Journal of Biological Chemistry
Volume 285, Issue 42, 15 October 2010, Pages 32293-32302
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Protein Structure and Folding
Novel Class of Spider Toxin: ACTIVE PRINCIPLE FROM THE YELLOW SAC SPIDER CHEIRACANTHIUM PUNCTORIUM VENOM IS A UNIQUE TWO-DOMAIN POLYPEPTIDE*

https://doi.org/10.1074/jbc.M110.104265Get rights and content
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Venom of the yellow sac spider Cheiracanthium punctorium (Miturgidae) was found unique in terms of molecular composition. Its principal toxic component CpTx 1 (15.1 kDa) was purified, and its full amino acid sequence (134 residues) was established by protein chemistry and mass spectrometry techniques. CpTx 1 represents a novel class of spider toxin with modular architecture. It consists of two different yet homologous domains (modules) each containing a putative inhibitor cystine knot motif, characteristic of the widespread single domain spider neurotoxins. Venom gland cDNA sequencing provided precursor protein (prepropeptide) structures of three CpTx 1 isoforms (a–c) that differ by single residue substitutions. The toxin possesses potent insecticidal (paralytic and lethal), cytotoxic, and membrane-damaging activities. In both fly and frog neuromuscular preparations, it causes stable and irreversible depolarization of muscle fibers leading to contracture. This effect appears to be receptor-independent and is inhibited by high concentrations of divalent cations. CpTx 1 lyses cell membranes, as visualized by confocal microscopy, and destabilizes artificial membranes in a manner reminiscent of other membrane-active peptides by causing numerous defects of variable conductance and leading to bilayer rupture. The newly discovered class of modular polypeptides enhances our knowledge of the toxin universe.

Confocal Microscopy
Peptide Biosynthesis
Protein Chemistry
Protein Purification
Protein Structure
Toxins
Electrophysiology
Membrane-active Peptide
Spider Venom
cDNA Sequence

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The protein sequences reported in this paper have been submitted to the UniProt Knowledgebase under accession numbers P86381, P86429, and P86430.

The nucleotide sequence(s) reported in this paper has been submitted to the Gen-BankTM/EBI Data Bank with accession number(s) FN594513 to FN594517.

*

This work was supported by the Federal Agency for Education of the Russian Federation State Contract P1388, the Russian Foundation for Basic Research Grants 08-04-00326, 08-04-00454, and 09-04-00883, the Russian Scientific Schools Grants 4821.2008.4 and 3796.2010.4, and the Program of Cell and Molecular Biology of the Russian Academy of Sciences.