Download MendeleyStructure and Dynamics of PD-L1 and an Ultra-High-Affinity PD-1 Receptor Mutant.
Pascolutti, R., Sun, X., Kao, J., Maute, R.L., Ring, A.M., Bowman, G.R., Kruse, A.C.(2016) Structure 24: 1719-1728
- PubMed: 27618663
- DOI: https://doi.org/10.1016/j.str.2016.06.026
- Primary Citation of Related Structures:
5IUS - PubMed Abstract:
The immune checkpoint receptor PD-1 and its ligand, PD-L1, have emerged as key regulators of anti-tumor immunity in humans. Recently, we reported an ultra-high-affinity PD-1 mutant, termed high-affinity consensus (HAC) PD-1, which shows superior therapeutic efficacy in mice compared with antibodies. However, the molecular details underlying the action of this agent remain incompletely understood, and a molecular view of PD-1/PD-L1 interactions in general is only beginning to emerge. Here, we report the structure of HAC PD-1 in complex with PD-L1, showing that it binds PD-L1 using a unique set of polar interactions. Biophysical studies and long-timescale molecular dynamics experiments reveal the mechanisms by which ten point mutations confer a 35,000-fold enhancement in binding affinity, and offer atomic-scale views of the role of conformational dynamics in PD-1/PD-L1 interactions. Finally, we show that the HAC PD-1 exhibits pH-dependent affinity, with pseudo-irreversible binding in a low pH setting akin to the tumor microenvironment.
Organizational Affiliation:
Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.
