Delta factor can displace sigma factor from Bacillus subtilis RNA polymerase holoenzyme and regulate its initiation activity.
A protein with a molecular weight of 21,000 daltons is found associated with a fraction of Bacillus subtilis RNA polymerase core. This protein (delta) does not react with antibody made against sigma factor and has a peptide map which is significantly different from sigma factor. At ratios of 2:1 to 4:1 (delta:holoenzyme) the delta displaces sigma factor completely from the core and associates in a 1:1 ratio with core to form delta-core. Under the same incubation conditions sigma factor at a ratio of 10:1 (sigma factor:delta-core) does not displace delta from the delta-core. The delta-core has much less activity as compared to holoenzyme on various DNA templates. However, sigma factor does stimulate the activity of delta-core enzyme under conditions of RNA synthesis. These observations and the results of others suggest that delta-core enzyme binds initially to specific DNA sites followed by delta release from the core-DNA complex and that the sigma factor binds to the core-DNA complex to initiate RNA synthesis. Thus both delta and sigma factors are required in a sequential fashion for specific transcription to occur in B subtilis.
D001412:Bacillus subtilis / Q000201:enzymology / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D012321:DNA-Directed RNA Polymerases / Q000235:genetics*; D004789:Enzyme Activation; D004792:Enzyme Precursors / Q000235:genetics; D010442:Peptide Chain Initiation, Translational; D012808:Sigma Factor / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004792:Enzyme Precursors; D012808:Sigma Factor; D014157:Transcription Factors; D012321:DNA-Directed RNA Polymerases