Template-independent poly(A) · poly(U) synthesizing activity of different forms of Bacillus subtilis RNA polymerase

Abstract

Several, but not all, forms of Bacillus subtilis RNA polymerase found in vegetative and sporulating cells can synthesize poly(A) · poly(U) in vitro. The vegetative delta-containing form of RNA polymerase (Eδ) has little or no poly(A) · poly(U)-synthesizing activity, whereas RNA polymerase core (E) and sigma-containing core (Eσ) both have significant activity. When purified vegetative delta factor was added to core, the core synthetic activity was reduced essentially to that of the vegetative enzyme Eδ. When Eσ enzymes from vegetative and sporulating cells were compared for their salt sensitivity, it was found that the sporulation enzyme Eσ retained much more of its activity at 0.1 M KCl than the vegetative enzyme Eσ. Furthermore, when sporulation enzyme Eδ 1 was compared with vegetative enzyme Eσ, it was found that the activity of the Eδ 1 form was much more resistant to high KCl concentrations than that of the vegetative Eσ form. These differences in enzyme activity, as affected by salt concentrations, suggest that the conformations of the sporulation Eσ and Eδ 1 enzymes are different from that found in vegetative Eσ enzyme. These differences in conformation may be involved in selective gene expression during sporularion.