One small genetic mutation leads to a non-toxic protein turning into venom, giving scorpions their deadly sting, shows research.
The researchers looked at defensins - small proteins found in plants and animals that help ward off viral, bacterial or fungal pests.
Based on structural similarity, they proposed that scorpion toxins and defensins could have a common ancestor.
To address how a non-toxic protein develops into a toxin, the researchers studied the evolution of scorpion venom-derived neurotoxins - known as ?-KTxs.
According to a study published in the journal Molecular Biology and Evolution, they analysed the ?-KTx family sequences to extract the conserved amino acid sites associated with neurotoxin structure and function - called 'Scorpion Toxin Signature' (STS).
"Our results show that a STS-containing insect defensin can be converted to the scorpion ?-KTx-like neurotoxin through just a single genetic mutation," said lead author Shunyi Zhu, professor of biochemistry and molecular biology at Chinese Academy of Sciences in Beijing.
This small genetic mutation leads to a new protein function to give scorpions their deadly sting.