Peptides from the Sea Anemone Metridium senile with Modified Inhibitor Cystine Knot (ICK) Fold Inhibit Nicotinic Acetylcholine Receptors

Toxins (Basel). 2022 Dec 30;15(1):28. doi: 10.3390/toxins15010028.

Abstract

Nicotinic acetylcholine receptors (nAChRs) play an important role in the functioning of the central and peripheral nervous systems, and other organs of living creatures. There are several subtypes of nAChRs, and almost all of them are considered as pharmacological targets in different pathological states. The crude venom of the sea anemone Metridium senile showed the ability to interact with nAChRs. Four novel peptides (Ms11a-1-Ms11a-4) with nAChR binding activity were isolated. These peptides stabilized by three disulfide bridges have no noticeable homology with any known peptides. Ms11a-1-Ms11a-4 showed different binding activity towards the muscle-type nAChR from the Torpedo californica ray. The study of functional activity and selectivity for the most potent peptide (Ms11a-3) revealed the highest antagonism towards the heterologous rat α9α10 nAChR compared to the muscle and α7 receptors. Structural NMR analysis of two toxins (Ms11a-2 and Ms11a-3) showed that they belong to a new variant of the inhibitor cystine knot (ICK) fold but have a prolonged loop between the fifth and sixth cysteine residues. Peptides Ms11a-1-Ms11a-4 could represent new pharmacological tools since they have structures different from other known nAChRs inhibitors.

Keywords: ICK fold peptides; Metridium senile; NMR structure; electrophysiology; nicotinic acetylcholine receptors; radioligand assay; sea anemone venom.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cystine
  • Nicotinic Antagonists* / chemistry
  • Nicotinic Antagonists* / isolation & purification
  • Nicotinic Antagonists* / pharmacology
  • Peptides* / chemistry
  • Peptides* / isolation & purification
  • Peptides* / pharmacology
  • Rats
  • Receptors, Nicotinic* / metabolism
  • Sea Anemones* / chemistry

Substances

  • Cystine
  • Nicotinic Antagonists
  • Peptides
  • Receptors, Nicotinic

Grants and funding

This work was supported by RFBR grant # 20-04-00761 and The Norwegian Research Council # 208546. Electrophysiological experiments were supported by Guangxi Science and Technology Base & Talents Fund (GUIKE AD22035948). NMR analysis of peptide structures was supported by the Russian Science Foundation grant #19-74-30014.