Expression of GtxA in E. coli. Western blot on whole cell lysate (WC) and extracellular protein (EC) from E. coli ER2566/pLG575 after induction with IPTG. Proteins were separated by SDS-PAGE in a 4–12% gel and blotted on a PVDF-membrane. The blot was probed with ApxI-antiserum. B = blank, -T1SS indicates the absence of plasmid pLG575. Size markers are indicated on the right (PageRuler Prestained Protein Ladder Plus, Fermentas, Burlington, Canada). The upper band in each lane has the expected size of full-length GtxA (215 kDa) or the RTX-domain (117 kDa). The smaller sized bands are likely degradation products.