Polymorphism in human cytomegalovirus UL40 impacts on recognition of human leukocyte antigen-E (HLA-E) by natural killer cells.
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Heatley SL, Pietra G, Lin J, Widjaja JML, Harpur CM, Lester S, Rossjohn J, Szer J, Schwarer A, Bradstock K, Bardy PG, Mingari MC, Moretta L, Sullivan LC, Brooks AG
Polymorphism in human cytomegalovirus UL40 impacts on recognition of human leukocyte antigen-E (HLA-E) by natural killer cells.
J Biol Chem. 2013 Mar 22;288(12):8679-8690. doi: 10.1074/jbc.M112.409672. Epub 2013 Jan 18.
- PubMed ID
- 23335510 [ View in PubMed]
- Abstract
Natural killer (NK) cell recognition of the nonclassical human leukocyte antigen (HLA) molecule HLA-E is dependent on the presentation of a nonamer peptide derived from the leader sequence of other HLA molecules to CD94-NKG2 receptors. However, human cytomegalovirus can manipulate this central innate interaction through the provision of a "mimic" of the HLA-encoded peptide derived from the immunomodulatory glycoprotein UL40. Here, we analyzed UL40 sequences isolated from 32 hematopoietic stem cell transplantation recipients experiencing cytomegalovirus reactivation. The UL40 protein showed a "polymorphic hot spot" within the region that encodes the HLA leader sequence mimic. Although all sequences that were identical to those encoded within HLA-I genes permitted the interaction between HLA-E and CD94-NKG2 receptors, other UL40 polymorphisms reduced the affinity of the interaction between HLA-E and CD94-NKG2 receptors. Furthermore, functional studies using NK cell clones expressing either the inhibitory receptor CD94-NKG2A or the activating receptor CD94-NKG2C identified UL40-encoded peptides that were capable of inhibiting target cell lysis via interaction with CD94-NKG2A, yet had little capacity to activate NK cells through CD94-NKG2C. The data suggest that UL40 polymorphisms may aid evasion of NK cell immunosurveillance by modulating the affinity of the interaction with CD94-NKG2 receptors.