Diversity of Conopeptides and Conoenzymes from the Venom Duct of the Marine Cone Snail Conus bayani as Determined from Transcriptomic and Proteomic Analyses

Marine cone snails are predatory gastropods characterized by a well-developed venom apparatus and highly evolved hunting strategies that utilize toxins to paralyze prey and defend against predators. The venom of each species of cone snail has a large number of pharmacologically active peptides known as conopeptides or conotoxins that are usually unique in each species. Nevertheless, venoms of only very few species have been characterized so far by transcriptomic approaches. In this study, we used transcriptome sequencing technologies and mass spectrometric methods to describe the diversity of venom components expressed by a worm-hunting species, Conus bayani. A total of 82 conotoxin sequences were retrieved from transcriptomic data that contain 54 validated conotoxin sequences clustered into 21 gene superfamilies including divergent gene family, 17 sequences clustered to 6 different conotoxin classes, and 11 conotoxins classified as unassigned gene family. Seven new conotoxin sequences showed unusual cysteine patterns. We were also able to identify 19 peptide sequences using mass spectrometry that completely overlapped with the conotoxin sequences obtained from transcriptome analysis. Importantly, herein we document the presence of 16 proteins that include five post-translational modifying enzymes obtained from transcriptomic data. Our results revealed diverse and novel conopeptides of an unexplored species that could be used extensively in biomedical research due to their therapeutic potentials.