Expression of the pyrimidine biosynthetic operon (pyr) in B. subtilis is modulated as a function of environmental pyrimidine conditions. Three attenuator regions alter expression of the pyr operon through a transcription attenuation mechanism. pyr repressor protein (PyrR) binding and stabilization of mRNA anti-antiterminator is essential for silencing of pyr expression. Previous RNET-seq data has identified NusG dependent pause sites in the attenuator regions of pyr, indicating potential involvement of NusG in regulation of pyr.