PDB 1SJH deposited: 2004-03-03 modified: 2009-02-24
Title HLA-DR1 complexed with a 13 residue HIV capsid peptide
Authors Norris, P.J., Stern, L.J., Strug, I., Walker, B.D., Zavala-Ruiz, Z.
Structure factors resolution 2.25 rfactor 0.22 rfree 0.245
DPI 0.63 theoretical min: 0.26
Related PDB Entries 1SJE

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.Usa 2004 Sep; 101(36):13279-13284 doi:10.1073/pnas.0403371101

Cross References
Database source Identifier Description
PubMed 15331779 PNASA6
Biomolecule Structure Assembly Serial Assembly Type Conformational State Chains Ligands Atoms
1SJH/1 1SJH 1 dodecamer 0 12 0 14742