Figure 6.

In vivo genomic reactivity of the fixRnifA promoter region to potassium permanganate. Anaerobic cultures were incubated with rifampicin for 10 min and exposed to KMnO₄ for another 10 min, and the total DNA was purified. The first lanes of each panel show the primer extension products of DNA samples from strain 8085 that were not treated with rifampicin. (A) Effect of promoter mutations in open complex formation. Strains 8085 and 2068 showed hyperreactivity to KMnO₄ of position −3, whereas in strain 2035 the hyperreactivity moved to position −5. The triple mutant strain 2030, for which no fixR-lacZ expression was detected (Table 1), did not show any hyperreactivity to KMnO₄. (B) Comparison of KMnO reactivity of strains 8085, N8085, and 8091. Lanes C, T, A, and G are a sequence ladder obtained with the same oligonucleotide used for the primer extension.