title: HLA-DQ-binding peptide motifs. 1. Comparative binding analysis of type II collagen-derived peptides to DR and DQ molecules of rheumatoid arthritis-susceptible and non-susceptible haplotypes.
abstract: The frequency of the HLA-DR4-DQ4 haplotype (DRB1(*)0405-DQA1(*)0302-DQB1(*)0401) is significantly increased in Japanese patients with rheumatoid arthritis (RA) and DRB1(*)0405-binding peptide motifs were identified in our previous studies. To clarify the DQ4-binding peptide motifs, the primary structure of DQ4-binding peptides was determined by affinity-based selection of a phage random peptide library. Analog peptides of a high-affinity DQ4 binder revealed that two major anchors (VxxxxxxxR; where x is any amino acid) play an essential role in binding to DQ4. The affinity of synthetic VAAAAAAAR-based analog peptides showed that substituting V to W, G, L, I, M, P, F, Y or A and R to H, M, L, I or V allows binding. The involvement of the ninth residue of the peptides, especially Arg, was critical for high-affinity binding. In comparison with other class II-binding peptide motifs reported to date, peptide motifs for DQ4 were unique, in that Gly and Pro are allowed as low-affinity N-terminal anchors. Interestingly, 94 putative DQ4-binding motifs were detected in the human type II collagen molecule, since it is composed of (Gly-X1-X2)n and is rich in R and P at positions X2. However, no significant differences were observed between the affinities of the collagen-derived peptides with DR or DQ molecules of RA-susceptible DR4-DQ4 and with those of non-susceptible DR4-DQ8 (DRB1(*)0406-DQA1(*)0301-DQB1(*)0302) haplotypes, indicating that the susceptibility to RA is not a simple immune response gene phenomenon specific to collagen. The immunogenetic implications of the unique peptide motifs for DQ are discussed.
authors.affiliation: Department of Neuroscience and Immunology, Kumamoto University Graduate School of Medical Sciences, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Matsushita
authors.forename: T
authors.initials: T
authors.lastname: Nishi
authors.forename: M
authors.initials: M
authors.lastname: Oiso
authors.forename: K
authors.initials: K
authors.lastname: Yamaoka
authors.forename: K
authors.initials: K
authors.lastname: Yone
authors.forename: T
authors.initials: T
authors.lastname: Kanai
authors.forename: Y
authors.initials: Y
authors.lastname: Nishimura
mesh_terms: D000595:Amino Acid Sequence; D001172:Arthritis, Rheumatoid / Q000235:genetics* / Q000276:immunology*; D003094:Collagen / Q000276:immunology / Q000378:metabolism*; D006683:HLA-DQ Antigens / Q000276:immunology / Q000378:metabolism*; D006684:HLA-DR Antigens / Q000276:immunology / Q000378:metabolism*; D006239:Haplotypes / Q000276:immunology; D006801:Humans; D008969:Molecular Sequence Data; D010455:Peptides / Q000276:immunology / Q000378:metabolism*; D011485:Protein Binding / Q000276:immunology; D011487:Protein Conformation
chemical_list: D006683:HLA-DQ Antigens; D006684:HLA-DR Antigens; D010455:Peptides; D003094:Collagen