Biochemical characterization and insecticidal activity of isolated peptides from the venom of the scorpion Centruroides tecomanus

• Published in: Toxicon (Oxford) 2022-01, Vol.206, p.90-102
• Main Authors: Bermúdez-Guzmán, M.J., Jiménez-Vargas, J.M., Possani, L.D., Zamudio, F., Orozco-Gutiérrez, G., Oceguera-Contreras, E., Enríquez-Vara, J.N., Vazquez-Vuelvas, O.F., García-Villalvazo, P.E., Valdez-Velázquez, L.L.
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Chromatography; Homology modeling; Insecticidal toxin; Insecticides; Mass spectrometry; Peptides; Peptides sequencing; Scorpion venom; Scorpion Venoms; Scorpions
• ISSN: 0041-0101; 1879-3150
• DOI: 10.1016/j.toxicon.2021.12.015

The venom of scorpions is a mixture of components that constitute a source of bioactive molecules. The venom of the scorpion Centruroides tecomanus contains peptides toxic to insects, however, to date no toxin responsible for this activity has yet been isolated and fully characterized. This communication describes two new peptides Ct-IT1 and Ct-IT2 purified from this scorpion. Both peptides contain 63 amino acids with molecular weight 6857.85 for Ct-IT1 and 6987.77 Da for Ct-IT2. The soluble venom was separated using chromatographic techniques of molecular size exclusion, cationic exchange, and reverse phase chromatography, allowing the identification of at least 99 components of which in 53 the insecticidal activity was evaluated. The LD50 determined for Ct-IT1 is 3.81 μg/100 mg of cricket weight, but low amounts of peptides (0.8 μg of peptide) already cause paralysis in crickets. The relative abundance of these two peptides in the venom is 2.1% for Ct-IT1 and 1% for Ct-IT2. The molecular masses and N-terminal sequences of both insecticidal toxins were determined by mass spectrometry and Edman degradation. The primary structure of both toxins was compared with other known peptides isolated from other scorpion venoms. The analysis of the sequence alignments revealed the position of a highly conserved amino acid residue, Gly39, exclusively present in anti-insect selective depressant β-toxins (DBTXs), which in Ct-IT1 and Ct-IT2 is at position Gly40. Similarly, a three-dimensional structure of this toxins was obtained by homology modeling and compared to the structure of known insect toxins of scorpions. An important similarity of the cavity formed by the trapping apparatus region of the depressant toxin LqhIT2, isolated from the scorpion Leiurus quinquestriatus hebraeus, was found in the toxins described here. These results indicate that Ct-IT1 and Ct-IT2 toxins have a high potential to be evaluated on pests that affect economically important crops to eventually consider them as a potential biological control method. •Two new insecticides (Ct-IT1 and Ct-IT2) were purified from Centruroides tecomanus scorpion.•Ct-IT1 and CT2 contain 63 amino acids with an experimental molecular mass of 6857.85 and 6987.77 Da, respectively.•Ct-IT1 and Ct-IT2 are highly toxic in insects, causing paralysis and eventual death in crickets at low doses.•The residue Gly40, is present in Ct-IT1 and Ct-IT2 toxins, this amino acid may be key to toxicity in insects.