New Insectotoxin from Tibellus Oblongus Spider Venom Presents Novel Adaptation of ICK Fold

• Main Authors: Yuliya Korolkova, Ekaterina Maleeva, Alexander Mikov, Anna Lobas, Elizaveta Solovyeva, Mikhail Gorshkov, Yaroslav Andreev, Steve Peigneur, Jan Tytgat, Fedor Kornilov, Vladislav Lushpa, Konstantin Mineev, Sergey Kozlov
• Format: Article
• Language: English
• Published: MDPI AG 2021-01-01
• Series: Toxins
• Subjects: spider venom; transcriptome; proteome; insectotoxin; ICK fold; NMR structure
• Online Access: https://www.mdpi.com/2072-6651/13/1/29

The <i>Tibellus oblongus </i>spider is an active predator that does not spin webs and remains poorly investigated in terms of venom composition. Here, we present a new toxin, named Tbo-IT2, predicted by cDNA analysis of venom glands transcriptome. The presence of Tbo-IT2 in the venom was confirmed by proteomic analyses using the LC-MS and MS/MS techniques. The distinctive features of Tbo-IT2 are the low similarity of primary structure with known animal toxins and the unusual motif of 10 cysteine residues distribution. Recombinant Tbo-IT2 (rTbo-IT2), produced in <i>E. coli</i> using the thioredoxin fusion protein strategy, was structurally and functionally studied. rTbo-IT2 showed insecticidal activity on larvae of the housefly <i>Musca domestica</i> (LD₁₀₀ 200 μg/g) and no activity on the panel of expressed neuronal receptors and ion channels. The spatial structure of the peptide was determined in a water solution by NMR spectroscopy. The Tbo-IT2 structure is a new example of evolutionary adaptation of a well-known inhibitor cystine knot (ICK) fold to 5 disulfide bonds configuration, which determines additional conformational stability and gives opportunities for insectotoxicity and probably some other interesting features.