Diwen Yang, Xiaoyun Wang, Jiabao Liu, Yufeng Gong, Pranav Nair, Jianxian Sun, Xing Qian, Jingyuan Cui, Hong Zeng, Aiping Dong, Rachel Harding, N. Burgess-Brown, Tyler S. Beyett, Datong Song, Henry M. Krause, Miriam L. Diamond, Derek L. Bolhuis, Nicholas G. Brown, C.H. Arrowsmith, A.M. Edwards, Levon Halabelian, Hui Peng
Chemical pollution is a global threat to human health, yet the toxicity mechanism of most contaminants remains unknown. Here, we applied an ultrahigh-throughput affinity-selection mass spectrometry (AS-MS) platform to systematically identify protein targets of prioritized chemical contaminants. After benchmarking the platform, we screened 50 human proteins against 481 prioritized chemicals, including 446 ToxCast chemicals and 35 per- and polyfluoroalkyl substances (PFAS). Among 24,050 interactions assessed, we discovered 35 novel interactions involving 14 proteins, with fatty acid-binding proteins (FABPs) emerging as the most ligandable protein family. Given this, we selected FABPs for further validation, which revealed a distinct PFAS binding pattern: legacy PFAS selectively bound to FABP1, whereas replacement compounds, PFECAs, unexpectedly interacted with all FABPs. X-ray crystallography further revealed that the ether group enhances molecular flexibility of alternative PFAS, to accommodate the binding pockets of FABPs. Our findings demonstrate that AS-MS is a robust platform for the discovery of novel protein targets beyond the scope of the ToxCast program and highlight the broader protein-binding spectrum of alternative PFAS as potential regrettable substitutes.