Crystal structure of the streptococcal pyrogenic exotoxin J (SPE-J)

Experimental Data Snapshot

  • Resolution: 1.75 Å
  • R-Value Free: 0.240 
  • R-Value Work: 0.210 
  • R-Value Observed: 0.213 

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This is version 1.4 of the entry. See complete history


Crystallographic and mutational data show that the streptococcal pyrogenic exotoxin j can use a common binding surface for T-cell receptor binding and dimerization

Baker, H.M.Proft, T.Webb, P.D.Arcus, V.L.Fraser, J.D.Baker, E.N.

(2004) J Biol Chem 279: 38571-38576

  • DOI: https://doi.org/10.1074/jbc.M406695200
  • Primary Citation of Related Structures:  
    1TY0, 1TY2

  • PubMed Abstract: 

    The protein toxins known as superantigens (SAgs), which are expressed primarily by the pathogenic bacteria Staphylococcus aureus and Streptococcus pyogenes, are highly potent immunotoxins with the ability to cause serious human disease. These SAgs share a conserved fold but quite varied activities. In addition to their common role of cross-linking T-cell receptors (TCRs) and major histocompatibility complex class II (MHC-II) molecules, some SAgs can cross-link MHC-II, using diverse mechanisms. The crystal structure of the streptococcal superantigen streptococcal pyrogenic exotoxin J (SPE-J) has been solved at 1.75 A resolution (R = 0.209, R(free) = 0.240), both with and without bound Zn(2+). The structure displays the canonical two-domain SAg fold and a zinc-binding site that is shared by a subset of other SAgs. Most importantly, in concentrated solution and in the crystal, SPE-J forms dimers. These dimers, which are present in two different crystal environments, form via the same face that is used for TCR binding in other SAgs. Site-directed mutagenesis shows that this face is also used for TCR binding SPE-J. We infer that SPE-J cross-links TCR and MHC-II as a monomer but that dimers may form on the antigen-presenting cell surface, cross-linking MHC-II and eliciting intracellular signaling.

  • Organizational Affiliation

    School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland, New Zealand.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
putative exotoxin (superantigen)
A, B, C
211Streptococcus pyogenesMutation(s): 0 
Gene Names: spe-j
Find proteins for Q7BAE3 (Streptococcus pyogenes)
Explore Q7BAE3 
Go to UniProtKB:  Q7BAE3
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ7BAE3
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 1.75 Å
  • R-Value Free: 0.240 
  • R-Value Work: 0.210 
  • R-Value Observed: 0.213 
  • Space Group: C 1 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 165.632α = 90
b = 46.348β = 90.56
c = 72.209γ = 90
Software Package:
Software NamePurpose
MOSFLMdata reduction
TRUNCATEdata reduction
CCP4data scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2004-08-03
    Type: Initial release
  • Version 1.1: 2008-04-30
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2024-02-14
    Changes: Data collection, Database references
  • Version 1.4: 2024-04-03
    Changes: Refinement description