Different pharmacological properties between scorpion toxin BmKcug2 and its degraded analogs highlight the diversity of K+ channel blockers from thermally processed scorpions

BmK86-P1, a New Degradation Peptide with Desirable Thermostability and Kv1.2 Channel-Specific Activity from Traditional Chinese Scorpion Medicinal Material

“…The turret and filter region of potassium channels have different effects on the toxin binding for different scorpion toxins [ 3 , 12 , 13 , 14 ]. To investigate the importance of these two regions of potassium channels in interacting with BmK86-P1, another two channel chimeras (i.e., hKv1.2-M2 and hKv1.2-M3) were constructed, in which the turret or the filter region of the hKv1.2 channel was substituted by the equivalent region of the hKv1.1 channel.…”

“…However, until now, we have known very little about the active substances in processed scorpion medicinal material. Recently, this medicinal material was reported to contain a variety of potassium channel-interacting peptides by mass spectrometry-based proteomics, and some of them exhibited high affinity to potassium channels [ 2 , 3 ]. In view of the close relationship between potassium channels and diseases [ 15 , 16 , 17 , 18 ], it is essential to characterize the potassium channel-interacting peptides in the processed scorpion medicinal material.…”

“…All these results indicated that these four residues of BmK86-P1 were important in mediating the recognition process toward hKv1.2 channels, and as the classical "functional dyads" of potassium channels inhibiting scorpion toxins, Lys 19 and Ile 21 control its affinity for the hKv1.2 channel. The turret and filter region of potassium channels have different effects on the toxin binding for different scorpion toxins [3,[12][13][14]. To investigate the importance of these two regions of potassium channels in interacting with BmK86-P1, another two channel chimeras (i.e., hKv1.2-M2 and hKv1.2-M3) were constructed, in which the turret or the filter region of the hKv1.2 channel was substituted by the equivalent region of the hKv1.1 channel.…”

“…All potassium channel expression vectors were given by others or constructed by ourselves [3]. HEK293T cells were cultured in Dulbecco's modified Eagle medium (Gibco, Pittsburgh, PA, USA) with 10% fetal bovine serum and penicillin/streptomycin (100 units/mL) in a 5% CO 2 incubator at 37 • C. Potassium channel expression vectors and pEGFP-N1 were co-transfected into HEK293T cells using TurboFect in vitro Transfection Reagent (Thermo Scientific, Waltham, MA, USA) according to the manufacturer's instructions.…”

“…Traditionally, the processed scorpions were regarded as effective for disease treatment based on the Chinese saying "combat poison with poison". Today, mass spectrometrybased proteomics has revealed that there is a large number of wild-type peptides and novel degraded peptides that have the potential to act on potassium channels in processed scorpion medicinal material [2], and some of these classical neurotoxins and degraded peptides have been shown to be potent potassium channel inhibitors, such as BmKKx2, BmKTX, BmKcug2 and BmKcug2-P1 [2,3]. In view of the close relationship between potassium channels and diseases [4][5][6][7], these channel-blocking peptides are increasingly Toxins 2021, 13, 610 2 of 13 considered to be new drug leads for Kv channelopathies [6,8].…”