Sequence motifs important for peptide binding to the human MHC class I molecule, HLA-A2.
Previous studies have indicated that most HLA-A2-binding peptides are 9 amino acid (aa) residues long, with a Leu at position 2 (P2), and a Val or Leu at P9. We compared the binding properties of different peptides by measuring the rate of dissociation of beta 2-microglobulin from peptide-specific HLA-A2 complexes. The simplest peptide that we identified that could form HLA-A2 complexes had the sequence (in single letter aa code) GLFGGGGGV, indicating that three nonglycine aa are sufficient for binding to HLA-A2. To determine whether most nonapeptides that contained Leu at P2 and Val or Leu at P9 could bind to HLA-A2, we tested the binding of nonapeptides selected from published HIV and melanoma protein sequences, and found that six of seven tested formed stable HLA-A2 complexes. We identified an optimal antigenic undecapeptide from the cytomegalovirus gB protein that could form stable HLA-A2 complexes that contained apparent anchor residues at P2 and P11 (sequence FIAGN-SAYEYV), indicating that the spacing between anchor residues can be somewhat variable. Finally, we tested the importance of every aa in the influenza A matrix peptide 58-66 (sequence GILGFVFTL) for binding to HLA-A2, by using Ala-substituted and Lys-substituted peptides. We found that multiple positions were important for stable binding, including P2, P3, P5-P7, and P9. We conclude that the P2 and P9 anchor residues are of prime importance for peptide binding to HLA-A2. However, other peptide side chains (especially at P3) contribute to the stability of the interaction. In certain cases, the optimal length for peptide binding can be longer than 9 residues.
Parker
K C
KC
Biological Resources Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892.
Bednarek
M A
MA
Hull
L K
LK
Utz
U
U
Cunningham
B
B
Zweerink
H J
HJ
Biddison
W E
WE
Coligan
J E
JE
D000595:Amino Acid Sequence; D000956:Antigens, Viral / Q000737:chemistry* / Q000276:immunology; D003587:Cytomegalovirus / Q000276:immunology; D005998:Glycine / Q000737:chemistry; D015488:HIV Antigens / Q000276:immunology; D015497:HIV-1 / Q000276:immunology; D015789:HLA-A2 Antigen / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D009980:Influenza A virus / Q000276:immunology; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000378:metabolism*; D013329:Structure-Activity Relationship; D014763:Viral Matrix Proteins / Q000737:chemistry / Q000276:immunology*
D000956:Antigens, Viral; D015488:HIV Antigens; D015789:HLA-A2 Antigen; D010455:Peptides; D014763:Viral Matrix Proteins; D005998:Glycine