Scorpion Stings Repel Its Predator (Video by LAI Ren's Team)
Venom is evolved to arm many otherwise defenseless animals with a lethal weapon, such as snakes, centipedes, scorpions and spiders. Although scorpion stings are well known to be extremely painful, it remains a serious problem worldwide because the molecular base is till poorly known.
Why scorpion stings produce an insufferable pain? LAI Ren and his colleagues at Kunming Institute of Zoology, CAS in China, UC Davis in USA and Zhejiang University in China have revealed this molecular mechanism.
Like tasting red chili pepper, scorpion toxin BmP01, a 29-amino acid peptide, activates capsaicin receptor (TRPV1) and induces burning pain. However, BmP01-induced TRPV1 activation is highly acid related and acts as a “one-two” punch mechanism.
Similar to most venoms, scorpion venom is weakly acidic (pH 6.5). Under acidic conditions, the E601 sites of TRPV1 are first occupied by protons, which makes TRPV1 ready to open.
Subsequently, occupying E649 by BmP01 can easily produce strong channel activation and an insufferable pain. On the contrary, BmP01 is not a potent activator at neutral pH because it occupies only the E649 site.
The authors suggest the functional and evolutionary importance of the venom acidity in scorpion toxin-induced pain. These data also offer some clues for clinical treatment of scorpion stings.