FIG. 4.

Protein translocation activity of selected espB mutants. (A) cAMP levels in HeLa cells infected with espB mutant strain UMD864 transformed with pBPM37 expressing an EspF-adenylate cyclase fusion protein and with control plasmids or plasmids containing selected mutant espB alleles. (B) cAMP levels in HeLa cells similarly transformed with pTir232-Cya expressing a Tir-adenylate cyclase fusion protein and control and espB plasmids. Black columns represent FAS-negative strains, white columns represent FAS-positive strains, and gray columns represent a mutant with an intermediate FAS phenotype. Data are the means of results from five independent experiments performed in triplicate. Error bars show standard errors of the means.