Information Processing by RNA Polymerase: Recognition of Regulatory Signals during RNA Chain Elongation

The primary function of RNA polymerase (RNAP) is to produce RNA transcripts optimal for a given environmental or developmental state of a cell. RNAP accomplishes this selection by deciding whether or not to initiate transcription of a gene and then both how fast and how far to elongate the RNA chains. Because each decision depends on information input to RNAP and can produce results that influence subsequent decisions, RNAP’s function in the cell in many ways resembles an information processor. In this short review, we will (i) briefly summarize the transcription cycle from the perspective of RNAP as a cellular information processor, (ii) describe the structure of the transcription elongation complex (TEC) and the protein-nucleic acid contacts that function as intrinsic inputs to its regulatory decisions, and (iii) present a model of pausing and ρ-independent termination as an example of information processing by RNAP.