Expression of the His-tagged mcbC gene product. Killing of strain O35E by (A) wild-type O12E, (B) O12E.mcbC::kan; (C) O12E.mcbC::kan(pWW115); (D) O12E.mcbC::kan(pAA111). (E) Western blot-based detection of His-tagged McbC protein purified from spent culture supernatant fluid from (lane 1) M. catarrhalis O12E.mcbC::kan(pAA111) and (lane 2) M. catarrhalis O12E.mcbC::kan(pWW115) (negative control). A His-tag specific antibody was used as the primary antibody for Western blot analysis. Molecular weight position markers (in kDa) are present on the left side of this panel.