Deletion analysis of the gyrB promoter region. PCR-produced gyrB deletions were fused to a promoter-less lacZ gene in the placZ/290 vector. Transcriptional activity, measured by β-galactosidase production, is shown as a percent of wild-type (pJEZ1.1) activity (3,968 units). For each construct, the percentage is based on a mean value calculated from β-galactosidase activities of three or more different mid-log phase cultures. The base pair positions relative to the start of transcription are marked below each fusion. White boxes indicate the promoter-less lacZ gene and gray boxes represent the gyrB coding sequence.