Spider toxins comprising disulfide‐rich and linear amphipathic domains: a new class of molecules identified in the lynx spider Oxyopes takobius

Abstract

In addition to the conventional neurotoxins and cytotoxins, venom of the lynx spider Oxyopes takobius was found to contain two-domain modular toxins named spiderines: OtTx1a, 1b, 2a and 2b. These toxins show both insecticidal activity (a median lethal dose against flesh fly larvae of 75 lgÁg À1) and potent antimicrobial effects (minimal inhibitory concentrations in the range 0.1-10 lM). Full sequences of the purified spiderines were established by a combination of Edman degradation, mass spectrometry and cDNA cloning. They are relatively large molecules (~110 residues, 12.0-12.5 kDa) and consist of two distinct modules separated by a short linker. The N-terminal part (~40 residues) contains no cysteine residues, is highly cationic, forms amphipathic a-helical structures in a membrane-mimicking environment, and shows potent cytolytic effects on cells of various origins. The C-terminal part (~60 residues) is disulfide-rich (five S-S bonds), and contains the inhibitor cystine knot (ICK/knottin) signature. The N-terminal part of spiderines is very similar to linear cytotoxic peptides found in various organisms, whereas the C-terminal part corresponds to the usual spider neurotoxins. We synthesized the modules of OtTx1a and compared their activity to that of full-length mature toxin produced recombinantly, highlighting the importance of the N-terminal part, which retained full-length toxin activity in both insecticidal and antimicrobial assays. The unique structure of spiderines completes the range of two-domain spider toxins. DatabaseThe protein sequences of the spiderines (OtTx) reported in this paper have been submitted to the UniProt Knowledgebase (UniProtKB) under accession numbers P86716-P86719, and the nucleotide sequences encoding OtTx have been submitted to the GenBank under accession numbers JX134894-JX134897.

Latarcins: versatile spider venom peptides

“…[40,41]), or the C-terminus of a disulfide-rich neurotoxin-like domain (as in CsTx-1 from Cupiennius salei [42] and latartoxins from L. tarabaevi [43]). Such molecules display the properties of both toxin groups.…”

Modular toxin from the lynx spider Oxyopes takobius: Structure of spiderine domains in solution and membrane‐mimicking environment

“…The differential membrane activity of the two domains of OtTx1a correlates with our previous results indicating that OtTx1a‐AMP is responsible for the biological activity of the full‐length toxin . We thereby attribute the observed insect toxicity of OtTx1a to its cytolytic activity, which in turn is due to its membrane‐damaging capacity with OtTx1a‐AMP acting as an efficient membrane anchor.…”

“…OtTx1a‐AMP was produced using solid‐phase peptide synthesis as described . Briefly, a peptide synthesizer Syro I (MultiSynTech) was used, and methods adhered to the Fmoc/ t ‐butyl chemistry.…”

“…A variety of spider toxins including purotoxin‐2 (PT2) from Alopecosa marikovskyi , latartoxins (LtTx) from L. tarabaevi , and CsTx1 from Cupiennius salei comprise both a “neurotoxin” ICK motif and C‐terminal extension alike linear cytotoxins. Finally, OtTx or spiderines from Oxyopes takobius venom show a “reversed” architecture with a long N‐terminal disulfide‐free part and C‐terminally located ICK …”

Insights into Antimicrobial Peptides from Spiders and Scorpions

“…During 2011 and 2012, oh-defensin and juruin were also established to have three disulfide bonds [24, 25]. There are even more disulfide bonds in LtTx-1a (four S-S bonds) and OtTx1a (five S-S bonds) [26, 27]. In addition, five glycine-rich AMPs were discovered from spiders in 2003 and 2010, respectively [28, 29].…”