Dataset Information

Crouching Tiger, Hidden Protein: Searching for Insecticidal Toxins in Venom of the Red Tiger Assassin Bug (Havinthus rufovarius).

ABSTRACT: Assassin bugs are venomous insects that prey on other arthropods. Their venom has lethal, paralytic, and liquifying effects when injected into prey, but the toxins responsible for these effects are unknown. To identify bioactive assassin bug toxins, venom was harvested from the red tiger assassin bug (Havinthus rufovarius), an Australian species whose venom has not previously been characterised. The venom was fractionated using reversed-phase high-performance liquid chromatography, and four fractions were found to cause paralysis and death when injected into sheep blowflies (Lucilia cuprina). The amino acid sequences of the major proteins in two of these fractions were elucidated by comparing liquid chromatography/tandem mass spectrometry data with a translated venom-gland transcriptome. The most abundant components were identified as a solitary 12.8 kDa CUB (complement C1r/C1s, Uegf, Bmp1) domain protein and a 9.5 kDa cystatin. CUB domains are present in multidomain proteins with diverse functions, including insect proteases. Although solitary CUB domain proteins have been reported to exist in other heteropteran venoms, such as that of the bee killer assassin bug Pristhesancus plagipennis, their function is unknown, and they have not previously been reported as lethal or paralysis-inducing. Cystatins occur in the venoms of spiders and snakes, but again with an unknown function. Reduction and alkylation experiments revealed that the H. rufovarius venom cystatin featured five cysteine residues, one of which featured a free sulfhydryl group. These data suggest that solitary CUB domain proteins and/or cystatins may contribute to the insecticidal activity of assassin bug venom.

SUBMITTER: Wait LC

PROVIDER: S-EPMC7822193 | biostudies-literature | 2020 Dec

REPOSITORIES: biostudies-literature

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Publications

Crouching Tiger, Hidden Protein: Searching for Insecticidal Toxins in Venom of the Red Tiger Assassin Bug (<i>Havinthus rufovarius</i>).

Wait Laura C LC Walker Andrew A AA King Glenn F GF

Toxins 20201222 1

Assassin bugs are venomous insects that prey on other arthropods. Their venom has lethal, paralytic, and liquifying effects when injected into prey, but the toxins responsible for these effects are unknown. To identify bioactive assassin bug toxins, venom was harvested from the red tiger assassin bug (<i>Havinthus rufovarius</i>), an Australian species whose venom has not previously been characterised. The venom was fractionated using reversed-phase high-performance liquid chromatography, and fo ...[more]

PMID: 33375154

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Project description:Assassin bugs (Hemiptera: Heteroptera: Reduviidae) are venomous insects that prey on invertebrates. Assassin bug venom has features in common with venoms from other animals, such as paralysing and lethal activity when injected, and a molecular composition that includes disulfide-rich peptide neurotoxins. Uniquely, this venom also has strong liquefying activity that has been hypothesised to facilitate feeding through the narrow channel of the proboscis—a structure inherited from sap- and phloem-feeding phytophagous hemipterans and adapted during the evolution of Heteroptera into a fang and feeding structure. However, further understanding of the function of assassin bug venom is impeded by the lack of proteomic studies detailing its molecular composition. In addition, the lack of knowledge regarding venoms of predaceous reduviids limits our understanding of how the venoms of the blood-feeding kissing bugs (Reduviidae: Triatominae) evolved to facilitate hematophagy. By using a combined transcriptomic/proteomic approach we show that the venom proteome of the harpactorine assassin bug Pristhesancus plagipennis includes a complex suite of >100 proteins comprising disulfide-rich peptides, CUB-domain proteins, cystatins, putative cytolytic toxins, triabin-like protein, odorant binding protein, serine proteases, catabolic enzymes, putative nutrient-binding proteins, plus eight families of proteins without homology to characterised proteins. Serine proteases, CUB domain proteins and other novel proteins in the 10–16 kDa mass range, as well as putative cytolytic toxins, were the most abundant venom components. Thus, in addition to putative neurotoxins, assassin bug venom includes a high proportion of enzymatic and cytolytic venom components well suited to tissue liquefaction. While some protein families such as lipocalin/triabins occur in the venoms of both predaceous and blood-feeding reduviids, the composition of venoms in these two groups differs markedly. These results provide insights into the venom evolution in the insect suborder Heteroptera.

Project description:Assassin bugs (Hemiptera: Heteroptera: Reduviidae) are venomous insects, most of which prey on invertebrates. Assassin bug venom has features in common with venoms from other animals, such as paralyzing and lethal activity when injected, and a molecular composition that includes disulfide-rich peptide neurotoxins. Uniquely, this venom also has strong liquefying activity that has been hypothesized to facilitate feeding through the narrow channel of the proboscis-a structure inherited from sap- and phloem-feeding phytophagous hemipterans and adapted during the evolution of Heteroptera into a fang and feeding structure. However, further understanding of the function of assassin bug venom is impeded by the lack of proteomic studies detailing its molecular composition.By using a combined transcriptomic/proteomic approach, we show that the venom proteome of the harpactorine assassin bug Pristhesancus plagipennis includes a complex suite of >100 proteins comprising disulfide-rich peptides, CUB domain proteins, cystatins, putative cytolytic toxins, triabin-like protein, odorant-binding protein, S1 proteases, catabolic enzymes, putative nutrient-binding proteins, plus eight families of proteins without homology to characterized proteins. S1 proteases, CUB domain proteins, putative cytolytic toxins, and other novel proteins in the 10-16-kDa mass range, were the most abundant venom components. Thus, in addition to putative neurotoxins, assassin bug venom includes a high proportion of enzymatic and cytolytic venom components likely to be well suited to tissue liquefaction. Our results also provide insight into the trophic switch to blood-feeding by the kissing bugs (Reduviidae: Triatominae). Although some protein families such as triabins occur in the venoms of both predaceous and blood-feeding reduviids, the composition of venoms produced by these two groups is revealed to differ markedly. These results provide insights into the venom evolution in the insect suborder Heteroptera.

Dataset Information

Crouching Tiger, Hidden Protein: Searching for Insecticidal Toxins in Venom of the Red Tiger Assassin Bug (Havinthus rufovarius).

Publications

Crouching Tiger, Hidden Protein: Searching for Insecticidal Toxins in Venom of the Red Tiger Assassin Bug (<i>Havinthus rufovarius</i>).

Similar Datasets

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