1SXT

STAPHYLOCOCCAL ENTEROTOXIN TYPE A (SEA) CO-CRYSTALLISED WITH ZINC

Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.70 Å
  • R-Value Free: 0.317 
  • R-Value Work: 0.206 
  • R-Value Observed: 0.206 

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This is version 1.2 of the entry. See complete history. 


Literature

The Co-crystal structure of staphylococcal enterotoxin type A with Zn2+ at 2.7 A resolution. Implications for major histocompatibility complex class II binding.

Sundstrom, M., Hallen, D., Svensson, A., Schad, E., Dohlsten, M., Abrahmsen, L.

(1996) J Biol Chem 271: 32212-32216

  • DOI: 10.1074/jbc.271.50.32212
  • Primary Citation of Related Structures:  
    1SXT

  • PubMed Abstract: 

    • Superantigens form complexes with major histocompatibility complex (MHC) class II molecules and T-cell receptors resulting in extremely strong immunostimulatory properties. Staphylococcus aureus enterotoxin A (SEA) belongs to a subgroup of the staphy ...

    Superantigens form complexes with major histocompatibility complex (MHC) class II molecules and T-cell receptors resulting in extremely strong immunostimulatory properties. Staphylococcus aureus enterotoxin A (SEA) belongs to a subgroup of the staphylococcal superantigens that utilizes Zn2+ in the high affinity interaction with MHC class II molecules. A high affinity metal binding site was described previously in SEA co-crystallized with Cd2+ in which the metal ion was octahedrally co-ordinated, involving the N-terminal serine. We have now co-crystallized SEA with its native co-factor Zn2+ and determined its crystal structure at 2.7 A resolution. As expected for a Zn2+ ion, the co-ordination was found to be tetrahedral. Three of the ligands are located on the SEA surface on a C-terminal domain beta-sheet, while the fourth varies with the conditions. Further analysis of the zinc binding event was performed using titration microcalorimetry, which showed that SEA binds Zn2+ with an affinity of KD = 0.3 microM in an entropy driven process. The differential Zn2+ co-ordination observed here has implications for the mechanism of the SEA-MHC class II interaction.

    Organizational Affiliation: 

    Department of Structural Biochemistry, Pharmacia & Upjohn, Stockholm, Sweden.



Macromolecules
Find similar proteins by: 
(by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
STAPHYLOCOCCAL ENTEROTOXIN TYPE AA, B233Staphylococcus aureusMutation(s): 0 
Gene Names: entA
Find proteins for P0A0L2 (Staphylococcus aureus)
Explore P0A0L2 
Go to UniProtKB:  P0A0L2
Protein Feature View
Expand
  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
ZN
Query on ZN
Download Ideal Coordinates CCD File 
A, B
ZINC ION
Zn
PTFCDOFLOPIGGS-UHFFFAOYSA-N		 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.70 Å
  • R-Value Free: 0.317 
  • R-Value Work: 0.206 
  • R-Value Observed: 0.206 
  • Space Group: P 31 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 75.59α = 90
b = 75.59β = 90
c = 175.31γ = 120
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling
X-PLORmodel building
X-PLORrefinement
X-PLORphasing

Structure Validation

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View more in-depth experimental data

Entry History 

Deposition Data

  • Deposited Date: 1996-11-14 
  • Released Date: 1997-11-19 
    • Deposition Author(s): Sundstrom, S.M.

Revision History 

  • Version 1.0: 1997-11-19
    Type: Initial release
  • Version 1.1: 2008-03-24
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance