Quantitation the lysine 2-hydroxyisobutyrylation of H-NS in TmcA KO and YiaC KO E. coli strains using PRM. PRM was performed on an Orbitrap Q Exactive Plus mass spectrometer with an EASY-Spray source coupled to a Nano-LC system (EASY-nLC 1000, Thermo Fisher Scientific, Waltham, MA).