title: Target promiscuity and heterogeneous effects of tarantula venom peptides affecting Na+ and K+ ion channels.
abstract: Venom-derived peptide modulators of ion channel gating are regarded as essential tools for understanding the molecular motions that occur during the opening and closing of ion channels. In this study, we present the characterization of five spider toxins on 12 human voltage-gated ion channels, following observations about the target promiscuity of some spider toxins and the ongoing revision of their "canonical" gating-modifying mode of action. The peptides were purified de novo from the venom of Grammostola rosea tarantulas, and their sequences were confirmed by Edman degradation and mass spectrometry analysis. Their effects on seven tetrodotoxin-sensitive Na(+) channels, the three human ether-à-go-go (hERG)-related K(+) channels, and two human Shaker-related K(+) channels were extensively characterized by electrophysiological techniques. All the peptides inhibited ion conduction through all the Na(+) channels tested, although with distinctive patterns. The peptides also affected the three pharmaceutically relevant hERG isoforms differently. At higher concentrations, all peptides also modified the gating of the Na(+) channels by shifting the activation to more positive potentials, whereas more complex effects were recorded on hERG channels. No effects were evident on the two Shaker-related K(+) channels at concentrations well above the IC(50) value for the affected channels. Given the sequence diversity of the tested peptides, we propose that tarantula toxins should be considered both as multimode and target-promiscuous ion channel modulators; both features should not be ignored when extracting mechanistic interpretations about ion channel gating. Our observations could also aid in future structure-function studies and might help the development of novel ion channel-specific drugs.
authors: From the Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, 20126 Milan, Italy.
authors: Elisa
authors: E
authors: Redaelli
authors: From the Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, 20126 Milan, Italy; the Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca 62210, México.
authors: Rita Restano
authors: RR
authors: Cassulini
authors: the Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior s/n, Ciudad Universitaria, Coyoacán DF 04510, México.
authors: Deyanira Fuentes
authors: DF
authors: Silva
authors: the Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca 62210, México.
authors: Herlinda
authors: H
authors: Clement
authors: From the Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, 20126 Milan, Italy.
authors: Emanuele
authors: E
authors: Schiavon
authors: the Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca 62210, México.
authors: Fernando Z
authors: FZ
authors: Zamudio
authors: the Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca 62210, México.
authors: George
authors: G
authors: Odell
authors: the Dipartimento di Patologia e Oncologia Sperimentali, Università di Firenze, Viale Morgagni 50, 50134 Firenze, Italy.
authors: Annarosa
authors: A
authors: Arcangeli
authors: Gene Expression and Protein Biochemistry, GlaxoSmithKline, Medicines Research Centre, Gunnels Wood Road, Stevenage, Herts SG1 2NY, United Kingdom, and.
authors: Jeffrey J
authors: JJ
authors: Clare
authors: the Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca 62210, México.
authors: Alejandro
authors: A
authors: Alagón
authors: the Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca 62210, México; the Structural and Computational Biology/Genome Biology Units, European Molecular Biology Laboratory, Meyerhofstrasse 1, Heidelberg 69117, Germany.
authors: Ricardo C Rodríguez
authors: RCR
authors: de la Vega
authors: the Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca 62210, México.
authors: Lourival D
authors: LD
authors: Possani
authors: From the Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, 20126 Milan, Italy. Electronic address: enzo.wanke@unimib.it.
authors: Enzo
authors: E
authors: Wanke
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D002851:Chromatography, High Pressure Liquid; D006224:Cricetinae; D003412:Cricetulus; D051638:Ether-A-Go-Go Potassium Channels / Q000235:genetics / Q000502:physiology; D006801:Humans; D015640:Ion Channel Gating / Q000187:drug effects*; D013058:Mass Spectrometry; D008564:Membrane Potentials / Q000187:drug effects; D008969:Molecular Sequence Data; D018408:Patch-Clamp Techniques; D010455:Peptides / Q000737:chemistry / Q000494:pharmacology; D026902:Potassium Channel Blockers / Q000494:pharmacology; D015221:Potassium Channels / Q000235:genetics / Q000502:physiology*; D020539:Sequence Analysis, Protein / Q000379:methods; D051637:Shaker Superfamily of Potassium Channels / Q000235:genetics / Q000502:physiology; D026941:Sodium Channel Blockers / Q000494:pharmacology; D015222:Sodium Channels / Q000235:genetics / Q000502:physiology*; D013111:Spider Venoms / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D051638:Ether-A-Go-Go Potassium Channels; C496884:KCNH1 protein, human; D010455:Peptides; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D051637:Shaker Superfamily of Potassium Channels; D026941:Sodium Channel Blockers; D015222:Sodium Channels; D013111:Spider Venoms