FIG. 1.
Regulation of stpA-lacZ fusions by H-NS and StpA. The expression level directed by stpA-lacZ fusions integrated into the chromosome was determined for the wild type (a) and for stpA::tet (b), hns::kan (c), hns::kan stpA::tet (d), hns::amp (e), hns::amp stpA::tet (f), and Δhns-kanKD4 (g) mutants (see legend in figure). The positions of the stpA fragments are given relative to the transcription start (16, 37). The lacZ gene carries its native ribosome binding site, and the lacUV5 promoter, which lacks lacO, encompasses positions −40 to +1 relative to the transcription start. stpAorf indicates that the stpA mRNA cannot be translated due to a mutation of the ATG start codon of stpA to ATA. β-Galactosidase activities were determined for cultures grown in LB to an OD600 of 0.5.