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Figure 4 | BMC Microbiology

Figure 4

From: Role of core promoter sequences in the mechanism of swarmer cell-specific silencing of gyrB transcription in Caulobacter crescentus

Figure 4

Transcription of gyrB promoter mutations designed to conform to the C. crescentus σ73 promoter consensus. (A) The plasmid pJEZP4 contains the template promoter construct used for mutagenesis (see Fig. 3). Shown below is the DNA sequence of the promoter, with the -10 and -35 consensus regions in reverse highlight above. The mutations, shown as boxed sequences with the altered bases in bold-face, were based upon sequence alignment and were aimed at increasing the promoter's conformity with the accepted σ73 consensus sequence. In a separate study, an alternative start site and subsequent alignment located the gyrB promoter further upstream; the mutations designed to take these data into account include an "L" in their names [14]. The transcriptional activity from the mutant promoters, as determined by β-galactosidase measurements of the corresponding lacZ fusions, is presented in the box in the lower right-hand corner as a percentage of wild-type (pJEZ1.1). (B) Temporal expression patterns of the gyrB promoter mutants. Transcription from the gyrB promoter mutants was analyzed during the C. crescentus cell cycle. The results for the mutants exhibiting the strongest quantitative transcription levels (pJEZP6m2 and pJEZP6m3) are shown beneath a schematic of the cell cycle that shows the corresponding developmental stage of the synchronized culture. Samples were labeled every 20 minutes.

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