FIG 4.
The region upstream of tosR exhibits transcriptional activity. (A) Within a representation of the tos operon, sequences harboring possible sites for tos promoters are denoted PR, PC, and PA. (B) A black arrowhead indicates the position where the PR, PC, and PA sequences were inserted into the BamHI and EcoRI sites upstream of lacZ in pRS551 to produce the indicated transcriptional fusions. The empty construct was native pRS551 plasmid. (C) The activity of each transcriptional fusion was assayed by the Miller assay. The transcriptional activity, determined indirectly through measurement of β-galactosidase activity (in Miller units), associated with the PR construct is significantly higher than that associated with the PC and PA constructs (P < 0.0001). Black and gray bars indicate the average values of Miller units for each construct (n = 6). Significance was determined by using Tukey's multiple-comparisons test following ANOVA (P < 0.0001). Error bars indicate the SD about the mean.