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PhcrTx2, a New Crab-Paralyzing Peptide Toxin from the Sea Anemone Phymanthus crucifer

  • Rodriguez, Armando Alexei;
  • Garateix, Anoland;
  • Salceda, Emilio;
  • Peigneur, Steve; 56122;
  • Zaharenko, Andre Junqueira;
  • Pons, Tirso;
  • Santos, Yulica;
  • Arreguin, Roberto;
  • Staendker, Ludger;
  • Forssmann, Wolf-Georg;
  • Tytgat, Jan; 18354;
  • Vega, Rosario;
  • Soto, Enrique;
Publication Date
Feb 01, 2018
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Sea anemones produce proteinaceous toxins for predation and defense, including peptide toxins that act on a large variety of ion channels of pharmacological and biomedical interest. Phymanthus crucifer is commonly found in the Caribbean Sea; however, the chemical structure and biological activity of its toxins remain unknown, with the exception of PhcrTx1, an acid-sensing ion channel (ASIC) inhibitor. Therefore, in the present work, we focused on the isolation and characterization of new P. crucifer toxins by chromatographic fractionation, followed by a toxicity screening on crabs, an evaluation of ion channels, and sequence analysis. Five groups of toxic chromatographic fractions were found, and a new paralyzing toxin was purified and named PhcrTx2. The toxin inhibited glutamate-gated currents in snail neurons (maximum inhibition of 35%, IC50 4.7 µM), and displayed little or no influence on voltage-sensitive sodium/potassium channels in snail and rat dorsal root ganglion (DRG) neurons, nor on a variety of cloned voltage-gated ion channels. The toxin sequence was fully elucidated by Edman degradation. PhcrTx2 is a new β-defensin-fold peptide that shares a sequence similarity to type 3 potassium channels toxins. However, its low activity on the evaluated ion channels suggests that its molecular target remains unknown. PhcrTx2 is the first known paralyzing toxin in the family Phymanthidae. / status: published

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