Abstact

The structure of H-2Dd complexed with the HIV-derived peptide P18-I10 (RGPGRAFVTI) has been determined by X-ray crystallography at 2.4 A resolution. This MHC class I molecule has an unusual binding motif with four anchor residues in the peptide (G2, P3, R/K/H5, and I/L/F9 or 10). The cleft architecture of H-2Dd includes a deep narrow passage accomodating the N-terminal part of the peptide, explaining the obligatory G2P3 anchor motif. Toward the C-terminal half of the peptide, p5R to p8V form a type I' reverse turn; residues p6A to p9T, and in particular p7F, are readily exposed. The structure is discussed in relation to functional data available for T cell and natural killer cell recognition of the H-2Dd molecule.