FIG. 1.

Sequences of the polh and p10 promoter regions within reporter plasmids. Plasmids phcwt and p10hcBC contain the cat gene driven by wt polh (A) and p10 (B) promoter sequences, respectively. Sequences modified by linker scan mutations are indicated by single underlining, and the mutant sequences and names of the corresponding reporter plasmids are shown below the mutated sequences. TAAG sequences are boxed. Restriction sites are doubly underlined. The numbering above the sequences is relative to the original translational initiation sites of the polh and p10 genes. In both cases, the ATG has been modified to a BglII site so that only the A (+1) remains. The translation initiation codon of the cat gene is marked by asterisks. Thick arrows indicate the positions of primers used to generate probes by PCR for DNase I footprint assays. The radioactively labeled 5′ end of the CAT3 primer is indicated by a star.