Plasticity in the Contribution of T Cell Receptor Variable Region Residues to Binding of Peptide-HLA-A2 Complexes

JOURNAL OF MOLECULAR BIOLOGY

卷:425

Article

Smith, Sheena N.¹  Sommermeyer, Daniel²  Piepenbrink, Kurt H.³  Blevins, Sydney J.³  Bernhard, Helga⁴  Uckert, Wolfgang²  Baker, Brian M.³  Kranz, David M.¹ 

[1] Univ Illinois, Dept Biochem, Urbana, IL 61801 USA

[2] Max Delbruck Ctr Mol Med, D-13125 Berlin, Germany

[3] Notre Dame Univ, Dept Chem & Biochem, South Bend, IN 46556 USA

[4] Klinikum Darmstadt, Med Klin 5, D-64283 Darmstadt, Germany

关键词: T cell receptors;    single-chain;    yeast display;    directed evolution;    germline codon bias;   

DOI  :  10.1016/j.jmb.2013.08.007

来源: Elsevier

【 摘 要 】

One hypothesis accounting for major histocompatibility complex (MHC) restriction by T cell receptors (TCRs) holds that there are several evolutionary conserved residues in TCR variable regions that contact MHC. While this germline codon hypothesis is supported by various lines of evidence, it has been difficult to test. The difficulty stems in part from the fact that TCRs exhibit low affinities for pep/MHC, thus limiting the range of binding energies that can be assigned to these key interactions using mutational analyses. To measure the magnitude of binding energies involved, here we used high-affinity TCRs engineered by mutagenesis of CDR3. The TCRs included a high-affinity, MART-1/HLA-A2-specific single-chain TCR and two other high-affinity TCRs that all contain the same V alpha region and recognize the same MHC allele (HLA-A2), with different peptides and V beta regions. Mutational analysis of residues in CDR1 and CDR2 of the three V alpha 2 regions showed the importance of the key germline codon residue Y51. However, two other proposed key residues showed significant differences among the TCRs in their relative contributions to binding. With the use of single-position, yeast-display libraries in two of the key residues, MART-1/HLA-A2 selections also revealed strong preferences for wild-type germline codon residues, but several alternative residues could also accommodate binding and, hence, MHC restriction. Thus, although a single residue (Y51) could account for a proportion of the energy associated with positive selection (i.e., MHC restriction), there is significant plasticity in requirements for particular side chains in CDR1 and CPR2 and in their relative binding contributions among different TCRs. (C) 2013 Elsevier Ltd. All rights reserved.

【 授权许可】

Free