Diversity of Conotoxin Gene Superfamilies in the Venomous Snail, Conus victoriae

Abstract

Animal venoms represent a vast library of bioactive peptides and proteins with proven potential, not only as research tools but also as drug leads and therapeutics. This is illustrated clearly by marine cone snails (genus Conus), whose venoms consist of mixtures of hundreds of peptides (conotoxins) with a diverse array of molecular targets, including voltage- and ligand-gated ion channels, G-protein coupled receptors and neurotransmitter transporters. Several conotoxins have found applications as research tools, with some being used or developed as therapeutics. The primary objective of this study was the large-scale discovery of conotoxin sequences from the venom gland of an Australian cone snail species, Conus victoriae. Using cDNA library normalization, high-throughput 454 sequencing, de novo transcriptome assembly and annotation with BLASTX and profile hidden Markov models, we discovered over 100 unique conotoxin sequences from 20 gene superfamilies, the highest diversity of conotoxins so far reported in a single study. Many of the sequences identified are new members of known conotoxin superfamilies, some help to redefine these superfamilies and others represent altogether new classes of conotoxins. In addition, we have demonstrated an efficient combination of methods to mine an animal venom gland and generate a library of sequences encoding bioactive peptides.

Optimized deep-targeted proteotranscriptomic profiling reveals unexplored Conus toxin diversity and novel cysteine frameworks

“…However, using traditional protein-centric drug discovery approaches has been a tedious and time-consuming task that allows only superficial mining of the huge chemical diversity of natural products and that usually leads to the identification of only a few bioactive peptides per experiment (77). During the past decade, several studies focusing solely on cone snail venom duct (43,44,49,(78)(79)(80) or salivary gland (9,43,44,49,(78)(79)(80) transcriptomes, and later complemented by proteome profiling (46,47,50,59,81), have allowed the report of no more than only a hundred (47 on average) full-length precursor conotoxins each. The great majority of these studies used the ROCHE 454 next-generation sequencing platform because it produced low amounts of long reads that were possible to annotate by performing simple homology BLAST searches.…”

A bioinformatics survey for conotoxin-like sequences in three turrid snail venom duct transcriptomes

“…4) contain non-disulfide rich toxins. The signal region of these non-disulfide rich sequences were found to be similar to the signal sequences of the non-disulfide rich toxins described in Conus victoriae (Robinson et al, 2014), Conus litteratus , and Conus consors (Violette et al, 2012) (Fig. 7).…”

“…A total of 41, 22, and 74 highly putative conotoxin-like sequences were identified from these turrid snails, respectively. Similar studies using high-throughput sequencing to search for peptide toxins have been done for cone snails such as Conus bullatus (Hu et al, 2011), Conus victoriae (Robinson et al, 2014), and Conus pulicarius (Lluisma et al, 2012), but none so far with turrid snails. The toxin sequences discovered here provide further proof that conotoxins and turrid toxins share superfamilies and cysteine frameworks not only limited to the I 2 , O, and P superfamilies but also to the B 2 , D, L, M, O 1 , and S superfamilies.…”

Cone Snail Venomics: From Novel Biology to Novel Therapeutics

“…However, the challenge of extracting conotoxin sequences from raw-sequence data has been addressed by bioinformatics programs and pipelines. One approach has been to assemble raw reads and use similarity search-ing using BLAST and profile Hidden Markov Models (pHMMs) against sequence databases [114,119]. However standalone programs such as ConoDictor [120] and ConoSorter [121] have now been released to take large-scale raw sequence data and rapidly classify them into conotoxin superfamilies and help accelerate the process of discovering novel conotoxins as well as novel conotoxin superfamilies.…”