Autoprocessing mutants induce necrosis in epithelial cells.

<p><i>A</i>, Toxins were applied to HeLa cells at concentrations ranging from 0.1 pM to 100 nM, and viability was measured after 2.5 hours with CellTiterGlo. <i>B</i>, Toxins were applied to Caco2 cells at concentrations ranging from 0.1 pM to 100 nM, and viability was measured after 18 hours with CellTiterGlo. Percent viability was determined by normalizing the signal from treated cells to the signal from untreated cells. <i>C</i>, Autoprocessing mutants did not induce caspase-3/7 activation after 25 hours. <i>D</i>, Comparable levels of extracellular LDH were detected after 8 hours in HeLa cells treated with wild-type TcdB and TcdB autoprocessing mutants. In each panel, the values represent the average of three experiments in which three replicates were averaged. Error bars indicate the standard deviation between the values obtained from the three experiments.