PMID: 28855257
Mobbs JI, Illing PT, Dudek NL, Brooks AG, Baker DG, Purcell AW, Rossjohn J, Vivian JP
The molecular basis for peptide repertoire selection in the Human Leucocyte Antigen (HLA) C*06:02 molecule.
J Biol Chem. 2017 Aug 30. pii: jbc.M117.806976. doi: 10.1074/jbc.M117.806976.
Human Leucocyte antigen (HLA) C*06:02 is identified as the allele associated with the highest risk for the development of the autoimmune skin disease psoriasis. However, the diversity and mode of peptide presentation by the HLA-C*06:02 molecule remains unclear. Here, we describe the endogenous peptide repertoire of approximately 3,000 sequences for HLA-C*06:02 that defines the peptide-binding motif for this HLA allomorph. We found that HLA-C*06:02 predominantly presents nonamer peptides with dominant arginine anchors at the P2 & P7 positions and a preference for small hydrophobic residues at the C-terminus (Pomega). To determine the structural basis of this selectivity, we determined crystal structures of HLA-C*06:02 in complex with two self-peptides (ARTELYRSL and ARFNDLRFV) and an analogue of a melanocyte auto-antigen (ADAMTSL5, VRSRR-abu-LRL) implicated in psoriasis. These structures revealed that HLA-C*06:02 possesses a deep peptide-binding groove comprising two electronegative B- and E-pockets that coincide with the preference for P2 and P7 arginine anchors. The ADAMTSL5 autoantigen possessed a P7-Leu instead of the P7-Arg residue, but nevertheless was accommodated within the HLA-C*06:02 antigen-binding cleft. Collectively, our results provide the structural basis for understanding peptide repertoire selection in HLA-C*06:02.