Structure of acrorhagin I from the sea anemone Actinia equina

Experimental Data Snapshot

  • Method: SOLUTION NMR
  • Conformers Calculated: 100 
  • Conformers Submitted: 20 
  • Selection Criteria: structures with the lowest energy 

wwPDB Validation   3D Report Full Report

This is version 1.2 of the entry. See complete history


A disulfide-stabilised helical hairpin fold in acrorhagin I: An emerging structural motif in peptide toxins.

Krishnarjuna, B.Sunanda, P.Villegas-Moreno, J.Csoti, A.A V Morales, R.Wai, D.C.C.Panyi, G.Prentis, P.Norton, R.S.

(2020) J Struct Biol 213: 107692-107692

  • DOI: https://doi.org/10.1016/j.jsb.2020.107692
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    Acrorhagin I (U-AITX-Aeq5a) is a disulfide-rich peptide identified in the aggressive organs (acrorhagi) of the sea anemone Actinia equina. Previous studies (Toxicon 2005, 46:768-74) found that the peptide is toxic in crabs, although the structural and functional properties of acrorhagin I have not been reported. In this work, an Escherichia coli (BL21 strain) expression system was established for the preparation of 13 C, 15 N-labelled acrorhagin I, and the solution structure was determined using NMR spectroscopy. Structurally, acrorhagin I is similar to B-IV toxin from the marine worm Cerebratulus lacteus (PDB id 1VIB), with a well-defined helical hairpin structure stabilised by four intramolecular disulfide bonds. The recombinant peptide was tested in patch-clamp electrophysiology assays against voltage-gated potassium and sodium channels, and in bacterial and fungal growth inhibitory assays and haemolytic assays. Acrorhagin I was not active against any of the ion channels tested and showed no activity in functional assays, indicating that this peptide may possess a different biological function. Metal ion interaction studies using NMR spectroscopy showed that acrorhagin I bound zinc and nickel, suggesting that its function might be modulated by metal ions or that it may be involved in regulating metal ion levels and their transport. The similarity between the structure of acrorhagin I and that of B-IV toxin from a marine worm suggests that this fold may prove to be a recurring motif in disulfide-rich peptides from marine organisms.

  • Organizational Affiliation

    Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
U-actitoxin-Aeq5a50Actinia equinaMutation(s): 0 
Find proteins for Q3C258 (Actinia equina)
Explore Q3C258 
Go to UniProtKB:  Q3C258
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ3C258
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: SOLUTION NMR
  • Conformers Calculated: 100 
  • Conformers Submitted: 20 
  • Selection Criteria: structures with the lowest energy 

Structure Validation

View Full Validation Report

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2020-11-18
    Type: Initial release
  • Version 1.1: 2021-06-02
    Changes: Database references
  • Version 1.2: 2023-06-14
    Changes: Database references, Other