Crystal structure of a superantigen bound to the high-affinity, zinc-dependent site on MHC class II.
Immunity
; 14(1): 93-104, 2001 Jan.
Article
em En
| MEDLINE
| ID: mdl-11163233
ABSTRACT
MHC class II molecules possess two binding sites for bacterial superantigens (SAGs) a low-affinity site on the alpha chain and a high-affinity, zinc-dependent site on the beta chain. Only the former has been defined crystallographically. We report the structure of streptococcal pyrogenic exotoxin C (SPE-C) complexed with HLA-DR2a (DRA*0101, DRB5*0101) bearing a self-peptide from myelin basic protein (MBP). SPE-C binds the beta chain through a zinc bridge that links the SAG and class II molecules. Surprisingly, SPE-C also makes extensive contacts with the MBP peptide, such that peptide accounts for one third of the surface area of the MHC molecule buried in the complex, similar to TCR-peptide/MHC complexes. Thus, SPE-C may optimize T cell responses by mimicking the peptide dependence of conventional antigen presentation and recognition.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Proteínas de Bactérias
/
Zinco
/
Antígeno HLA-DR2
/
Superantígenos
/
Exotoxinas
/
Proteínas de Membrana
Limite:
Animals
/
Humans
Idioma:
En
Revista:
Immunity
Ano de publicação:
2001
Tipo de documento:
Article