Nucleotide-dependent inactivation of RNA polymerase from Bacillus brevis.

RNA polymerase has been purified from vegetative cells of Bacillus brevis and resolved into "core" enzyme and sigma factor. The purified enzyme is rapidly inactivated by incubation at low temperatures in the presence of 1-2 mM ATP, dATP, or NAD(+), while other nucleotides at this concentration have little or no effect. Inactivation is not accompanied by the incorporation of an adenylyl or phosphoryl moiety into RNA polymerase; nevertheless, it is essentially irreversible. DNA, high concentrations of glycerol, as well as low concentrations (1 mM) of orthophosphate protect RNA polymerase from the nucleotide-dependent inactivation.A similar inactivation of RNA polymerase in the presence of ATP is observed with crude preparations from Bacillus subtilis and Bacillus polymyxa. This phenomenon may represent a novel mode of regulation of transcription that does not involve a covalent modification of RNA polymerase or its interaction with other protein factors, but rather is due to a structural transition to an inactive form induced by small molecules.