title: An Engineered Switch in T Cell Receptor Specificity Leads to an Unusual but Functional Binding Geometry.
abstract: Utilizing a diverse binding site, T cell receptors (TCRs) specifically recognize a composite ligand comprised of a foreign peptide and a major histocompatibility complex protein (MHC). To help understand the determinants of TCR specificity, we studied a parental and engineered receptor whose peptide specificity had been switched via molecular evolution. Altered specificity was associated with a significant change in TCR-binding geometry, but this did not impact the ability of the TCR to signal in an antigen-specific manner. The determinants of binding and specificity were distributed among contact and non-contact residues in germline and hypervariable loops, and included disruption of key TCR-MHC interactions that bias αβ TCRs toward particular binding modes. Sequence-fitness landscapes identified additional mutations that further enhanced specificity. Our results demonstrate that TCR specificity arises from the distributed action of numerous sites throughout the interface, with significant implications for engineering therapeutic TCRs with novel and functional recognition properties.
authors.affiliation: Department of Biochemistry, University of Illinois, 600 S. Matthews Ave., Urbana, IL 61801, USA.
authors.forename: Daniel T
authors.initials: DT
authors.lastname: Harris
authors.affiliation: Department of Chemistry and Biochemistry and the Harper Cancer Research Institute, University of Notre Dame, 1234 Notre Dame Avenue, South Bend, IN 46557, USA.
authors.forename: Nishant K
authors.initials: NK
authors.lastname: Singh
authors.affiliation: Department of Biochemistry, University of Illinois, 600 S. Matthews Ave., Urbana, IL 61801, USA.
authors.forename: Qi
authors.initials: Q
authors.lastname: Cai
authors.affiliation: Department of Biochemistry, University of Illinois, 600 S. Matthews Ave., Urbana, IL 61801, USA.
authors.forename: Sheena N
authors.initials: SN
authors.lastname: Smith
authors.affiliation: Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY 40506, USA.
authors.forename: Craig
authors.initials: C
authors.lastname: Vander Kooi
authors.affiliation: Department of Biochemistry, University of Illinois, 600 S. Matthews Ave., Urbana, IL 61801, USA.
authors.forename: Erik
authors.initials: E
authors.lastname: Procko
authors.affiliation: Department of Biochemistry, University of Illinois, 600 S. Matthews Ave., Urbana, IL 61801, USA.
authors.forename: David M
authors.initials: DM
authors.lastname: Kranz
authors.affiliation: Department of Chemistry and Biochemistry and the Harper Cancer Research Institute, University of Notre Dame, 1234 Notre Dame Avenue, South Bend, IN 46557, USA.
authors.forename: Brian M
authors.initials: BM
authors.lastname: Baker
mesh_terms: D000818:Animals; D001666:Binding Sites, Antibody; D015789:HLA-A2 Antigen / Q000737:chemistry / Q000276:immunology; D006801:Humans; D051379:Mice; D062105:Molecular Docking Simulation; D009154:Mutation; D011485:Protein Binding; D011948:Receptors, Antigen, T-Cell / Q000737:chemistry* / Q000235:genetics / Q000276:immunology
chemical_list: D015789:HLA-A2 Antigen; D011948:Receptors, Antigen, T-Cell