Insights into MHC class I peptide loading from the structure of the tapasin-ERp57 thiol oxidoreductase heterodimer.Dong, G., Wearsch, P.A., Peaper, D.R., Cresswell, P., Reinisch, K.M.
(2009) Immunity 30: 21-32
- PubMed: 19119025
- DOI: https://doi.org/10.1016/j.immuni.2008.10.018
- Primary Citation of Related Structures:
- PubMed Abstract:
Tapasin is a glycoprotein critical for loading major histocompatibility complex (MHC) class I molecules with high-affinity peptides. It functions within the multimeric peptide-loading complex (PLC) as a disulfide-linked, stable heterodimer with the thiol oxidoreductase ERp57, and this covalent interaction is required to support optimal PLC activity. Here, we present the 2.6 A resolution structure of the tapasin-ERp57 core of the PLC. The structure revealed that tapasin interacts with both ERp57 catalytic domains, accounting for the stability of the heterodimer, and provided an example of a protein disulfide isomerase family member interacting with substrate. Mutational analysis identified a conserved surface on tapasin that interacted with MHC class I molecules and was critical for peptide loading and editing functions of the tapasin-ERp57 heterodimer. By combining the tapasin-ERp57 structure with those of other defined PLC components, we present a molecular model that illuminates the processes involved in MHC class I peptide loading.
Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06520, USA.