Protein Footprinting and X-ray Crystallography Reveal the Interaction of PD-L1 and a Macrocyclic Peptide

作者：Ben Niu, T.C. Appleby, Ruth Wang, Mariya Morar, Johannes Voight, Armando G. Villaseñor, Sheila Clancy, Sarah Wise, Jean-Philippe Belzile, Giuseppe A. Papalia, Melanie Wong, Katherine M. Brendza, Latesh Lad, Michael L. Gross · 发表于：Biochemistry · 年份：2019 · DOI：10.1021/acs.biochem.9b00822 · 被引用次数：35 · 研究领域：Monoclonal and Polyclonal Antibodies Research、Cancer Immunotherapy and Biomarkers、Mass Spectrometry Techniques and Applications

Blocking interactions between PD-1 and PD-L1 opens a new era of cancer treatment involving immunity modulation. Although most immunotherapies use monoclonal antibodies, small-molecule inhibitors offer advantages. To facilitate development of small-molecule therapeutics, we implemented a rapid approach to characterize the binding interfaces of small-molecule inhibitors with PD-L1. We determined its interaction with a synthetic macrocyclic peptide by using two mass spectrometry-based approaches, hydrogen-deuterium exchange and fast photochemical oxidation of proteins (FPOP), and corroborated the findings with our X-ray structure of the PD-L1/macrocycle complex. Although all three approaches show that the macrocycle binds directly to PD-L1 over the regions of residues 46-87 and 114-125, the two protein footprinting approaches show additional binding at the N-terminus of PD-L1, and FPOP reveals some critical binding residues. The outcomes not only show the binding regions but also demonstrate the utility of MS-based footprinting in probing protein/ligand inhibitory interactions in cancer immunotherapy.