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

Core Facility Functional Peptidomics, Ulm University Medical Center, Albert-Einstein-Allee 47, 89081 Ulm, Germany
Department of Experimental and Clinical Peptide Chemistry, Hannover Medical School (MHH), Feodor-Lynen-Straße 31, D-30625 Hannover, Germany
Centro de Bioproductos Marinos (CEBIMAR), Loma y 37, Alturas del Vedado, Habana CP 10600, Cuba
Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, 14 sur 6301, CU, San Manuel, Puebla CP 72750, Mexico
Toxicology & Pharmacology, University of Leuven (KU Leuven), Campus Gasthuisberg O&N2, Herestraat 49, P.O. Box 922, 3000 Leuven, Belgium
Laboratory of Genetics, Butantan Institute, São Paulo 05503-900, Brazil
Centro Nacional de Biotecnología (CNB-CSIC), Departamento de Inmunología y Oncología, C/Darwin 3, Campus de Cantoblanco, 28049 Madrid, Spain
Department of Plant Pathology, Citrus Research and Education Center, University of Florida, Lake Alfred, FL 33850, USA
Instituto de Química, Universidad Nacional Autónoma de México, Delegación Coyoacán, Ciudad de México 04510, Mexico
Author to whom correspondence should be addressed.
Toxins 2018, 10(2), 72;
Received: 22 January 2018 / Revised: 1 February 2018 / Accepted: 2 February 2018 / Published: 7 February 2018
(This article belongs to the Section Animal Venoms)
PDF [3323 KB, uploaded 7 February 2018]


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. View Full-Text
Keywords: sea anemone; neutoxin; glutamate receptor; defensin-like fold; ion channels; Phymanthus crucifer sea anemone; neutoxin; glutamate receptor; defensin-like fold; ion channels; Phymanthus crucifer

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Rodríguez, A.A.; Garateix, A.; Salceda, E.; Peigneur, S.; Zaharenko, A.J.; Pons, T.; Santos, Y.; Arreguín, R.; Ständker, L.; Forssmann, W.-G.; Tytgat, J.; Vega, R.; Soto, E. PhcrTx2, a New Crab-Paralyzing Peptide Toxin from the Sea Anemone Phymanthus crucifer. Toxins 2018, 10, 72.

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