A point mutation in the groove of HLA-DO allows egress from the endoplasmic reticulum independent of HLA-DM Journal Article
| Authors: | Deshaies, F.; Brunet, A.; Diallo, D. A.; Denzin, L. K.; Samaan, A.; Thibodeau, J. |
| Article Title: | A point mutation in the groove of HLA-DO allows egress from the endoplasmic reticulum independent of HLA-DM |
| Abstract: | B lymphocytes express the nonclassical class II molecule HLA-DO, which modulates the peptide loading activity of HLA-DM in the endocytic pathway. Binding to HLA-DM is required for HLA-DO to egress from the endoplasmic reticulum (ER). To gain insights into the mode of action of DO and on the role of DM in ER release, we sought to identify DM-binding residues on DO. Our results show that DOa encompasses the binding site for HLA-DM. More specifically, mutation of residue DOα41 on an exposed lateral loop of the α1 domain affects the binding to DM, ER egress, and activity of DO. Using a series of chimeric DR/DO molecules, we confirmed the role of the α chain and established that a second DM-binding region is located C-terminal to the DOα80 residue, most probably in the α2 domain. Interestingly, after mutation of a buried proline (α11) on the floor of the putative peptide-binding groove, HLA-DO remained functional but became independent of HLA-DM for ER egress and intracellular trafficking. Collectively, these results suggest that the binding of HLA-DM to DOα allows the complex to egress from the ER by stabilizing intramolecular contacts between the N-terminal antiparallel β-strands of the DOαβ heterodimer. © 2005 by The National Academy of Sciences of the USA. |
| Keywords: | controlled study; human cell; flow cytometry; protein domain; carboxy terminal sequence; protein binding; hela cells; b lymphocyte; b-lymphocytes; blotting, western; endoplasmic reticulum; antigen presentation; antibodies, monoclonal; recombinant fusion proteins; hla dr antigen; major histocompatibility antigen class 2; protein transport; immunoprecipitation; plasmids; microscopy, fluorescence; protein structure, tertiary; point mutation; antigen binding; antigen processing; hla dm antigen; hla do antigen; hla-d antigens; endocytosis; mutagenesis; hla-dr; mhc; class ii; doa |
| Journal Title: | Proceedings of the National Academy of Sciences of the United States of America |
| Volume: | 102 |
| Issue: | 18 |
| ISSN: | 0027-8424 |
| Publisher: | National Academy of Sciences |
| Date Published: | 2005-05-03 |
| Start Page: | 6443 |
| End Page: | 6448 |
| Language: | English |
| DOI: | 10.1073/pnas.0500853102 |
| PUBMED: | 15849268 |
| PROVIDER: | scopus |
| PMCID: | PMC1088373 |
| DOI/URL: | |
| Notes: | --- - "Cited By (since 1996): 9" - "Export Date: 24 October 2012" - "CODEN: PNASA" - "Source: Scopus" |
