A naturally processed mitochondrial self-peptide in complex with thymic MHC molecules functions as a selecting ligand for a viral-specific T cell receptor.
Peptide fragments of self-proteins bound to major histocompatibility complex molecules within the thymus are important for positively selecting T cell receptor (TCR)-bearing CD4(+)CD8(+) double positive (DP) thymocytes for further maturation. The relationship between naturally processed thymic self-peptides and TCR-specific cognate peptides is unknown. Here we employ HPLC purification of peptides released from H-2K(b) molecules of the C57BL/6 thymus in conjunction with mass spectrometry (MS) and functional profiling to identify a naturally processed K(b)-bound peptide positively selecting the N15 TCR specific for the vesicular stomatitis virus octapeptide (VSV8) bound to K(b). The selecting peptide was identified in 1 of 80 HPLC fractions and shown by tandem MS (MS/MS) sequencing to correspond to residues 68-75 of the MLRQ subunit of the widely expressed mitochondrial NADH ubiquinone oxidoreductase (NUbO(68-75)). Of note, the peptide differs at six of its eight residues from the cognate peptide VSV8 and functions as a weak agonist for mature CD8 single positive (SP) N15 T cells, with activity 10,000-fold less than VSV8. In N15 transgenic (tg) recombinase activating gene 2(-/)- transporter associated with antigen processing 1(-/)- fetal thymic organ culture, NUbO(68-75) induces phenotypic and functional differentiation of N15 TCR bearing CD8 SP thymocytes. Failure of NUbO(68-75) to support differentiation of a second K(b)-restricted TCR indicates that its inductive effects are not general.
Sasada
T
T
Laboratory of Immunobiology and Department of Cancer Immunology & AIDS, Dana-Farber Cancer Institute and Department of Medicine, Harvard Medical School, Boston, MA 02115, USA.
Ghendler
Y
Y
Neveu
J M
JM
Lane
W S
WS
Reinherz
E L
EL
D000818:Animals; D017951:Antigen Presentation; D042967:Electron Transport Complex I; D006183:H-2 Antigens / Q000276:immunology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008928:Mitochondria / Q000201:enzymology / Q000276:immunology*; D009247:NADH, NADPH Oxidoreductases / Q000276:immunology; D009842:Oligopeptides / Q000276:immunology* / Q000302:isolation & purification; D010446:Peptide Fragments / Q000276:immunology; D011948:Receptors, Antigen, T-Cell / Q000235:genetics / Q000276:immunology*; D012641:Selection, Genetic; D013950:Thymus Gland / Q000166:cytology / Q000276:immunology*; D014721:Vesicular stomatitis Indiana virus / Q000276:immunology*
D006183:H-2 Antigens; C032876:H-2Kb protein, mouse; D009842:Oligopeptides; D010446:Peptide Fragments; D011948:Receptors, Antigen, T-Cell; D009247:NADH, NADPH Oxidoreductases; D042967:Electron Transport Complex I