Changes in the association between Bacillus subtilis RNA polymerase core and two specificity-determining subunits during transcription.

The Bacillus subtilis RNA polymerase sigma subunit and the phage SPO1-coded gene 28 protein are responsible for selective binding of RNA polymerase to early and middle SPO1 promoters, respectively. The association of the RNA polymerase core with each of these subunits weakens during the elongation of RNA chains. Similar changes are known to be an essential part of the Escherichia coli RNA polymerase sigma cycle.