A T cell receptor flattens a bulged antigenic peptide presented by a major histocompatibility complex class I molecule

Abstract

Plasticity of the T cell receptor (TCR) is a hallmark of major histocompatibility complex (MHC)-restricted T cell recognition. However, it is unclear whether interactions of TCR and peptide-MHC class I (pMHCI) always conform to this paradigm. Here we describe the structure of a TCR, ELS4, in its non-ligand-bound form and in complex with a prominent 'bulged' Epstein-Barr virus peptide bound to HLA-B*3501. This complex was atypical of previously characterized TCR-pMHCI interactions in that a rigid face of the TCR crumpled the bulged antigenic determinant. This peptide 'bulldozing' created a more featureless pMHCI determinant, allowing the TCR to maximize MHC class I contacts essential for MHC ..