Novel Class of Spider Toxin: ACTIVE PRINCIPLE FROM THE YELLOW SAC SPIDER CHEIRACANTHIUM PUNCTORIUM VENOM IS A UNIQUE TWO-DOMAIN POLYPEPTIDE* |
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Authors: | Alexander A Vassilevski Irina M Fedorova Ekaterina E Maleeva Yuliya V Korolkova Svetlana S Efimova Olga V Samsonova Ludmila V Schagina Alexei V Feofanov Lev G Magazanik Eugene V Grishin |
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Institution: | From the ‡M. M. Shemyakin and Yu. A. Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 117997.;the §I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, Saint Petersburg 194223, and ;the ¶Institute of Cytology, Russian Academy of Sciences, Saint Petersburg 194064, Russia |
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Abstract: | 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. |
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Keywords: | Confocal Microscopy Peptide Biosynthesis Protein Chemistry Protein Purification Protein Structure Toxins Electrophysiology Membrane-active Peptide Spider Venom cDNA Sequence |
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