Ribosomal RNA synthesis in vitro: a protein-DNA complex from Bacillus subtilis active in initiation of transcription.

A protein-DNA transcription complex, isolated from logarithmic-phase cells of Bacillus subtilis, is active in the initiation of new rounds of RNA synthesis in vitro. Transcription directed by the endogenous DNA of the complex is sensitive to inhibitors of initiation. In addition, the effect of addition of a competing template indicates that RNA polymerase in the complex is bound to endogenous DNA in a dissociable, preinitiation state. Hybridization-competition analysis of the RNA product obtained from the in vitro reaction indicates that it is greatly enriched for ribosomal RNA sequences. This initiating complex should be useful for the study of regulation of expression of ribosomal RNA genes.