Download MendeleyPeptide exchange on MHC-I by TAPBPR is driven by a negative allostery release cycle.
McShan, A.C., Natarajan, K., Kumirov, V.K., Flores-Solis, D., Jiang, J., Badstubner, M., Toor, J.S., Bagshaw, C.R., Kovrigin, E.L., Margulies, D.H., Sgourakis, N.G.(2018) Nat Chem Biol 14: 811-820
- PubMed: 29988068
- DOI: https://doi.org/10.1038/s41589-018-0096-2
- Primary Citation of Related Structures:
6B9K - PubMed Abstract:
Chaperones TAPBPR and tapasin associate with class I major histocompatibility complexes (MHC-I) to promote optimization (editing) of peptide cargo. Here, we use solution NMR to investigate the mechanism of peptide exchange. We identify TAPBPR-induced conformational changes on conserved MHC-I molecular surfaces, consistent with our independently determined X-ray structure of the complex. Dynamics present in the empty MHC-I are stabilized by TAPBPR and become progressively dampened with increasing peptide occupancy. Incoming peptides are recognized according to the global stability of the final pMHC-I product and anneal in a native-like conformation to be edited by TAPBPR. Our results demonstrate an inverse relationship between MHC-I peptide occupancy and TAPBPR binding affinity, wherein the lifetime and structural features of transiently bound peptides control the regulation of a conformational switch located near the TAPBPR binding site, which triggers TAPBPR release. These results suggest a similar mechanism for the function of tapasin in the peptide-loading complex.
Organizational Affiliation:
Department of Chemistry and Biochemistry, University of California Santa Cruz, Santa Cruz, CA, USA.
