TY - JOUR
T1 - Analysis of the mutant HLA-A*0201 heavy chain H74L
T2 - Impaired TAP- dependent peptide loading
AU - Caley, Rebecca R.P.
AU - Peace-Brewer, Amy L.
AU - Matsui, Masanori
AU - Frelinger, Jeffrey A.
N1 - Funding Information:
We would like to thank Dr. H. Ploegh, Dr. J. Ting, Dr. R. Kubo, and Dr. F. Brodsky for their very generous gifts of the HCA2 antibody, anti-TAP1 antisera, the 5H9 antibody, and UCSF-2 antisera, respectively. A special thanks to Dr. Roberta Greenwood for helpful discussions, to Fabio Rosas for technical assistance, and to Dr. Edward Collins for biochemical modeling of the H74L mutation. This work was supported by the following grants: AI20288 and AI29324 as well as the NIH training grant AI07273 to R.P.C. and A.L.P-B.
PY - 1999/9
Y1 - 1999/9
N2 - A mutation of the HLA-A*0201 heavy chain at position 74 from histidine to leucine (H74L) resulted in a molecule with an interesting phenotype. H74L- expressing targets were recognized by peptide-specific HLA-A*0201-restricted cytotoxic T lymphocytes at lower peptide concentrations than wild type HLA- A*0201. H74L's improved ability to sensitize cells for lysis was due to its enhanced capability to bind exogenous peptide. Furthermore, this phenotype of improved exogenous binding and functional recognition was not peptide- specific, in contrast, the H74L molecule failed to present the HIV-1 HLA-A2- restricted pol peptide when expressed and processed endogenously. The inability to bind endogenous pol could be rescued by preceding the pol peptide with a signal sequence. The defect affecting endogenous presentation, therefore, appeared to be limited to the TAP-dependent pathway. Surprisingly, the H74L heavy chain was able to enter the defined MHC class I pathway and associate with β2M, calreticulin, tapasin, and TAP. Despite the presence of the H74L heavy chain at the TAP complex, H74L was functionally inefficient at loading TAP-dependent peptides. H74L may help elucidate further steps in the process of loading TAP-dependent peptides into the class I cleft.
AB - A mutation of the HLA-A*0201 heavy chain at position 74 from histidine to leucine (H74L) resulted in a molecule with an interesting phenotype. H74L- expressing targets were recognized by peptide-specific HLA-A*0201-restricted cytotoxic T lymphocytes at lower peptide concentrations than wild type HLA- A*0201. H74L's improved ability to sensitize cells for lysis was due to its enhanced capability to bind exogenous peptide. Furthermore, this phenotype of improved exogenous binding and functional recognition was not peptide- specific, in contrast, the H74L molecule failed to present the HIV-1 HLA-A2- restricted pol peptide when expressed and processed endogenously. The inability to bind endogenous pol could be rescued by preceding the pol peptide with a signal sequence. The defect affecting endogenous presentation, therefore, appeared to be limited to the TAP-dependent pathway. Surprisingly, the H74L heavy chain was able to enter the defined MHC class I pathway and associate with β2M, calreticulin, tapasin, and TAP. Despite the presence of the H74L heavy chain at the TAP complex, H74L was functionally inefficient at loading TAP-dependent peptides. H74L may help elucidate further steps in the process of loading TAP-dependent peptides into the class I cleft.
KW - Antigen binding
KW - Antigen presentation
KW - MHC
KW - Transporters
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U2 - 10.1016/S0198-8859(99)00022-1
DO - 10.1016/S0198-8859(99)00022-1
M3 - Article
C2 - 10527381
AN - SCOPUS:0032866988
SN - 0198-8859
VL - 60
SP - 743
EP - 754
JO - Human Immunology
JF - Human Immunology
IS - 9
ER -