Direct assay for sigma factor activity and demonstration of the loss of this activity during sporulation in Bacillus subtilis.

Abstract

Summary. The change in template specificity of RNA polymerase, which in Bacillus subtilis takes place during the two hours following cessation of exponential growth (to--t2), has been confirmed with enzyme extracted in the presence of several protease inhibitors. With these enzyme preparations no alteration of the fl subunits could be detected. It is concluded that such an alteration cannot account for the loss by the enzyme of the ability to transcribe phage ~e DNA. An assay specific for vegetative sigma factor activity is described. When applied to crude extracts prepared in the presence of protease inhibitors, it was possible to demonstrate directly a loss in this activity, occurring between t o and t 2. This loss seems to account for the change in RNA polymerase template specificity which takes place during the same time period.