Transcriptome Analysis in Venom Gland of the Predatory Giant Ant Dinoponera quadriceps: Insights into the Polypeptide Toxin Arsenal of Hymenopterans

Abstract

Background Dinoponera quadriceps is a predatory giant ant that inhabits the Neotropical region and subdues its prey (insects) with stings that deliver a toxic cocktail of molecules. Human accidents occasionally occur and cause local pain and systemic symptoms. A comprehensive study of the D. quadriceps venom gland transcriptome is required to advance our knowledge about the toxin repertoire of the giant ant venom and to understand the physiopathological basis of Hymenoptera envenomation.ResultsWe conducted a transcriptome analysis of a cDNA library from the D. quadriceps venom gland with Sanger sequencing in combination with whole-transcriptome shotgun deep sequencing. From the cDNA library, a total of 420 independent clones were analyzed. Although the proportion of dinoponeratoxin isoform precursors was high, the first giant ant venom inhibitor cysteine-knot (ICK) toxin was found. The deep next generation sequencing yielded a total of 2,514,767 raw reads that were assembled into 18,546 contigs. A BLAST search of the assembled contigs against non-redundant and Swiss-Prot databases showed that 6,463 contigs corresponded to BLASTx hits and indicated an interesting diversity of transcripts related to venom gene expression. The majority of these venom-related sequences code for a major polypeptide core, which comprises venom allergens, lethal-like proteins and esterases, and a minor peptide framework composed of inter-specific structurally conserved cysteine-rich toxins. Both the cDNA library and deep sequencing yielded large proportions of contigs that showed no similarities with known sequences.ConclusionsTo our knowledge, this is the first report of the venom gland transcriptome of the New World giant ant D. quadriceps. The glandular venom system was dissected, and the toxin arsenal was revealed; this process brought to light novel sequences that included an ICK-folded toxins, allergen proteins, esterases (phospholipases and carboxylesterases), and lethal-like toxins. These findings contribute to the understanding of the ecology, behavior and venomics of hymenopterans.

Diversity of peptide toxins from stinging ant venoms

“…The recent transcriptome analysis of the venom glands of the ant Dinoponera quadriceps (Ponerinae) has confirmed the presence and sequence of the first ICK-like peptide in ant venoms (Torres et al, 2014). This Dinoponera ICK-like peptide is a minor component of the venom of Dinoponera quadriceps but has a VI/VII cysteine framework (eCeCeCCeCeCe) consistent with other ICK toxins (Fig.…”

“…However, proteinaceous venoms remain highly understudied despite the fact that they appear to be very common in both the Poneroid and Formicoid clades of ant venoms. Thus, venoms from Poneroid ants have been shown to be rich in peptides especially venoms from the subfamilies Ponerinae (Cologna et al, 2013;Johnson et al, 2010;Torres et al, 2014;Touchard et al, 2014a) and Paraponerinae (Piek et al, 1991a(Piek et al, , 1991bRykaczewska-Czerwinska et al, 2008). Peptides have also been characterized from the venoms of Formicoid ants belonging to the subfamilies Myrmicinae (Bouzid et al, 2013;Rifflet et al, 2012), Myrmeciinae (Davies et al, 2004;Inagaki et al, 2004Inagaki et al, , 2008aLewis et al, 1968;Mackintosh et al, 1998;Wiese et al, 2006;Wu et al, 1998), Pseudomyrmecinae (Touchard et al, 2014b) and Ectatomminae Nolde et al, 1995;Pluzhnikov et al, 1999).…”

The complexity and structural diversity of ant venom peptidomes is revealed by mass spectrometry profiling

“…In particular, the inhibitor cystine knot (ICK) structural motif is relatively common in small cysteine‐rich peptide toxins from a variety of animal venoms and plants . While large numbers of ICK peptide toxins have been reported in other arthropods such as cone snails, sea anemones, spiders and scorpions, only two such ant venom peptides with a disulfide connectivity consistent with ICK toxins have been described: a Dinoponera ICK‐like peptide and SKTXs . Indeed, all the disulfide‐rich peptides previously isolated from ant venoms were homo‐ and heterodimeric complexes such as the myrmexins, pilosulins, and ectatomins found in venoms from the subfamilies Myrmeciinae, Pseudomyrmecinae and Ectatomminae (for a complete review, see Aili et al …”

Antimicrobial effect of Dinoponera quadriceps (Hymenoptera: Formicidae) venom against Staphylococcus aureus strains

“…Recently, our group produced a D. quadriceps venom gland cDNA library to investigate the toxin repertoire in the venom used in this work. It was observed that dinoponeratoxins are major components, but also peptides pilosulin-like were found, and these peptides reported primarily for its antimicrobial effect (Torres et al 2014). However, these antimicrobial peptides have been subjected to further analysis and molecular modelling in order to reduce its toxic effects, such as the pilosulins (Zelezetsky et al 2005).…”