title: Isolation and characterization of Ts19 Fragment II, a new long-chain potassium channel toxin from Tityus serrulatus venom.
abstract: Ts19 Fragment II (Ts19 Frag-II) was first isolated from the venom of the scorpion Tityus serrulatus (Ts). It is a protein presenting 49 amino acid residues, three disulfide bridges, Mr 5534Da and was classified as a new member of class (subfamily) 2 of the β-KTxs, the second one described for Ts scorpion. The β-KTx family is composed by two-domain peptides: N-terminal helical domain (NHD), with cytolytic activity, and a C-terminal CSαβ domain (CCD), with Kv blocking activity. The extensive electrophysiological screening (16 Kv channels and 5 Nav channels) showed that Ts19 Frag-II presents a specific and significant blocking effect on Kv1.2 (IC50 value of 544±32nM). However, no cytolytic activity was observed with this toxin. We conclude that the absence of 9 amino acid residues from the N-terminal sequence (compared to Ts19 Frag-I) is responsible for the absence of cytolytic activity. In order to prove this hypothesis, we synthesized the peptide with these 9 amino acid residues, called Ts19 Frag-III. As expected, Ts19 Frag-III showed to be cytolytic and did not block the Kv1.2 channel. The post-translational modifications of Ts19 and its fragments (I-III) are also discussed here. A mechanism of post-translational processing (post-splitting) is suggested to explain Ts19 fragments production. In addition to the discovery of this new toxin, this report provides further evidence for the existence of several compounds in the scorpion venom contributing to the diversity of the venom arsenal.
authors.affiliation: Department of Physics and Chemistry, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Av. do Café, s/n, 14040-903 Ribeirão Preto, SP, Brazil.
authors.forename: Felipe Augusto
authors.initials: FA
authors.lastname: Cerni
authors.affiliation: Department of Physics and Chemistry, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Av. do Café, s/n, 14040-903 Ribeirão Preto, SP, Brazil.
authors.forename: Manuela Berto
authors.initials: MB
authors.lastname: Pucca
authors.affiliation: Department of Physics and Chemistry, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Av. do Café, s/n, 14040-903 Ribeirão Preto, SP, Brazil.
authors.forename: Fernanda Gobbi
authors.initials: FG
authors.lastname: Amorim
authors.affiliation: Department of Physics and Chemistry, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Av. do Café, s/n, 14040-903 Ribeirão Preto, SP, Brazil.
authors.forename: Karla
authors.initials: K
authors.lastname: de Castro Figueiredo Bordon
authors.affiliation: Laboratory of Mass Spectrometry, Department of Chemistry, University of Liège, Allée de la chimie 6, B6c, B-4000 Liège, Belgium.
authors.forename: Julien
authors.initials: J
authors.lastname: Echterbille
authors.affiliation: Laboratory of Mass Spectrometry, Department of Chemistry, University of Liège, Allée de la chimie 6, B6c, B-4000 Liège, Belgium.
authors.forename: Loïc
authors.initials: L
authors.lastname: Quinton
authors.affiliation: Laboratory of Mass Spectrometry, Department of Chemistry, University of Liège, Allée de la chimie 6, B6c, B-4000 Liège, Belgium.
authors.forename: Edwin
authors.initials: E
authors.lastname: De Pauw
authors.affiliation: Toxicology and Pharmacology, University of Leuven, O&N 2, Herestraat 49, P.O. Box 922, 3000 Leuven, Belgium.
authors.forename: Steve
authors.initials: S
authors.lastname: Peigneur
authors.affiliation: Toxicology and Pharmacology, University of Leuven, O&N 2, Herestraat 49, P.O. Box 922, 3000 Leuven, Belgium.
authors.forename: Jan
authors.initials: J
authors.lastname: Tytgat
authors.affiliation: Department of Physics and Chemistry, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Av. do Café, s/n, 14040-903 Ribeirão Preto, SP, Brazil. Electronic address: ecabraga@fcfrp.usp.br.
authors.forename: Eliane Candiani
authors.initials: EC
authors.lastname: Arantes
mesh_terms: D000818:Animals; D004594:Electrophysiology / Q000379:methods; D004912:Erythrocytes / Q000187:drug effects; D005260:Female; D051663:Kv1.2 Potassium Channel / Q000037:antagonists & inhibitors; D051379:Mice; D009865:Oocytes / Q000187:drug effects; D010455:Peptides / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology*; D026902:Potassium Channel Blockers / Q000737:chemistry / Q000494:pharmacology; D011499:Protein Processing, Post-Translational; D012604:Scorpion Venoms / Q000737:chemistry* / Q000302:isolation & purification; D012605:Scorpions / Q000737:chemistry; D061566:Voltage-Gated Sodium Channels / Q000378:metabolism; D014982:Xenopus laevis
chemical_list: D051663:Kv1.2 Potassium Channel; D010455:Peptides; D026902:Potassium Channel Blockers; D012604:Scorpion Venoms; D061566:Voltage-Gated Sodium Channels; C000614676:tityustoxin-19, Tityus serrulatus
keywords: Electrophysiology; Post-splitting; Potassium channels; Scorpion toxin; Scorpion β-KTxs; Tityus serrulatus