Mu-conotoxin KIIIA isomer 2

  • Classification: TOXIN
  • Organism(s): Conus kinoshitai
  • Mutation(s): Yes 

  • Deposited: 2021-09-23 Released: 2022-05-25 
  • Deposition Author(s): Schroeder, C.I., Tran, H.N.T.
  • Funding Organization(s): National Health and Medical Research Council (NHMRC, Australia), Australian Research Council (ARC)

Experimental Data Snapshot

  • Method: SOLUTION NMR
  • Conformers Calculated: 50 
  • Conformers Submitted: 20 
  • Selection Criteria: structures with the lowest energy 

wwPDB Validation   3D Report Full Report

This is version 1.1 of the entry. See complete history


Structural and functional insights into the inhibition of human voltage-gated sodium channels by mu-conotoxin KIIIA disulfide isomers.

Tran, H.N.T.McMahon, K.L.Deuis, J.R.Vetter, I.Schroeder, C.I.

(2022) J Biol Chem 298: 101728-101728

  • DOI: https://doi.org/10.1016/j.jbc.2022.101728
  • Primary Citation of Related Structures:  
    7SAV, 7SAW

  • PubMed Abstract: 

    μ-Conotoxins are components of cone snail venom, well-known for their analgesic activity through potent inhibition of voltage-gated sodium channel (Na V ) subtypes, including Na V 1.7. These small, disulfide-rich peptides are typically stabilized by three disulfide bonds arranged in a 'native' CysI-CysIV, CysII-CysV, CysIII-CysVI pattern of disulfide connectivity. However, μ-conotoxin KIIIA, the smallest and most studied μ-conotoxin with inhibitory activity at Na V 1.7, forms two distinct disulfide bond isomers during thermodynamic oxidative folding, including Isomer 1 (CysI-CysV, CysII-CysIV, CysIII-CysVI) and Isomer 2 (CysI-CysVI, CysII-CysIV, CysIII-CysV), but not the native μ-conotoxin arrangement. To date, there has been no study on the structure and activity of KIIIA comprising the native μ-conotoxin disulfide bond arrangement. Here, we evaluated the synthesis, potency, sodium channel subtype selectivity, and 3D structure of the three isomers of KIIIA. Using a regioselective disulfide bond-forming strategy, we synthetically produced the three μ-conotoxin KIIIA isomers displaying distinct bioactivity and Na V subtype selectivity across human Na V channel subtypes 1.2, 1.4, and 1.7. We show that Isomer 1 inhibits Na V subtypes with a rank order of potency of Na V 1.4 > 1.2 > 1.7 and Isomer 2 in the order of Na V 1.4≈1.2 > 1.7, while the native isomer inhibited Na V 1.4 > 1.7≈1.2. The three KIIIA isomers were further evaluated by NMR solution structure analysis and molecular docking with hNa V 1.2. Our study highlights the importance of investigating alternate disulfide isomers, as disulfide connectivity affects not only the overall structure of the peptides but also the potency and subtype selectivity of μ-conotoxins targeting therapeutically relevant Na V subtypes.

  • Organizational Affiliation

    Institute for Molecular Bioscience, The University of Queensland, St Lucia, Queensland, Australia.


Find similar proteins by:  Sequence   |   3D Structure  

Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Mu-conotoxin KIIIA17Conus kinoshitaiMutation(s): 1 
Find proteins for P0C195 (Conus kinoshitai)
Explore P0C195 
Go to UniProtKB:  P0C195
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP0C195
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: SOLUTION NMR
  • Conformers Calculated: 50 
  • Conformers Submitted: 20 
  • Selection Criteria: structures with the lowest energy 

Structure Validation

View Full Validation Report

Entry History & Funding Information

Deposition Data

Funding OrganizationLocationGrant Number
National Health and Medical Research Council (NHMRC, Australia)AustraliaAPP1080405
National Health and Medical Research Council (NHMRC, Australia)Australia2002860
National Health and Medical Research Council (NHMRC, Australia)AustraliaAPP1162503
National Health and Medical Research Council (NHMRC, Australia)AustraliaAPP1139961
Australian Research Council (ARC)AustraliaFT160100055

Revision History  (Full details and data files)

  • Version 1.0: 2022-05-25
    Type: Initial release
  • Version 1.1: 2023-06-14
    Changes: Other