2G9H

Crystal Structure of Staphylococcal Enterotoxin I (SEI) in Complex with a Human MHC class II Molecule


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.00 Å
  • R-Value Free: 0.252 
  • R-Value Work: 0.213 
  • R-Value Observed: 0.215 

Starting Model: experimental
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This is version 1.4 of the entry. See complete history


Literature

Crystal structure of staphylococcal enterotoxin I (SEI) in complex with a human major histocompatibility complex class II molecule.

Fernandez, M.M.Guan, R.Swaminathan, C.P.Malchiodi, E.L.Mariuzza, R.A.

(2006) J Biol Chem 281: 25356-25364

  • DOI: https://doi.org/10.1074/jbc.M603969200
  • Primary Citation of Related Structures:  
    2G9H

  • PubMed Abstract: 

    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.


  • Organizational Affiliation

    Instituto de Estudios de la Inmunidad Humoral, Laboratorio de Inmunología Estructural, Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina.


Macromolecules
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Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
HLA class II histocompatibility antigen, DR alpha chain182Homo sapiensMutation(s): 0 
Gene Names: HLA-DRA
UniProt & NIH Common Fund Data Resources
Find proteins for P01903 (Homo sapiens)
Explore P01903 
Go to UniProtKB:  P01903
PHAROS:  P01903
GTEx:  ENSG00000204287 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP01903
Sequence Annotations
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  • Reference Sequence
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Entity ID: 2
MoleculeChains Sequence LengthOrganismDetailsImage
HLA class II histocompatibility antigen, DRB1-1 beta chain190Homo sapiensMutation(s): 0 
Gene Names: HLA-DRB1
UniProt & NIH Common Fund Data Resources
Find proteins for P01911 (Homo sapiens)
Explore P01911 
Go to UniProtKB:  P01911
PHAROS:  P01911
GTEx:  ENSG00000196126 
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UniProt GroupP01911
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  • Reference Sequence

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Entity ID: 3
MoleculeChains Sequence LengthOrganismDetailsImage
Hemagglutinin13N/AMutation(s): 0 
UniProt
Find proteins for P04664 (Influenza A virus (strain A/England/878/1969 H3N2))
Explore P04664 
Go to UniProtKB:  P04664
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UniProt GroupP04664
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  • Reference Sequence
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Entity ID: 4
MoleculeChains Sequence LengthOrganismDetailsImage
extracellular enterotoxin type I218Staphylococcus aureusMutation(s): 0 
UniProt
Find proteins for Q52T95 (Staphylococcus aureus)
Explore Q52T95 
Go to UniProtKB:  Q52T95
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UniProt GroupQ52T95
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  • Reference Sequence
Small Molecules
Ligands 4 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
EPE
Query on EPE

Download Ideal Coordinates CCD File 
G [auth A]4-(2-HYDROXYETHYL)-1-PIPERAZINE ETHANESULFONIC ACID
C8 H18 N2 O4 S
JKMHFZQWWAIEOD-UHFFFAOYSA-N
SO4
Query on SO4

Download Ideal Coordinates CCD File 
E [auth A],
F [auth A],
J [auth C],
L [auth D]
SULFATE ION
O4 S
QAOWNCQODCNURD-UHFFFAOYSA-L
DIO
Query on DIO

Download Ideal Coordinates CCD File 
H [auth A],
I [auth A]
1,4-DIETHYLENE DIOXIDE
C4 H8 O2
RYHBNJHYFVUHQT-UHFFFAOYSA-N
ZN
Query on ZN

Download Ideal Coordinates CCD File 
K [auth D]ZINC ION
Zn
PTFCDOFLOPIGGS-UHFFFAOYSA-N
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.00 Å
  • R-Value Free: 0.252 
  • R-Value Work: 0.213 
  • R-Value Observed: 0.215 
  • Space Group: C 1 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 150.395α = 90
b = 99.933β = 92
c = 72.917γ = 90
Software Package:
Software NamePurpose
REFMACrefinement
CrystalCleardata scaling
PHASERphasing

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2006-07-11
    Type: Initial release
  • Version 1.1: 2008-05-01
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Advisory, Version format compliance
  • Version 1.3: 2017-10-18
    Changes: Refinement description
  • Version 1.4: 2023-08-30
    Changes: Data collection, Database references, Derived calculations, Refinement description