RNA polymerase from Clostridium acidi-urici. Characterization of a naturally occurring rifampicin-resistant bacterial enzyme.

We report here the isolation of a prokaryotic RNA polymerase that shows pronounced template specificity. The enzyme from Clostridium acidi-urici is highly active on DNA templates isolated from phage that infect Gram-positive organisms and is essentially inactive at either high or low ionic strength on DNA from phage associated with Gram-negative bacteria. The enzyme is also unique among RNA polymerases isolated from wild type bacteria in being highly resistant to inhibition by rifampicin. These properties are characteristic of the enzyme present in several independently isolated strains of C. acidi-urici. However, RNA polymerase present in other clostridial species resembles the enzyme present in Bacillus subtilis in sensitivity to rifampicin and template specificity.