Crystal structure of a dimeric form of streptococcal pyrogenic exotoxin A (SpeA1)

Matthew D. Baker, Inessa Gendlina, Carleen M. Collins, K. Ravi Acharya

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


Streptococcal pyrogenic exotoxin A (SpeA1) is a bacterial superantigen associated with scarlet fever and streptococcal toxic shock syndrome (STSS). SpeA1 is found in both monomeric and dimeric forms, and previous work suggested that the dimer results from an intermolecular disulfide bond between the cysteines at positions 90 of each monomer. Here, we present the crystal structure of the dimeric form of SpeA1. The toxin crystallizes in the orthorhombic space group P21,21,21, with two dimers in the crystallographic asymmetric unit. The final structure has a crystallographic R-factor of 21.52% for 7248 protein atoms, 136 water molecules, and 4 zinc atoms (one zinc atom per molecule). The implications of SpeA1 dimer on MHC class II and T-cell receptor recognition are discussed.

Original languageEnglish (US)
Pages (from-to)2285-2290
Number of pages6
JournalProtein Science
Issue number9
StatePublished - Sep 2004
Externally publishedYes


  • MHC class II molecule
  • Streptococcal pyrogenic exotoxin A1
  • Superantigen
  • T-cell receptor
  • X-ray crystallography

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology


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