rpoZ

rpoZ is the gene that encodes the omega subunit (RpoZ) of bacterial RNA polymerase. The omega subunit is a small, acidic protein that is part of the RNA polymerase core enzyme, which also includes two alpha subunits, a beta subunit, and a beta' subunit. In Escherichia coli, rpoZ encodes a protein of about 91 amino acids.

The omega subunit is thought to participate in the assembly and stabilization of the RNAP core, particularly by interacting with the beta' subunit. This interaction helps ensure proper folding and assembly of the enzyme and can influence the formation of the holoenzyme with sigma factors. The precise role of RpoZ can vary among bacteria, and its contribution to transcription initiation or promoter selectivity may be more pronounced under certain growth conditions or stresses.

Distribution and evolution of rpoZ are widespread among bacteria that possess a conventional RNAP core. The gene is not universal; some lineages have lost rpoZ or possess divergent homologs. Archaea and eukaryotes do not have a direct omega subunit like bacterial RNAP, reflecting differences in RNA polymerase architecture across domains of life.

Genetic and phenotypic effects of rpoZ perturbation are typically modest under standard laboratory conditions. Deletion or reduction of rpoZ often results in slower growth and altered global transcription, with more pronounced effects under stress or elevated temperatures in some species. Overall, rpoZ is considered non-essential in many bacteria but contributes to the efficiency and stability of RNA polymerase function under various environmental conditions.