5t70

Publication Abstract from PubMed

Major histocompatibility complex class I (MHC-I) molecules play a crucial role in immunity by capturing peptides for presentation to T cells and natural killer (NK) cells. The peptide termini are tethered within the MHC-I antigen-binding groove, but it is unknown whether other presentation modes occur. Here we show that 20% of the HLA-B*57:01 peptide repertoire comprises N-terminally extended sets characterized by a common motif at position 1 (P1) to P2. Structures of HLA-B*57:01 presenting N-terminally extended peptides, including the immunodominant HIV-1 Gag epitope TW10 (TSTLQEQIGW), showed that the N terminus protrudes from the peptide-binding groove. The common escape mutant TSNLQEQIGW bound HLA-B*57:01 canonically, adopting a dramatically different conformation than the TW10 peptide. This affected recognition by killer cell immunoglobulin-like receptor (KIR) 3DL1 expressed on NK cells. We thus define a previously uncharacterized feature of the human leukocyte antigen class I (HLA-I) immunopeptidome that has implications for viral immune escape. We further suggest that recognition of the HLA-B*57:01-TW10 epitope is governed by a 'molecular tension' between the adaptive and innate immune systems.

MHC-I peptides get out of the groove and enable a novel mechanism of HIV-1 escape.,Pymm P, Illing PT, Ramarathinam SH, O'Connor GM, Hughes VA, Hitchen C, Price DA, Ho BK, McVicar DW, Brooks AG, Purcell AW, Rossjohn J, Vivian JP Nat Struct Mol Biol. 2017 Feb 20. doi: 10.1038/nsmb.3381. PMID:28218747^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.