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Publication Abstract from PubMed

alphabeta T cell receptors (TCRs) interact with peptides bound to the polymorphic Major Histocompatibility Complex class Ia (MHC-Ia) and class II (MHC-II) molecules, as well as the essentially monomorphic MHC class Ib (MHC-Ib) molecules. While there is a large amount of information on how TCRs engage with MHC-Ia and MHC-II, our understanding of TCR-MHC-Ib interactions is very limited. Infection with cytomegalovirus (CMV) can elicit a CD8+ T cell response restricted by the human MHC-Ib molecule, Human Leukocyte Antigen (HLA)-E, and specific for an epitope from UL40 (VMAPRTLIL), which is characterized by biased TRBV14 gene usage. Here we describe an HLA-E-restricted CD8+ T cell able to recognize an allotypic variant of the UL40 peptide, with a modification at position 8 (P8) of the peptide (VMAPRTLVL) that uses the TRBV9 gene segment. We report the structures of a TRBV9+ TCR in complex with the HLA-E molecule presenting the two peptides. Our data revealed that the TRBV9+ TCR adopts a different docking mode and molecular footprint atop HLA-E when compared with the TRBV14+ TCR-HLA-E ternary complex. Additionally, despite their differing V gene segment usage and different docking mechanisms, mutational analyses showed that the TCRs shared a conserved energetic footprint on the HLA-E molecule, focussed around the peptide-binding groove. Hence, we provide new insights into how monomorphic MHC molecules interact with T cells.

A conserved energetic footprint underpins recognition of Human Leukocyte Antigen-E by two distinct alphabeta T cell receptors.,Sullivan LC, Walpole NG, Farenc C, Pietra G, Sum MJW, Clements CS, Lee EJ, Beddoe T, Falco M, Mingari MC, Moretta L, Gras S, Rossjohn J, Brooks AG J Biol Chem. 2017 Sep 25. pii: jbc.M117.807719. doi: 10.1074/jbc.M117.807719. PMID:28972140^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.