Increased Diversity of the HLA-B40 Ligandome by the Presentation of Peptides Phosphorylated at Their Main Anchor Residue
| Autor: | Juan Pablo Albar, Adán Alpízar, Manuel João Ramos, Miguel Marcilla, Antonio Ramos-Fernández, Manuel Lombardía |
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| Rok vydání: | 2014 |
| Předmět: |
Proteome
Antigen presentation Peptide Human leukocyte antigen Biology Ligands Biochemistry Analytical Chemistry chemistry.chemical_compound Affinity chromatography Protein Interaction Mapping Humans Amino Acid Sequence Phosphorylation Binding site Molecular Biology Peptide sequence chemistry.chemical_classification Antigen Presentation Binding Sites Research HLA-B40 Antigen Phosphoproteins Antigenic Variation Molecular biology Peptide Fragments Epitope mapping chemistry Phosphoserine Epitope Mapping T-Lymphocytes Cytotoxic |
| Zdroj: | Repisalud Instituto de Salud Carlos III (ISCIII) |
| Popis: | The massspectrometry proteomics data have been deposited at the Proteome-Xchange Consortium (http://proteomecentral.proteomexchange.org)via the PRIDE partner repository with the dataset identifier PXD000450and the PRIDE accession number 31118 Human leukocyte antigen (HLA) class I molecules bind peptides derived from the intracellular degradation of endogenous proteins and present them to cytotoxic T lymphocytes, allowing the immune system to detect transformed or virally infected cells. It is known that HLA class I-associated peptides may harbor posttranslational modifications. In particular, phosphorylated ligands have raised much interest as potential targets for cancer immunotherapy. By combining affinity purification with high-resolution mass spectrometry, we identified more than 2000 unique ligands bound to HLA-B40. Sequence analysis revealed two major anchor motifs: aspartic or glutamic acid at peptide position 2 (P2) and methionine, phenylalanine, or aliphatic residues at the C terminus. The use of immobilized metal ion and TiO2 affinity chromatography allowed the characterization of 85 phosphorylated ligands. We further confirmed every sequence belonging to this subset by comparing its experimental MS2 spectrum with that obtained upon fragmentation of the corresponding synthetic peptide. Remarkably, three phospholigands lacked a canonical anchor residue at P2, containing phosphoserine instead. Binding assays showed that these peptides bound to HLA-B40 with high affinity. Together, our data demonstrate that the peptidome of a given HLA allotype can be broadened by the presentation of peptides with posttranslational modifications at major anchor positions. We suggest that ligands with phosphorylated residues at P2 might be optimal targets for T-cell-based cancer immunotherapy. Sí |
| Databáze: | OpenAIRE |
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