Identification and Characterization of Novel Superantigens from <i>Streptococcus pyogenes </i>

DOI PDF 被引用文献5件
  • Thomas Proft
    From the Department of Molecular Medicine, School of Medicine, University of Auckland, 92019 Auckland, New Zealand
  • S. Louise Moffatt
    From the Department of Molecular Medicine, School of Medicine, University of Auckland, 92019 Auckland, New Zealand
  • Celia J. Berkahn
    From the Department of Molecular Medicine, School of Medicine, University of Auckland, 92019 Auckland, New Zealand
  • John D. Fraser
    From the Department of Molecular Medicine, School of Medicine, University of Auckland, 92019 Auckland, New Zealand

抄録

<jats:p>Three novel streptococcal superantigen genes (spe-g, spe-h, and spe-j) were identified from the Streptococcus pyogenes M1 genomic database at the University of Oklahoma. A fourth novel gene (smez-2) was isolated from the S. pyogenes strain 2035, based on sequence homology to the streptococcal mitogenic exotoxin z (smez) gene. SMEZ-2, SPE-G, and SPE-J are most closely related to SMEZ and streptococcal pyrogenic exotoxin (SPE)-C, whereas SPE-H is most similar to the staphylococcal toxins than to any other streptococcal toxin. Recombinant (r)SMEZ, rSMEZ-2, rSPE-G, and rSPE-H were mitogenic for human peripheral blood lymphocytes with half-maximal responses between 0.02 and 50 pg/ml (rSMEZ-2 and rSPE-H, respectively). SMEZ-2 is the most potent superantigen (SAg) discovered thus far. All toxins, except rSPE-G, were active on murine T cells, but with reduced potency. Binding to a human B-lymphoblastoid line was shown to be zinc dependent with high binding affinity of 15–65 nM. Evidence from modeled protein structures and competitive binding experiments suggest that high affinity binding of each toxin is to the major histocompatibility complex class II β chain. Competition for binding between toxins was varied and revealed overlapping but discrete binding to subsets of class II molecules in the hierarchical order (SMEZ, SPE-C) &gt; SMEZ-2 &gt; SPE-H &gt; SPE-G. The most common targets for the novel SAgs were human Vβ2.1- and Vβ4-expressing T cells. This might reflect a specific role for this subset of Vβs in the immune defense of gram-positive bacteria.</jats:p>

収録刊行物

被引用文献 (5)*注記

もっと見る

キーワード

詳細情報 詳細情報について

問題の指摘

ページトップへ