1sxt: Difference between revisions

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{{STRUCTURE_1sxt|  PDB=1sxt  |  SCENE=  }}  
{{STRUCTURE_1sxt|  PDB=1sxt  |  SCENE=  }}  


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




==Overview==
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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.
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{{ABSTRACT_PUBMED_8943278}}


==About this Structure==
==About this Structure==
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[[Category: Superantigen]]
[[Category: Superantigen]]
[[Category: Toxin]]
[[Category: Toxin]]
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Revision as of 21:03, 28 July 2008

File:1sxt.png

Template:STRUCTURE 1sxt

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

Template:ABSTRACT PUBMED 8943278

About this StructureAbout this Structure

1SXT is a Single protein structure of sequence from Staphylococcus aureus. Full crystallographic information is available from OCA.

ReferenceReference

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, J Biol Chem. 1996 Dec 13;271(50):32212-6. PMID:8943278

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