title: Directed evolution of a single-chain class II MHC product by yeast display.
abstract: 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-A(g7). The I-A(g7) 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-A(g7). A library containing mutations at two residues (positions 56 and 57 of the I-A(g7) beta-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-A(g7) followed by selection with an anti-I-A(g7) 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.
authors.affiliation: Department of Biochemistry, University of Illinois, 600 S Matthews Avenue, Urbana, IL 61801, USA.
authors.forename: Scott E
authors.initials: SE
authors.lastname: Starwalt
authors.forename: Emma L
authors.initials: EL
authors.lastname: Masteller
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Bluestone
authors.forename: David M
authors.initials: DM
authors.lastname: Kranz
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D000918:Antibody Specificity; D002460:Cell Line; D019020:Directed Molecular Evolution; D004355:Drug Stability; D005434:Flow Cytometry; D000949:Histocompatibility Antigens Class II / Q000737:chemistry / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019151:Peptide Library; D016271:Proto-Oncogene Proteins c-myc / Q000276:immunology; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D020539:Sequence Analysis, Protein; D014162:Transfection
chemical_list: D000911:Antibodies, Monoclonal; D000949:Histocompatibility Antigens Class II; D019151:Peptide Library; D016271:Proto-Oncogene Proteins c-myc; D011994:Recombinant Proteins