title: A novel sea anemone peptide that inhibits acid-sensing ion channels.
abstract: Sea anemones produce ion channels peptide toxins of pharmacological and biomedical interest. However, peptides acting on ligand-gated ion channels, including acid-sensing ion channel (ASIC) toxins, remain poorly explored. PhcrTx1 is the first compound characterized from the sea anemone Phymanthus crucifer, and it constitutes a novel ASIC inhibitor. This peptide was purified by gel filtration, ion-exchange and reversed-phase chromatography followed by biological evaluation on ion channels of isolated rat dorsal root ganglia (DRG) neurons using patch clamp techniques. PhcrTx1 partially inhibited ASIC currents (IC50∼100 nM), and also voltage-gated K(+) currents but the effects on the peak and on the steady state currents were lower than 20% in DRG neurons, at concentrations in the micromolar range. No significant effect was observed on Na(+) voltage-gated currents in DRG neurons. The N-terminal sequencing yielded 32 amino acid residues, with a molecular mass of 3477 Da by mass spectrometry. No sequence identity to other sea anemone peptides was found. Interestingly, the bioinformatic analysis of Cys-pattern and secondary structure arrangement suggested that this peptide presents an Inhibitor Cystine Knot (ICK) scaffold, which has been found in other venomous organisms such as spider, scorpions and cone snails. Our results show that PhcrTx1 represents the first member of a new structural group of sea anemones toxins acting on ASIC and, with much lower potency, on Kv channels. Moreover, this is the first report of an ICK peptide in cnidarians, suggesting that the occurrence of this motif in venomous animals is more ancient than expected.
authors.affiliation: Centro de Bioproductos Marinos (CEBIMAR), Loma y 37, Alturas del Vedado, CP 10400 Habana, Cuba. Electronic address: armando@cebimar.cu.
authors.forename: Armando Alexei
authors.initials: AA
authors.lastname: Rodríguez
authors.affiliation: Instituto de Fisiología, Universidad Autónoma de Puebla, 14 sur 6301, CU, San Manuel, Puebla, Puebla CP 72750, Mexico. Electronic address: emilio.salceda@gmail.com.
authors.forename: Emilio
authors.initials: E
authors.lastname: Salceda
authors.affiliation: Centro de Bioproductos Marinos (CEBIMAR), Loma y 37, Alturas del Vedado, CP 10400 Habana, Cuba. Electronic address: agarateix@gmail.com.
authors.forename: Anoland Georgina
authors.initials: AG
authors.lastname: Garateix
authors.affiliation: Laboratory of Genetics, Butantan Institute, São Paulo 05503-900, Brazil. Electronic address: a.j.zaharenko@ig.com.br.
authors.forename: André Junqueira
authors.initials: AJ
authors.lastname: Zaharenko
authors.affiliation: Laboratory of Toxicology, University of Leuven (KU Leuven), Campus Gasthuisberg O&N2, Herestraat 49, P.O. Box 922, 3000 Leuven, Belgium. Electronic address: Steve.Peigneur@pharm.kuleuven.be.
authors.forename: Steve
authors.initials: S
authors.lastname: Peigneur
authors.affiliation: Instituto de Fisiología, Universidad Autónoma de Puebla, 14 sur 6301, CU, San Manuel, Puebla, Puebla CP 72750, Mexico. Electronic address: omar.lpz.r@gmail.com.
authors.forename: Omar
authors.initials: O
authors.lastname: López
authors.affiliation: Centro Nacional de Investigaciones Oncológicas (CNIO), C/ Melchor Fernández Almagro 3, 28029 Madrid, Spain. Electronic address: tirsopons@gmail.com.
authors.forename: Tirso
authors.initials: T
authors.lastname: Pons
authors.affiliation: Fundação Ezequiel Dias-FUNED, Rua Conde Pereira Carneiro 80, CEP 30510-010 Belo Horizonte, MG, Brazil. Electronic address: mmikeana@yahoo.com.br.
authors.forename: Michael
authors.initials: M
authors.lastname: Richardson
authors.affiliation: Centro de Bioproductos Marinos (CEBIMAR), Loma y 37, Alturas del Vedado, CP 10400 Habana, Cuba. Electronic address: maylin.diaz60@yahoo.com.
authors.forename: Maylín
authors.initials: M
authors.lastname: Díaz
authors.affiliation: Centro de Bioproductos Marinos (CEBIMAR), Loma y 37, Alturas del Vedado, CP 10400 Habana, Cuba. Electronic address: yasnay@cebimar.cu.
authors.forename: Yasnay
authors.initials: Y
authors.lastname: Hernández
authors.affiliation: Kompetenzzentrum Ulm Peptide Pharmaceuticals (U-PEP), Universität Ulm (West), Albert-Einstein Allee 47, 89081 Ulm, Germany. Electronic address: l.standker@gmx.de.
authors.forename: Ludger
authors.initials: L
authors.lastname: Ständker
authors.affiliation: Laboratory of Toxicology, University of Leuven (KU Leuven), Campus Gasthuisberg O&N2, Herestraat 49, P.O. Box 922, 3000 Leuven, Belgium. Electronic address: Jan.Tytgat@pharm.kuleuven.be.
authors.forename: Jan
authors.initials: J
authors.lastname: Tytgat
authors.affiliation: Instituto de Fisiología, Universidad Autónoma de Puebla, 14 sur 6301, CU, San Manuel, Puebla, Puebla CP 72750, Mexico. Electronic address: esoto24@gmail.com.
authors.forename: Enrique
authors.initials: E
authors.lastname: Soto
mesh_terms: D062565:Acid Sensing Ion Channels / Q000378:metabolism*; D000818:Animals; D002478:Cells, Cultured; D005260:Female; D005727:Ganglia, Spinal / Q000166:cytology; D008297:Male; D009474:Neurons / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D051381:Rats; D012615:Sea Anemones / Q000378:metabolism*
chemical_list: D062565:Acid Sensing Ion Channels
keywords: ASIC; Animal venom; Inhibitor Cystine Knot; Ion channel; Sea anemone; Toxin