Bacterial Protein Extraction and Quantification

Protein extraction was carried out as described previously (Böhme et al., 2010a (link), b (link); Carrera et al., 2017 (link)). Briefly, a loop full of each bacterial culture was harvested, and the biomass was mixed with 100 μL of a solution containing 50% acetonitrile (50% ACN) (Merck, Darmstadt, Germany) and 1% aqueous trifluoroacetic acid (1% TFA) (Acros Organics, NJ, United States). After vortexing and centrifugation, the supernatant was treated with a solution of lysis buffer [60 mM Tris-HCl pH 7.5, 1% lauryl maltoside, 5 mM phenylmethanesulfonyl fluoride (5 mM PMSF) and 1% dithiothreitol (1% DTT)]. The supernatants were transferred to a new tube and then quantified using the bicinchoninic acid method (Sigma Chemical Co., United States). All analyses were performed in triplicate.