Recombinant Production and Structure–Function Study of the Ts1 Toxin from the Brazilian Scorpion Tityus serrulatus

This work introduces an effective bacterial system for the production of β-toxin Ts1, the main component of the Brazilian scorpion Tityus serrulatus venom. Recombinant toxin and its 15N-labeled analogue are obtained by direct expression of the synthetic gene in Escherichia coli, with subsequent folding from the inclusion bodies. NMR spectroscopy data assert that the recombinant toxin is structured in aqueous solution and is composed of a significant fraction of β-structure. Moreover, the formation of a stable Ts1 disulfide-bond isomer of a disordered structure is observed during folding; recombinant Ts1 blocks Na+ current through Na V 1.5 channels, without affecting the processes of activation and inactivation. Simultaneously, the effect upon Na V 1.4 channels is associated with a shift of the activation curve toward the more negative membrane potentials.