Diversity of conopeptides and conoenzymes from the venom duct of the marine cone snail Conus bayani using transcriptomic and proteomic analyses

Marine cone snails are predatory gastropods characterised by a well developed venom apparatus and highly evolved hunting strategies, employing toxins to paralyse prey and to defend themselves 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. All together, 800 species of cone snails likely produce about 160,000 different peptides. Nevertheless, very few species have been characterised so far by transcriptome sequencing. In this study, we have used transcriptome sequencing technologies and mass spectrometric methods to discover the conotoxin diversity in the venom duct of a worm-hunting species, Conus bayani. A total of 82 conotoxin sequences were retrieved from transcriptomic data that contain 65 validated conotoxin sequences clustered into 19 gene superfamilies and 8 different conotoxin classes with one novel superfamily showing unique signal peptide signature. Four new conotoxin sequences showed odd numbers of cysteine patterns. We were also able to identify 18 peptide sequences using mass spectrometry that matched perfectly with the conotoxin sequences obtained from transcriptome analysis. Importantly, herein we document the presence of 16 enzymes that includes 5 post-translational modifiying enzymes with post-translational modifications obtained from transcriptomic data.