title: Staphylococcal enterotoxins A and B share a common structural motif for binding class II major histocompatibility complex molecules.
abstract: A comparative site-directed mutagenesis study of staphylococcal enterotoxins A and B was undertaken to identify key amino-acid residues which govern interactions with major histocompatibility class II molecules. This involved generating a three-dimensional homology model for enterotoxin A in complex with the HLA-DR1 molecule, based on the reported X-ray crystal structures of enterotoxin B, both free and bound to HLA-DR1. A binding motif previously described for enterotoxin B was found to be conserved in enterotoxin A. An examination of the experimental data with the homology model clarifies how T-cell responses to enterotoxin A, and most bacterial superantigens, are likely to be mediated by variations of a structurally conserved HLA-DR alpha binding motif.
authors.affiliation: Department of Immunology and Molecular Biology, Army Medical Research Institute of Infectious Diseases, Frederick, Maryland 21702, USA.
authors.forename: R G
authors.initials: RG
authors.lastname: Ulrich
authors.forename: S
authors.initials: S
authors.lastname: Bavari
authors.forename: M A
authors.initials: MA
authors.lastname: Olson
mesh_terms: D000595:Amino Acid Sequence; D004768:Enterotoxins / Q000737:chemistry*; D015798:HLA-DR1 Antigen / Q000737:chemistry*; D006801:Humans; D008213:Lymphocyte Activation; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011485:Protein Binding; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013329:Structure-Activity Relationship; D018089:Superantigens / Q000737:chemistry*; D013601:T-Lymphocytes / Q000378:metabolism
chemical_list: D004768:Enterotoxins; D015798:HLA-DR1 Antigen; D018089:Superantigens; C026066:enterotoxin A, Staphylococcal; C031818:enterotoxin B, staphylococcal