Dimeric alpha-cobratoxin X-ray structure: Localization of intermolecular disulfides and possible mode of binding to nicotinic acetylcholine receptors

Experimental Data Snapshot

  • Resolution: 1.94 Å
  • R-Value Free: 0.251 
  • R-Value Work: 0.219 
  • R-Value Observed: 0.220 

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Dimeric Alpha-Cobratoxin X-Ray Structure: Localization of Intermolecular Disulfides and Possible Mode of Binding to Nicotinic Acetylcholine Receptors.

Osipov, A.V.Rucktooa, P.Kasheverov, I.E.Filkin, S.Y.Starkov, V.G.Andreeva, T.V.Sixma, T.K.Bertrand, D.Utkin, Y.N.Tsetlin, V.I.

(2012) J Biol Chem 287: 6725

  • DOI: https://doi.org/10.1074/jbc.M111.322313
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    In Naja kaouthia cobra venom, we have earlier discovered a covalent dimeric form of α-cobratoxin (αCT-αCT) with two intermolecular disulfides, but we could not determine their positions. Here, we report the αCT-αCT crystal structure at 1.94 Å where intermolecular disulfides are identified between Cys(3) in one protomer and Cys(20) of the second, and vice versa. All remaining intramolecular disulfides, including the additional bridge between Cys(26) and Cys(30) in the central loops II, have the same positions as in monomeric α-cobratoxin. The three-finger fold is essentially preserved in each protomer, but the arrangement of the αCT-αCT dimer differs from those of noncovalent crystallographic dimers of three-finger toxins (TFT) or from the κ-bungarotoxin solution structure. Selective reduction of Cys(26)-Cys(30) in one protomer does not affect the activity against the α7 nicotinic acetylcholine receptor (nAChR), whereas its reduction in both protomers almost prevents α7 nAChR recognition. On the contrary, reduction of one or both Cys(26)-Cys(30) disulfides in αCT-αCT considerably potentiates inhibition of the α3β2 nAChR by the toxin. The heteromeric dimer of α-cobratoxin and cytotoxin has an activity similar to that of αCT-αCT against the α7 nAChR and is more active against α3β2 nAChRs. Our results demonstrate that at least one Cys(26)-Cys(30) disulfide in covalent TFT dimers, similar to the monomeric TFTs, is essential for their recognition by α7 nAChR, although it is less important for interaction of covalent TFT dimers with the α3β2 nAChR.

  • Organizational Affiliation

    Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, ul Miklukho-Maklaya 16/10, Moscow 117997, Russia.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
A, B
71Naja kaouthiaMutation(s): 0 
Find proteins for P01391 (Naja kaouthia)
Explore P01391 
Go to UniProtKB:  P01391
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP01391
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 2 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Query on MPD

Download Ideal Coordinates CCD File 
C6 H14 O2
Query on GLY

Download Ideal Coordinates CCD File 
C2 H5 N O2
Experimental Data & Validation

Experimental Data

  • Resolution: 1.94 Å
  • R-Value Free: 0.251 
  • R-Value Work: 0.219 
  • R-Value Observed: 0.220 
  • Space Group: P 31 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 86α = 90
b = 86β = 90
c = 37.12γ = 120
Software Package:
Software NamePurpose
XDSdata reduction
SCALAdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2012-01-25
    Type: Initial release
  • Version 1.1: 2012-08-15
    Changes: Database references
  • Version 1.2: 2023-12-20
    Changes: Data collection, Database references, Derived calculations, Other, Refinement description