Fig. 4: Similarity between the pMHC structures with pMLL_747–755 and pDOT1L_998–1006 epitopes indicates the presence of a shared TCR recognition motif.

In a and b, amino acid residues are sticks, H-bonds (distance cutoff <3.5 Å) - dotted lines. a Alignment of the crystal structures for pMLL_747–755/HLA-B*0702 (carbon atoms are gray) and DOT1L_998–1006/HLA-B*0702 (carbon atoms are yellow). H-bonds are shown between DOT1L_998–1006 and Arg₆₂ or Arg₁₅₆. The arrow points to the direction of a helical shift. b Distinct H-bond patterns (bonds are dotted lines) in the crystal structures of pMLL_747–755/HLA-B*0702 and pDOT1L_998–1006/HLA-B*0702. Only HLA residues with different conformations and/or interaction patterns are shown. The carbon atoms in epitopes are colored in gray. Individual residues in pMLL_747–755 (c) or pDOT1L_998–1006 (e) peptides (all atoms are presented as Van-der-Waals spheres) are shaded according to relative solvent exposure (from none - white to 100% - dark blue). The cartoon models display the respective peptide-binding sites in HLA-B*0702. The minor alternate conformation of pSer-P₄ in the pMHC structure with pMLL_747–755 was omitted for clarity. Identical residues in epitope sequences are red-colored. Relative solvent-exposed surface area (SASA) is presented as a percentage of all surface area (ASA) for each epitope residue in the crystal structures of pMLL_747–755/HLA-B*0702 (d) or pDOT1L_998–1006/HLA-B*0702/ (f). Anchor residues are marked by down arrows.