rpoC

rpoC is the gene that encodes the beta' subunit of bacterial RNA polymerase. In bacteria, RNA polymerase responsible for transcription consists of the core enzyme formed by the beta' (RpoC) and beta (RpoB) subunits, together with the alpha (RpoA) and omega (RpoZ) subunits, and the holoenzyme complex associates with sigma factors to initiate transcription at promoter sequences. The beta' subunit contributes to DNA binding and to the catalytic process in concert with the beta subunit; it plays a central role in promoter recognition, initiation, elongation, and overall processivity of transcription. The rpoC gene is essential in most bacterial species, and many organisms cannot survive without a functional rpoC product.

The rpoC gene is highly conserved across bacteria, with orthologs found in diverse lineages. Its protein product is large and modular, and crystal structures of bacterial RNA polymerase highlight domains in RpoC responsible for core enzyme assembly and interaction with DNA and other subunits. Because of its essential and conserved nature, rpoC is sometimes used as a molecular marker in comparative genomics and phylogenetic studies.

Mutations in rpoC can alter transcriptional properties and have been observed in experiments on adaptive evolution and antibiotic resistance. Such mutations may change promoter selectivity, transcription rates, or coupling with other subunits, and in some cases occur in combination with rpoB mutations under selection pressure by antibiotics such as rifamycins or under environmental stresses. See also rpoA, rpoB, rpoZ, and RNA polymerase (bacterial).