The σ(E) subunit of Bacillus subtilis RNA polymerase is present in both forespore and mother cell compartments

Bacillus subtilis cells harvested 3.5 h after the onset of sporulation (t_3.5) were fractionated into extracts enriched in either mother cell or forespore components and were analyzed immunologically for σ(E) and its precursor protein, P₃₁. We determined by Western blot (immunoblot) analysis that equivalent amounts of P³¹ and σ(E) were present in both mother cell and forespore extracts. This result implies that, although σ(E) is not synthesized until a stage in development when the cell is partitioned into progenitor forespore and mother cell compartments, it probably directs the transcription of genes that are expressed in both of these structures.