Open AccessProbing the Ligand-Binding Pocket of BTN3A1
Author(s) -
M. Poe,
Sherry S Agabiti,
Caroline Liu,
Victoria Li,
Kelly A. Teske,
ChiaHung Christine Hsiao,
Andrew J. Wiemer
Publication year - 2019
Publication title -
journal of medicinal chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.01
H-Index - 261
eISSN - 1520-4804
pISSN - 0022-2623
DOI - 10.1021/acs.jmedchem.9b00825
Subject(s) - chemistry , docking (animal) , antigenicity , ligand (biochemistry) , binding site , ligand binding assay , homology modeling , stereochemistry , plasma protein binding , receptor , biochemistry , biophysics , antigen , enzyme , biology , genetics , medicine , nursing
Small-molecule phosphoantigens such as ( E )-4-hydroxy-3-methyl-but-2-enyl diphosphate stimulate human Vγ9Vδ2 T cells after binding to the intracellular B30.2 domain of the immune receptor butyrophilin 3 isoform A1 (BTN3A1). To understand the ligand-target interaction in greater detail, we performed molecular docking. Based on the docking results, we synthesized the novel ligand ( E )-(7-hydroxy-6-methylhept-5-en-1-yl)phosphonate and mutated proposed binding site residues. We evaluated the impact on butyrophilin binding of existing and novel ligands using a newly developed high-throughput fluorescence polarization assay. We also evaluated the ability of the compounds to stimulate proliferation and interferon-γ production of Vγ9Vδ2 T cells. Mutation of H381 fully blocked ligand binding, whereas mutations to charged surface residues impacted diphosphate interactions. Monophosphonate analogs bind similarly to BTN3A1, although they differ in their antigenicity, demonstrating that binding and efficacy are not linearly correlated. These results further define the structure-activity relationships underlying BTN3A1 ligand binding and antigenicity and support further structure-guided drug design.