5knm
Human leukocyte antigen F (HLA-F) presents peptides and regulates immunity through interactions with NK-cell receptors
Structural highlights
FunctionHLAF_HUMAN Non-classical major histocompatibility class Ib molecule postulated to play a role in immune surveillance, immune tolerance and inflammation. Functions in two forms, as a heterotrimeric complex with B2M/beta-2 microglobulin and a peptide (peptide-bound HLA-F-B2M) and as an open conformer (OC) devoid of peptide and B2M (peptide-free OC). In complex with B2M, presents non-canonical self-peptides carrying post-translational modifications, particularly phosphorylated self-peptides. Peptide-bound HLA-F-B2M acts as a ligand for LILRB1 inhibitory receptor, a major player in maternal-fetal tolerance. Peptide-free OC acts as a ligand for KIR3DS1 and KIR3DL2 receptors (PubMed:28636952). Upon interaction with activating KIR3DS1 receptor on NK cells, triggers NK cell degranulation and anti-viral cytokine production (PubMed:27455421). Through interaction with KIR3DL2 receptor, inhibits NK and T cell effector functions (PubMed:24018270). May interact with other MHC class I OCs to cross-present exogenous viral, tumor or minor histompatibility antigens to cytotoxic CD8+ T cells, triggering effector and memory responses (PubMed:23851683). May play a role in inflammatory responses in the peripheral nervous system. Through interaction with KIR3DL2, may protect motor neurons from astrocyte-induced toxicity (PubMed:26928464).[1] [2] [3] [4] [5] Publication Abstract from PubMedEvidence is mounting that the major histocompatibility complex (MHC) molecule HLA-F (human leukocyte antigen F) regulates the immune system in pregnancy, infection, and autoimmunity by signaling through NK cell receptors (NKRs). We present structural, biochemical, and evolutionary analyses demonstrating that HLA-F presents peptides of unconventional length dictated by a newly arisen mutation (R62W) that has produced an open-ended groove accommodating particularly long peptides. Compared to empty HLA-F open conformers (OCs), HLA-F tetramers bound with human-derived peptides differentially stained leukocytes, suggesting peptide-dependent engagement. Our in vitro studies confirm that NKRs differentiate between peptide-bound and peptide-free HLA-F. The complex structure of peptide-loaded beta2m-HLA-F bound to the inhibitory LIR1 revealed similarities to high-affinity recognition of the viral MHC-I mimic UL18 and a docking strategy that relies on contacts with HLA-F as well as beta2m, thus precluding binding to HLA-F OCs. These findings provide a biochemical framework to understand how HLA-F could regulate immunity via interactions with NKRs. Human Leukocyte Antigen F Presents Peptides and Regulates Immunity through Interactions with NK Cell Receptors.,Dulberger CL, McMurtrey CP, Holzemer A, Neu KE, Liu V, Steinbach AM, Garcia-Beltran WF, Sulak M, Jabri B, Lynch VJ, Altfeld M, Hildebrand WH, Adams EJ Immunity. 2017 Jun 20;46(6):1018-1029.e7. doi: 10.1016/j.immuni.2017.06.002. PMID:28636952[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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