RESUMO
The structural determination of peptide:HLA (human leucocyte antigen) class I complexes by X-ray crystallography has provided valuable information for understanding how peptides bind to individual HLA class I molecules and how this may influence the immune response. We compared 101 crystal structures of 9-mer peptide:HLA class I complexes available in the protein data bank (PDB) by performing a contact analysis using the Contact Map Analysis webserver http://ligin.weizmann.ac.il/cma. An InterSystems Caché 'post-relational' database containing residue position, amino acid (AA) and buried surface that contact a particular peptide position was then created allowing data comparison for all the structures (Pocketcheck). The analysis illustrates that the HLA class I residues 24, 45, 63 and 67 show high contact frequencies to both the p1 and/or p2 position of bound peptides, indicating that they might influence the nature of a peptide anchor. To determine the influence of these residues we utilized soluble HLA technology and mass spectrometry to analyze peptides derived from HLA-B*44:06 since it differs from the previously described allele B*44:02 by seven AA exchanges located in the alpha 1 domain (residues 24, 32, 41, 45, 63, 67 and 80). HLA-B*44:06 features an anchor motif of P or A at p2 and Y or W at the C-terminal. Additionally B*44:06-derived peptides feature an auxiliary anchor motif at p1, comprising D or E. Our results illustrate that structural analysis can provide valuable information to understand allogenicity and provides a further step towards intelligent HLA mismatching.
Assuntos
Antígenos de Histocompatibilidade Classe I/química , Antígenos de Histocompatibilidade Classe I/imunologia , Peptídeos/química , Peptídeos/imunologia , Alelos , Sequência de Aminoácidos , Aminoácidos/metabolismo , Linhagem Celular , Biologia Computacional , Bases de Dados de Proteínas , Antígenos de Histocompatibilidade Classe I/genética , Humanos , Ligantes , Dados de Sequência Molecular , Polimorfismo Genético , Ligação ProteicaRESUMO
Sequencing of HLA-C*07:55N assessed the presence of a premature TAG stop codon at residue 113.
Assuntos
Antígenos HLA-C/genética , Alelos , Aminoácidos , Sequência de Bases , Códon sem Sentido , Éxons , Alemanha , Antígenos HLA-C/imunologia , Teste de Histocompatibilidade , Homozigoto , Humanos , Dados de Sequência Molecular , Nucleotídeos , Reação em Cadeia da Polimerase , Ligação Proteica , Estrutura Terciária de Proteína , Análise de Sequência de DNA , Transplante de Células-TroncoRESUMO
The new allele HLA-B*35:87 was generated by recombination between HLA-B*35:01 and B*08:01 in intron 2.
Assuntos
Alelos , Antígenos HLA-B/classificação , Antígenos HLA-B/genética , Íntrons/genética , Recombinação Genética , Humanos , Dados de Sequência Molecular , Alinhamento de Sequência , Homologia de Sequência do Ácido NucleicoRESUMO
In this study we sequenced the bound peptides from three alleles belonging to the HLA-A*74 group (HLA-A*74:04, A*74:06 and A*74:07) that are distinguished by four polymorphic residues within the peptide-binding region. Our data illustrates that A*74:04 exhibits preference for L, M or I at P2 and L, S or P at PΩ, while for A*74:07 the P2 anchor prefers L, P or I and the PΩ anchor S, P, L. In contrast A*74:06 features a P2 anchor motif of S or L, while a PΩ anchor could not be defined; however, a preference for polar residues S, T, Q or the charged residue R at the PΩ position could be detected.
Assuntos
Antígenos HLA-A/genética , Peptídeos/genética , Alelos , Motivos de Aminoácidos , Sequência de Aminoácidos , Sítios de Ligação , Antígenos HLA-A/química , Antígenos HLA-A/imunologia , Humanos , Dados de Sequência Molecular , Peptídeos/química , Peptídeos/imunologiaRESUMO
We here describe the identification of the novel human leukocyte antigen allele HLA-A*02:182 which has been detected in a potential bone marrow donor. The new allele differs from the sequence of HLA-A*02:01:01:01 only by a non-synonymous nucleotide exchange of Guanin (G) â Cytosin (C) at position 199 in exon 3 replacing amino acid (AA) Arginine (Arg, R) by Threonine (Thr, T) in codon 157. Since the HLA-A*02:01:01:01 allele differs from A*02:182 only at AA position 157, it is assumed that the protein structures of these alleles are highly similar. A mismatch between HLA-A*02:01:01:01 and HLA-A*02:182 is predicted to have a very low allogeneic potential in hematopoietic stem cell transplantation.
Assuntos
Variação Genética/genética , Antígenos HLA-A/genética , Transplante de Células-Tronco Hematopoéticas , Doadores de Tecidos , Alelos , Sequência de Aminoácidos , Sequência de Bases , Medula Óssea/imunologia , Antígeno HLA-A2 , Humanos , Dados de Sequência Molecular , Reação em Cadeia da Polimerase , Homologia de Sequência de Aminoácidos , Homologia de Sequência do Ácido NucleicoRESUMO
The human leukocyte antigen (HLA)-A*03 group has more than 90 known members and is one of the largest families of HLA class I alleles, with the most common variant being HLA-A*0301. In this study, we determined the peptide-binding motif of the highly frequent Sudanese allele A*0302 and compared it with the previously published peptide-binding motif of A*0301. The two alleles differ only at two distinct residues Glu152Val and Leu156Gln, which are predicted to be part of specificity pockets D, C and E and thus in contact with the peptide. Soluble recombinant A*0302 was expressed, affinity purified and the bound peptides were then eluted and analysed by mass spectrometry. The peptide-binding motif of A*0302 differs significantly from the previously published HLA-A*0301 and the Glu152Val/Leu156Gln mismatches appear to have a significant impact on the peptide-binding features of A*0302 and A*0301.
