New Insights into the Type II Toxins from the Sea Anemone Heteractis crispa

Toxins (Basel). 2020 Jan 10;12(1):44. doi: 10.3390/toxins12010044.

Abstract

Toxins modulating NaV channels are the most abundant and studied peptide components of sea anemone venom. Three type-II toxins, δ-SHTX-Hcr1f (= RpII), RTX-III, and RTX-VI, were isolated from the sea anemone Heteractis crispa. RTX-VI has been found to be an unusual analog of RTX-III. The electrophysiological effects of Heteractis toxins on nine NaV subtypes were investigated for the first time. Heteractis toxins mainly affect the inactivation of the mammalian NaV channels expressed in the central nervous system (NaV1.1-NaV1.3, NaV1.6) as well as insect and arachnid channels (BgNaV1, VdNaV1). The absence of Arg13 in the RTX-VI structure does not prevent toxin binding with the channel but it has changed its pharmacological profile and potency. According to computer modeling data, the δ-SHTX-Hcr1f binds within the extracellular region of the rNaV1.2 voltage-sensing domain IV and pore-forming domain I through a network of strong interactions, and an additional fixation of the toxin at the channel binding site is carried out through the phospholipid environment. Our data suggest that Heteractis toxins could be used as molecular tools for NaV channel studies or insecticides rather than as pharmacological agents.

Keywords: electrophysiology; sea anemone; type II toxins; voltage-gated sodium channels.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Binding Sites
  • Cell Line
  • Cnidarian Venoms / chemistry
  • Cnidarian Venoms / toxicity*
  • Ion Channel Gating
  • Peptides
  • Sea Anemones
  • Sodium Channels
  • Structure-Activity Relationship
  • Toxins, Biological

Substances

  • Cnidarian Venoms
  • Peptides
  • Sodium Channels
  • Toxins, Biological
  • toxin III (Anemonia sulcata)