Investigation of the relationship between the structure and function of Ts2, a neurotoxin from Tityus serrulatus venom

Abstract

Scorpion toxins targeting voltage-gated sodium (Na V ) channels are peptides that comprise 60-76 amino acid residues cross-linked by four disulfide bridges. These toxins can be divided in two groups (a and b toxins), according to their binding properties and mode of action. The scorpion a-toxin Ts2, previously described as a b-toxin, was purified from the venom of Tityus serrulatus, the most dangerous Brazilian scorpion. In this study, seven mammalian Na V channel isoforms (rNa V 1.2, rNa V 1.3, rNa V 1.4, hNa V 1.5, mNa V 1.6, rNa V 1.7 and rNa V 1.8) and one insect Na V channel isoform (DmNa V 1) were used to investigate the subtype specificity and selectivity of Ts2. The electrophysiology assays showed that Ts2 inhibits rapid inactivation of Na V 1.2, Na V 1.3, Na V 1.5, Na V 1.6 and Na V 1.7, but does not affect Na V 1.4, Na V 1.8 or DmNa V 1. Interestingly, Ts2 significantly shifts the voltage dependence of activation of Na V 1.3 channels. The 3D structure of this toxin was modeled based on the high sequence identity (72%) shared with Ts1, another T. serrulatus toxin. The overall fold of the Ts2 model consists of three b-strands and one a-helix, and is arranged in a triangular shape forming a cysteine-stabilized a-helix ⁄ b-sheet (CSab) motif. DatabaseModel data are available in the PMDB under accession number PM0077533.

Electrophysiological characterization of the first Tityus serrulatus alpha-like toxin, Ts5: Evidence of a pro-inflammatory toxin on macrophages

“…Moreover, Ts5 presented electrophysiological results very similar to the Ts alpha-toxin Ts2 except on Nav1.4 and DmNav1 channels [30]. Indeed, Ts5 presents the highest identity with Ts2 compared with Ts1 (see Fig.…”

“…This concentration was previously used for electrophysiological characterization of other toxins [22,30]. Immediately after adding the toxin in the chamber containing the oocyte, the bath solution was mixed to obtain a homogenous final concentration within few seconds.…”

Scorpion toxin peptide action at the ion channel subunit level

“…Inhibit current (32%), Rat, mM, (Peigneur et al, 2015) HEK293, 100 nM, (Peigneur et al, 2015) HEK293, 100 nM, (Peigneur et al, 2015) inhibit current, Rat, HEK293, 100 nM, (Peigneur et al, 2015) ( Peigneur et al, 2015) HEK293, 100 nM, (Peigneur et al, 2015) Ts2 Tityus serrulatus Inhibit rapid inactivation, Rat, Xenopus oocytes, 1 mM, (Cologna et al, 2012) Inhibit rapid inactivation and hyperpolarisation of activation threshold, Rat, Xenopus oocytes, 1 mM, (Cologna et al, 2012) Inhibit rapid inactivation, Human, Xenopus oocytes, 1 mM, (Cologna et al, 2012) Inhibit rapid inactivation, Mouse, Xenopus oocytes, 1 mM, (Cologna et al, 2012) Inhibit rapid inactivation, Rat, Xenopus oocytes, 1 mM, (Cologna et al, 2012) Ts4 Hyperpolarisation of activation threshold, Human, HEK293, 500 nM, (Coronas et al, 2015) Inhibit current, Human, HEK293, 500 nM, (Coronas et al, 2015) Inhibit current, Human, HEK293, 500 nM, (Coronas et al, 2015) Tz1 Tityus zulianus Hyperpolarisation of activation threshold, HEK293, 10 mM, (Leipold et al, 2006) Hyperpolarisation of activation threshold, HEK293, (Leipold et al, 2006); Hyperpolarisation of activation threshold, Rat, HEK293, EC 50 ¼ 3.5 mM, (Borges et al, 2004) Hyperpolarisation of activation threshold, HEK293, 10 mM, (Leipold et al, 2006) Note: Data represented sequentially as: Action, channel species origin for recombinant expression (if reported), expression system, concentration, reference. (Garcia et al, 1994) Inhibit current, Rat, Xenopus oocytes, Ki ¼ 136 nM, (Garcia et al, 1994) Inhibit current, Rat, Xenopus oocytes, Ki ¼ 1.3 nM, (Garcia et al, 1994) Inhibit current, Xenopus oocytes, Ki ¼ 149 nM, (Garcia et al, 1994) Agitoxin 2 (AgTX 2)…”

A peçonha do escorpião Tityus serrulatus é reconhecida por receptores de reconhecimento padrão e induz ativação celular e inflamação

“…O simples contato da ponta de metal na membrana entre os dois últimos segmentos do télson do escorpião, estimula a liberação da peçonha pelo aguilhão (Figura 2). A peçonha é opalescente, com aspecto leitoso e constituída por uma mistura complexa de muco, componentes de baixo peso molecular (aminoácidos, sais e compostos orgânicos) e muitas proteínas básicas neurotóxicas (MULLER, 1993;GWEE et al, 2002;COLOGNA et al, 2009 Escorpiões: biologia, envenenamento e mecnismos de ação de suas toxinas .…”

“…Ts2 é uma α-neurotoxina que inibe a inativação rápida dos subtipos dos canais de sódio NaV1.2, NaV1.3, NaV1.5, NaV1.6 e NaV1.7, mas não afeta NaV1.4, NaV1.8 ou DmNaV1 (COLOGNA et al, 2012).…”