FIG. 2.

Strain NU14 induces FimH-dependent caspase 3 activity. (A) TEU-1 cells were infected with strain NU14, with the ΔfimH mutant NU14-1, or with NU14 in the presence of 25 mM methyl α-d-mannopyranoside (Mann). All infections were performed at an initial MOI of 250, and urothelial caspase 3 enzymatic activity levels were then determined for cell extracts by cleavage of the fluorogenic substrate Ac-DEVD-AFC and compared with the activity level for extracts of untreated cultures (−). (B) The caspase 3 activity level was also determined in a similar experiment using cultures of SR22A bladder urothelial cells. Caspase 3 activity was induced in both TEU-1 and SR22A cultures by strain NU14 but was blocked by the competitive inhibitor methyl α-d-mannopyranoside or a mutation in the gene encoding FimH. Error represents the standard deviation for triplicate infections.