Purification and Properties of the Sigma Subunit of Ribonucleic Acid Polymerase from Vegetative Bacillus subtilis

The sigma subunit of DNA-dependent RNA polymerase from vegetative Bacillus subfilis has been purified to at least 90% purity.Purified sigma binds to core RNA polymerase and stimulates in vifro transcription of phage Be DNA by core RNA polymerase in the presence of up to 0.2 M KCI.Sigma also stimulates RNA synthesis to different extents with phage T4 DNA and poly(dA-dT) as templates, but this stimulation is markedly sensitive to increasing ionic strength.At 0.2 M KC1 sigma subunit fails to stimulate transcription of T4 DNA and actually inhibits the synthesis of RNA with poly(dA-dT) as template.