Insecticidal activity of a recombinant knottin peptide from Loxosceles intermedia venom and recognition of these peptides as a conserved family in the genus

Abstract

Loxosceles intermedia venom comprises a complex mixture of proteins, glycoproteins and low molecular mass peptides that act synergistically to immobilize envenomed prey. Analysis of a venom-gland transcriptome from L. intermedia revealed that knottins, also known as inhibitor cystine knot peptides, are the most abundant class of toxins expressed in this species. Knottin peptides contain a particular arrangement of intramolecular disulphide bonds, and these peptides typically act upon ion channels or receptors in the insect nervous system, triggering paralysis or other lethal effects. Herein, we focused on a knottin peptide with 53 amino acid residues from L. intermedia venom. The recombinant peptide, named U -sicaritoxin-Li1b (Li1b), was obtained by expression in the periplasm of Escherichia coli. The recombinant peptide induced irreversible flaccid paralysis in sheep blowflies. We screened for knottin-encoding sequences in total RNA extracts from two other Loxosceles species, Loxosceles gaucho and Loxosceles laeta, which revealed that knottin peptides constitute a conserved family of toxins in the Loxosceles genus. The insecticidal activity of U -SCTX-Li1b, together with the large number of knottin peptides encoded in Loxosceles venom glands, suggests that studies of these venoms might facilitate future biotechnological applications of these toxins.

Brown Spider (Loxosceles) Venom Toxins as Potential Biotools for the Development of Novel Therapeutics

“…By studying Loxosceles intermedia venom gland, a cDNA of a 53 amino acid ICK peptide was obtained, heterologously expressed in the periplasm of Escherichia coli , and after purification caused irreversible flaccid paralysis in sheep blowflies. Such ICK peptide is biologically conserved in two other species: L. laeta and L. gaucho [64]. This biological activity of ICK peptides has an important biotechnological significance since it can lead to the development of effective bioinsecticides against pests of economic interest.…”

“…A fraction of L. intermedia containing LiTx1, LiTx2 and LiTx3 proved to be toxic against a lepidopteran larva [7]. A LiTx3 orthologue (Li1b) was heterologously expressed and also showed toxic activity in sheep blowflies [64]. Asterisks indicate conserved cysteine residues and the lines below the alignments indicate the pattern of disulphide bonds that form the inhibitor cystine knot motif [64].…”

Screening and Validation of Highly-Efficient Insecticidal Conotoxins from a Transcriptome-Based Dataset of Chinese Tubular Cone Snail

“…Peptides are a valuable alternative to chemical pesticides for control of insect pests in agriculture because of their high killing efficiency, low pest-specificity and human safety [ 5 , 24 , 29 ]. Reported examples of insecticidal conotoxins include the α-conotoxin ImI from C. imperialis [ 16 ], omega conotoxin GVIA from C. geographus , MVIIC from C. magus , and kappa conotoxin k-PVIIA from C. purpurascen [ 30 , 31 ].…”

Versatile spider venom peptides and their medical and agricultural applications

“…As indicated in table 5, not all novel ISPs immediately induced lethality in the target insects. Some ISPs caused completely reversible paralysis (Herzig et al, 2016;Smith et al, 2017;Sousa et al, 2017), while others caused a long-lasting paralysis that eventually resulted in death by starvation (Ikonomopoulou et al, 2016;Matsubara et al, 2017). And these ISP-induced effects did not only vary between ISPs, but also within ISPs tested across a range of target insect species.…”