FIG. 4.

The sigF ORF is transcribed as part of a tricistronic operon. (A) Arrangement of the sigF locus in SM101, based on sequencing results (22). The locations of the primers used in panel B for overlap PCR are indicated by R1 to R5. (B) Overlap PCR analysis of the sigF locus region in five reactions (R1 to R5). The results of a DNA PCR (top) and an RNA RT-PCR (bottom) using reaction R1 to R5 primers (Table 1) are shown. Size markers are shown on the right. (C) Northern blot analysis using a DIG-labeled sigF probe. Results for wild-type, SM101::sigF, and SM101sigFcomp strains are shown. Size markers are shown on the left.