1sje

From Proteopedia

HLA-DR1 complexed with a 16 residue HIV capsid peptide bound in a hairpin conformation

Overview

T cells generally recognize peptide antigens bound to MHC proteins through, contacts with residues found within or immediately flanking the seven- to, nine-residue sequence accommodated in the MHC peptide-binding groove., However, some T cells require peptide residues outside this region for, activation, the structural basis for which is unknown. Here, we have, investigated a HIV Gag-specific T cell clone that requires an unusually, long peptide antigen for activation. The crystal structure of a minimally, antigenic 16-mer bound to HLA-DR1 shows that the peptide C-terminal region, bends sharply into a hairpin turn as it exits the binding site, orienting, peptide residues outside the MHC-binding region in position to interact, with a T cell receptor. Peptide truncation and substitution studies show, that both the hairpin turn and the extreme C-terminal residues are, required for T cell activation. These results demonstrate a previously, unrecognized mode of MHC-peptide-T cell receptor interaction.

About this Structure

1SJE is a Protein complex structure of sequences from Homo sapiens and Staphylococcus aureus. Full crystallographic information is available from OCA.

Reference

A hairpin turn in a class II MHC-bound peptide orients residues outside the binding groove for T cell recognition., Zavala-Ruiz Z, Strug I, Walker BD, Norris PJ, Stern LJ, Proc Natl Acad Sci U S A. 2004 Sep 7;101(36):13279-84. Epub 2004 Aug 26. PMID:15331779

Page seeded by OCA on Mon Nov 12 19:14:36 2007