1sxt
From Proteopedia
(New page: 200px<br /><applet load="1sxt" size="450" color="white" frame="true" align="right" spinBox="true" caption="1sxt, resolution 2.7Å" /> '''STAPHYLOCOCCAL ENTERO...) |
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| - | [[Image:1sxt.gif|left|200px]]<br /><applet load="1sxt" size=" | + | [[Image:1sxt.gif|left|200px]]<br /><applet load="1sxt" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1sxt, resolution 2.7Å" /> | caption="1sxt, resolution 2.7Å" /> | ||
'''STAPHYLOCOCCAL ENTEROTOXIN TYPE A (SEA) CO-CRYSTALLISED WITH ZINC'''<br /> | '''STAPHYLOCOCCAL ENTEROTOXIN TYPE A (SEA) CO-CRYSTALLISED WITH ZINC'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Superantigens form complexes with major histocompatibility complex (MHC) | + | 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. |
==About this Structure== | ==About this Structure== | ||
| - | 1SXT is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Staphylococcus_aureus Staphylococcus aureus] with ZN as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http:// | + | 1SXT is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Staphylococcus_aureus Staphylococcus aureus] with <scene name='pdbligand=ZN:'>ZN</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1SXT OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Staphylococcus aureus]] | [[Category: Staphylococcus aureus]] | ||
| - | [[Category: Sundstrom, S | + | [[Category: Sundstrom, S M.]] |
[[Category: ZN]] | [[Category: ZN]] | ||
[[Category: enterotoxin]] | [[Category: enterotoxin]] | ||
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[[Category: toxin]] | [[Category: toxin]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 15:06:57 2008'' |
Revision as of 13:07, 21 February 2008
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STAPHYLOCOCCAL ENTEROTOXIN TYPE A (SEA) CO-CRYSTALLISED WITH ZINC
Overview
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.
About this Structure
1SXT is a Single protein structure of sequence from Staphylococcus aureus with as ligand. Full crystallographic information is available from OCA.
Reference
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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