| Type: | Family | Name: | DNA-directed RNA polymerase subunit F (Rpo4) |
| Description: | DNA-directed RNA polymerases,also known as DNA-dependent RNA polymerases, are responsible for the polymerisation of ribonucleotides into a sequence complementary to the template DNA. Eukaryotes have three different DNA-directed RNA polymerases (RNAPs), Pol I, II, and III, whereas Archaea and Bacteria have single enzymes.RNAPs are multisubunit enzymes. Archaeal RNAP is closely related to eukaryotic RNAP II [], which consists of 12 subunits. Archaeal RNAP has an additional subunit, Rpo13, with no orthologue in the eukaryotic enzyme []. Eukaryotic RNA polymerase II (RNAPII) is composed of a ten-subunit core and an Rpb4-Rpb7 heterodimer that reversibly associates with the core []. The heterodimer both binds RNA and serves to stabilise the transcription complex. The Rpb4 and Rpb7 homologues in Archaea are known as subunits F and E, and have been more recently renamed as Rpo4 and Rpo7, respectively []. While the Rpb7 homologue is reasonably well conserved, the similarity between the eukaryotic Rpb4 and the archaeal F subunit is barely detectable at the primary sequence level [, ]. Like their eukaryotic counterparts, the archaeal E and F subunits have been shown to form a stable heterodimer []. Structural studies of the Methanocaldococcus jannaschii(Methanococcus jannaschii) E-F heterodimer indicate that subunit E likely mediates binding to the nascent RNA transcript, while the F subunit serves to stabilise the conformation of the E subunit [].This family represents the archaeal subunit F (Rpo4). | Short Name: | RNAP_F |
