High affinity T cell receptors from yeast display libraries block T cell activation by superantigens

Michele C. Kieke, Eric Sundberg, Eric V. Shusta, Roy A. Mariuzza, K. Dane Wittrup, David M. Kranz

Research output: Contribution to journalArticle

Abstract

The αβ T cell receptor (TCR) can be triggered by a class of ligands called superantigens. Enterotoxins secreted by bacteria act as superantigens by simultaneously binding to an MHC class II molecule on an antigen-presenting cell and to a TCR β-chain, thereby causing activation of the T cell. The cross-reactivity of enterotoxins with different Vβ regions can lead to stimulation of a large fraction of T cells. To understand the molecular details of TCR-enterotoxin interactions and to generate potential antagonists of these serious hyperimmune reactions, we engineered soluble TCR mutants with improved affinity for staphylococcal enterotoxin C3 (SEC3). A library of randomly mutated, single-chain TCRs (Vβ-linker-Vα) were expressed as fusions to the Aga2p protein on the surface of yeast cells. Mutants were selected by flow cytometric cell sorting with a fluorescent-labeled SEC3. Various mutations were identified, primarily in Vβ residues that are located at the TCR:SEC3 interface. The combined mutations created a remodeled SEC3-binding surface and yielded a Vβ domain with an affinity that was increased by 1000-fold (KD = 7 nM). A soluble form of this Vβ mutant was a potent inhibitor of SEC3-mediated T cell activity, suggesting that these engineered proteins may be useful as antagonists.

Original languageEnglish (US)
Pages (from-to)1305-1315
Number of pages11
JournalJournal of Molecular Biology
Volume307
Issue number5
DOIs
StatePublished - Apr 13 2001

Keywords

  • Antagonists
  • Directed evolution
  • Staphylococcus aureus
  • T cell activity
  • Yeast surface display

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology

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