Figure 2.

Structure of the heteroduplex templates. Oligonucleotide primers containing either 8 or 12 nucleotides of template sequence corresponding to the −10 region of the promoter (−7 to −14 or −3 to −14, respectively) were used to mutate the spoIIG promoter sequence as described in Experimental Procedures. Single-stranded DNA of mutant and wild-type promoters were produced by infection of the E. coli clones with helper phage and annealed with the complementary wild-type or mutant strands to produce double-stranded DNA containing the desired region of heteroduplex. The noncomplementary regions of heteroduplex templates used in the subsequent transcription assays are shown. Mismatch bubbles (MB) of 8 or 12 bp were created containing the nontemplate sequence (NT) or the template sequence (T) of the −10 site (boldface) within the noncomplementary region. Not shown is the wild-type template produced by annealing the wild-type (+) and (−) DNA strands.