Summary
PDB 1SJE deposited: 2004-03-03 modified: 2009-02-24
Title HLA-DR1 complexed with a 16 residue HIV capsid peptide bound in a hairpin conformation
Authors Norris, P.J., Stern, L.J., Strug, I., Walker, B.D., Zavala-Ruiz, Z.
Method X-RAY DIFFRACTION
Structure factors resolution 2.45 rfactor 0.196 rfree 0.223
DPI 0.73 theoretical min: 0.30
Related PDB Entries 1SJH
Citations

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.

Proc Natl Acad Sci U S A. 2004 Sep 7;101(36):13279-84. Epub 2004 Aug 26.

Cross References
Database source Identifier Description
PubMed 15331779 PNASA6
Biomolecule Structure Assembly Serial Assembly Type Conformational State Chains Ligands Atoms
1SJE/1 1SJE 1 dodecamer 0 12 0 14496