SARS_CoV-2 substrate profiling in interferon-treated BEAS-2B cell proteomes

To profile the human substrate degradome of the SARS-CoV-2 main viral protease and to investigate whether 3CLpro cleavage of cellular substrates dampens host antiviral responses induced by type I interferons, we treated BEAS-2B cells with interferon-alpha (N = 3), interferon-beta (N = 3), or vehicle (N = 3), retrieve and exposed native proteome extracts from human embryonic kidney to 3CLpro cleavage. Then, N Terminal Amine Labeling of Substates (TAILS) was used to identify the substrates. Here, heavy [+34] isotope dimethyl labeling is performed at the whole protein level in the 3CLpro-exposed samples, and the P1' side of substrates substrates was revealed by comparing to the samples exposed to inactive mutant labeled with ligh [+28 Da] dimethyl.