Directed evolution of a single-chain class II MHC product by yeast display

Scott E. Starwalt, Emma L. Mastellela, Jeffrey A. Bluestone, David M Kranz

Research output: Contribution to journalArticle


Many autoimmune diseases have been linked to the class II region of the major histocompatibility complex (MHC). The linkage is thought to be a result of autoreactive T cells that recognize self-peptides bound to a product of this locus. For example, T cells from non-obese diabetic mice recognize specific 'diabetogenic' peptides bound to a class II MHC allele called I-Ag7. The I-Ag7 molecule is noted for being unstable and difficult to work with, especially in soluble form. In this work, yeast surface display combined with fluorescence-activated cell sorting was used as a means of directed evolution to engineer stabilized variants of a single-chain form of I-Ag7. A library containing mutations at two residues (positions 56 and 57 of the I-Ag7 β-chain) that are important in the class II disease associations yielded stabilized mutants with preferences for a glutamic acid at residue 56 and a leucine at residue 57. Random mutation of I-Ag7 followed by selection with an anti- I-Ag7 antibody also yielded stabilized variants with mutations in other residues. The methods described here allow the discovery of novel MHC complexes that could facilitate structural studies and provide new opportunities in the development of diagnostics or antagonists of class II MHC-associated diseases.

Original languageEnglish (US)
Pages (from-to)147-156
Number of pages10
JournalProtein Engineering
Issue number2
StatePublished - Feb 1 2003


  • Antigens
  • Class II
  • Major histocompatibility complex
  • Protein stability
  • Yeast display

ASJC Scopus subject areas

  • Molecular Biology
  • Biochemistry

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    Starwalt, S. E., Mastellela, E. L., Bluestone, J. A., & Kranz, D. M. (2003). Directed evolution of a single-chain class II MHC product by yeast display. Protein Engineering, 16(2), 147-156.