Taxonomic distribution of proteins containing RPOLA_N domains

The tree below includes only several representative species and genera. The complete taxonomic breakdown of all proteins containing RPOLA_N domains can be accessed here. Click the counts or percentage values to display the corresponding proteins.

Structural modules of the large subunits of RNA polymerase. Introducing archaebacterial and chloroplast split sites in the beta and beta' subunits of Escherichia coli RNA polymerase.

Severinov K, Mustaev A, Kukarin A, Muzzin O, Bass I, Darst SA, Goldfarb A
J Biol Chem. 1996; 271: 27969-74

The beta and beta' subunits of Escherichia coli DNA-dependent RNA polymerase are highly conserved throughout eubacterial and eukaryotic kingdoms. However, in some archaebacteria and chloroplasts, the corresponding sequences are "split" into smaller polypeptides that are encoded by separate genes. To test if such split sites can be accommodated into E. coli RNA polymerase, subunit fragments encoded by the segments of E. coli rpoB and rpoC genes corresponding to archaebacterial and chloroplast split subunits were individually overexpressed. The purified fragments, when mixed in vitro with complementing intact RNA polymerase subunits, yielded an active enzyme capable of catalyzing the phosphodiester bond formation. Thus, the large subunits of eubacteria and eukaryotes are composed of independent structural modules corresponding to the smaller subunits of archaebacteria and chloroplasts.