PT - JOURNAL ARTICLE AU - Yang, Shilong AU - Yang, Fan AU - Zhang, Bei AU - Lee, Bo Hyun AU - Li, Bowen AU - Luo, Lei AU - Zheng, Jie AU - Lai, Ren TI - A bimodal activation mechanism underlies scorpion toxin–induced pain AID - 10.1126/sciadv.1700810 DP - 2017 Aug 01 TA - Science Advances PG - e1700810 VI - 3 IP - 8 4099 - http://advances.sciencemag.org/content/3/8/e1700810.short 4100 - http://advances.sciencemag.org/content/3/8/e1700810.full SO - Sci Adv2017 Aug 01; 3 AB - Venomous animals use peptide toxins for hunting and self-defense. To achieve these goals, toxins need to bind to their targets with high affinity due to the small amount that a single bite or sting can deliver. The scorpion toxin BmP01 is linked to sting-induced excruciating pain; however, the reported minimum concentrations for activating TRPV1 channel or inhibiting voltage-gated potassium (Kv) channels (both in the micromolar range) appear too high to be biologically relevant. We show that the effective concentration of BmP01 is highly pH-dependent—it increases by about 10-fold in inhibiting Kv channels upon a 1-U drop in pH but decreases more than 100-fold in activating TRPV1. Mechanistic investigation revealed that BmP01 binds to one of the two proton-binding sites on TRPV1 and, together with a proton, uses a one-two punch approach to strongly activate the nociceptive channel. Because most animal venoms are acidic, proton-facilitated synergistic action may represent a general strategy for maximizing toxin potency.