TsTX-kappa beta (Ts8), a neurotoxin from the venom of the scorpion Tityus serrulatus: antimicrobial and hemolytic activity.

Increase of infections caused by microorganisms resistant to conventional antibiotics is a health problem in Brazil and worldwide. The search for new molecules capable of inhibiting the growth of pathogens is a challenge for researchers, who find in venoms a rich source of biomolecules, including antimicrobial peptides (AMPs). The Brazilian scorpion, Tityus serrulatus, is one of the species that cause serious accidents; its venom is rich in neurotoxins that have been well characterized, highlighting their activities on channels (especially sodium and potassium). In this study we identifified and characterized one AMPs in T. serrulatus venom. After milking, the venom was fractioned by high performance liquid chromatography and the fractions were tested by liquid growth inhibition assay, the minimum inhibitory concentration (MIC) against Escherichia coli, Micrococcus luteus, Candida albicans and Aspergillus niger. The fraction identified with antimicrobial activity was analyzed by electrophoresis and mass spectrometry and this AMP (with molecular mass 6.882 kDa) has a similar amino acid sequence to TsTX-{kappa} beta, a neurotoxin that acts on ion channels. The TsTX-{kappa} beta in this study was identified by de novo sequencing. This peptide showed activity against all microorganisms tested. At high concentrations, this peptide, showed hemolytic activity against human erythrocytes. This is a new function described for this peptide, the identification of antimicrobial activity in a neurotoxin already known. Key ContributionMultifunction: antimicrobial and hemolytic activity associated to TsTX-{kappa} beta, a neurotoxin that acts on potassium channels.