TY - JOUR
T1 - TAPBPR employs a ligand-independent docking mechanism to chaperone MR1 molecules
AU - McShan, Andrew C.
AU - Devlin, Christine A.
AU - Papadaki, Georgia F.
AU - Sun, Yi
AU - Green, Adam I.
AU - Morozov, Giora I.
AU - Burslem, George M.
AU - Procko, Erik
AU - Sgourakis, Nikolaos G.
N1 - Funding Information:
This study was supported by a research fund of the “Jung Foundation for Science and Research”. Open Access funding enabled and organized by Projekt DEAL.
Funding Information:
This research was supported through grants by the National Institute of Allergy and Infectious Diseases (NIAID) (no. 5R01AI143997) and NIGMS (no. 5R35GM125034) to N.G.S., grant no R35GM142505 to G.M.B. and NIGMS grant no. 3R35GM125034-05S to N.G.S. that funded a cryoprobe-equipped 600 MHz NMR spectrometer at UPenn. We acknowledge K. Natarajan and D. Margulies (NIAID) for helpful discussions, E. Adams (University of Chicago) for providing DNA plasmids for hpMR1, hMR1, hMR1 C262S and bβ2 m as well as the 5-N-RU precursor compound. We thank J.P. Brady (Novartis) for providing the broadband19F CPMG pulse sequence. We further acknowledge J. Cassel (Wistar Institute), A. Majumdar (Johns Hopkins University) and H. Roder/Takuya Mizukami (Fox Chase Cancer Center) for assistance with instrumentation and scheduling.
Publisher Copyright:
© 2022, The Author(s), under exclusive licence to Springer Nature America, Inc.
PY - 2022/8
Y1 - 2022/8
N2 - Chaperones tapasin and transporter associated with antigen processing (TAP)-binding protein related (TAPBPR) associate with the major histocompatibility complex (MHC)-related protein 1 (MR1) to promote trafficking and cell surface expression. However, the binding mechanism and ligand dependency of MR1/chaperone interactions remain incompletely characterized. Here in vitro, biochemical and computational studies reveal that, unlike MHC-I, TAPBPR recognizes MR1 in a ligand-independent manner owing to the absence of major structural changes in the MR1 α2-1 helix between empty and ligand-loaded molecules. Structural characterization using paramagnetic nuclear magnetic resonance experiments combined with restrained molecular dynamics simulations reveals that TAPBPR engages conserved surfaces on MR1 to induce similar adaptations to those seen in MHC-I/TAPBPR co-crystal structures. Finally, nuclear magnetic resonance relaxation dispersion experiments using 19F-labeled diclofenac show that TAPBPR can affect the exchange kinetics of noncovalent metabolites with the MR1 groove, serving as a catalyst. Our results support a role of chaperones in stabilizing nascent MR1 molecules to enable loading of endogenous or exogenous cargo. [Figure not available: see fulltext.]
AB - Chaperones tapasin and transporter associated with antigen processing (TAP)-binding protein related (TAPBPR) associate with the major histocompatibility complex (MHC)-related protein 1 (MR1) to promote trafficking and cell surface expression. However, the binding mechanism and ligand dependency of MR1/chaperone interactions remain incompletely characterized. Here in vitro, biochemical and computational studies reveal that, unlike MHC-I, TAPBPR recognizes MR1 in a ligand-independent manner owing to the absence of major structural changes in the MR1 α2-1 helix between empty and ligand-loaded molecules. Structural characterization using paramagnetic nuclear magnetic resonance experiments combined with restrained molecular dynamics simulations reveals that TAPBPR engages conserved surfaces on MR1 to induce similar adaptations to those seen in MHC-I/TAPBPR co-crystal structures. Finally, nuclear magnetic resonance relaxation dispersion experiments using 19F-labeled diclofenac show that TAPBPR can affect the exchange kinetics of noncovalent metabolites with the MR1 groove, serving as a catalyst. Our results support a role of chaperones in stabilizing nascent MR1 molecules to enable loading of endogenous or exogenous cargo. [Figure not available: see fulltext.]
UR - http://www.scopus.com/inward/record.url?scp=85132550970&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85132550970&partnerID=8YFLogxK
U2 - 10.1038/s41589-022-01049-9
DO - 10.1038/s41589-022-01049-9
M3 - Article
C2 - 35725941
AN - SCOPUS:85132550970
SN - 1552-4450
VL - 18
SP - 859
EP - 868
JO - Nature chemical biology
JF - Nature chemical biology
IS - 8
ER -