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| | {{STRUCTURE_2g9h| PDB=2g9h | SCENE= }} | | {{STRUCTURE_2g9h| PDB=2g9h | SCENE= }} |
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| - | '''Crystal Structure of Staphylococcal Enterotoxin I (SEI) in Complex with a Human MHC class II Molecule'''
| + | ===Crystal Structure of Staphylococcal Enterotoxin I (SEI) in Complex with a Human MHC class II Molecule=== |
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| - | ==Overview==
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| - | Superantigens are bacterial or viral proteins that elicit massive T cell activation through simultaneous binding to major histocompatibility complex (MHC) class II and T cell receptors. This activation results in uncontrolled release of inflammatory cytokines, causing toxic shock. A remarkable property of superantigens, which distinguishes them from T cell receptors, is their ability to interact with multiple MHC class II alleles independently of MHC-bound peptide. Previous crystallographic studies have shown that staphylococcal and streptococcal superantigens belonging to the zinc family bind to a high affinity site on the class II beta-chain. However, the basis for promiscuous MHC recognition by zinc-dependent superantigens is not obvious, because the beta-chain is polymorphic and the MHC-bound peptide forms part of the binding interface. To understand how zinc-dependent superantigens recognize MHC, we determined the crystal structure, at 2.0 A resolution, of staphylococcal enterotoxin I bound to the human class II molecule HLA-DR1 bearing a peptide from influenza hemagglutinin. Interactions between the superantigen and DR1 beta-chain are mediated by a zinc ion, and 22% of the buried surface of peptide.MHC is contributed by the peptide. Comparison of the staphylococcal enterotoxin I.peptide.DR1 structure with ones determined previously revealed that zinc-dependent superantigens achieve promiscuous binding to MHC by targeting conservatively substituted residues of the polymorphic beta-chain. Additionally, these superantigens circumvent peptide specificity by engaging MHC-bound peptides at their conformationally conserved N-terminal regions while minimizing sequence-specific interactions with peptide residues to enhance cross-reactivity.
| + | The line below this paragraph, {{ABSTRACT_PUBMED_16829512}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 16829512 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_16829512}} |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: Superantigen]] | | [[Category: Superantigen]] |
| | [[Category: Zn]] | | [[Category: Zn]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 04:51:00 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Jul 27 15:54:06 2008'' |
Revision as of 12:54, 27 July 2008
Template:STRUCTURE 2g9h
Crystal Structure of Staphylococcal Enterotoxin I (SEI) in Complex with a Human MHC class II Molecule
Template:ABSTRACT PUBMED 16829512
About this Structure
2G9H is a Protein complex structure of sequences from Homo sapiens and Staphylococcus aureus. Full crystallographic information is available from OCA.
Reference
Crystal structure of staphylococcal enterotoxin I (SEI) in complex with a human major histocompatibility complex class II molecule., Fernandez MM, Guan R, Swaminathan CP, Malchiodi EL, Mariuzza RA, J Biol Chem. 2006 Sep 1;281(35):25356-64. Epub 2006 Jul 6. PMID:16829512
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