | |
Poneratoxin is a paralyzing neurotoxic peptide from the bullet ant Paraponera clavata that affects voltage-dependent sodium ion channels and blocks the synaptic transmission in the central nervous system. Poneratoxin becomes insoluble when it is transferred from the cytoplasm of the cell into the cellular membrane. Poneratoxin is being studied for its uses in biological insecticides. It is through the use of a recombinant poneratoxin-producing baculovirus that poneratoxin's biological properties are being studied.
Contents
Function
Poneratoxin blocks nicotinic synaptic transmission in the central nervous system of insects, while also affecting voltage gated sodium channels. It depolarizes large interneurons while also acting as a strong, but slowly acting agonist for smooth muscles.
Structure
The poneratoxin peptide is stored in an inactive 25-residue peptide in the venom reservoir. It has a V shape, along with two αlpha helices connected by a βeta turn. The two αlpha helices, however, have different characteristics. The first helix is apolar, while the second helix contains polar and charged amino acids, which results in different interactions with regards to cellular membranes. The extremely hydrophobic N-terminal αlpha helix will react with uncharged lipid bilayers composed of phosphatidylcholine easily, whereas the C-terminal αlpha helix, which is terminating with arginine and slightly positive, will be able to attach to negatively charged cell surfaces. Researchers also noted that the poneratoxin sequence begins with a hydrophobic phenylalanine, which plays an important role in membrane penetration and that native poneratoxin does not contain cysteine.