1ste
From Proteopedia
(New page: 200px<br /><applet load="1ste" size="450" color="white" frame="true" align="right" spinBox="true" caption="1ste, resolution 2.0Å" /> '''STAPHYLOCOCCAL ENTERO...) |
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| - | [[Image:1ste.gif|left|200px]]<br /><applet load="1ste" size=" | + | [[Image:1ste.gif|left|200px]]<br /><applet load="1ste" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1ste, resolution 2.0Å" /> | caption="1ste, resolution 2.0Å" /> | ||
'''STAPHYLOCOCCAL ENTEROTOXIN C2 FROM STAPHYLOCOCCUS AUREUS'''<br /> | '''STAPHYLOCOCCAL ENTEROTOXIN C2 FROM STAPHYLOCOCCUS AUREUS'''<br /> | ||
==Overview== | ==Overview== | ||
| - | BACKGROUND: Staphylococcus aureus enterotoxin C2 (SEC2) belongs to a | + | BACKGROUND: Staphylococcus aureus enterotoxin C2 (SEC2) belongs to a family of proteins, termed 'superantigens', that form complexes with class II MHC molecules enabling them to activate a substantial number of T cells. Although superantigens seem to act by a common mechanism, they vary in many of their specific interactions and biological properties. Comparison of the structure of SEC2 with those of two other superantigens--staphylococcal enterotoxin B (SEB) and toxic shock syndrome toxin-1 (TSST-1)--may provide insight into their mode of action. RESULTS: The crystal structure of SEC2 has been determined at 2.0 A resolution. The overall topology of the molecule resembles that of SEB and TSST-1, and the regions corresponding to the MHC class II and T-cell receptor binding sites on SEB are quite similar in SEC2. A unique feature of SEC2 is the presence of a zinc ion located in a solvent-exposed region at the interface between the two domains of the molecule. The zinc ion is coordinated to Asp83, His118, His122 and Asp9* (from the neighbouring molecule in the crystal lattice). Atomic absorption spectrometry demonstrates that zinc is also bound to SEC2 in solution. CONCLUSIONS: SEC2 appears to be capable of binding to MHC class II molecules in much the same manner as SEB. However, structure-function studies have suggested an alternative binding mode that involves a different site on the toxin. The zinc ion of SEC2 lies within this region and thus may be important for complex formation, for example by acting as a bridge between the two molecules. Other possible roles for the metal cation, including a catalytic one, are also considered. |
==About this Structure== | ==About this Structure== | ||
| - | 1STE 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:// | + | 1STE 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=1STE OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Staphylococcus aureus]] | [[Category: Staphylococcus aureus]] | ||
| - | [[Category: Acharya, K | + | [[Category: Acharya, K R.]] |
| - | [[Category: Papageorgiou, A | + | [[Category: Papageorgiou, A C.]] |
[[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 15:05:01 2008'' |
Revision as of 13:05, 21 February 2008
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STAPHYLOCOCCAL ENTEROTOXIN C2 FROM STAPHYLOCOCCUS AUREUS
Overview
BACKGROUND: Staphylococcus aureus enterotoxin C2 (SEC2) belongs to a family of proteins, termed 'superantigens', that form complexes with class II MHC molecules enabling them to activate a substantial number of T cells. Although superantigens seem to act by a common mechanism, they vary in many of their specific interactions and biological properties. Comparison of the structure of SEC2 with those of two other superantigens--staphylococcal enterotoxin B (SEB) and toxic shock syndrome toxin-1 (TSST-1)--may provide insight into their mode of action. RESULTS: The crystal structure of SEC2 has been determined at 2.0 A resolution. The overall topology of the molecule resembles that of SEB and TSST-1, and the regions corresponding to the MHC class II and T-cell receptor binding sites on SEB are quite similar in SEC2. A unique feature of SEC2 is the presence of a zinc ion located in a solvent-exposed region at the interface between the two domains of the molecule. The zinc ion is coordinated to Asp83, His118, His122 and Asp9* (from the neighbouring molecule in the crystal lattice). Atomic absorption spectrometry demonstrates that zinc is also bound to SEC2 in solution. CONCLUSIONS: SEC2 appears to be capable of binding to MHC class II molecules in much the same manner as SEB. However, structure-function studies have suggested an alternative binding mode that involves a different site on the toxin. The zinc ion of SEC2 lies within this region and thus may be important for complex formation, for example by acting as a bridge between the two molecules. Other possible roles for the metal cation, including a catalytic one, are also considered.
About this Structure
1STE is a Single protein structure of sequence from Staphylococcus aureus with as ligand. Full crystallographic information is available from OCA.
Reference
Crystal structure of the superantigen enterotoxin C2 from Staphylococcus aureus reveals a zinc-binding site., Papageorgiou AC, Acharya KR, Shapiro R, Passalacqua EF, Brehm RD, Tranter HS, Structure. 1995 Aug 15;3(8):769-79. PMID:7582894
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