Crystal structure of a dimeric form of streptococcal pyrogenic exotoxin A (SpeA1).
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 P212121, 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.
Department of Biology and Biochemistry, Building 4 South, University of Bath, Claverton Down, Bath BA2 7AY, UK.
Matthew D
MD
Baker
Inessa
I
Gendlina
Carleen M
CM
Collins
K Ravi
KR
Acharya
D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D018360:Crystallography, X-Ray; D019281:Dimerization; D004220:Disulfides / Q000737:chemistry / Q000378:metabolism; D005098:Exotoxins / Q000737:chemistry* / Q000378:metabolism; D000949:Histocompatibility Antigens Class II / Q000378:metabolism; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D011487:Protein Conformation; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism; D015032:Zinc / Q000378:metabolism
D001426:Bacterial Proteins; D004220:Disulfides; D005098:Exotoxins; D000949:Histocompatibility Antigens Class II; D008565:Membrane Proteins; D011948:Receptors, Antigen, T-Cell; C117980:SpeA protein, Streptococcus pyogenes; D015032:Zinc