Characterization of the first two toxins isolated from the venom of the ancient scorpion Tityus (Archaeotityus) mattogrossensis (Borelli, 1901)

Abstract Background: Almost all Tityus characterized toxins are from subgenera Atreus and Tityus, there are only a few data about toxins produced by Archaeotityus, an ancient group in Tityus genus. Methods: Tityus (Archaeotityus) mattogrossensis crude venom was fractionated by high performance liquid chromatography, the major fractions were tested in a frog sciatic nerve single sucrose-gap technique. Two fractions (Tm1 and Tm2) were isolated, partially sequenced by MALDI-TOF/MS and electrophysiological assayed on HEK293 Nav 1.3, HEK293 Nav 1.6, DUM and DRG cells. Results: The sucrose-gap technique showed neurotoxicity in four fractions. One fraction caused a delay of action potential repolarization and other three caused a reduction in amplitude. An electrophysiological assay showed that Tm1 is active on HEK293 Nav 1.3, HEK293 Nav 1.6, DUM and DRG cells, and Tm2 on HEK293 Nav 1.3 and DRG cells, but not in HEK293 Nav 1.6. In addition, Tm1 and Tm2 did promote a shift to more negative potentials strongly suggesting that both are -NaScTx. Conclusion: Although Tityus (Archaeotityus) mattogrossensis is considered an ancient group in Tityus genus, the primary structure of Tm1 and Tm2 is more related to Tityus subgenus. The patch clamp electrophysiological tests suggest that Tm1 and Tm2 are NaScTx, and also promoted no shift to more negative potentials, strongly suggesting that both are -NaScTx. This paper aimed to explore and characterize for the first time toxins from the ancient scorpion Tityus (Archaeotityus) mattogrossensis.

Scorpions from the primeval subgenus Archaeotityus produce putative homologs of Tityus serrulatus toxins active on voltage-gated sodium channels

It has been proposed that the subgenus Archaeotityus comprises the most ancient species group within the medically important scorpion genus Tityus. cDNA encoding sodium-channel active toxins from the type species of this subgenus, Tityus clathratus (central Venezuela), have been isolated and sequenced. Two cDNAs were retrieved that encoded 61 amino acid-long putative neurotoxins named Tcl1 and Tcl2. Sequence identity was highest (87%) when both were compared with -toxin Ts1 from the Brazilian scorpion Tityus serrulatus and its homologs from T. bahiensis, T. stigmurus, and T. costatus. A Bayesian analysis indicated statistical support for the grouping of T. clathratus Tcl1 and Tcl2 with Brazilian gamma-like -toxins, reinforcing previous phylogenetic studies which suggested an evolutionary relationship between the subgenus Archaeotityus and scorpion species inhabiting southeast South America belonging to the subgenus Tityus.