1KXI

STRUCTURE OF CYTOTOXIN HOMOLOG PRECURSOR


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.19 Å
  • R-Value Free: 0.305 
  • R-Value Work: 0.207 
  • R-Value Observed: 0.207 

wwPDB Validation   3D Report Full Report


This is version 1.2 of the entry. See complete history


Literature

Crystal structure of cardiotoxin V from Taiwan cobra venom: pH-dependent conformational change and a novel membrane-binding motif identified in the three-finger loops of P-type cardiotoxin.

Sun, Y.J.Wu, W.G.Chiang, C.M.Hsin, A.Y.Hsiao, C.D.

(1997) Biochemistry 36: 2403-2413

  • DOI: 10.1021/bi962594h
  • Primary Citation of Related Structures:  
    1KXI

  • PubMed Abstract: 
  • The crystal structure of cardiotoxin V from Taiwan cobra venom (CTX A5) has been solved at pH 8.5 and refined to an R-factor of 20.7% for 7013 reflections [>2sigma(F)] between 8- and 2.19-A resolution. The refined model shows that CTX A5 exists as a dimer ...

    The crystal structure of cardiotoxin V from Taiwan cobra venom (CTX A5) has been solved at pH 8.5 and refined to an R-factor of 20.7% for 7013 reflections [>2sigma(F)] between 8- and 2.19-A resolution. The refined model shows that CTX A5 exists as a dimer. The assembly consists of 974 non-hydrogen atoms from 124 residues and 73 water molecules. The global monomeric structure is similar to that determined by NMR at pH 3.7, characterized by a core formed by two beta-sheets connected with three-finger loops. However, local conformational differences are detected in two functionally important regions, loops I and II. A disparity between the NMR and X-ray structure of CTX A5 is detected near the tip of loop I and can be attributed to the difference in the protonation state of His4 at different pH, resulting in a reorientation of the His4 imidazole ring. A concerted motion of amino acid side chains located near His4 is detected and possibly contributes to the pH-dependent binding ability of CTX A5 to phospholipid model membranes. The second difference, detected at the tip of loop II, is due to the hydrophobic contact between CTX dimers in the crystal packing and the interaction of water molecules with amino acid residues in the loop II region of the CTX containing Pro31 (P-type CTX). This interaction forces loop II into a more rigid omega shape bridging the main chain at positions 27 and 34, contradictory to the flexible, tapering shape detected by NMR. Thus, a novel continuous hydrophobic column capable of binding to and possibly penetrating the membrane lipid bilayer is formed by the tips of the three-finger loops. In this respect, the X-ray crystal structure of CTX A5 may represent the CTX structure in the membrane-binding mode.


    Related Citations: 
    • Two Distinct Types of Cardiotoxin as Revealed by the Structure and Activity Relationship of Their Interaction with Zwitterionic Phospholipid Dispersions
      Chien, K.Y., Chiang, C.M., Hseu, Y.C., Vyas, A.A., Rule, G.S., Wu, W.G.
      (1994) J Biol Chem 269: 14473
    • Fusion of Sphingomyelin Vesicles Induced by Proteins from Taiwan Cobra (Naja Naja Atra) Venom. Interactions of Zwitterionic Phospholipids with Cardiotoxin Analogues
      Chien, K.Y., Huang, W.N., Jean, J.H., Wu, W.G.
      (1991) J Biol Chem 266: 3252

    Organizational Affiliation

    Crystallography Laboratory, Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
CARDIOTOXIN V AB62Naja atraMutation(s): 0 
Find proteins for P62375 (Naja atra)
Explore P62375 
Go to UniProtKB:  P62375
Protein Feature View
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.19 Å
  • R-Value Free: 0.305 
  • R-Value Work: 0.207 
  • R-Value Observed: 0.207 
  • Space Group: P 41 21 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 43.3α = 90
b = 43.3β = 90
c = 147.8γ = 90
Software Package:
Software NamePurpose
DENZOdata reduction
X-PLORmodel building
X-PLORrefinement
X-PLORphasing

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 1997-04-21
    Type: Initial release
  • Version 1.1: 2008-03-24
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance