FIG. 6.

Analyses of BfpE–dual-reporter sandwich fusion proteins. The labels indicate restriction sites in the bfpE gene into which a dual-reporter (′phoA-lacZα) cassette was inserted. (A) Activities of sandwich fusion proteins. The BfpE protein is depicted as in Fig. 4, with the arrows indicating the approximate point at which the dual reporter is inserted into the protein. Alkaline phosphatase or β-galactosidase enzyme assays were performed on cultures of E. coli TG1 carrying sandwich fusion plasmids. The bar graph data represent the mean and standard error values for three separate experiments, with four (alkaline phosphatase) or three (β-galactosidase) enzyme activity determinations per experiment. (B) Expression of sandwich fusion proteins. Whole-cell extracts were prepared from the strains described above and separated by SDS-PAGE on a 6% polyacrylamide gel. The fusion proteins were detected with an anti-PhoA antibody. The first three lanes display samples from strains carrying control plasmids, while the remaining lanes display samples from strains carrying sandwich fusions.