Moving pieces in a venomic puzzle: unveiling post-translationally modified toxins from Tityus serrulatus

Besides being a public health problem, scorpion venoms have a potential biotechnological application since they contain peptides that may be used as drug leads and/or to reveal novel pharmacological targets. A comprehensive Tityus serrulatus venom proteome study with emphasis on the phosphoproteome and N-glycoproteome was performed to improve our knowledge on the molecular diversity of the proteinaceous toxins. We combined two peptide identification methodologies, i.e., database search and de novo sequencing, to achieve a more comprehensive overview of the molecular diversity of the venoms. A total of 147 proteins were identified, including neurotoxins, enzymes, bradykinin-potentiating peptides, and molecules with antimicrobial and diuretic activities. Among those, three proteins were found to be phosphorylated, and one N-glycosylated. Finally, cleavage of toxin polypeptide chains seems to be a common post-translational modification in the venom since 80% of the identified molecules were, in fact, products of toxins proteolysis.