Identification of novel HLA-B27 ligands derived from polymorphic regions of its own or other class I molecules based on direct generation by 20 S proteasome.
HLA-B27 is strongly associated with ankylosing spondylitis. Natural HLA-B27 ligands derived from polymorphic regions of its own or other class I HLA molecules might be involved in autoimmunity or provide diversity among HLA-B27-bound peptide repertoires from individuals. In particular, an 11-mer spanning HLA-B27 residues 169-179 is a natural HLA-B27 ligand with homology to proteins from Gram-negative bacteria. Proteasomal digestion of synthetic substrates demonstrated direct generation of the B27-(169-179) ligand. Cleavage after residue 181 generated a B27-(169-181) 13-mer that was subsequently found as a natural ligand of B*2705 and B*2704. Its binding to HLA-B27 subtypes in vivo correlated better than B27-(169-179) with association to spondyloarthropathy. Proteasomal cleavage generated also a peptide spanning B*2705 residues 150-158. This region is polymorphic among HLA-B27 subtypes and class I HLA antigens. The peptide was a natural B*2704 ligand. Since this subtype differs from B*2705 at residue 152, it was concluded that the ligand arose from HLA-B*3503, synthesized in the cells used as a source for B*2704-bound peptides. Thus, polymorphic HLA-B27 ligands derived from HLA-B27 or other class I molecules are directly produced by the 20 S proteasome in vitro, and this can be used for identification of such ligands in the constitutive HLA-B27-bound peptide pool.
Alvarez
I
I
Centro de Biologia Molecular Severo Ochoa (C.S.I.C.-U.A.M.), Universidad Autónoma de Madrid, Facultad de Ciencias, Madrid, Spain.
Sesma
L
L
Marcilla
M
M
Ramos
M
M
Marti
M
M
Camafeita
E
E
de Castro
J A
JA
D000595:Amino Acid Sequence; D001665:Binding Sites; D002460:Cell Line; D002851:Chromatography, High Pressure Liquid; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D015796:HLA-B27 Antigen / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D008024:Ligands; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000378:metabolism*; D010446:Peptide Fragments / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D010950:Plasma Cells / Q000276:immunology; D011110:Polymorphism, Genetic; D046988:Proteasome Endopeptidase Complex; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013167:Spondylitis, Ankylosing / Q000235:genetics / Q000276:immunology
D015796:HLA-B27 Antigen; D008024:Ligands; D009097:Multienzyme Complexes; D010446:Peptide Fragments; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex