Molecular cloning and nucleotide sequence analysis of a cDNA encoding the main β‐neurotoxin from the venom of the South American scorpion Tityus serrulatus

Abstract

A cDNA encoding the main T@II,F .wwhru.r ,%ncurotoxin was isolated from a venom gland cDNA library by using an oligonuclcotidc probe, The amino iICid scqucncr deduced I'rom the cDNA nucteotidc sequcncc indicated that the toxin is the processed product or a precursor containing:(i) a signal peptide of 20 residues: (ii) the amino acid sequence of the mature loxin: and (iii) an extra Gly-Lys-Lya tail al the C-terminal end before the termination codon. Thus, in addition to the remov;ll of the signal peptide by a signal pcptidasc, the generation of the mature toxin requires both a post-translational ClCUvagC by a carboxypcplidasc specific for basic rcsiducs and the XIion of an a-amidating enzyme. These results also show that the biosynthetic pathwuy for &toxins of"Ncw World' scorpion venoms is similar LO Ihat already described for a-toxins of 'Old World' scorpion venoms.

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

“…It is clear that Tcl1 and Tcl2 belong to the b-toxin family, bearing the same secondary structure elements found by Polikarpov et al (39) in Ts1, the most abundant T. serrulatus b-toxin (40). Since Tityus venoms also contain a-toxins (16), the fact that we did not retrieve cDNAs coding for putative T. clathratus a-toxins could be either due to their absence in T. clathratus venom or that their cDNAs were not amplified under our conditions due to variations in the leader-peptide nucleotide sequence of T. clathratus a-toxin genes, which may prevent the degenerate primer from anchoring at the selected site, identified as conserved amongst genes encoding other Tityus toxins (10).…”

Genomic organization of the KTX2 gene, encoding a ‘short’ scorpion toxin active on K+ channels

“…B: cDNAs of toxins active on voltage-dependent Na + channels, i.e. from top to bottom, the a-toxin AaH I' from the Tunisian Androctonus australis [19]; the ß-toxin y from the Brazilian scorpion Tityus serrulatus [20]; cDNA of toxins active on the voltage-dependent K + channel, i.e. KTX2 [4]; gene of the defensin from the fly Drosophila megalogaster [15].…”

Nematode-derived drosomycin-type antifungal peptides provide evidence for plant-to-ecdysozoan horizontal transfer of a disease resistance gene

“…2a). Cremycin-1 to cremycin-14 display high sequence similarity to each other but they have low similarity to cremycin-15 that has a unique amidated C-terminus due to the presence of a Gly-Arg motif 18 (Fig. 2a).…”