FIG 4.
Regulation of the LMD gene cluster. (A) Organization of the LMD gene cluster. Arrows indicate the direction of transcription of genes. There are only two putative promoters located between gene osaR and PA0057, which have a cross in the −35 box. (B) Cotranscription of osaR and PA0055 determined by RT-PCR. Lanes 1 and 2, PA0055 (181 bp) and osaR (122 bp) cDNA as the template, respectively; lanes 3 and 4, no-reverse transcriptase controls with PA0055 and osaR primers, respectively; lanes 5 and 6, genome template as a positive control. (C) Cotranscription of PA0057 and dsbM by RT-PCR. Lanes 1 and 2, PA0057 (176 bp) and dsbM (110 bp) cDNA as the template, respectively; lanes 3 and 4, no-reverse transcriptase controls with PA0057 and dsbM primers, respectively; lanes 5 and 6, genome template as a positive control. Lane M, 2-kb DNA ladder (from the bottom up, 100 bp, 250 bp, 500 bp, 750 bp, 1,000 bp, and 2,000 bp). The transcriptional activity of PA0055 and osaR was assessed. (D and E) Effects of ΔosaR (D) and osaR overexpression and PA0055 overexpression (E) on LMD gene cluster transcription. (F and G) β-Galactosidase activity assay of the PosaR-lacZ (F) and PPA0057-lacZ (G) transcriptional fusion in the overexpression of PA0055 or osaR strains. 55OE indicates the PA0055 overexpression strain. All data were obtained from at least three independent experiments with three replicates. Error bars indicate SDs. **, P < 0.01; *, P < 0.05 by Student's t test.