Characterization of ion channels on subesophageal ganglion neurons from Chinese tarantula Ornithoctonus huwena: Exploring the myth of the spider insensitive to its venom.

Chinese tarantula Ornithoctonus huwena is one of the most venomous spiders distributing in the hilly areas of southern China. In this study, using whole-cell patch-clamp technique we investigated electrophysiological and pharmacological properties of ion channels from tarantula subesophageal ganglion neurons. It was found that the neurons express multiple kinds of ion channels at least including voltage-gated calcium channels, TTX-sensitive sodium channels and two types of potassium channels.

Mapping the interaction site for the tarantula toxin hainantoxin-IV (β-TRTX-Hn2a) in the voltage sensor module of domain II of voltage-gated sodium channels.

Peptide toxins often have pharmacological applications and are powerful tools for investigating the structure-function relationships of voltage-gated sodium channels (VGSCs). Although a group of potential VGSC inhibitors have been reported from tarantula venoms, little is known about the mechanism of their interaction with VGSCs. In this study, we showed that hainantoxin-IV (β-TRTX-Hn2a, HNTX-IV in brief), a 35-residue peptide from Ornithoctonus hainana venom, preferentially inhibited rNav1.

Screening for voltage-gated sodium channel interacting peptides.

The voltage-gated sodium channel (VGSC) interacting peptide is of special interest for both basic research and pharmaceutical purposes. In this study, we established a yeast-two-hybrid based strategy to detect the interaction(s) between neurotoxic peptide and the extracellular region of VGSC. Using a previously reported neurotoxin JZTX-III as a model molecule, we demonstrated that the interactions between JZTX-III and the extracellular regions of its target hNav1.

Structure and function of hainantoxin-III, a selective antagonist of neuronal tetrodotoxin-sensitive voltage-gated sodium channels isolated from the Chinese bird spider Ornithoctonus hainana.

In the present study, we investigated the structure and function of hainantoxin-III (HNTX-III), a 33-residue polypeptide from the venom of the spider Ornithoctonus hainana. It is a selective antagonist of neuronal tetrodotoxin-sensitive voltage-gated sodium channels. HNTX-III suppressed Nav1.

Functional expression of spider neurotoxic peptide huwentoxin-I in E. coli.

The coding sequence of huwentoxin-I, a neurotoxic peptide isolated from the venom of the Chinese spider Ornithoctonus huwena, was amplified by PCR using the cDNA library constructed from the spider venom glands. The cloned fragment was inserted into the expression vector pET-40b and transformed into the E. coli strain BL21 (DE3).

Molecular basis of the tarantula toxin jingzhaotoxin-III (β-TRTX-Cj1α) interacting with voltage sensors in sodium channel subtype Nav1.5.

With conserved structural scaffold and divergent electrophysiological functions, animal toxins are considered powerful tools for investigating the basic structure-function relationship of voltage-gated sodium channels. Jingzhaotoxin-III (β-TRTX-Cj1α) is a unique sodium channel gating modifier from the tarantula Chilobrachys jingzhao, because the toxin can selectively inhibit the activation of cardiac sodium channel but not neuronal subtypes. However, the molecular basis of JZTX-III interaction with sodium channels remains unknown.

Jingzhaotoxin-IX, a novel gating modifier of both sodium and potassium channels from Chinese tarantula Chilobrachys jingzhao.

Tarantula Chilobrachys jingzhao is one of the most venomous species distributed in China. In this study, we have isolated and characterized a novel neurotoxin named Jingzhaotoxin-IX (JZTX-IX) from the venom of the tarantula. JZTX-IX is a C-terminally amidated peptide composed of 35 amino acid residues.