Peptide Research News - Alternative peptide repertoire of HLA-E reveals a binding motif that is strikingly similar to HLA-A2.

Alternative peptide repertoire of HLA-E reveals a binding motif that is strikingly similar to HLA-A2.

Mol Immunol. 2012 Aug 13;53(1-2):126-131

Authors: Lampen MH, Hassan C, Sluijter M, Geluk A, Dijkman K, Tjon JM, de Ru AH, van der Burg SH, van Veelen PA, van Hall T

Abstract
The non-classical HLA-E is a conserved class I molecule that mainly presents monomorphic leader peptides derived from other HLA class I molecules. These leader peptides comprise an optimized sequence for tight and deep binding into the HLA-E groove. In a TAP-deficient environment, as it can be generated during viral infection or in tumor tissue, loading of the classical leader peptide sequences is hampered leading to an alternative HLA-E peptide repertoire. In this study, we characterized this alternative peptide repertoire using cells in which TAP activity is inhibited. We identified more than 500 unique peptide sequences carried by HLA-E and found that their binding motif is different from the dominant leader peptides. Hydrophobic amino acids were only found at positions 2 and 9, in close resemblance to the peptide binding motif of HLA-A*0201. HLA-E-eluted peptides were indeed able to bind this classical HLA class I molecule. Our findings suggest that the dominant leader peptides uniquely conform to HLA-E, but that in their absence a peptide pool is presented like that of HLA-A*0201.

PMID: 22898188 [PubMed - as supplied by publisher]