Participates in both the initiation and recycling phases of transcription. In the presence of the delta subunit, RNAP displays an increased specificity of transcription, a decreased affinity for nucleic acids, and an increased efficiency of RNA synthesis because of enhanced recycling (By similarity). RNAP is composed of a core of 2 alpha, a beta and a beta' subunits. The core is associated with a delta subunit and one of several sigma factors (By similarity). Belongs to the RpoE family.