2IGU

Deamidated analogue of ImI Conotoxin

  • Classification: TOXIN
  • Mutation(s): No 

  • Deposited: 2006-09-25 Released: 2007-08-14 
  • Deposition Author(s): Kini, R.M., Kang, T.S.

Experimental Data Snapshot

  • Method: SOLUTION NMR
  • Conformers Calculated: 200 
  • Conformers Submitted: 14 
  • Selection Criteria: structures with the lowest energy 

wwPDB Validation   3D Report Full Report


This is version 1.1 of the entry. See complete history


Literature

Protein folding determinants: structural features determining alternative disulfide pairing in alpha- and chi/lambda-conotoxins

Kang, T.S.Talley, T.T.Jois, S.D.Taylor, P.Kini, R.M.

(2007) Biochemistry 46: 3338-3355

  • DOI: 10.1021/bi061969o
  • Primary Citation of Related Structures:  
    2IFJ, 2IFI, 2IFZ, 2IHA, 2IH7, 2IGU, 2IH6

  • PubMed Abstract: 
  • Alpha-conotoxins isolated from Conus venoms contain 11-19 residues and preferentially fold into the globular conformation that possesses a specific disulfide pairing pattern (C1-3, C2-4). We and others isolated a new family of chi-conotoxins (also called lambda conotoxins) with the conserved cysteine framework of alpha-conotoxins but with alternative disulfide pairing (C1-4, C2-3) resulting in the ribbon conformation ...

    Alpha-conotoxins isolated from Conus venoms contain 11-19 residues and preferentially fold into the globular conformation that possesses a specific disulfide pairing pattern (C1-3, C2-4). We and others isolated a new family of chi-conotoxins (also called lambda conotoxins) with the conserved cysteine framework of alpha-conotoxins but with alternative disulfide pairing (C1-4, C2-3) resulting in the ribbon conformation. In both families, disulfide pairing and hence folding are important for their biological potency. By comparing the structural differences, we identified potential structural determinants responsible for the folding tendencies of these conotoxins. We examined the role of conserved proline in the first intercysteine loop and the conserved C-terminal amide on folding patterns of synthetic analogues of ImI conotoxin by comparing the isoforms with the regiospecifically synthesized conformers. Deamidation at the C-terminus and substitution of proline in the first intercysteine loop switch the folding pattern from the globular form of alpha-conotoxins to the ribbon form of chi/lambda-conotoxins. The findings are corroborated by reciprocal folding of CMrVIA chi/lambda-conotoxins. Substitution of Lys-6 from the first intercysteine loop of CMrVIA conotoxin with proline, as well as the inclusion of an amidated C-terminal shifted the folding preference of CMrVIA conotoxin from its native ribbon conformation toward the globular conformation. Binding assays of ImI conotoxin analogues with Aplysia and Bulinus acetylcholine binding protein indicate that both these substitutions and their consequent conformational change substantially impact the binding affinity of ImI conotoxin. These results strongly indicate that the first intercysteine loop proline and C-terminal amidation act as conformational switches in alpha- and chi/lambda-conotoxins.


    Related Citations: 
    • Effect of C-terminal amidation on folding and disulfide-pairing of alpha-conotoxin ImI
      Kang, T.S., Vivekanandan, S., Jois, S.D., Kini, R.M.
      (2005) Angew Chem Int Ed Engl 44: 6333

    Organizational Affiliation

    Protein Science Laboratory, Department of Biological Sciences, National University of Singapore, Singapore.



Macromolecules
  • Find similar proteins by:  Sequence   |   Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Alpha-conotoxin ImIA12N/AMutation(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: 200 
  • Conformers Submitted: 14 
  • Selection Criteria: structures with the lowest energy 
  • OLDERADO: 2IGU Olderado

Structure Validation

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Entry History 

Deposition Data

  • Deposited Date: 2006-09-25 
  • Released Date: 2007-08-14 
  • Deposition Author(s): Kini, R.M., Kang, T.S.

Revision History  (Full details and data files)

  • Version 1.0: 2007-08-14
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance