Distinct CDR3 conformations in TCRs determine the level of cross-reactivity for diverse antigens, but not the docking orientation.

ABSTRACT: T cells are known to cross-react with diverse peptide MHC Ags through their alphabeta TCR. To explore the basis of such cross-reactivity, we examined the 2C TCR that recognizes two structurally distinct ligands, SIY-K(b) and alloantigen QL9-L(d). In this study we characterized the cross-reactivity of several high-affinity 2C TCR variants that contained mutations only in the CDR3alpha loop. Two of the TCR lost their ability to cross-react with the reciprocal ligand (SIY-K(b)), whereas another TCR (m67) maintained reactivity with both ligands. Crystal structures of four of the TCRs in complex with QL9-L(d) showed that CDR1, CDR2, and CDR3beta conformations and docking orientations were remarkably similar. Although the CDR3alpha loop of TCR m67 conferred a 2000-fold higher affinity for SIY-K(

SUBMITTER: Jones LL 

PROVIDER: S-EPMC2598777 | biostudies-literature | 2008 Nov

REPOSITORIES: biostudies-literature