A novel strategy for the identification of toxinlike structures in spider venom

Abstract

We compared two different approaches to sequence information analysis from the expressed sequence tag (EST) library constructed for the venom glands of the spider Agelena orientalis. Some results were more illustrative and reliable by the contig analysis technique, whereas our novel method, with specific structural markers introduced for protein structure detection, allowed us to overcome some limitations of the contig analysis. A novel technique was suggested for the identification in data banks of the spider's ion channel inhibitor toxins using primary structure features common to all spiders. Analysis of about 150 polypeptides made it possible to introduce 3 primary structure motifs for spider toxins: the Principal Structural Motif (PSM), which postulates the existence of 6 amino acid residues between the first and second cysteine residue and the Cys-Cys sequence at a distance of 5-10 amino acid residues from the second cysteine; the Extra Structural Motif (ESM), which postulates the existence of a pair of CXC fragments in the C-region; and the Processing Quadruplet Motif (PQM), which specifies the Arg residue at position -1 and Glu residues at positions -2, -3, and/or -4 in the precursor sequences just before the postprocessing site. In the processed data bank we found 48 toxinlike structures with ion channel inhibitor motifs. These include agelenin earlier isolated from Agelena opulenta and 25 more homologous sequences, 15 homologs of mu-agatoxin 2 from the spider Agelenopsis aperta, 3 structures with low homology to omega-agatoxin-IIIA, and 4 new structures. Also we showed that toxinlike structures exceed two thirds of the overall database sequences.

Variability of Potassium Channel Blockers in Mesobuthus eupeus Scorpion Venom with Focus on Kv1.1

“…cDNA Library Construction and Analysis-All stages of cDNA library construction were completed in collaboration with DuPont Agriculture and Nutrition as described earlier (30). Briefly, venom glands of M. eupeus were harvested, homogenized, and lysed by TRIzol (Life Technologies).…”

“…-A raw cDNA library from the lesser Asian scorpion Mesobuthus eupeus (Buthidae) venom glands was obtained using a conventional approach (30). The total number of cDNA sequences in the database was 1911, and the number of corresponding putative peptide sequences was 11,466 (translation was performed in three frames, both direct and reverse).…”

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

“…This signature may be reduced to the more general principal structural motif CX 6 CX n CC (C 1 X 6 C 2 X 5 C 4 C 5 in our case), and extra structural motif CXCX n CXC (C 6 XC 7 X m C 8 XC 9 in our case) that are characteristic of spider neurotoxins [23]. The principal structural motif and the extra structural motif in turn conform to the more general ICK motif CX 2-7 CX 3-11 CX 0-7 CX 1-17 CX [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] …”

“…We then performed library analysis in accordance with a previously described strategy that included searches for structural elements and motifs specific for secreted polypeptide sequences and spider toxins [23][24][25]. As a result, putative spider toxin sequences were deduced.…”

“…This motif is known to indicate the processing cleavage site in precursors of spider toxins and separate the prosequence from the mature chain [23]. It may be represented as X 1 X 2 X 3 R, where X n = E, and R is the functionally important arginine residue: cleavage occurs at its carbonyl group.…”