Toxins under a Rock: Proteo-transcriptomic analysis reveals the venom composition of the Pseudoscorpion Ammogarypus lawrencei (Pseudoscorpiones: Garypidae).

Pseudoscorpions represent one of the venomous animal groups least investigated with respect to their venom composition. So far, the venom of only a few species of these tiny arachnids has been analyzed, among which only the cosmopolitan species Chelifer cancroides and the Australian Synsphyronus apimelus have been investigated in more detail. Here, we advance the current understanding on pseudoscorpion toxins by unveiling the venom composition of the African species Ammogarypus lawrencei via proteo-transcriptomics-guided venomics. Belonging to the same family as S. apimelus whose venom was analyzed solely by a transcriptomic approach, we found the highest similarities between putative venom compounds in these species. Instead of an enzyme-rich venom predicted for S. apimelus, we found the venom of A. lawrencei to be dominated by Cysteine-rich peptides (CRPs). Many of these peptides show moderate similarity to neurotoxins found primarily in other arachnids, although a large proportion could not be annotated in more detail due to their high sequence disparity. Enzymes are a minor component in the venom of A. lawrencei and classified mostly as peptidases and triacylglycerol lipases, likely fulfilling a predigestive function or acting as spreading factors. Lastly, we identified a range of linear and putatively antimicrobial peptides in the A. lawrencei venom, which seem to be unrelated to the previously identified checacin-type linear peptides identified in the venom of C. cancroides. Our study provides valuable insights into the molecular diversity encoded in pseudoscorpion venom glands and identifies a range of novel biomolecules with putative translational potential.