DNA strand specificity of transcripts produced in vivo and in vitro by RNA polymerase from SP82-infected Bacillus subtilis.

Phage-specific RNA synthesized early in the infection of Bacillus subtilis with SP82 hybridizes to both heavy (H) and light (L) strands of SP82 DNA nearly equally. Phage RNA synthesized during the middle of the infection hybridizes preferentially to the H strand. The ratio of H/L strand binding of RNAs synthesized in vitro by RNA polymerases isolated from uninfected and infected cells resembles the ratios of early and middle phage RNA classes, respectively. This supports the conclusion that a modified RNA polymerase is required for the transcription of middle RNA classes.