Concerted in vitro trimming of viral HLA-B27-restricted ligands by human ERAP1 and ERAP2 aminopeptidases.
In the classical human leukocyte antigen (HLA) class I antigen processing and presentation pathway, the antigenic peptides are generated from viral proteins by multiple proteolytic cleavages of the proteasome (and in some cases other cytosolic proteases) and transported to the endoplasmic reticulum (ER) lumen where they are exposed to aminopeptidase activity. In human cells, two different ER-resident enzymes, ERAP1 and ERAP2, can trim the N-terminally extended residues of peptide precursors. In this study, the possible cooperative effect of generating five naturally processed HLA-B27 ligands by both proteases was analyzed. We identified differences in the products obtained with increased detection of natural HLA-B27 ligands by comparing double versus single enzyme digestions by mass spectrometry analysis. These in vitro data suggest that each enzyme can use the degradation products of the other as a substrate for new N-terminal trimming, indicating concerted aminoproteolytic activity of ERAP 1 and ERAP2.
Centro Nacional de Microbiología, Instituto de Salud Carlos III, Madrid, Spain.
Elena
E
Lorente
Alejandro
A
Barriga
Carolina
C
Johnstone
Carmen
C
Mir
Mercedes
M
Jiménez
Daniel
D
López
D000595:Amino Acid Sequence; D000626:Aminopeptidases / Q000737:chemistry / Q000378:metabolism*; D015796:HLA-B27 Antigen / Q000378:metabolism*; D006801:Humans; D008024:Ligands; D015778:Minor Histocompatibility Antigens; D008969:Molecular Sequence Data; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary; D059748:Proteolysis; D018113:Respiratory Syncytial Virus, Human / Q000378:metabolism; D014764:Viral Proteins / Q000737:chemistry / Q000378:metabolism*
D015796:HLA-B27 Antigen; D008024:Ligands; D015778:Minor Histocompatibility Antigens; D014764:Viral Proteins; D000626:Aminopeptidases; C464841:ERAP1 protein, human; C503944:ERAP2 protein, human