Colombian Scorpion Centruroides margaritatus: Purification and Characterization of a Gamma Potassium Toxin with Full-Block Activity on the hERG1 Channel

Abstract

The Colombian scorpion Centruroides margaritatus produces a venom considered of low toxicity. Nevertheless, there are known cases of envenomation resulting in cardiovascular disorders, probably due to venom components that target ion channels. Among them, the humanether-à-go-go-Related gene (hERG1) potassium channels are critical for cardiac action potential repolarization and alteration in its functionality are associated with cardiac disorders. This work describes the purification and electrophysiological characterization of a Centruroides margaritatus venom component acting on hERG1 channels, the CmERG1 toxin. This novel peptide is composed of 42 amino acids with a MW of 4792.88 Da, folded by four disulfide bonds and it is classified as member number 10 of the γ-KTx1 toxin family. CmERG1 inhibits hERG1 currents with an IC50 of 3.4 ± 0.2 nM. Despite its 90.5% identity with toxin ɣ-KTx1.1, isolated from Centruroides noxius, CmERG1 completely blocks hERG1 current, suggesting a more stable plug of the hERG channel, compared to that formed by other ɣ-KTx.

Comparison of the Scorpionism Caused by Centruroides margaritatus, Tityus pachyurus and Tityus n. sp. aff. metuendus Scorpion Venoms in Colombia

“…Previous works confirm this for, Centruroides margaritatus venom, also causing renal alterations [49], cardiovascular effects through alpha-1 adrenergic receptors [77]. It possesses a potent gamma potassium toxin with full-block activity on the hERG1 channel [78].…”

Characterization and Chemical Synthesis of Cm39 (α-KTx 4.8): A Scorpion Toxin That Inhibits Voltage-Gated K+ Channel KV1.2 and Small- and Intermediate-Conductance Ca2+-Activated K+ Channels KCa2.2 and KCa3.1

“…A number of peptide toxins were isolated from the venom of C. margaritatus following a three-step purification scheme. A comprehensive description about the purification and proteomic analysis of these peptides was reported in our earlier publication [ 29 ]. The first step was size-exclusion chromatography, resulting in three fractions FI, FII and FIII.…”

“…Fraction FII, which typically contains the toxic components of the venom, was subjected to ion-exchange chromatography (IEC) using a carboxy-methylcellulose (CMC) column. The resulting 10 subfractions (FII.1-10) were individually separated by HPLC using a C 18 column and molecular weights (MW) were analyzed for the principal peaks by ESI-MS as shown in the previous publication [ 29 ]. A peptide of 3980.2 Da MW was found in sub-fraction FII.8 ( Figure 1 A) and named “Cm39” after the scorpion C. margaritatus and its MW.…”

“…However, previous studies report that the intravenous dose of a chromatographic fraction (containing peptides between 2.5–6 kDa) of its venom caused severe toxic effects in rats as biological models [ 28 ]. A detailed characterization of a Colombian scorpion C. margaritatus venom was performed previously by our group [ 29 ] and we discovered two new K V channel blocker peptide toxins: 1) CmERG1 (γ-KTx 10.1) that fully blocks the human ether-à-gogo-Related gene (hERG1) K + channel (K V 11.1) with high affinity, and 2) Cm28 (α-KTx 32.1) which is a high affinity inhibitor of K V 1.2 and K V 1.3 channels [ 30 ]. In the current work, while screening the venom components against various potassium ion channels, we identified another peptide toxin with a molecular weight of 3980 Da, named Cm39.…”

A scorpion toxin takes the sting out of T cell activation

“…Panyi and colleagues, including Muhammad Umair Naseem, a graduate student who received a Stipendium Hungaricum Scholarship from the Tempus Public Foundation, set out to characterize a novel peptide isolated from the Columbian scorpion Centruroides margaritatus by Lourival Possani’s group at the Universidad Nacional Autónoma de México ( 4 ). Phylogenetic analysis of this peptide, named Cm28, shows that it clusters with the α-KTx family, and structural modeling suggests that it adopts a similar α/β structure with three disulfide bonds ( 1 ).…”