Figure 6
Expression of the various sacB-lacZ fusions. A. The 5' and 3' endpoints of sacB-lacZ are indicated. The open rectangles on the line indicate the DegU-binding motifs. The mutant fusions tested included the del series of fusions, in which increasingly large deletions were made from the 5' end, and the M series, in which point mutations (replaced nucleotides are shown in B. M3 is the mutation where one T residue is deleted.) were introduced (indicated by the filled circles on the line). All fusions were constructed by cloning various PCR products into pIS284. Consequently, all strains are derivatives of OAM371 (amyE::sacB-lacZ). The oligonucleotides used to construct the pIS284 derivatives are shown in Additional file 1. The β-galactosidase activities of sacB-lacZ were measured from cells grown in MC medium containing 1 M NaCl as described previously [45]. The activities were assayed hourly from T0 through to T4. At least three independent assays were performed and the averages of the peak values are shown. Standard deviations did not exceed 15%. The "degU" columns show the β-galactosidase activities of each fusion in the degU::Kmr background.