Fig. 3. Identification of CopZ in B. pertussis.

a Lysates of wild type B. pertussis (wt) or the deletion mutant (∆bp1727) grown in SS medium supplemented (+ Cu) or not with 2 mM CuSO₄ were subjected to SDS-PAGE electrophoresis in Tris-tricine gels for the detection of CopZ. The gel was stained with colloidal Coomassie blue dye. CopZ migrates below the 10 kDa band of the markers. b, c The protein band was cut from the gel, and CopZ was identified by mass fingerprinting analyses. The m/z ratios of the peptides identified by MALDI-TOF are shown in panel b, and the sequences of the peptides are in c. This experiment complements the proteomic analyses, because the small size of CopZ hampered its detection in global proteomic approaches (see Fig. 2b and Supplementary Data S4).