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. 2011 Jul 14;7(7):e1002135. doi: 10.1371/journal.ppat.1002135

Figure 5. Removal or single point mutations of the CTP affect the folding of aerolysin in vivo.

Figure 5

A: WT and H132N aerolysin, with and without the CTP, were expressed in the periplasm of E. coli upon induction with IPTG. Cell extracts were analyzed by SDS-PAGE and Coomassie blue staining before and after induction, as were the periplasmic (perip.) and the remaining spheroplast (sphero.) fractions. B: WT toxin, with and without the CTP, was expressed in the periplasm of E. coli upon induction with IPTG. Cell extracts, periplasmic and spheroplast fractions were analyzed by western blotting against aerolysin, revealing the signal peptidase dependent processing of signal peptide harboring precursors. C: WT and mutant proaerolysin were expressed in the periplasm of E. coli. Bacterial extracts and periplasmic fractions were analyzed by SDS-PAGE and Coomassie blue staining as in A. D: The amount of toxin present in cell extracts after IPTG induction as well as in the periplasmic fraction were quantified for 3 independent experiments using ImageJ (n = 3). Error bars represent standard deviations. Periplasmic toxin was normalized to the amount of toxin in the cell extracts. **: p<0.005.