2KTX

COMPLETE KALIOTOXIN FROM ANDROCTONUS MAURETANICUS MAURETANICUS, NMR, 18 STRUCTURES


Experimental Data Snapshot

  • Method: SOLUTION NMR
  • Conformers Calculated: 35 
  • Conformers Submitted: 18 
  • Selection Criteria: TOTAL ENERGY/DISTANCE VIOLATIONS 

wwPDB Validation 3D Report Full Report


This is version 1.3 of the entry. See complete history

Literature

3D structure of kaliotoxin: is residue 34 a key for channel selectivity?

Gairi, M.Romi, R.Fernandez, I.Rochat, H.Martin-Eauclaire, M.F.Van Rietschoten, J.Pons, M.Giralt, E.

(1997) J.Pept.Sci. 3: 314-319

  • DOI: 10.1002/(SICI)1099-1387(199707)3:4<314::AID-PSC117>3.0.CO;2-E

  • PubMed Abstract: 
  • Kaliotoxin (KTX) is a natural peptide blocker of voltage-dependent K+ channels. The 3D structure of a truncated analogue of KTX (Fernandez et al. (1994) Biochemistry 33, 14256-14263) was determined by NMR spectroscopy and showed significant differenc ...

    Kaliotoxin (KTX) is a natural peptide blocker of voltage-dependent K+ channels. The 3D structure of a truncated analogue of KTX (Fernandez et al. (1994) Biochemistry 33, 14256-14263) was determined by NMR spectroscopy and showed significant differences from structures established for other related scorpion toxins. A recent publication with the structure of the complete toxin (Aiyar et al. (1995) Neuron 15, 1169-1181) did not confirm these differences. In this communication we report NMR data for KTX at pH 3.0, 5.5 and 7.2 and the 3D structure obtained from data at pH = 5.5. Complete KTX displays a folding similar to that of other toxins with an alpha-helix and a beta-sheet linked by two disulphide bonds. The pKa of His 34 is anomalously low (4.7-5.2 depending on the buffer) owing to its interaction with two Lys residues (including the essential Lys 27), the charged N-terminus and the side chain of Met 29. Charged residues are placed symmetrically with respect to an axis that approximately coincides with one of the principal components of the moment of inertia of the toxin. His 34, which occupies a well-defined position between two conserved Cys, is located on the centre of a layer of charged groups. Positively and negatively charged residues are found at the same position in related toxins. It is suggested that electrostatic effects modulate the distances between positive charges in flexible side chains, contributing to the fine tuning of the selectivity toward different channel subclasses and that the approximate coincidence between the moment of inertia and the charge axis facilitate the approach of the toxin to the channel. The very low pKa of His 34 implies that it will be completely unprotonated at physiological pH.


    Related Citations: 
    • Kaliotoxin, a Novel Peptidyl Inhibitor of Neuronal Bk-Type Ca(2+)-Activated K+ Channels Characterized from Androctonus Mauretanicus Mauretanicus Venom
      Crest, M.,Jacquet, G.,Gola, M.,Zerrouk, H.,Benslimane, A.,Rochat, H.,Mansuelle, P.,Martin-Eauclaire, M.F.
      (1992) J.Biol.Chem. 267: 1640


    Organizational Affiliation

    Departament de Química Orgànica, Universitat de Barcelona, Spain.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
KALIOTOXIN
A
38Androctonus mauritanicus mauritanicusMutation(s): 0 
Find proteins for P24662 (Androctonus mauritanicus mauritanicus)
Go to UniProtKB:  P24662
Experimental Data & Validation

Experimental Data

  • Method: SOLUTION NMR
  • Conformers Calculated: 35 
  • Conformers Submitted: 18 
  • Selection Criteria: TOTAL ENERGY/DISTANCE VIOLATIONS 
  • Olderado: 2KTX Olderado

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 1997-06-16
    Type: Initial release
  • Version 1.1: 2008-03-03
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance
  • Version 1.3: 2017-12-20
    Type: Database references, Derived calculations, Other