Specialized functions of major histocompatibility complex class I molecules. II. Hmt binds N-formylated peptides of mitochondrial and prokaryotic origin.
The physiological functions of the mouse telomeric major histocompatibility complex (MHC) class I molecules, including Hmt, are unknown. Hmt presents a polymorphic, N-formylated peptide encoded by the mitochondrial gene ND1 forming the cell surface maternally transmitted antigen (Mta). Because the N-formyl moiety is required for Hmt binding, we proposed that Hmt may function generally in presentation of N-formylated antigens. This hypothesis was validated by a competitive binding assay, demonstrating that synthetic N-formyl peptides from other mitochondrial genes also bound Hmt. Bacteria similarly initiate protein synthesis with N-formylmethionine; indeed, we established that Hmt can also present prokaryotic peptides in an N-formyl-dependent manner. These results indicate biochemical specialization of this MHC-peptide interaction and suggest a unique role for Hmt in prokaryotic host defenses.
Shawar
S M
SM
Howard Hughes Medical Institute Laboratory, Baylor College of Medicine, Houston, Texas 77030.
Vyas
J M
JM
Rodgers
J R
JR
Cook
R G
RG
Rich
R R
RR
D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000378:metabolism; D002460:Cell Line; D005260:Female; D005561:Formates; D015395:Histocompatibility Antigens Class I / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D008928:Mitochondria / Q000378:metabolism*; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000138:chemical synthesis / Q000378:metabolism*; D011485:Protein Binding; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*
D001426:Bacterial Proteins; D005561:Formates; D015395:Histocompatibility Antigens Class I; D009842:Oligopeptides