Related Experiment Video
Updated: May 21, 2026
08:07
Personalized Peptide Arrays for Detection of HLA Alloantibodies in Organ Transplantation
Published on: September 6, 2017
Mapping the HLA-DO/HLA-DM complex by FRET and mutagenesis
Taejin Yoon1, Henriette Macmillan, Sarah E Mortimer
1Department of Pediatrics, Program in Immunology, Stanford University, Stanford, CA 94305, USA.
Summary
Human Leukocyte Antigen-DO (DO) inhibits HLA-DM (DM) function. Researchers mapped the DO/DM binding site using stable recombinant proteins and FRET, revealing a lateral surface on DO and a key region on DM.
Area of Science:
- Immunology
- Molecular Biology
- Structural Biology
Background:
- Human Leukocyte Antigen-DO (DO) is a nonclassic class II heterodimer.
- DO inhibits the class II peptide exchange catalyst, HLA-DM (DM), and influences its localization.
- DM also chaperones DO, facilitating its exit from the endoplasmic reticulum (ER).
Purpose of the Study:
- To determine the binding topology of DO/DM complexes.
- To overcome technical limitations posed by DO instability.
- To elucidate the mechanism of DO inhibition of DM.
Main Methods:
- Generation of stable recombinant soluble DO variants (zippered DOαP11A and chimeric sDO-Fc).
- Confirmation of conformational integrity and inhibitory function of DO variants.
- Intermolecular fluorescence resonance energy transfer (FRET) and mutagenesis to probe DO/DM interactions.
Main Results:
- Stable DO variants retained inhibitory activity across the active pH range of DM (4.7 to ~6.0).
- A lateral surface spanning the α1 and α2 domains of DO was identified as the binding site for DM.
- A specific region on DM was identified as important for interaction with DO.
Conclusions:
- The study defines a putative binding surface and orientation for the DO/DM complex.
- These findings provide insights into the mechanism by which DO inhibits DM.
- Understanding DO/DM interactions is crucial for antigen presentation research.
