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

Abstract

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 β-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 gammalike β-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.

Amazonian scorpions and scorpionism: integrating toxinological, clinical, and phylogenetic data to combat a human health crisis in the world’s most diverse rainfores

“…Of the Amazonian species of medical importance, the phylogenetic position of T. silvestris would be of particular interest. The species is currently classified in subgenus Archaeotityus [ 40 ], which comprises small (18-40 mm), variegated scorpions, known to be of little medical significance outside of Amazonia [ 41 ]. Within the Amazon River Basin, however, T. silvestris has caused serious envenomations in Brazil, with presentation of neurological manifestations (see section 3).…”

“…Molecular phylogenetic analyses of other scorpions in subgenus Archeotityus have grouped them in a clade that is sister to southern South American Tityus [ 32 , 31 ]. Interestingly, T. clathratus , the type species of this subgenus, produces neurotoxins that are structurally related to β-toxins targeting sodium channels from congeneric southern South America species of medical significance [ 41 ].…”

Bringing order to a complex system: phenotypic and genotypic evidence contribute to the taxonomy of Tityus (Scorpiones, Buthidae) and support the description of a new species

“…Nevertheless, the phylogenetic analysis of Ojanguren-Affilastro et al (2017a) recovered Tityus ( Archaeotityus ) as the sister group of a clade composed of some Tityus ( Tityus ) terminals, not the sister group of all Tityus subgenera, something that we also recovered in our results (Figs 1 – 3 ). Likewise, Borges et al (2012) found a close relationship between the toxin composition of the T. clathratus and T. stigmurus species-groups. Based on a comprehensive phylogenetic analysis of Tityus ( Archaeotityus ) carried ( Moreno-González 2021 ) and the results of this investigation, Tityus ( Archaeotityus ) cannot be considered as the sister clade of other Tityus subgenera or species-groups, as previously believed.…”

A checklist of the scorpions of Ecuador (Arachnida: Scorpiones), with notes on the distribution and medical significance of some species

“…[e.g. Tityus ( Archaeotityus ) clathratus Koch] but they are not considered medically significant due to the low amount of venom injected [ 102 ]. In Ecuador these species are T .…”