The venom composition of the parasitic wasp Chelonus inanitus resolved by combined expressed sequence tags analysis and proteomic approach

Abstract

BackgroundParasitic wasps constitute one of the largest group of venomous animals. Although some physiological effects of their venoms are well documented, relatively little is known at the molecular level on the protein composition of these secretions. To identify the majority of the venom proteins of the endoparasitoid wasp Chelonus inanitus (Hymenoptera: Braconidae), we have randomly sequenced 2111 expressed sequence tags (ESTs) from a cDNA library of venom gland. In parallel, proteins from pure venom were separated by gel electrophoresis and individually submitted to a nano-LC-MS/MS analysis allowing comparison of peptides and ESTs sequences.ResultsAbout 60% of sequenced ESTs encoded proteins whose presence in venom was attested by mass spectrometry. Most of the remaining ESTs corresponded to gene products likely involved in the transcriptional and translational machinery of venom gland cells. In addition, a small number of transcripts were found to encode proteins that share sequence similarity with well-known venom constituents of social hymenopteran species, such as hyaluronidase-like proteins and an Allergen-5 protein.An overall number of 29 venom proteins could be identified through the combination of ESTs sequencing and proteomic analyses. The most highly redundant set of ESTs encoded a protein that shared sequence similarity with a venom protein of unknown function potentially specific of the Chelonus lineage. Venom components specific to C. inanitus included a C-type lectin domain containing protein, a chemosensory protein-like protein, a protein related to yellow-e3 and ten new proteins which shared no significant sequence similarity with known sequences. In addition, several venom proteins potentially able to interact with chitin were also identified including a chitinase, an imaginal disc growth factor-like protein and two putative mucin-like peritrophins.ConclusionsThe use of the combined approaches has allowed to discriminate between cellular and truly venom proteins. The venom of C. inanitus appears as a mixture of conserved venom components and of potentially lineage-specific proteins. These new molecular data enrich our knowledge on parasitoid venoms and more generally, might contribute to a better understanding of the evolution and functional diversity of venom proteins within Hymenoptera.

Comparative venomics of Psyttalia lounsburyi and P. concolor, two olive fruit fly parasitoids: a hypothetical role for a GH1 β-glucosidase

“…Among these, a family of five related proteins contains a signal peptide and the DUF4803 domain of unknown function (Supplementary Figure S3). They share similarities with venom proteins of the braconids C. inanitus 11, M. demolitor 12 and M. hyperodae 20, and of N. vitripennis 21.…”

“…Comparison of P. lounsburyi and P. concolor venom was performed using a combined transcriptomic and proteomic approach, and it was extended at the intraspecific level using two geographically distant African strains of P. lounsburyi (South Africa and Kenya). We also compared data with large-scale venomics results from other braconids, either associated with PDVs, as Chelonus inanitus 11 and Microplitis demolitor 12, or devoid of PDVs, as Aphidius ervi 13, since using various parasitism strategies could possibly impact venom evolution and composition.…”

The transcriptome recipe for the venom cocktail of Tityus bahiensis scorpion

“…Chitinase might thus be involved in the spread of venom components throughout the prey. Chitinase has been reported from spiders Chen et al, 2008) to parasitoid wasps (Vincent et al, 2010;de Graaf et al, 2010). Since arthropods use extra-oral digestion as a means of consuming relatively large prey with intractable cuticles through injection of proteolytic enzymes (Cohen, 1995;(McCormick and Polis, 1990), the venom chitinases found here may complement the action of the digestive system.…”

Function of the Dufour’s gland in solitary and social Hymenoptera

“…Since the Dufour's gland is believed to have evolved from the colleterial gland (an accessory reproductive gland) that is present in other insects (Carlet 1884, Maschwitz and Kloft 1971, Hermann 1969 Brothers (1998), Schmitz and Moritz (1998), Whitfield and Cameron (1998), Grimaldi and Engel (2005), Brady et al (2009), Vincent et al (2010), and Cardinal et al (2010. References cited in parenthesis below the names of compounds.…”

“…3). Brothers (1998), Schmitz and Moritz (1998), Whitfield and Cameron (1998), Grimaldi and Engel (2005), Brady et al (2009), Vincent et al (2010), and Cardinal et al (2010. Figures in parenthesis beside each function denote references cited.…”