TITLE

CSTX-9, a toxic peptide from the spider Cupiennius salei: amino acid sequence, disulphide bridge pattern and comparison with other spider toxins containing the cystine knot structure

AUTHOR(S)
Schaller, J.; Kämpfer, U.; Schürch, S.; Kuhn-Nentwig, L.; Haeberli, S.; Nentwig, W.
PUB. DATE
September 2001
SOURCE
Cellular & Molecular Life Sciences;Sep2001, Vol. 58 Issue 10, p1538
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
CSTX-9 (68 residues, 7530.9 Da) is one of the most abundant toxic polypeptides in the venom of the wandering spider Cupiennius salei. The amino acid sequence was determined by Edman degradation using reduced and alkylated CSTX-9 and peptides generated by cleavages with endoproteinase Asp-N and trypsin, respectively. Sequence comparison with CSTX-1, the most abundant and the most toxic polypeptide in the crude spider venom, revealed a high degree of similarity (53% identity). By means of limited proteolysis with immobilised trypsin and RP-HPLC, the cystine-containing peptides of CSTX-9 were isolated and the disulphide bridges were assigned by amino acid analysis, Edman degradation and nanospray tandem mass spectrometry. The four disulphide bonds present in CSTX-9 are arranged in the following pattern: 1-4, 2-5, 3-8 and 6-7 (Cys6-Cys21, Cys13-Cys30, Cys20-Cys48, Cys32-Cys46). Sequence comparison of CSTX-1 with CSTX-9 clearly indicates the same disulphide bridge pattern, which is also found in other spider polypeptide toxins, e.g. agatoxins (ω-AGA-IVA, ω-AGA-IVB, μ-AGA-I and μ-AGA-VI) from Agelenopsis aperta, SNX-325 from Segestria florentina and curtatoxins (CT-I, CT-II and CT-III) from Hololena curta. CSTX-1/CSTX-9 belong to the family of ion channel toxins containing the inhibitor cystine knot structural motif. CSTX-9, lacking the lysine-rich C-terminal tail of CSTX-1, exhibits a ninefold lower toxicity to Drosophila melanogaster than CSTX-1. This is in accordance with previous observations of CSTX-2a and CSTX-2b, two truncated forms of CSTX-1 which, like CSTX-9, also lack the C-terminal lysine-rich tail.
ACCESSION #
15728260

 

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