In vitro and in vivo antibacterial activity of TsAP-2 from Tityus stigmurus scorpion venom in multidrug-resistant strains and its NMR three-dimensional structure

Microbial infections are a public health problem that combined with the emergence of resistant microorganisms have boosted the search for new antibiotic agents. In this approach, the antibacterial and antibiofilm effects in vitro of TsAP-2 (peptide from the Tityus stigmurus scorpion venom) were evaluated. In addition, its antimicrobial action in the skin wound model infected with Staphylococcus aureus and Galleria mellonella larvae infected with a multidrug-resistant strain and the effect of the combination with conventional antibiotics in vitro were investigated. TsAP-2 demonstrated broad-spectrum antibacterial activity in vitro, with antibiofilm action against standard and multidrug-resistant strains during early biofilm formation. Furthermore, TsAP-2 exhibited additive and synergistic effects when combined with conventional antibiotics. TsAP-2 revealed antibacterial and healing activity in vivo, reducing wound area and necrosis, while promoting an increase in neovascularization and epithelialization. TsAP-2 decreased the number of resistant bacteria in infected larvae, increasing their survival rate. The structural conformation of the peptide was assessed using circular dichroism and its three-dimensional structure was determined through NMR spectroscopy. In zwitterionic vesicles, TsAP-2 revealed a random conformation and a predominant helical structure in the presence of anionic vesicles. The three-dimensional structure of TsAP-2 obtained by NMR analysis indicates a helical segment from the 7th to the 15th residue, with flexibility in the N and C-terminal peptide domains. Taken together, this approach indicates the ability of TsAP-2 to change its conformation when interacting with biomimetic medium, highlights its extensive pharmacological potential, being an attractive candidate for the exploration of new anti-infective drugs.