1IM1

NMR SOLUTION STRUCTURE OF ALPHA-CONOTOXIN IM1, 20 STRUCTURES


Experimental Data Snapshot

  • Method: SOLUTION NMR
  • Conformers Calculated: 20 
  • Conformers Submitted: 20 
  • Selection Criteria: LOWEST RESIDUAL TARGET FUNCTION 

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This is version 1.3 of the entry. See complete history


Literature

NMR solution structure of alpha-conotoxin ImI and comparison to other conotoxins specific for neuronal nicotinic acetylcholine receptors.

Rogers, J.P.Luginbuhl, P.Shen, G.S.McCabe, R.T.Stevens, R.C.Wemmer, D.E.

(1999) Biochemistry 38: 3874-3882

  • DOI: 10.1021/bi9826254
  • Primary Citation of Related Structures:  
    1IM1

  • PubMed Abstract: 
  • Alpha-Conotoxins, peptides produced by predatory species of Conus marine snails, are potent antagonists of nicotinic acetylcholine receptors (nAChRs), ligand-gated ion channels involved in synaptic transmission. We determined the NMR solution structure of the smallest known alpha-conotoxin, ImI, a 12 amino acid peptide that binds specifically to neuronal alpha7-containing nAChRs in mammals ...

    Alpha-Conotoxins, peptides produced by predatory species of Conus marine snails, are potent antagonists of nicotinic acetylcholine receptors (nAChRs), ligand-gated ion channels involved in synaptic transmission. We determined the NMR solution structure of the smallest known alpha-conotoxin, ImI, a 12 amino acid peptide that binds specifically to neuronal alpha7-containing nAChRs in mammals. Calculation of the structure was based on a total of 80 upper distance constraints and 31 dihedral angle constraints resulting in 20 representative conformers with an average pairwise rmsd of 0.44 A from the mean structure for the backbone atoms N, Calpha, and C' of residues 2-11. The structure of ImI is characterized by two compact loops, defined by two disulfide bridges, which form distinct subdomains separated by a deep cleft. Two short 310-helical regions in the first loop are followed by a C-terminal beta-turn in the second. The two disulfide bridges and Ala 9 form a rigid hydrophobic core, orienting the other amino acid side chains toward the surface. Comparison of the three-dimensional structure of ImI to those of the larger, 16 amino acid alpha-conotoxins PnIA, PnIB, MII, and EpI-also specific for neuronal nAChRs-reveals remarkable similarity in local backbone conformations and relative solvent-accessible surface areas. The core scaffold is conserved in all five conotoxins, whereas the residues in solvent-exposed positions are highly variable. The second helical region, and the specific amino acids that the helix exposes to solvent, may be particularly important for binding and selectivity. This comparative analysis provides a three-dimensional structural basis for interpretation of mutagenesis data and structure-activity relationships for ImI as well other neuronal alpha-conotoxins.


    Related Citations: 
    • Alpha-Conotoxin Imi Exhibits Subtype-Specific Nicotinic Acetylcholine Receptor Blockade: Preferential Inhibition of Homomeric Alpha 7 and Alpha 9 Receptors
      Johnson, D.S., Martinez, J., Elgoyhen, A.B., Heinemann, S.F., Mcintosh, J.M.
      (1995) Mol Pharmacol 48: 194
    • A Nicotinic Acetylcholine Receptor Ligand of Unique Specificity, Alpha-Conotoxin Imi
      Mcintosh, J.M., Yoshikami, D., Mahe, E., Nielsen, D.B., Rivier, J.E., Gray, W.R., Olivera, B.M.
      (1994) J Biol Chem 269: 16733

    Organizational Affiliation

    Department of Chemistry, University of California, Berkeley 94720, USA.



Macromolecules
  • Find similar proteins by:  Sequence   |   Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
ALPHA-CONOTOXIN IM1A12Conus imperialisMutation(s): 0 
UniProt
Find proteins for P50983 (Conus imperialis)
Explore P50983 
Go to UniProtKB:  P50983
Protein Feature View
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: SOLUTION NMR
  • Conformers Calculated: 20 
  • Conformers Submitted: 20 
  • Selection Criteria: LOWEST RESIDUAL TARGET FUNCTION 
  • OLDERADO: 1IM1 Olderado

Structure Validation

View Full Validation Report




Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 1999-06-15
    Type: Initial release
  • Version 1.1: 2008-03-24
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2016-05-25
    Changes: Source and taxonomy