FIG. 2.

The activity of the rExoU cofactor is susceptible to heat and protease treatment. (A) Yeast extract (10 μg) was incubated at 30 or 56°C for 30 min or boiled for 5 min, followed by the addition of 1 μg of rExoU and radiolabeled liposomes. (B) Twenty micrograms of yeast extract was digested with chymotrypsin at 30°C for 15 min. After the proteolysis reaction was stopped by the addition of protease inhibitors, the treated extract was added to 1 μg of rExoU and substrate liposomes.