title: Structure-activity relationship of T-cell receptors based on alanine scanning.
abstract: T-cell receptors (TCR) recognize complexes between human leukocyte antigens (HLA) and peptides derived from intracellular proteins. Their therapeutic use for antigen targeting, however, has been hindered by the very low binding affinity of TCRs, typically in the 1- to 100-μM range. Therefore, to construct mutant TCRs with high binding affinity, we need to understand the relationship between the structure and activity of these molecules. Here, we attempted to identify the amino acids of the TCR that are important for binding to the peptide/HLA complex. We used a TCR that recognizes complexes between HLA-A(∗)0201 and the peptide from tyrosinase, antigen overexpressed in melanoma. We changed 16 amino acids in the third complementarity-determining region within the TCR to alanine and examined the effect on binding affinity. Five alanine substitutions decreased the binding affinity to below 10% compared with that of wild-type TCR. In contrast, one alanine substitution caused a faster on-rate and slower off-rate, and increased the binding affinity to three times that of the wild-type TCR. Our results provide fundamental information for constructing mutant TCRs with high binding affinity.
authors.affiliation: Laboratory of Biotechnology and Therapeutics, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6, Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Shogo
authors.initials: S
authors.lastname: Narimatsu
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Yoshioka
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Morishige
authors.forename: Xinglei
authors.initials: X
authors.lastname: Yao
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Tsunoda
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Tsutsumi
authors.forename: Michael I
authors.initials: MI
authors.lastname: Nishimura
authors.forename: Yohei
authors.initials: Y
authors.lastname: Mukai
authors.forename: Naoki
authors.initials: N
authors.lastname: Okada
authors.forename: Shinsaku
authors.initials: S
authors.lastname: Nakagawa
mesh_terms: D000409:Alanine / Q000737:chemistry; D001324:Autoantigens / Q000276:immunology; D015234:HLA-A Antigens / Q000276:immunology*; D006801:Humans; D014442:Monophenol Monooxygenase / Q000737:chemistry; D009419:Nerve Tissue Proteins / Q000276:immunology; D011485:Protein Binding; D011948:Receptors, Antigen, T-Cell / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D013329:Structure-Activity Relationship
chemical_list: D001324:Autoantigens; C063762:CDR1 protein, human; D015234:HLA-A Antigens; D009419:Nerve Tissue Proteins; D011948:Receptors, Antigen, T-Cell; D011994:Recombinant Proteins; D014442:Monophenol Monooxygenase; D000409:Alanine