Discovery of Novel Bilaterian Signaling Peptides Using Cone Snail Toxins
Peptide hormones and neuropeptides form a diverse class of signaling molecules that control essential processes in animals. Despite several breakthroughs in peptide discovery, many signaling peptides remain undiscovered. Recently, we demonstrated the use of somatostatin-like toxins from cone snail venom to identify homologous signaling peptides in prey. Here, we demonstrate that this toxin-based approach can be systematically applied to the discovery of other unknown bilaterian signaling peptides. Using large sequencing datasets, we searched for homologies between cone snail toxins and putative peptides from several important model organisms representing the snails prey. We identified five toxin families that share strong similarities with previously unknown signaling peptides from mollusks and annelids. One of the peptides was also identified in rotifers, brachiopods, platyhelminths, and arthropods, and another was found to be structurally related to crustacean hyperglycemic hormone, a peptide not previously known to exist in Spiralia. Based on several lines of evidence we propose that these signaling peptides not only exist but serve important physiological functions. Finally, we propose that the discovery pipeline developed here can be more broadly applied to other systems in which one organism has evolved molecules to manipulate the physiology of another.